Carbon monoxide - beyond toxicity?

Carbon monoxide (CO) intoxication is one of the most frequent causes of accidental poisoning, mechanistically related to the inhibition of oxygen transport following blockage of the oxygen binding site of hemoglobin. However, it has become evident that CO is also a gaseous signaling molecule like nitric oxide and capable to trigger cellular stress responses in complex organisms. Endogenously, CO is synthesized upon degradation of heme by heme oxygenases (HOs) of which two enzymatically active isoenzymes are known in mammals; the stress-inducible HO-1 and the constitutively expressed HO-2. Among other pathways, HO-1 expression is stimulated by the Nrf2/Keap1 system which senses electrophilic compounds including alkylating agents and reactive oxygen species (ROS) such as superoxide or hydrogen peroxide. In context with ROS, HO-1 expression has been associated with antioxidant defense related to the heme-metabolite redox pair biliverdin/bilirubin. Studies on CO signaling were facilitated by the introduction of so called "CO releasing molecules" (CORMs), which allow for the controlled release of the compound in biological systems. Obviously, major biological targets of CO comprise intracellular heme-proteins such as cytochrome c oxidase of the respiratory chain, cytochrome P450-dependent monooxygenases (CYPs), or NADPH oxidases. From toxicological studies it is known that exposure to high amounts of CO provokes an inhibition of mitochondrial respiration and increased generation of ROS. In contrast, biological response to low amounts of CO comprises moderate mitochondrial uncoupling (proton leakage) due to the activation of channels including phosphate carrier (PiC), adenine nucleotide translocase (ANT) or large-conductance Ca2+-activated K+ channels (BKCa). Uncoupling of mitochondrial respiration from ATP production is accompanied by a loss of mitochondrial membrane potential - a key sensor and regulator of mitochondrial quality control and mitophagy. Inhibitory effects of CO on mitochondrial respiration are compensated by an increased glycolysis. However, on a short term, utilization of glucose is shifted to the pentose phosphate pathway, to provide NADPH for detoxification. It is notable that endogenous CO production is associated with the physiological response against exogenous electrophilic insult like Nrf2-dependent expression of phase II enzymes or glutathione synthesis. In contrast phase I enzymes such as CYPs which usually generate more electrophiles are inhibited by CO. Together with direct and indirect transient effects on energy metabolism and mitochondrial quality control CO may be an important regulator in cellular stress response.

Molecular evidence that oral supplementation with lycopene or lutein protects human skin against ultraviolet radiation: results from a double-blinded, placebo-controlled, crossover study.

BACKGROUND: Increasing evidence suggests photoprotection by oral supplementation with ß-carotene and lycopene. OBJECTIVES: To examine the capacity of lycopene-rich tomato nutrient complex (TNC) and lutein, to protect against ultraviolet (UV)A/B and UVA1 radiation at a molecular level. METHODS: In a placebo-controlled, double-blinded, randomized, crossover study two active treatments containing either TNC or lutein were assessed for their capacity to decrease the expression of UVA1 the radiation-inducible genes HO1, ICAM1 and MMP1. Sixty-five healthy volunteers were allocated to four treatment groups and subjected to a 2-week washout phase, followed by two 12-week treatment phases separated by another 2 weeks of washout. Volunteers started either with active treatment and were then switched to placebo, or vice versa. At the beginning and at the end of each treatment phase skin was irradiated and 24 h later biopsies were taken from untreated, UVA/B- and UVA1-irradiated skin for subsequent reverse transcriptase polymerase chain reaction analysis of gene expression. Moreover, blood samples were taken after the washout and the treatment phases for assessment of carotenoids. RESULTS: TNC completely inhibited UVA1- and UVA/B-induced upregulation of heme-oxygenase 1, intercellular adhesion molecule 1 and matrix metallopeptidase 1 mRNA, no matter the sequence (anova, P < 0·05). In contrast, lutein provided complete protection if it was taken in the first period but showed significantly smaller effects in the second sequence compared with TNC. CONCLUSIONS: Assuming the role of these genes as indicators of oxidative stress, photodermatoses and photoageing, these results might indicate that TNC and lutein could protect against solar radiation-induced health damage.

Prevalence of nosocomial pathogens in German ambulances: the SEKURE study.

OBJECTIVE: The increasing prevalence of multidrug resistant bacteria is a problem in the inpatient care setting, and in the emergency care system. The aim of this observational, cross-sectional study was to evaluate the prevalence of pathogens on well-defined surfaces in German ambulances that have been designated as 'ready for service'. METHODS: After informed consent was obtained, ambulance surfaces were sampled with agar plates for microbiological examination during an unannounced visit. A standardised questionnaire was used to obtain information regarding the disinfection protocols used at each rescue station. RESULTS: Methicillin resistant staphylococcus aureus contamination was present in 18 sampling surfaces from 11 out of 150 ambulance vehicles (7%) that were designated as ready for service. Contact surfaces directly surrounding patients or staff were most frequently contaminated with pathogens. However, bacterial contamination was not related to annual missions, methods or frequency of disinfection. CONCLUSIONS: In accordance with previous studies, disinfection and cleaning of areas with direct contact to patients or staff seem to be the most challenging. This should also be reflected in disinfection guidelines and the related continuing education.

Conformational analysis of green apple flavour: the gas-phase structure of ethyl valerate validated by microwave spectroscopy.

We report on the microwave spectrum of ethyl valerate, C(4)H(9)-COO-C(2)H(5), observed by molecular beam Fourier transform microwave spectroscopy (MB-FTMW). Highly accurate rotational and centrifugal distortion constants of the two most abundant conformers were determined. Their structure was investigated by comparison of the experimental rotational constants with those obtained by quantum chemical calculations. MP2/ 6-311++G(d,p) calculations failed to give a proper description of the observed conformers in the supersonic jet. Therefore, also other basis sets were tried using Hartree-Fock, second-order Møller-Plesset (MP2), and B3LYP methods to predict the observed gas-phase structures of the molecule. The quantum chemical results guided the conformer assignment of the rotational constants, obtained from the microwave experiment. One of the two observed conformers has C(s) symmetry, while the most abundant conformer has C(1) symmetry. The main conformer possesses a strong spectrum with high intensities. Additionally, harmonic frequency calculations at different levels of theory where carried out and a low lying vibration of the entire n-butyl group against the rest of the molecule was identified. The symbiotic interplay of microwave gas-phase investigations and quantum chemical calculations becomes evident in our results.

[Influence of vascular comorbidities on the antioxidant defense system in Alzheimer's disease]. / Einfluss vaskulärer Komorbiditäten auf die antioxidative Abwehr bei Alzheimer-Demenz.

BACKGROUND AND AIM: Oxidative stress is a critical factor in the pathophysiology of dementia, but the role of oxidant/antioxidant imbalance in relation to vascular pathology in the onset and progression of Alzheimer's disease (AD) is poorly understood. The aim of this study was the identification of an association between vascular comorbidities/vascular risk factors and plasma levels of antioxidant micronutrients in patients with AD. PATIENTS AND METHODS: 41 patients with AD  and 34 controls were included in the study. Atherosclerosis (increased intima-media thickness of the common carotid artery) and/or type 2 diabetes mellitus were diagnosed in 21 AD  patients (AD  Plus group). 20 patients with AD were free of vascular comorbidities and risk factors (AD group). A neuropsychological assessment (Mini-Mental State Examination, MMSE; Clock drawing test; DemTect) and the measurement of plasma levels of lipophilic micronutrients including retinol (vitamin A), α-tocopherol (vitamin E), lutein, zeaxanthin, ß-cryptoxanthin, lycopene, α-carotene and ß-carotene by HPLC were performed in all study subjects. RESULTS: Plasma levels of retinol, vitamin E, lutein, zeaxanthin, lycopene and ß-carotene were significantly lower in the AD  Plus group than in controls. Furthermore, vitamin A levels were correlated with MMSE scores and the levels of vitamin E, lutein, zeaxanthin and lycopene were correlated with all neuropsychological tests. CONCLUSION: The depletion of circulating antioxidant micronutrients observed in AD  patients is associated with vascular comorbidities and risk factors. The vascular comorbidities of patients with AD should also be identified in light of the presence and degree of depletion of the antioxidant defense system of the organism. This might lead to a better lifestyle-related counselling of patients with AD  and their caregivers, with possible positive preventive effects on worsening in the long run. Further studies with a larger patient sample are needed to verify the negative effect of vascular pathology in AD-related oxidative stress.

[Cardioprotection by thoracic epidural anesthesia? : meta-analysis]. / Kardioprotektion durch thorakale Periduralanästhesie? : Metaanalyse.

BACKGROUND: Thoracic epidural analgesia (EDA) is thought to provide cardioprotective effects in patients undergoing noncardiac surgery. The results of two previous meta-analysis showed controversial conclusions regarding the impact of EDA on perioperative survival. The purpose of the present meta-analysis was to evaluate, whether thoracic EDA has the potential to reduce perioperative cardiac morbidity or mortality on the basis of available randomized controlled trials. PATIENTS AND METHODS: A systematic literature search was conducted in medical databases (Med-Line, EBM-Reviews, Embase, Biosis and Biological Abstracts) and relevant clinical trials including patients undergoing noncardiac surgery were evaluated by two independent investigators. All randomized controlled trials investigating the effects of thoracic EDA on perioperative outcome, published from 1980 up to the end of 2008 were included into this quantitative systematic review. Calculations were performed using the statistics program Review Manager 4.1 using a fixed-effects model. RESULTS: Nine studies with a total of 2,768 patients were included in the meta-analysis. Thoracic EDA did not reduce perioperative mortality [odds ratio (Peto OR): 1.08; 95% confidence interval (CI) 0.74-1.58]. Patients receiving thoracic EDA demonstrated a tendency to a lower rate of perioperative myocardial infarction. However, this effect of thoracic EDA did not reach statistical significance (Peto OR: 0.65; 95% CI 0.4-1.05). CONCLUSIONS: The present meta-analysis did not prove any positive influence of thoracic EDA on perioperative in-hospital mortality in patients undergoing noncardiac surgery. Furthermore, it remains questionable if thoracic EDA has the potential to reduce the rate of perioperative myocardial infarction.

Plasma levels of vitamin E and carotenoids are decreased in patients with Nonalcoholic Steatohepatitis (NASH).

OBJECTIVES: Oxidative stress is suggested to play an important role in the pathogenesis of nonalcoholic steatohepatitis (NASH). The present study was aimed to compare plasma levels of antioxidants in patients suffering from NASH and healthy controls. METHODS: Plasma levels of the antioxidants α-tocopherol, γ-tocopherol, lutein, zeaxanthin, ß-cryptoxanthin, lycopene, α-carotene ß-carotene were determined in 57 patients with biopsy-proven NASH and 40 healthy controls. RESULTS: Levels of α-tocopherol (22.4 vs. 26.8 nmol/ ml; p<0.01), lutein (0.19 vs. 0.33 nmol/ml; p<0.0001), zeaxanthin (0.04 vs. 0.08 nmol/ml; p<0.0001), lyco?pene (0.15 vs. 0.42 nmol/ml; p<0.0001), α-carotene (0.03 vs. 0.06 nmol/ml; p<0.005) and ß-carotene (0.25 vs. 0.39 nmol/ml; p<0.01) were significantly decreased in NASH patients compared to controls. Age, aminotransferase status (ALT, AST) and BMI were not correlated with the levels of tocopherols or caro?tenoids. CONCLUSIONS: Given the decreased levels supplementation of lipophilic antioxidants might be a rational treatment option for patients with NASH.

Supplementation of flaxseed oil diminishes skin sensitivity and improves skin barrier function and condition.

BACKGROUND: Skin sensitivity is a common problem in the Western population correlated with changes of skin properties like skin barrier function, hydration and skin physiology. Skin properties can be modulated by dietary fatty acids (FA), especially poly-unsaturated FA. The present study was performed to evaluate the effect of daily supplementation with flaxseed oil and safflowerseed oil on healthy volunteers with sensitive skin. METHODS: The study was designed as a randomized, double-blind 12-week intervention with 2 female treatment groups (n = 13). Plasma FA profile, skin sensitivity, skin hydration, transepidermal water loss (TEWL) and skin surface were evaluated on day 0, week 6 and week 12. RESULTS: Supplementation with flaxseed oil led to significant decreases in sensitivity (after nicotinate irritation), TEWL, skin roughness and scaling, while smoothness and hydration were increased. Concomitantly, the ratio of n-6/n-3 FA in plasma decreased. Upon supplementation with safflowerseed oil, only a significant improvement in skin roughness and hydration was observed; however, the effects were less pronounced and determined at a later point in time than with flaxseed oil. The plasma n-6/n-3 FA ratio increased. CONCLUSION: The data provide evidence that daily intake of flaxseed oil modulates skin condition.

Oxidative LDL modification is increased in vascular dementia and is inversely associated with cognitive performance.

It is not known whether the association between increased plasma homocysteine (Hcy) associated with LDL modification and propensity for LDL uptake by macrophages in cardiovascular disease patients holds true in vascular dementia (VaD). Plasma from 83 subjects diagnosed with Alzheimer's disease (AD), VaD, mild cognitive impairment (MCI) and from controls was analysed to examine (1) whether LDL isolated from the plasma of VaD is biochemically and functionally distinct from that isolated from AD, MCI or controls; and (2) whether such biomarkers of LDL phenotype are related to plasma folate levels, Hcy levels and/or to disease severity. Folate and vitamin B6 levels were significantly lower in VaD subjects than in controls. VaD-LDL showed increased protein carbonyl content (p < 0.05) and was more susceptible to scavenging by macrophages (p < 0.05) than AD- or control-LDL. Patients from the VaD cohort were more prevalent in the lowest tertile for HDL:LDL and the upper tertile for LDL oxidation; the combined parameters of HDL cholesterol, LDL oxidation and scavenging by macrophages show 87% sensitivity towards VaD detection. The association between folate deficiency, LDL modification and dysfunction in VaD but not in AD may provide a novel biomarker assessment to discriminate between the diseases.

Antioxidant supplements improve parameters related to skin structure in humans.

In the present study we investigated the influence of two different antioxidant supplements composed of carotenoids, vitamin E and selenium on parameters related to skin health and skin aging. Thirty-nine volunteers with healthy, normal skin of skin type 2 were divided into 3 groups (n = 13) and supplemented for a period of 12 weeks. Group 1 received a mixture of lycopene (3 mg/day), lutein (3 mg/day), beta-carotene (4.8 mg/day), alpha-tocopherol (10 mg/day) and selenium (75 microg/day). Group 2 was supplemented with a mixture of lycopene (6 mg/day), beta-carotene (4.8 mg/day), alpha-tocopherol (10 mg/day) and selenium (75 microg/day). Group 3 was the placebo control. Upon supplementation serum levels of selected carotenoids increased in both verum groups. Skin density and thickness were determined by ultrasound measurements. A significant increase for both parameters was determined in the verum groups. Roughness, scaling, smoothness and wrinkling of the skin were determined by Surface Evaluation of Living Skin (Visioscan). Roughness and scaling were improved by the supplementation with antioxidant micronutrients. In the placebo group no changes were found for any of the parameters.

[Systemic photoprotection through carotenoids]. / Systemische Photoprotektion durch Karotinoide.

Nutritional supplements are increasingly used to protect human skin against environmentally-induced damage, most importantly as a consequence of ultraviolet radiation exposure. beta-carotene is a major constituent of comercially available products administered for systemic photoprotection. Studies on the systemic use of beta-carotene provide evidence that 15-30 mg/d over a period of about 10-12 wk produces a protective effect against UV-induced erythema. Similar effects have been attributed to mixtures of carotenoids or after long-term intake of dietary products rich in carotenoids. Supplementation with carotenoids contributes to basal protection of the skin but is not sufficent to obtain complete protection against severe UV irradiation.

Macular carotenoids: lutein and zeaxanthin.

The yellow color of the macula lutea is due to the presence of the carotenoid pigments lutein and zeaxanthin. In contrast to human blood and tissues, no other major carotenoids including Beta-carotene or lycopene are found in this tissue. The macular carotenoids are suggested to play a role in the protection of the retina against light-induced damage. Epidemiological studies provide some evidence that an increased consumption of lutein and zeaxanthin with the diet is associated with a lowered risk for age-related macular degeneration, a disease with increasing incidence in the elderly. Protecting ocular tissue against photooxidative damage carotenoids may act in two ways: first as filters for damaging blue light, and second as antioxidants quenching excited triplet state molecules or singlet molecular oxygen and scavenge further reactive oxygen species like lipid peroxides or the superoxide radical anion.

Lycopene oxidation product enhances gap junctional communication.

Carotenoids as well as their metabolites and oxidation products stimulate gap junctional communication (GJC) between cells, which is thought to be one of the protective mechanisms related to cancer-preventive activities of these compounds. Increased intake of lycopene by consumption of tomatoes or tomato products has been epidemiologically associated with a diminished risk of prostate cancer. Here, we report a stimulatory effect of a lycopene oxidation product on GJC in rat liver epithelial WB-F344 cells. The active compound was obtained by complete in vitro oxidation of lycopene with hydrogen peroxide/osmium tetroxide. For structural analysis high performance liquid chromatography, gas chromatography coupled with mass spectrometry, ultraviolet/visible-, and infrared spectrophotometry were applied. The biologically active oxidation product was identified as 2,7,11-trimethyl-tetradecahexaene-1,14-dial. The present data indicate a potential role of lycopene degradation products in cell signaling enhancing cell-to-cell communication via gap junctions.

Cerebellar anomalies in congenital murine toxoplasmosis.

Gravid Nya:NYLAR mice, infected with Toxoplasma gondii on gestation day 7, experienced embryo resorptions, abortions, stillbirths, and a reduction in average litter size by one-third. Postnatally, all congenitally infected pups showed growth retardation, cachexia, and hind limb weakness. Some pups developed necrotic petechiae on the ears and tail, and a blood-tinged nasal discharge. Coronal sections of the cerebellum at age 1 month revealed developmental abnormalities including: persistence of remnants of an external granular layer; fragmented and disoriented Bergmann glial foot processes; numerous ectopic granule cells stranded in the molecular layer; focal disorganization and edema of the Purkinje cell layer; and thinning of the internal granular layer. Our working hypothesis is that the cerebellar anomalies originated with parasite invasion of the fetal vascular endothelium leading to vasculitis and microcirculatory dysfunction, perivascular edema, perfusion impairment, and tissue anoxia. In the cerebellar folia, the cellular migration defects are attributed to edema-induced swelling and fragmentation of the Bergmann glial foot processes that guide migrating neurons, whereas the focal loss of Purkinje and granule cells is ascribed to hypoxia-ischemia. Although Toxoplasma cysts were detected in the cerebellum, morphologic evidence of parasite association with neuropathology was not obtained.

The 5-aminolevulinic acid-induced porphyrin biosynthesis in benign and malignant cells of the skin.

In fluorescence diagnosis and photodynamic therapy of neoplastic tissues 5-aminolevulinic acid is used to synthesize endogenous porphyrins as photosensitizers. The efficacy of neoplastic tissues to fluorescence diagnosis and photodynamic therapy is thought to be dependent on the total level of intralesional formed porphyrins. The available profiles of porphyrin metabolites in normal and in neoplastic cell lines after administration of 5-aminolevulinic acid vary considerably. Thus, this is the first in-vitro study which compares the porphyrin biosynthesis in normal skin cells (HaCaT, fibroblasts) with melanoma cells (Bro, SKMel-23, SKMel-28). After incubation with 1 mM 5-aminolevulinic acid, kinetics of porphyrin levels and metabolites were determined in the cells and the corresponding supernatants. Exogenous 5-aminolevulinic acid induced porphyrin formation in all cells with maximum values after an incubation period of 16-36 h. Increase of porphyrin levels varied from 10- to 80-fold (SKMel-28>HaCaT>fibroblasts>SKMel-23>>Bro) with minimum 1.5 times higher levels of porphyrins in the supernatants than in the cells. In cells and supernatants protoporphyrin and coproporphyrin were the predominantly formed porphyrin metabolites. Metastatic melanoma cells (SKMel-23, SKMel-28) accumulated much higher porphyrin levels than primary melanoma cells (Bro). In conclusion, by optimizing the treatment modalities, especially the light source, topical photodynamic therapy (PDT) could become a treatment alternative of melanoma metastases in progressive disease.

Stimulation of gap junctional intercellular communication by thalidomide and thalidomide analogs in human fetal skin fibroblasts (HFFF2) and in rat liver epithelial cells (WB-F344).

Gap junction channels maintain cell-cell communication and are essential for the coordination of tissues, playing a pivotal role in embryonal development. Gap junctional intercellular communication (GJIC), studied here in human fetal skin fibroblasts (HFFF2) and in rat liver epithelial cells (WB-F344), was almost doubled upon exposure to thalidomide (10 microM) in the presence of NADH or NADPH (20 microM). Neither in HFFF2 nor in WB-F344 cells did any detectable alteration in GJIC occur with the thalidomide analog EM 16 (10 microM), known as a non-teratogenic compound. The thalidomide analog EM 364 (10 microM) increased GJIC without prior metabolic activation. It is suggested that GJIC modification may be related to the pharmacological and toxicological properties of thalidomide.

Stress response during weaning after cardiac surgery.

We compared the effects of weaning using synchronized intermittent mandatory ventilation (SIMV) with the use of biphasic positive airway pressure (BIPAP) on the stress response, oxygen uptake (VO2) and work of breathing (WOB) in 10 patients after aortocoronary bypass surgery. All three ventilatory settings were investigated in each patient, for example, volume-controlled mechanical ventilation immediately before weaning was followed, in randomized order, by both SIMV and BIPAP. In addition to routine monitoring of continuous and respiratory state, we measured VO2, WOB, and pressure-time product (PTP) as well as the plasma concentrations of epinephrine, norepinephrine, ACTH, cortisol, vasopressin, and prolactin. Although respiratory rate (f), WOB and PTP were greater with both SIMV and BIPAP when compared with control, other variables did not change with the ventilatory mode. In conclusion, weaning from mechanical ventilation using partial support modes does not affect the postoperative stress response in patients who have had uncomplicated cardiac surgery.

Sulfur-to-nitrogen transnitrosation: transfer of nitric oxide from S-nitroso compounds to diethanolamine and the role of intermediate sulfur-to-sulfur transnitrosation.

S-Nitrosothiols are formed in vivo and are involved in NO signaling. We investigated the sulfur-to-nitrogen transnitrosation activity of S-nitrosocysteine, S-nitrosoglutathione, S-nitrosohomocysteine, S-nitrosocysteinylglycine and S-nitroso-N-acetylcysteine in their reaction with the secondary amine diethanolamine in vitro. The resulting N-nitrosodiethanolamine, a strong carcinogen, was formed in yields of up to 11% from S-nitrosocysteine and S-nitrosocysteinylglycine, whereas the transnitrosation activity of the other S-nitroso compounds was weak. However, the addition of L-cysteine to a solution of S-nitrosohomocysteine and diethanolamine accelerated the decomposition of S-nitrosohomocysteine and resulted in a significant formation of N-nitrosodiethanolamine accompanied by the intermediate generation of S-nitrosocysteine. Thus, reactive nitrosothiols can be formed from less reactive analogs via sulfur-to-sulfur transnitrosation. We suggest that this affects regulation of NO trafficking in vivo. The reaction provides an alternative mechanism for the generation of carcinogenic N-nitroso derivatives.

Macular pigments lutein and zeaxanthin as blue light filters studied in liposomes.

Lutein and zeaxanthin are the predominant carotenoids in the human macula lutea. Epidemiological data suggest that an increased intake of a lutein-rich diet correlates with a diminished risk for age-related macular degeneration, a major cause of impaired vision in the elderly. Filtering of blue light has been proposed as a possible mechanism of protection. Here, the blue light filter efficacy of carotenoids was investigated in unilamellar liposomes loaded in the hydrophilic core space with a fluorescent dye, Lucifer yellow, excitable by blue light. Carotenoids were incorporated into the lipophilic membrane. Fluorescence emission in carotenoid-containing liposomes was lower than in carotenoid-free controls when exposed to blue light, indicating a filter effect. Filter efficacy was in the order lutein > zeaxanthin > beta-carotene > lycopene. Some of the difference in blue light filter efficacy of carotenoids is attributable to differences in extinction coefficients, and a major further contribution is suggested to be related to the orientation of the incorporated molecules in the liposomal membrane.