Plasma coenzyme Q10 concentrations are not decreased in male patients with coronary atherosclerosis

Coenzyme Q₁₀ (CoQ₁₀) is an important mitochondrial electron transfer component and has been postulated to function as a powerful antioxidant protecting LDL from oxidative damage. It could thus reduce the risk of cardiovascular disease. Thus far, beneficial effects of supplementation with CoQ₁₀ have been reported. To study the relation between unsupplemented concentrations of plasma CoQ₁₀ and coronary atherosclerosis, we performed a case-control study among 71 male cases with angiographically documented severe coronary atherosclerosis and 69 healthy male controls free from symptomatic cardiovascular disease and without atherosclerotic plaques in the carotid artery.

Plasma CoQ₁₀ concentrations (mean ± SE) were 0.86 ± 0.04 vs. 0.83 ± 0.04 μmol/l for cases and controls, respectively. The CoQ₁₀/LDL-cholesterol ratio (μmol/mmol) was slightly lower in cases than in controls (0.22 ± 0.01 vs. 0.26 ± 0.03). Differences in CoQ₁₀ concentrations and CoQ₁₀/LDL-cholesterol ratio did not reach significance. The odds ratios (95% confidence interval) for the risk of coronary atherosclerosis calculated per μmol/l increase of CoQ₁₀ was 1.12 (0.28-4.43) after adjustment for age, smoking habits, total cholesterol and diastolic blood pressure.

We conclude that an unsupplemented plasma CoQ₁₀ concentration is not related to risk of coronary atherosclerosis.     

Coenzyme Q concentration and total antioxidant capacity of human milk at different stages of lactation in mothers of preterm and full-term infants

Coenzyme Q₁₀(CoQ₁₀) in human milk at different stages of maturity in mothers of preterm and full-term infants and its relation to the total antioxidant capacity of milk is described for the first time. Thirty healthy breastfeeding women provided colostrum, transition-milk and mature-milk samples. Coenzyme Q, α-, γ- and δ-tocopherol, fatty acids and the total antioxidant capacity of the milk were analyzed. Coenzyme Q₁₀ was found at higher concentrations for colostrum (0.81 ± 0.06 vs. 0.50 ± 0.05 μmol/l) and transition milk (0.75 ± 0.06 vs. 0.45 ± 0.05 μmol/l) in the full-term vs. the preterm group (similar results were found for total antioxidant capacity). Concentrations of α- and γ-tocopherol were higher in the full-term group and decreased with time. In conclusion, CoQ₁₀ is present in breast milk, with higher concentration in mothers of full-term infants. CoQ₁₀ in breast milk decreases through lactation in mothers delivering full-term infants. Also, CoQ₁₀, α- and γ-tocopherol concentration in human milk directly correlates with the antioxidant capacity of the milk.     

Pediatric reference intervals for muscle coenzyme Q10

Coenzyme Q₁₀ (CoQ₁₀) is present in humans in both the reduced (ubiquinol, CoQ₁₀H₂) and oxidized (ubiquinone, CoQ₁₀) forms. CoQ₁₀ is an essential cofactor in mitochondrial oxidative phosphorylation, and is necessary for ATP production. Total, reduced and oxidized CoQ₁₀ levels in skeletal muscle of 148 children were determined by HPLC coupled with electrochemical detection, and we established three level thresholds for total CoQ₁₀ in muscle. We defined as “severe deficiency”, CoQ₁₀ levels falling in the range between 0.82 and 4.88 μmol/g tissue; as “intermediate deficiency”, those ranging between 5.40 and 9.80 μmol/g tissue, and as “mild deficiency”, the amount of CoQ₁₀ included between 10.21 and 19.10 μmol/g tissue. Early identification of CoQ₁₀ deficiency has important implications in children, not only for those with primary CoQ₁₀ defect, but also for patients with neurodegenerative disorders, in order to encourage earlier supplementation with this agent also in mild and intermediate deficiency.     

Preparation and characterization of novel coenzyme Q<Subscript>10</Subscript> nanoparticles engineered from microemulsion precursors

The purpose of these studies was to prepare and characterize nanoparticles into which Coenzyme Q₁₀ (CoQ₁₀) had been incorporated (CoQ₁₀-NPs) using a simple and potentially scalable method. CoQ₁₀-NPs were prepared by cooling warm microemulsion precursors composed of emulsifying wax, CoQ₁₀, Brij 78, and/or Tween 20. The nanoparticles were lyophilized, and the stability of CoQ₁₀-NPs in both lyophilized form and aqueous suspension was monitored over 7 days. The release of CoQ₁₀ from the nanoparticles was investigated at 37°C. Finally, an in vitro study of the uptake of CoQ₁₀-NPs by mouse macrophage, J774A.1, was completed. The incorporation efficiency of CoQ₁₀ was approximately 74%±5%. Differential Scanning Calorimetry (DSC) showed that the nanoparticle was not a physical mixture of its individual components. The size of the nanoparticles increased over time if stored in aqueous suspension. However, enhanced stability was observed when the nanoparticles were stored at 4°C. Storage in lyophilized form demonstrated the highest stability. The in vitro release profile of CoQ₁₀ from the nanoparticles showed an initial period of rapid release in the first 9 hours followed by a period of slower and extended release. The uptake of CoQ₁₀-NPs by the J774A.1 cells was over 4-fold higher than that of the CoQ₁₀-free nanoparticles (P<.05). In conclusion, CoQ₁₀-NPs with potential application for oral CoQ₁₀ delivery were engineered readily from microemulsion precursors.     

Effects of dietary L-carnitine and coenzyme Q10 at different supplemental ages on growth performance and some immune response in ascites-susceptible broilers

Abstract

Effects of dietary L-carnitine and coenzyme Q₁₀ (CoQ₁₀) at different supplemental ages on performance and some immune response were investigated in ascites-susceptible broilers. A 3 × 2 × 2 factorial design was used consisting of L-carnitine supplementation (0, 75, and 100 mg/kg), CoQ₁₀ supplementation (0 and 40 mg/kg) and different supplemental ages (from day 1 on and from day 10 on). A total of 480 one-day-old Arbor Acre male broiler chicks were randomly allocated to 12 groups, every group had five replicates, each with eight birds. The birds were fed a corn-soybean based diet for six weeks. From day 10 – 21, all the birds were exposed to a low ambient temperature (12 – 15°C) to increase the susceptibility to ascites. No significant effects were observed on growth performance by L-carnitine, CoQ₁₀ supplementation, and different supplemental ages. Packed cell volume was significantly decreased by L-carnitine supplementation alone, and ascites heart index and ascites mortality were decreased by L-carnitine, CoQ₁₀ supplementation alone, and L-carnitine + CoQ₁₀ supplementation together (p < 0.05). Heart index of broilers was significantly improved by L-carnitine, CoQ₁₀ supplementation alone during 0 – 3 week. Serum IgG content was improved by L-carnitine supplementation alone (p < 0.05), but lysozyme activity was increased by L-carnitine + CoQ₁₀ supplementation together (p < 0.05). A significant L-carnitine by supplemental age interaction was observed in lysozyme activity. L-carnitine supplementation alone had no effects on the peripheral blood lymphocyte (PBL) proliferation in response to concanavalin A (ConA) and lipopolysaccharide, but supplemental CoQ₁₀ alone and L-carnitine + CoQ₁₀ together decreased the PBL proliferation in response to ConA (p < 0.05). The present study suggested that L-carnitine + CoQ₁₀ supplementation together had positive effects on some immune response of ascites-susceptible broilers, which might benefit for the reduction of broilers' susceptibility to ascites.     

Intracellular cholesterol accumulation and coenzyme Q10 deficiency in Familial Hypercholesterolemia

Familial Hypercholesterolemia (FH) is an autosomal co-dominant genetic disorder characterized by elevated low-density lipoprotein (LDL) cholesterol levels and increased risk for premature cardiovascular disease. Here, we examined FH pathophysiology in skin fibroblasts derived from FH patients harboring heterozygous mutations in the LDL-receptor.Fibroblasts from FH patients showed a reduced LDL-uptake associated with increased intracellular cholesterol levels and coenzyme Q₁₀ (CoQ₁₀) deficiency, suggesting dysregulation of the mevalonate pathway.Secondary CoQ₁₀ deficiency was associated with mitochondrial depolarization and mitophagy activation in FH fibroblasts. Persistent mitophagy altered autophagy flux and induced inflammasome activation accompanied by increased production of cytokines by mutant cells. All the pathological alterations in FH fibroblasts were also reproduced in a human endothelial cell line by LDL-receptor gene silencing.Both increased intracellular cholesterol and mitochondrial dysfunction in FH fibroblasts were partially restored by CoQ₁₀ supplementation. Dysregulated mevalonate pathway in FH, including increased expression of cholesterogenic enzymes and decreased expression of CoQ₁₀ biosynthetic enzymes, was also corrected by CoQ₁₀ treatment.Reduced CoQ₁₀ content and mitochondrial dysfunction may play an important role in the pathophysiology of early atherosclerosis in FH. The diagnosis of CoQ₁₀ deficiency and mitochondrial impairment in FH patients may also be important to establish early treatment with CoQ₁₀.     

Effects of dissolved oxygen concentration and DO-stat feeding strategy on CoQ10 production with Rhizobium radiobacter

The cell growth and CoQ₁₀ (coenzyme Q₁₀) formation of Rhizobium radiobacter WSH2601 were investigated in a 7-1 bioreactor under different dissolved oxygen (DO) concentrations. A maximal CoQ₁₀ content (C/B) of 1.91 mg/g dry cell weight (DCW) and CoQ₁₀ concentration of 32.1 mg/l were obtained at the appropriate DO concentration of 40% (of air saturation). High DO concentration was favourable to the cell growth of Rhizobium radiobacter WSH2601. In order to achieve the maximal yield of CoQ₁₀ production, a new DO-stat feeding strategy was proposed, which significantly improved cell growth and CoQ₁₀ formation. With this strategy, the maximal CoQ₁₀ concentration and DCW reached 51.1 mg/l and 23.9 g/l, respectively, which were 67 and 44.8% higher than those obtained in the batch culture with DO concentration controlled.     

Effects and mechanisms of ghrelin on cardiac microvascular endothelial cells in rats

Ghrelin is thought to directly exert a protective effect on the cardiovascular system, specifically by promoting vascular endothelial cell function. Our study demonstrates the ability of ghrelin to promote rat CMEC (cardiac microvascular endothelial cell) proliferation, migration and NO (nitric oxide) secretion. CMECs were isolated from left ventricle of adult male Sprague—Dawley rat by enzyme digestion and maintained in endothelial cell medium. Dil‐ac‐LDL (1,1′‐dioctadecyl‐3,3,3′,3′‐ tetramethylindocarbocyanine‐labelled acetylated low‐density lipoprotein) intake assays were used to identify CMECs. Cells were split into five groups and treated with varying concentrations of ghrelin as follows: one control non‐treated group; three ghrelin dosage groups (1×10^?9, 1×10^?8, 1×10^?7 mol/l) and one ghrelin+PI3K inhibitor group (1×10^?7 mol/l ghrelin+20 μmol/l LY294002). After 24 h treatment, cell proliferation capability was measured by MTT [3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyl‐2H‐tetrazolium bromide] assay and Western blot for PCNA (proliferating cell nuclear antigen) protein expression. Migration of CMECs was detected by transwell assays, and NO secretion of CMECs was measured via nitrate reduction. Protein expression of AKT and phosphorylated AKT in CMECs was measured by Western blot after exposure to various concentrations of ghrelin and the PI3K inhibitor LY294002. Our results indicate that ghrelin significantly enhanced cell growth at concentrations of 10^?8 mol/l (0.271±0.041 compared with 0.199±0.021, P=0.03) and 10^?7 mol/l (0.296±0.039 compared with 0.199±0.021, P<0.01). However, addition of the PI3K/AKT inhibitor LY294002 inhibited the ghrelin‐mediated enhancement in cell proliferation (0.227±0.042 compared with 0.199±0.021, P=0.15). At a concentration between 10^?8 and 10^?7 mol/l, ghrelin caused a significant increase in the number of migrated cells compared with the control group (126±9 compared with 98±7, P=0.02; 142±6 compared with 98±7, P<0.01), whereas no such change could be observed in the presence of 20 μmol/l of the PI3K/Akt inhibitor LY294002 (103±7 compared with 98±7, P=0.32). Ghrelin treatment significantly enhanced NO production in a dose‐dependent fashion compared with the untreated control group [(39.93±2.12) μmol/l compared with (30.27±2.71) μmol/l, P=0.02; (56.80±1.98) μmol/l compared with (30.27±2.71) μmol/l, P<0.01]. However, pretreatment with 20 μmol/l LY294002 inhibited the ghrelin‐stimulated increase in NO secretion [(28.97±1.64) μmol/l compared with (30.27±2.71) μmol/l, P=0.37]. In summary, we have found that ghrelin treatment promotes the proliferation, migration and NO secretion of CMECs through activation of PI3K/AKT signalling pathway.     

Attenuation of cryopreservation-induced oxidative stress by antioxidant: Impact of Coenzyme Q10 on the quality of post-thawed buck spermatozoa

The aim of this study was to determine the quality of post-thawed buck spermatozoa by attenuation of cryopreservation-induced oxidative stress using CoQ₁₀, a lipophilic antioxidant. Ejaculates at every sampling period were collected from four Mahabadi bucks, pooled and diluted in soybean lecithin-based extenders containing 0 (negative control, NC), 0.5 (CQ0.05), 1 (CQ1), and 1.5 (CQ1.5) μM CoQ₁₀ and 0.9% (v/v) DMSO (positive control, PC). The diluted semen was gradually cooled to 4 °C, then frozen and stored in liquid nitrogen. After thawing, total motility although was significantly higher in CQ1 (53.40 ± 1.83) than control groups (43.60 ± 1.83% and 42.20 ± 1.83%; P < 0.05), but this parameter did not differ between CQ1 and CQ1.5. Sperm viability was significantly higher in CQ1 (54.20 ± 2.03%) than that of control and CQ0.5. The CQ1 and CQ1.5 led to significantly higher the plasma membrane functionality compared to control groups. Sperm abnormality was significantly lower in CQ1 than that of NC. The results also showed that MDA level was significantly lower in CQ1 and CQ1.5 compared with control and CQ0.5. The CQ1 (59.43 ± 3.93%) was significantly increased mitochondrial activity compared to control groups. Although a greater value for %DFI was found in NC (10.24 ± 0.48%) and PC (9.77 ± 0.48%) groups compared to others, it was lower in CQ1 group (4.26 ± 0.48%). In conclusion, based on our research results, 1 μM CoQ₁₀ could protect buck spermatozoa from cryoinjury.     

Acute Effects of Dietary Glycemic Index on Antioxidant Capacity in a Nutrient‐controlled Feeding Study

Oxidative stress, caused by an imbalance between antioxidant capacity and reactive oxygen species, may be an early event in a metabolic cascade elicited by a high glycemic index (GI) diet, ultimately increasing the risk for cardiovascular disease and diabetes. We conducted a feeding study to evaluate the acute effects of low‐GI compared with high‐GI diets on oxidative stress and cardiovascular disease risk factors. The crossover study comprised two 10‐day in‐patient admissions to a clinical research center. For the admissions, 12 overweight or obese (BMI: 27–45 kg/m²) male subjects aged 18–35 years consumed low‐GI or high‐GI diets controlled for potentially confounding nutrients. On day 7, after an overnight fast and then during a 5‐h postprandial period, we assessed total antioxidant capacity (total and perchloric acid (PCA) protein‐precipitated plasma oxygen radical absorbance capacity (ORAC) assay) and oxidative stress status (urinary F_2α‐isoprostanes (F₂IP)). On day 10, we measured cardiovascular disease risk factors. Under fasting conditions, total antioxidant capacity was significantly higher during the low‐GI vs. high‐GI diet based on total ORAC (11,736 ± 668 vs. 10,381 ± 612 µmol Trolox equivalents/l, P = 0.002) and PCA‐ORAC (1,276 ± 96 vs. 1,210 ± 96 µmol Trolox equivalents/l, P = 0.02). Area under the postprandial response curve also differed significantly between the two diets for total ORAC and PCA‐ORAC. No diet effects were observed for the other variables. Enhancement in plasma total antioxidant capacity occurs within 1 week on a low‐GI diet, before changes in other risk factors, raising the possibility that this phenomenon may mediate, at least in part, the previously reported effects of GI on health.     

The Effect of Dietary Energy Restriction on Body Weight Gain and the Development of Noninsulin-Dependent Diabetes Mellitus (NIDDM) in Psammomys obesus

Food intake was restricted to 75% of ad libitum levels in 37 male Psammomys obesus (Israeli Sand Rats) from the ages of 4 (weaning) to 10 weeks. Energy restriction reduced the mean body weight at 10 weeks by 29% compared with 44 ad libitum fed controls. Hyperglycemia was prevented completely in the food-restricted group, and mean blood glucose concentrations were significantly reduced (3.8 ± 0.2 vs. 5.5 ± 0.4 μmol/L; p<0.05) compared with control animals. Plasma insulin concentrations were also decreased significantly compared with ad libitum fed controls (105 ± 13 vs. 241 ± 29 mU/L;p<0.05). Although energy restriction prevented hyperglycemia from developing in 10-week-old P. obesus, 19% of the food restricted animals still developed hyperinsu-linemia. We concluded that hyperphagia between the ages of 4 to 10 weeks may be essential for the development of noninsulin-dependent diabetes mellitus in P. obesus, but that hyperinsulinemia may still occur in the absence of hyperphagia and hyperglycemia, suggesting a significant genetic influence on the development of hyperinsulinemia in this animal model.     

Preparation and characterization of monoclonal antibodies to human adiponectin for its quantitative measurement in serum

Mouse Monoclonal antibodies against human adiponectin were produced by the routine method and the specificity of antibodies was verified. These monoclonal antibodies (MoAbs) interacted with the monomeric and trimeric forms of recombinant adiponectin according to the results of a Western blot analysis. Human blood serum was fractionated by gel filtration, and the protein of these fractions was stained using labeled MoAbs. It was established that a single high-molecular-weight form (HMW) of endogenous adiponectin was detected by this method. The use of competitive enzymelinked immunoassay on the basis of the obtained MoAbs allowed us to show that the sera of healthy male donors contains lower adiponectin concentrations than that of female donors (8.42 ± 1.59 μg/ml vs. 11.01 ± 2.58 μg/ml, p = 0.01). We also detected statistically significant lower adiponectin levels in the serum of patients with coronary artery disease for both men (6.01 ± 2.73 μg/ml vs. 8.42 ± 1.59 μg/ml, p = 0.015) and women (5.79 ± 2.98 μg/ml vs. 11.01 ± 2.58 μg/ml, p = 0.0003). Therefore, the developed methods for the analysis of the HMW form of adiponectin can be helpful in the diagnostics of the possible implications and assessment of unfavorable prognoses in patients with cardiovascular disorders.     

Role of metal-catalyzed autoxidation in Maillard reaction damage to proteins in vivo

Summary

Administration of 0.1 mmol/kg of diquat to Fischer-344 rats causes acute hepatic necrosis by mechanisms that appear to involve increased generation of reactive oxygen species, but the critical targets of the proposed oxidations have not been identified. In the present study the effects of diquat-induced redox stresses on hepatic protein thiol status were determined by derivatization of subcellular fractions with monobromobimane and separation of the fluorescent derivatives by SDS-PAGE. No differences in hepatic thiol status were seen in animals 2 or 6 h after diquat, relative to saline-treated controls, despite documentation of injury by elevated plasma transaminase activities. Hepatic DNA fragmentation was increased in diquat-treated animals (24.9±5.1 vs 6.7±0.3% (controls) at 2 h; 57.2±4.1 vs 4.6±0.3% (controls) at 6 h, P<0.001). However, 8-hydroxydeoxyguanosine (8-OHdG) contents in hepatic DNA were not increased by diquat (35.3±6.2 μmol 8-OHdG/mol deoxyguanosine (dG)) over saline-treated controls (28.3±2.6). Plasma NH₃ concentrations increased in diquat-treated rats from 49 μM in controls to 170 μM 6 h after treatment with diquat. Hepatic activities of glutamine synthetase (GS) were lower in diquat-treated rats (39.7±13.0 mU/mg protein) than in controls (65.8±13.4, P<0.001), but activities of carbamyl phosphate synthetase-I (CPS-I), were not decreased significantly. The oxidation of proteins to forms reactive with 2,4-dinitrophenylhydrazine (DNPH) was investigated in subcellular fractions by Western blot analyses with a monoclonal antibody to DNP-derivatized bovine serum albumin (BSA). N-terminal sequencing of bands exhibiting reactivity with anti-DNP-BSA antibodies indicated protein carbonyl formation in malate dehydrogenase, protein disulfide isomerase, and glutathione transferase. The functional consequences of oxidation of these proteins are not known but the observation of protein carbonyl formation and no measurable loss of protein thiol content are consistent with iron chelate-mediated oxidation in the transformation critical to expression of tissue damage. The time course data are consistent with DNA fragmentation as a mechanism contributing to the development of cell injury, but the absence of increases in 8-OHdG indicates that direct oxidation of DNA may not be responsible.     

Decreased Serum Selenium Levels are Correlated with Diminished Coronary Flow Reserve Among Hemodialysis Patients

Cardiovascular diseases are the main reason of high mortality among hemodialysis patients. Decreased serum selenium levels may have a role in accelerated atherosclerosis in this patient group. The hypothesis of this study was to show a correlation between decreased serum selenium levels and coronary flow reserve as an indicator of endothelial dysfunction and atherosclerosis in HD patients. Seventy-one chronic hemodialysis patients and age 65 and sex-matched healthy controls were included in the study. Plasma selenium levels were measured by spectrophotometry, and coronary flow reserve was assessed by transthoracic Doppler echocardiography. Serum selenium levels (34.16?±?6.15 ng/ml vs. 52.4?±?5.51 ng/ml, P?<?0.001) and coronary flow reserve values (1.73?±?0.11 vs. 2.32?±?0.28, P?<?0.001) were significantly lower in hemodialysis patients compared with controls, respectively. There was a significant positive correlation between coronary flow reserve and serum levels of selenium (r?=?0.676, P?<?0.001). A linear regression analysis showed that serum levels of selenium were independently and positively correlated with coronary flow reserve (regression coefficient?=?0.650, P?<?0.05). This study was the first to show a positive and independent correlation between decreased selenium levels and diminished coronary flow reserve as an indicator of endothelial dysfunction and atherosclerosis in hemodialysis patients. Our data suggest that decreased serum selenium levels may facilitate the development of endothelial dysfunction and disruption of coronary flow reserve which occur before the development of overt atherosclerosis.     

Stereoselective binding of isradipine to human plasma proteins

Isradipine (PN 200–110) is a highly potent calcium entry blocker with an asymmetrically substituted dihydropyridine ring (methyl- and isopropylester, respectively). The binding of the (+)-(S)-isradipine and (?)-(R)-isradipine to isolated human serum albumin (HSA, 30 μmol/l) and α₁-acid glycoprotein (AAG, 10 μmol/l) has been studied in vitro over a wide range of isradipine concentrations (0.06–20 μmol/l) using high-performance liquid chromatography (HPLC). HPLC experiments revealed that both isradipine enantiomers were bound to one class of high-affinity binding sites on the AAG molecule (n_(S) = 0.83 ± 0.05, K_a(S) = (1.33 ± 0.25) × 10⁶ 1/mol, n_(R) = 0.85 ± 0.07, K_a(R) = (1.17 ± 0.44) × 10⁷ l/mol). The (R)-enantiomer also exhibited an interaction with the secondary low-affinity binding sites (n′K′_{a (R)} = (2.66 ± 0.65) × 10⁴ l/mol). In contrast, the pharmacologically more potent (+)-(S)-enantiomer was more strongly bound to HSA than its optical antipode (n_(S) = 1.07 ± 0.07, K_a(S) = (1.76 ± 0.26) × 10⁵ l/mol, nK_a(R) = (3.62 ± 0.06) × 10⁴ l/mol). In general, the resulting binding characteristics of individual isradipine enantiomers showed stereoselectivity, but this was opposite for the two most important plasma binding proteins. The process of accumulation of isradipine by human platelets in the therapeutically relevant range (10–80 ng/ml) at 37°C was devoid of stereoselectivity. © 1995 Wiley-Liss, Inc.     

Coenzyme Q<Subscript>10</Subscript> production by <Emphasis Type="Italic">Rhodobacter sphaeroides</Emphasis> in stirred tank and in airlift bioreactor

A higher Coenzyme Q₁₀ (CoQ₁₀) concentration of 25.04 mg/l was found in airlift bioreactor than the value of 18.11 mg/l obtained in stirred tank under the aerobic-dark cultivation of Rhodobacter sphaeroides. Aeration rate didn’t show obvious impact to CoQ₁₀ production in airlift bioreactor. The fed-batch operation in airlift bioreactor could increase the biomass concentration and led to the maximum CoQ₁₀ concentration of 33.91 mg/l measured, but a lower CoQ₁₀ cell content (3.5 mg CoQ₁₀/DCW) was observed in the fed-batch operation as compared to the batch operation. To enhance the CoQ₁₀ content, an aeration-change strategy was proposed in the fed-batch operation of airlift bioreactor. This strategy led to the maximum CoQ₁₀ concentration of 45.65 mg/l, a 35% increase as compared to the simple fed-batch operation. The results of this study suggested that a fed-batch operation in airlift bioreactor accompanying aeration-change could be suitable for CoQ₁₀ production.     

Controlling the sucrose concentration increases Coenzyme Q10 production in fed-batch culture of <Emphasis Type="Italic">Agrobacterium tumefaciens</Emphasis>

The production yield of Coenzyme Q₁₀ (CoQ₁₀) from the sucrose consumed by Agrobacterium tumefaciens KCCM 10413 decreased, and high levels of exopolysaccharide (EPS) accumulated after switching from batch culture to fed-batch culture. Therefore, we examined the effect of sucrose concentration on the fermentation profile by A. tumefaciens. In the continuous fed-batch culture with the sucrose concentration maintained constantly at 10, 20, 30, and 40 g l⁻¹, the dry cell weight (DCW), specific CoQ₁₀ content, CoQ₁₀ production, and the production yield of CoQ₁₀ from the sucrose consumed increased, whereas EPS production decreased as maintained sucrose concentration decreased. The pH-stat fed-batch culture system was adapted for CoQ₁₀ production to minimize the concentration of the carbon source and osmotic stress from sucrose. Using the pH-stat fed-batch culture system, the DCW, specific CoQ₁₀ content, CoQ₁₀ production, and the product yield of CoQ₁₀ from the sucrose consumed increased by 22.6, 13.7, 39.3, and 39.3%, respectively, whereas EPS production decreased by 30.7% compared to those of fed-batch culture in the previous report (Ha SJ, Kim SY, Seo JH, Oh DK, Lee JK, Appl Microbiol Biotechnol, 74:974–980, 2007). The pH-stat fed-batch culture system was scaled up to a pilot scale (300 l), and the CoQ₁₀ production results obtained (626.5 mg l⁻¹ of CoQ₁₀ and 9.25 mg g DCW⁻¹ of specific CoQ₁₀ content) were similar to those obtained at the laboratory scale. Thus, an efficient and highly competitive process for microbial CoQ₁₀ production is available.     

DECREASED RATE OF GLUCOSE UTILIZATION BY RAT BRAIN IN VIVO AFTER EXPOSURE TO ATMOSPHERES CONTAINING HIGH CONCENTRATIONS OF CO2

—(1) The effects of exposure of rats to increased atmospheric concentrations of CO₂ on brain metabolism in vivo were studied. (2) After 2·5 min exposure to an atmosphere of 20% CO₂, the rate of glucose utilization by brain decreased from 0·61 μmol/min per g to 0·32 μmol/min per g and remained between 0·3 and 0·4 μmol/min per g for 60 min, the longest interval studied. O₂ utilization, calculated from the arteriovenous difference of O₂ across the brain and blood flow, was 3·5 μmol/min per g in controls and was 4·7 μmol/min per g after 5 min in the 20% CO₂ atmosphere. (3) The concentrations of glucose, glucose 6-phosphate and aspartate were increased during the first 10 min of CO₂ exposure whereas the concentrations of other glycolytic intermediates, tricarboxylic acid cycle intermediates and glutamate were decreased. The amount of endogenous substrate which disappeared during the first 10 min was sufficient, if used to supplement glucose as a fuel, to maintain the O₂ consumption at, or slightly above, the control level. Glutamate and lactate were quantitatively the most important energy sources. (4) The mechanism whereby‘CO₂ decreased the rate of glucose utilization is uncertain. The initial rise in glucose 6-phosphate and fall in fructose 1,6-diphosphate concentrations suggested that an inhibition of phosphofructokinase was responsible. However, after 60 min in 20% CO₂, the concentrations of both of these metabolites returned to normal while the rate of glucose utilization remained depressed.     

Parathyroid hormone, but not vitamin D, is associated with the metabolic syndrome in morbidly obese women and men: a cross-sectional study

Background

Asymmetric dimethylarginine (ADMA) is a competitive inhibitor of endothelial nitric oxide synthase (eNOS) that is associated with endothelial dysfunction, and is a risk marker for cardiovascular disease, a significant problem in Type 1 diabetes. The aim of the present study was to measure circulating ADMA, and define its association with endothelial dysfunction and endothelial markers in people with Type 1 diabetes with low likelihood of macrovascular disease.

Methods

Sixty-one young people with Type 1 diabetes without macrovascular disease or nephropathy and 62 healthy volunteers underwent brachial artery flow-mediated dilatation (FMD) and assay of plasma ADMA and adhesion molecules.

Results

Age, gender, BMI, lipid profile and renal function were similar in the two groups. People with Type 1 diabetes had impaired FMD compared to healthy controls (5.0 ± 0.4 vs 8.9 ± 0.4%; p < 0.001). Plasma ADMA levels were significantly lower in the people with diabetes compared to healthy controls (0.52 ± 0.12 vs 0.66 ± 0.20 μmol/l, p < 0.001). Plasma ICAM-1, E-selectin and PAI-1 levels were significantly higher in people with diabetes compared to healthy controls (median 201 (IQR 172–226) vs 180 (156–216) μg/l, p = 0.027; 44.2 (32.6–60.9) vs. 33.1 (22.4–51.0) μg/l; p = 0.003 and 70.8 (33.3–85.5) vs 46.3 (23.9–76.8) μg/l, p = 0.035). Plasma ADMA and VCAM-1 levels were positively correlated (r = 0.37, p = 0.003) in people with diabetes. There was no correlation between the plasma ADMA and FMD.

Conclusion

ADMA levels are not associated with endothelial dysfunction in young adults with Type 1 diabetes without microalbuminuria or known macrovascular disease. This suggests that the impaired endothelial function in these individuals is not a result of eNOS inhibition by ADMA.