[Association of polycyclic aromatic hydrocarbon exposure and CYP1A1 gene and enzyme activity of peripheral blood monocyte cells in coke oven workers]

Objective: To explore the association between polycyclic aromatic hydrocarbons (PAHs) exposure and cytochrome P450 CYP1A1 expression at gene and enzyme activity levels in the peripheral blood monocyte cells in coke oven workers, and to provide a certain basis for the biological monitoring of health damage in coke oven workers. Methods: We surveyed 118 coke oven workers and 63 controls (energy power workers in the same company) using self-designed questionnaire, determined their post-shift urinary 1-hydroxypyrene (1-OH-Py) concentration using high performance liquid chromatography (HPLC)-fluorescence detector method. We also isolated the peripheral blood mononuclear cell (PBMC) from fasting venous blood, and detected DNA damage using comet assay, CYP1A1 mRNA level using the real-time fluorescent quantitative PCR (FQ-PCR), and EROD activity using spectrophotometry. Statistical analyses including one-way analysis of variance and multiple linear regressions were used to analyze the association of urinary 1-OH-Py and CYP1A1 mRNA level and EROD activity. Results: Compared to the control group, the urinary 1-OH-Py concentration and PBMC DNA tail moment were significantly increased in coke oven workers (P<0.05), and CYP1A1 gene level and EROD activity in PBMC were significantly decreased (P<0.05). Multiple linear regression showed that a ten-fold increase of urinary 1-OH-Pycon centration was associated with a decrease of 0.77 (95%CI: -1.33--0.21) in CYP1A1 gene level, and a decline of 0.15 (95%CI: -0.76--0.16) in EROD activity of PBMC in coke oven workers (P<0.05). Conclusion: Occupational PAHs exposure induced DNA damage, which was associated with the decreased level in CYP1A1 gene cavel and EROD activity in PBMC of coke oven workers.

Defining a Materials Database for the Design of Copper Binary Alloy Catalysts for Electrochemical CO2 Conversion

While Cu electrodes are a versatile material in the electrochemical production of desired hydrocarbon fuels, Cu binary alloy electrodes are recently proposed to further tune reaction directionality and, more importantly, overcome the intrinsic limitation of scaling relations. Despite encouraging empirical demonstrations of various Cu-based metal alloy systems, the underlying principles of their outstanding performance are not fully addressed. In particular, possible phase segregation with concurrent composition changes, which is widely observed in the field of metallurgy, is not at all considered. Moreover, surface-exposed metals can easily form oxide species, which is another pivotal factor that determines overall catalytic properties. Here, the understanding of Cu binary alloy catalysts for CO₂ reduction and recent progress in this field are discussed. From the viewpoint of the thermodynamic stability of the alloy system and elemental mixing, possible microstructures and naturally generated surface oxide species are proposed. These basic principles of material science can help to predict and understand metal alloy structure and, moreover, act as an inspiration for the development of new binary alloy catalysts to further improve CO₂ conversion and, ultimately, achieve a carbon-neutral cycle.

Quantitative Analysis of Calcium Phosphate Nanocluster Growth Using Time-of-Flight Medium-Energy-Ion-Scattering Spectroscopy

One of the remaining challenges in material chemistry is to unveil the quantitative compositional/structural information and thermodynamic nature of inorganic materials especially in the initial nucleation and growth step. In this report, we adopted newly developed time-of-flight medium-energy-ion-scattering (TOF-MEIS) spectroscopy to address this challenge and explored heterogeneously grown nanometer-sized calcium phosphate as a model system. With TOF-MEIS, we discovered the existence of calcium-rich nanoclusters (Ca/P ∼ 3) in the presence of the non-collagenous-protein-mimicking passivating ligands. Over the reaction, these clusters progressively changed their compositional ratio toward that of a bulk phase (Ca/P ∼ 1.67) with a concurrent increase in their size to ∼2 nm. First-principles studies suggested that the calcium-rich nanoclusters can be stabilized through specific interactions between the ligands and clusters, emphasizing the important role of template on guiding the chemical and thermodynamic nature of inorganic materials at the nanoscale.

Synthetic Mechanism Discovery of Monophase Cuprous Oxide for Record High Photoelectrochemical Conversion of CO2 to Methanol in Water

Precise control of the oxidation state of transition-metal oxides, such as copper, is important for high selectivity of CO₂ reduction in an aqueous condition to compete with the reduction of water. The phase of copper oxide nanofibers was controlled by predictive synthesis, which controls the nanoscale gas-solid reaction by considering thermodynamics and kinetics. The driving force of the phase transformation between the different oxidation states of copper oxide is calculated by comparing the Gibbs free energy of each of the oxidation states. From the calculation, the kinetically processable window for the fabrication of Cu₂O in which monophase Cu₂O can be fabricated in a reasonable reaction time scale is discovered. Herein, we report the monophase Cu₂O nanofiber photocathode, which photoelectrochemically converted CO₂ into methanol with over 90% selectivity in an aqueous electrolyte, and a hierarchical structure is developed to optimize the photoactivity and stability of the electrode. Our work suggests a rational design of the calcination strategy for precisely controlling the oxidation states of transition metals that can be applied to various applications in which the phase of the materials plays an important role.

[Effects of bisphenol A on the expression of N-cadherin, Vimentin and FSHR in rat Sertoli cells]

Objective: To explore the effects of BPA on the expression of N-cadherin, Vimentin and FSHR in rat Sertoli cells. Methods: Primary Sertoli cells collected from prepuberty rats (18-21 d) were cultured for 48 h, and then they were treated with 0, 30, 50, 70 μmol/L BPA respectively for 24 h. The methods of MTT, real-time quantitative PCR and Western blotting were utilized to measure the cell ability of Sertoli cells, the mRNA and protein expression levels of N-cadherin, Vimentin and FSHR respectively. Results: Compared with control, the cell abilities of Sertoli cells in 50 μmol/L BPA group and 70 μmol/L BPA group increased significantly (P<0.05) . The cell abilities of Sertoli cells decreased with the increases of exposure doses of BPA. Compared with control, the expression of N-cadherin mRNA only increased in 30 μmol/L BPA group (P<0.05) , the expression of Vimentin mRNA decreased significantly in all doses group of BPA (P<0.05) , the expression of FSHR mRNA increased in all doses group of BPA (P<0.05) . Compared with the control, the protein levels of N-cadherin increased significantly in 50 μmol/L BPA group (P<0.05) , the protein levels of Vimentin decreased significantly in all doses group of BPA (P<0.05) , the protein levels of FSHR decreased significantly in 50 μmol/L BPA group and 70 μmol/L BPA group (P<0.05) . Conclusion: The mechanism of testicular toxicity from BPA might be the alterations of N-cadherin, Vimentin and FSHR by disturbing normal spermatogenesis.

Current Status and Bioinspired Perspective of Electrochemical Conversion of CO2 to a Long-Chain Hydrocarbon

Electrocatalytic conversion of CO₂ into a long-chain hydrocarbon represents an important research direction in adding value to CO₂-based chemicals and realizing its practical application. Long-chain hydrocarbons may change the current fossil fuel-based industry in that those chemicals have a similar energy density as gasoline, high compatibility with the current infrastructure, and low hydroscopicity for pipeline distribution. However, most of the electrocatalysts produce C₁, C₂, and C₃ chemicals, and methods for producing long-chain hydrocarbons are not available thus far. Interestingly, nature utilizes many enzymes to generate long-chain hydrocarbons using C₂ building blocks and suggests key mechanisms, inspiring new perspective in the design of electrocatalysts. In this Perspective, we present case studies to demonstrate how CO₂ and its reductive derivatives interact with the electrode surface during C-C bond formation and introduce how these issues are addressed in biological systems. We end this Perspective by outlining possible strategies to translate the natural mechanism into a heterogeneous electrode.

Morphology-Directed Selective Production of Ethylene or Ethane from CO2 on a Cu Mesopore Electrode

The electrocatalytic conversion of CO₂ to value-added hydrocarbons is receiving significant attention as a promising way to close the broken carbon-cycle. While most metal catalysts produce C₁ species, such as carbon monoxide and formate, the production of various hydrocarbons and alcohols comprising more than two carbons has been achieved using copper (Cu)-based catalysts only. Methods for producing specific C₂ reduction outcomes with high selectivity, however, are not available thus far. Herein, the morphological effect of a Cu mesopore electrode on the selective production of C₂ products, ethylene or ethane, is presented. Cu mesopore electrodes with precisely controlled pore widths and depths were prepared by using a thermal deposition process on anodized aluminum oxide. With this simple synthesis method, we demonstrated that C₂ chemical selectivity can be tuned by systematically altering the morphology. Supported by computational simulations, we proved that nanomorphology can change the local pH and, additionally, retention time of key intermediates by confining the chemicals inside the pores.

Concave Rhombic Dodecahedral Au Nanocatalyst with Multiple High-Index Facets for CO2 Reduction

A concave rhombic dodecahedron (RD) gold nanoparticle was synthesized by adding 4-aminothiophenol (4-ATP) during growth from seeds. This shape is enclosed by stabilized facets of various high-indexes, such as (331), (221), and (553). Because it is driven thermodynamically and stabilized by 4-ATP ligands, the concave RD maintains its structure over a few months, even after rigorous electrochemical reactions. We discussed the mechanism of the shape evolution controlled by 4-ATP and found that both the binding energy of Au-S and the aromatic geometry of 4-ATP are major determinants of Au atom deposition during growth. As a possible application, we demonstrated that the concave RD exhibits superior electrocatalytic performance for the selective conversion of CO2 to CO in aqueous solution.

Hybrid system of semiconductor and photosynthetic protein

Photosynthetic protein has the potential to be a new attractive material for solar energy absorption and conversion. The development of semiconductor/photosynthetic protein hybrids is an example of recent progress toward efficient, clean and nanostructured photoelectric systems. In the review, two biohybrid systems interacting through different communicating methods are addressed: (1) a photosynthetic protein immobilized semiconductor electrode operating via electron transfer and (2) a hybrid of semiconductor quantum dots and photosynthetic protein operating via energy transfer. The proper selection of materials and functional and structural modification of the components and optimal conjugation between them are the main issues discussed in the review. In conclusion, we propose the direction of future biohybrid systems for solar energy conversion systems, optical biosensors and photoelectric devices.

Increased IL-17A secreting CD4+ T cells, serum IL-17 levels and exhaled nitric oxide are correlated with childhood asthma severity

BACKGROUND

Measuring fractional exhaled nitric oxide (FeNO) is a simple and non-invasive method for assessing airway inflammation. IL-17 plays an important role in T cell-dependent inflammatory response that occurs in allergic asthma, it could act as a potent activator of inducible nitric oxide synthase (iNOS) to amplify FeNO levels.

OBJECTIVES

To evaluate the differences in the CD4(+) IL-17A(+) T cell counts, serum IL-17 levels, and FeNO levels in children with mild intermittent to moderate to severe persistent asthma classified by using the Global Initiative for Asthma (GINA).

METHODS

One hundred and twenty asthmatic children divided into the mild intermittent (n = 42), mild persistent (n = 42), and moderate to severe persistent (n = 36) groups, and 20 healthy controls were recruited for the study. Information obtained at visits included the assessment of asthma severity according to GINA guidelines and C-ACT, lung function parameters, FeNO levels, CD4(+) IL-17A(+) T cells counts from PBMCs, iNOS production by sputum cells and serum IL-17 levels.

RESULTS

Serum IL-17 and FeNO levels were significantly higher in mild to severe persistent asthmatic patients than in intermittent asthmatics or healthy controls (P < 0.05). The percentage of CD4(+) IL-17A(+) T cells was higher in moderate to severe persistent asthmatics than in mild asthmatics (P < 0.01). Moderate to severe asthmatics (n = 5) exhibited greater iNOS production in sputum cells than mild cases (n = 5). Decreased iNOS expression in sputum cells was noted in all subjects after IL-17 neutralizing antibody (P < 0.05). Serum IL-17 levels were positively correlated with FeNO (rho = 0.74; P < 0.01), negatively correlated with C-ACT (rho = -0.63; P < 0.01) in asthmatics.

CONCLUSION AND CLINICAL RELEVANCE

CD4(+) IL-17A(+) T cells counts and serum IL-17 levels in conjunction with augmented FeNO levels are systemic markers of childhood asthma, using these markers, prediction and potential therapeutics for persistent asthmatics may be developed.

Prenatal and postnatal probiotics reduces maternal but not childhood allergic diseases: a randomized, double-blind, placebo-controlled trial

BACKGROUND

The prevalence of atopic diseases has increased rapidly in recent decades globally. The administration of probiotics to reduce gastrointestinal inflammation has been popular, but its role in the prevention or treatment of allergic disease remains controversial. This study evaluated the effectiveness of prenatal and postnatal probiotics in the prevention of early childhood and maternal allergic diseases.

METHODS

In a prospective, double-blind, placebo-controlled clinical trial, pregnant women with atopic diseases determined by history, total immunoglobulin (Ig)E > 100 kU/L, and/or positive specific IgE were assigned to receive either probiotics (Lactobacillus GG; ATCC 53103; 1 × 10(10) colony-forming units daily) or placebo from the second trimester of pregnancy. Both of clinical evaluation performed by questionnaires concerning any allergic symptoms and plasma total IgE, and allergen-specific IgE were obtained in high-risk parents and children at 0, 6, 18, and 36 months of age. The primary and secondary outcomes were the point and cumulative prevalence of sensitization and developing of allergic diseases, and improvement of maternal allergic symptom score and plasma immune parameters before and after intervention, respectively.

RESULTS

In total, 191 pregnant women (LGG group, n = 95; control group, n = 96) were enrolled. No significant effects of prenatal and postnatal probiotics supplementation on sensitization, development of allergic diseases, and maternal IgE levels between placebo and LGG groups. Symptoms of maternal allergic scores improved significantly in the LGG group (P = 0.002). Maternal allergic diseases improvement was more prominent in pregnant women with IgE > 100 kU/L (P = 0.01) and significantly associated with higher interleukin-12p70 levels (P = 0.013).

CONCLUSIONS

LGG administration beginning at the second trimester of pregnancy reduced the severity of maternal allergic disease through increment of Th1 response, but not the incidence of childhood allergic sensitization or allergic diseases (ClinicalTrials.govnumber, IDNCT00325273).

Prevalence of haematuria positively associated with urine albumin excretion in Type 2 diabetes

AIMS

Some guidelines or studies consider haematuria an indication for renal biopsy or a potential cause of albuminuria that precludes accurate assessment of urinary albumin excretion. This study examined the justification of excluding haematuria in interpreting urinary albumin excretion in patients with Type 2 diabetes and its associations with other diabetes-related variables.

METHODS

Between May and November 2008, patients with Type 2 diabetes at a single centre with data on urinary albumin excretion and urinalysis in the same urine sample were recruited. Urinary albumin excretion was determined by urine albumin/creatinine ratio in spot urine. Diagnosis of haematuria was made by positive urine occult blood from 1+ to 4+ and/or presence of more than nine red blood cells/ml in urinalysis. Demographic, anthropometric, clinical and laboratory variables and diabetes-associated complications were analysed.

RESULTS

In total, 743 patients were enrolled. Prevalence of haematuria among patients with normoalbuminuria, microalbuminuria, or macroalbuminuria was 8.7% (n = 13), 16.1% (n = 67) and 35.8% (n = 64), respectively. Urine albumin/creatinine ratio was significantly higher, while macroalbuminuria was more common in patients with haematuria (n = 144) than in those without (n = 599). Multiple regression analysis identified urine albumin/creatinine ratio (odds ratio 1.33, P = 0.01) and macroalbuminuria (odds ratio 2.66, P = 0.01) as the only independent predictors of haematuria. Moreover, urine albumin/creatinine ratio was an independent predictor of haematuria in the macroalbuminuria subgroup (odds ratio 1.30, P = 0.04).

CONCLUSIONS

Increased urine albumin/creatinine ratio and macroalbuminuria were the only independent predictors of haematuria in patients with Type 2 diabetes, raising questions on the justifications of excluding haematuria in interpreting urinary albumin excretion in patients with Type 2 diabetes and including haematuria as an indication for renal biopsy in those with macroalbuminuria.

MicroRNA-21 expression in neonatal blood associated with antenatal immunoglobulin E production and development of allergic rhinitis

BACKGROUND

The prevalence of allergic diseases has increased in the past decades. It is unknown whether expression of certain microRNAs (miRNAs) in neonatal leucocytes is correlated to IgE production and/or allergic diseases.

OBJECTIVE

This study investigated the association of miRNA expression in neonatal leucocytes with cord blood IgE (CBIgE) elevation and development of allergic disease.

METHODS

We screened for the expression of a panel of 157 miRNAs in mononuclear leucocytes from human umbilical cord blood (CB) samples with elevated CBIgE and tracked the association of down-regulated miRNA expression to the miRNA-targeted gene expression and to children with allergic rhinitis (AR).

RESULTS

Among the initial screen of 10 CB samples with elevated CBIgE, expression of eight of the 157 miRNAs was low. Of these eight down-expressed miRNAs, three remained down-regulation in a validation with other 20 CB samples, and two of the three miRNAs, miR-21 and miR-126, were significantly lower in monocytes from AR children. Further analysis of mRNA expression of the miR-21-targeted genes identified that TGFBR2 expression on monocytes was significantly up-regulated in CB with elevated CBIgE, and in AR patients. Transfection of miR-21 precursor into monocytes from patients with AR increased miR-21 expression and decreased TGFBR2 expression.

CONCLUSION

This study demonstrated the first in the literature that lower miR-21 expression in CB and increased TGFBR2 expression is associated with antenatal IgE production and development of AR.

Gene-gene and gene-environment interactions on IgE production in prenatal stage

BACKGROUND

Prevalence of allergic diseases in children has increased worldwide over the past decades. Allergy sensitization may occur in fetal life. This study investigated whether gene-gene and gene-environment interactions affected cord blood IgE (CBIgE) levels.

METHODS

A total of 575 cord blood DNA samples were subjected to a multiplex microarray for 384 single nucleotide polymorphisms (SNPs) in 159 allergy candidate genes. Genetic association was initially assessed by univariate and multivariate analyses. Multifactor dimensionality reduction (MDR) was used to identify gene-gene and gene-environment interactions. Environmental factors for analysis included maternal atopy, paternal atopy, parental smoking, gender, and prematurity.

RESULTS

Twenty-one SNPs in 14 genes were associated with CBIgE elevation (>or =0.5 KU/l) in univariate analysis. Multivariate analysis identified eleven genes (IL13, IL17A, IL2RA, CCL17, CXCL1, PDGFRA, FGF1, HAVCR1, GNAQ, C11orf72, and ADAM33) which were significantly associated with CBIgE elevation. MDR analyses of gene-gene interactions identified IL13 interacted with IL17A and/or redox genes on CBIgE elevation with the prediction accuracy of 62.52%. Analyses of gene-environment interactions identified that maternal atopy combined with IL13, rs1800925 and CCL22, rs170359 SNPs had the highest prediction accuracy of 67.15%. All the high and low risk classifications on gene-gene and gene-environment interactions by MDR analyses could be validated by Chi-square test.

CONCLUSIONS

Gene-gene (e.g. immune and redox genes) and gene-environment (e.g. maternal atopy and FGF1or redox genes) interactions on IgE production begin in prenatal stage, suggesting that prevention of IgE-mediated diseases may be made possible by control of maternal atopy and redox responses in prenatal stage.

Extracorporeal shockwave for hip necrosis in systemic lupus erythematosus

Patients with systemic lupus erythematosus (SLE) frequently received corticosteroid therapy, resulting in osteonecrosis of the femoral head (ONFH). Prior studies demonstrated the effectiveness of extracorporeal shockwave treatment (ESWT) for ONFH.. This study evaluated the effectiveness of ESWT for ONFH in patients with SLE. We studied 39 patients, including 15 patients with SLE (26 hips) and 24 controls (29 hips). To each affected hip we applied ESWT (6000 impulses at 28 kV in a single session). Patients were ambulated with partial weight bearing for 4-6 weeks. The primary endpoint was the need for hip replacement. The secondary endpoints were improvement in hip pain and function and image changes on X-ray and MRI. Patients received total hip replacement in 12% of patients with SLE and in 14% of controls (P = 0.802). There was no statistically significant difference in pain scores (0.86 vs. 0.89; P = 0.467) and function scores (89% vs. 91%; P = 0.194) between patients with SLE and controls. SLE response to ESWT for ONFH is comparable with ONFH in patients without SLE.

Regular Tai Chi Chuan exercise improves T cell helper function of patients with type 2 diabetes mellitus with an increase in T-bet transcription factor and IL-12 production

BACKGROUND

Exercise has been shown to be beneficial in the treatment of type 2 diabetes mellitus (DM); its benefit to immune function, however, remains to be determined.

OBJECTIVE

This study investigated the effect of a 12-week course of Tai Chi Chuan (TCC) exercise on T cell helper (Th) reaction in patients with type 2 DM.

METHODS

A case-control study was performed in 30 pairs of patients with type 2 DM and normal age-matched adults. Fasting blood glucose, HbA1c, mediators (interleukin (IL)-12, IL-4 and transforming growth factor (TGF)beta) and transcription factors (T-bet, GATA-3 and FoxP3) of Th1/Th2/T regulatory (Treg) reaction were measured before and after a 12-week TCC exercise programme.

RESULTS

Fasting glucose and HbA1c levels in the patients with type 2 DM were significantly higher than in age-matched controls before exercise. After TCC exercise, HbA1c levels in patients with type 2 DM significantly decreased (7.59 (0.32)% vs 7.16 (0.22)%; p = 0.047) and blood levels of IL-12 increased significantly (5.96 (1.10) vs 12.96 (3.07); p = 0.035). To study the molecular Th1/Th2/Treg reaction, patients with type 2 DM were found to have lower T-bet but not GATA-3 or FoxP3 expression than normal controls before TCC exercise. After the 12-week TCC exercise T-bet expression significantly increased in patients with type 2 DM.

CONCLUSIONS

A 12-week TCC exercise programme decreases HbA1c levels along with an increase in the Th1 reaction. A combination of TCC with medication may provide an even better improvement in both metabolism and immunity of patients with type 2 DM.

Interaction of maternal atopy, CTLA-4 gene polymorphism and gender on antenatal immunoglobulin E production

BACKGROUND

Genetic heritability and maternal atopy have been correlated to antenatal IgE production, but very few studies have studied gene-maternal atopy interaction on antenatal IgE production. This study investigated the interaction of CTLA-4 polymorphism with prenatal factors on the elevation of cord blood IgE (CBIgE).

METHODS

Pregnant women were antenatally recruited for collection of prenatal environmental factors by a questionnaire. Umbilical cord blood samples were collected for CBIgE detection by fluorescence-linked enzyme assay and CTLA-4 polymorphism measurement by restriction fragment length polymorphism.

RESULTS

A total of 1104 pregnant women initially participated in this cohort study, and 898 of them completed cord blood collection. 21.4% of the newborns had elevation of CBIgE (>or=0.5 kU/L). The CTLA-4+49A allele (P=0.021), maternal atopy (P<0.001) and gender (P=0.034), but not the CTLA-4+49G allele, -318C allele, -318T allele, parental smoking or paternal atopy, were significantly correlated with the CBIgE elevation in multivariate analysis. A dichotomous analysis of gene-maternal atopy interactions identified maternal atopy and CTLA-4+49A allele had an additive effect on the CBIgE elevation, especially prominent in male newborns; and in the absence of maternal atopy, CTLA-4+49GG genotype had a protective effect on CBIgE elevation in female newborns.

CONCLUSIONS

Maternal but not paternal atopy has significant impacts on CBIgE elevation depending on gender and CTLA-4+49A/G polymorphism of newborns. Control of maternal atopy and modulation of CTLA-4 expression in the prenatal stage may be a target for the early prevention of perinatal allergy sensitization.

Effects on protein and mRNA expression levels of p53 induced by fluoride in human embryonic hepatocytes

We investigated the effects of protein and mRNA expression levels on p53 induced by fluoride in human embryo hepatocyte L-02 cells. The protein and mRNA levels of p53 in L-02 cells were measured after in vitro cultured L-02 was exposed to sodium fluoride at different doses (40, 80, and 160 microg/ml) for 24 h. The results showed that the cell survival rate of L-02 cells in the high dose fluoride group was significantly lower than that of the control group. The protein expression levels of p53 in the middle and high dose fluoride group were significantly higher than in the control group and elevated with increasing fluoride concentration. The mRNA expression levels of p53 in the fluoride groups were markedly higher than in the control group. The mRNA expression level of p53 in the high dose fluoride group was however lower compared to the middle dose fluoride group, but similar to the low dose fluoride group. These finding suggest that fluoride can decrease the L-02 cells survival rate and induce protein and mRNA expressions of p53; however, there is no consistency between the protein expression level of p53 and the mRNA expression level.

Increased plasma concentration of nitric oxide in type 2 diabetes but not in nondiabetic individuals with insulin resistance

OBJECTIVE

Insulin resistance (IR) is a key element in the pathogenesis of type 2 diabetes. The results of recent experiments on insulin-mediated vasodilatation have suggested that vascular insensitivity is a component of IR. However, it is still controversial that patients with type 2 diabetes have a decreased ability of insulin to increase endothelial nitric oxide (NO) release.

METHOD

Plasma concentration of NO was examined in 26 patients with type 2 diabetes and 78 nondiabetic volunteers during an insulin suppression test. The test measured the efficacy of insulin in promoting disposal of the infused glucose load, in which the steady state plasma glucose (SSPG) during the 150-180 min of the test was used as an index of IR. Plasma NO levels were assayed by measurement of the stable end products of their metabolism. Comparison of plasma NO levels between groups were performed by Mann-Whitney test and relationships between SSPG and different variables were analyzed by partial correlations.

RESULTS

Our results showed that the plasma NO levels were significantly higher in the diabetic group. When the nondiabetic subjects were analyzed according to their SSPG levels, there was no difference of plasma NO levels between those with SSPG>160 mg/dl and those with SSPG<160 mg/dl. There were also no difference of NO levels between those with a family history of type 2 diabetes and those without. In the nondiabetic group, SSPG correlated with BMI, fasting insulin, triglyceride and HDL-cholesterol, but neither with plasma NO levels nor fasting plasma glucose.

CONCLUSION

Our data suggests that the impairment of NO activity in patients with type 2 diabetes is due to an impaired effect rather than its production. This altered NO signaling pathway is not an early event in insulin resistant individuals. Any such changes will not be apparent until type 2 diabetes with overt hyperglycemia develops.