Lactate is an energy substrate for rodent cortical neurons and enhances their firing activity

Glucose is the mandatory fuel for the brain, yet the relative contribution of glucose and lactate for neuronal energy metabolism is unclear. We found that increased lactate, but not glucose concentration, enhances the spiking activity of neurons of the cerebral cortex. Enhanced spiking was dependent on ATP-sensitive potassium (KATP) channels formed with KCNJ11 and ABCC8 subunits, which we show are functionally expressed in most neocortical neuronal types. We also demonstrate the ability of cortical neurons to take-up and metabolize lactate. We further reveal that ATP is produced by cortical neurons largely via oxidative phosphorylation and only modestly by glycolysis. Our data demonstrate that in active neurons, lactate is preferred to glucose as an energy substrate, and that lactate metabolism shapes neuronal activity in the neocortex through KATP channels. Our results highlight the importance of metabolic crosstalk between neurons and astrocytes for brain function.

Prognostic value of intracoronary imaging-derived measures for non-infarct related vessel revascularization throughout 7 years among patients with ST-elevation myocardial infarction

Background

Underlying plaque characteristics that lead to future revascularization during long-term follow-up remain poorly understood.

Purpose

We aimed to explore intracoronary imaging-derived measures as assessed by intravascular ultrasound (IVUS) and optical coherence tomography (OCT) associated with non-infarct related vessel revascularization (non-TVR) arising from imaged segments during long-term (up to 7 years) follow-up among patients with ST-elevated myocardial infarction (STEMI).

Methods

A total of 94 STEMI patients enrolled into the IBIS-4 (Integrated Biomarker Imaging Study-4) study undergoing serial (baseline and 13 months) IVUS and OCT in 2 non-infarct-related coronary arteries under high-intensity statin therapy were analyzed in the present study. Patients were divided into 2 groups according to the occurrence of non-TVR within previously imaged vessel segments (non-TVR: n=14, no non-TVR: n=80).

Results

Baseline characteristics including LDL level were comparable between groups. At baseline, lesions with future non-TVR were associated with greater percent atheroma volume by IVUS (55.6±5.4% vs. 49.6±6.1%, P<0.001), minimum lumen area by OCT (3.4±1.7 mm2 vs. 6.0±3.3 mm2, P=0.004), and a higher prevalence of fibroatheroma (60.0% vs. 20.1%, P=0.007) by OCT compared with those without. Among patients with serial imaging, lesions with non-TVR had a trend towards a less reduction of percent atheroma volume (−0.2±3.8% vs. −2.4±4.2%, P=0.083).

Conclusion

Greater plaque burden, smaller lumen area, and higher prevalence of OCT-detected fibroatheroma at baseline were associated with non-infarct related vessel revascularization. Lesions with non-TVR tend to have less-pronounced regression of coronary atheroma despite intensive statin therapy and achieved LDL levels.

Non-TVR 7 years after index PCI

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): Swiss National Science Foundation

SAT0312 SUBCLINICAL ATHEROSCLEROSIS IN SYSTEMIC SCLEROSIS AND RHEUMATOID ARTHRITIS: A COMPARATIVE MATCHED-COHORT STUDY

Background:

Systemic autoimmune inflammatory disorders confer a higher risk of cardiovascular (CV) disease leading to increased morbidity and mortality compared to the general population. CV risk in Systemic Sclerosis (SSc) has not been studied so extensively as in other diseases, such as Rheumatoid Arthritis (RA), and the real impact of CV disease on SSc prognosis remains unknown. Surrogate markers of atherosclerosis namely carotid intima media thickness (cIMT) and pulse wave velocity (PWV) are impaired in some but not all studies in SSc patients.

Objectives:

The aim of the study was to investigate the prevalence of subclinical atherosclerosis assessed by cIMT and PWV between two well-characterized SSc and RA cohorts.

Methods:

Consecutive SSc patients attending the Scleroderma Clinic were compared with RA patients recruited in the Dudley Rheumatoid Arthritis Co-morbidity Cohort (DRACCO), a prospective study examining CV burden in RA. Cardiovascular risk was assessed using the QRisk3 and cIMT, Augmentation Index (AIx75) and central systolic and diastolic blood pressure were measured in all participants. Propensity score matching, was utilized to select patients from the two cohorts with similar demographic characteristics, CV risk factors (smoking, hypertension, obesity, dyslipidemia, diabetes) and inflammatory load. Unpaired t-test and Chi-square test of independence were applied.

Results:

Fifty five age- and sex-matched SSc and RA patients with similar distribution of CV risk factors were included. No difference was demonstrated between SSc and RA regarding cIMT and AIx75% (0.65 vs 0,61mm p=0,17 and 33.4 vs 31,7 p=0,397 respectively). However average QRisk3 score was significantly higher in the RA compared to the SSc group (P<0.05).

Conclusion:

The results of this comparative study show that subclinical atherosclerosis is comparable between individuals with SSc and RA, a systemic disease with well-defined high atherosclerotic burden. RA patients have higher CV risk (QRisk3 algorithm) suggesting that disease-specific factors such chronic high-grade inflammation may influence the CV risk in this population.

References:

[1]Ozen G, et al. Subclinical Atherosclerosis in Systemic Sclerosis: Not Less Frequent Than Rheumatoid Arthritis and Not Detected With Cardiovascular Risk Indices. Arthritis Care Res (Hoboken) 2016; 68:1538-46

[2]Pagkopoulou E, et al., Cardiovascular risk in systemic sclerosis: Micro- and Macro-vascular involvement. Indian J Rheumatol 2017;12: 211-7

Table 1.

Demographic and cardiovascular risk factors of the matched patients

RASScPN=55N=55Age63.6 (14.8)61.3 (10.9)0.140Female49 (89.1%)53 (96.4%)0.438Smoking10 (18.2%)13 (23.6%)0.5Diabetes0 (0.00%)1 (1.82%)0.364Hyperlipidemia:7 (12.7%)6 (10.9%)1.000Hypertension:23 (41.8%)19 (34.5%)0.441ESRD20.4 (18.4)22.0 (19.1)0.666CRP8.38 (11.6)6.65 (30.2)0.692Table 2.

Comparison of IMT, AIx75, Framingham and QRISK3 between matched patients

RASScPN=55N=55IMT right average0.65 (0.17)0.61 (0.12)0.175IMT left average0.67 (0.15)0.64 (0.13)0.214IMT average0.66 (0.14)0.63 (0.10)0.137AIX 75% (%)33.4 (9.23)31.7 (10.8)0.397Framingham risk< 0.001< 10%9 (31.0%)37 (74.0%)10 – 20%12 (41.4%)9 (18.0%)20 – 30%3 (10.3%)4 (8.00%)>30%5 (17.2%)0 (0.00%)QRISK318.2 (15.3)11.1 (10.6)0.006

Disclosure of Interests:

Pantelis Baniotopoulos: None declared, Eleni Pagkopoulou: None declared, Stergios Soulaidopoulos: None declared, Aamer Sandoo: None declared, Niki Katsiki: None declared, Asterios Karagiannis: None declared, Karen Douglas: None declared, Alexandros Garyfallos Grant/research support from: MSD, Aenorasis SA, Speakers bureau: MSD, Novartis, gsk, Georeg Kitas: None declared, Theodoros Dimitroulas: None declared

FRI0256 ADVANCED MICROCIRCULATORY DAMAGE IS ASSOCIATED WITH INCREASED PULSE WAVE REFLECTIONS IN PATIENTS WITH SSC

Background:

In systemic sclerosis (SSc), inflammation and microvascular damage are fundamental in the progressive fibrotic process. Although the presence of accelerated atherosclerosis in SSc is not as well-described as in other systemic disorders namely rheumatoid arthritis, it appears that individuals suffering from the disease are at higher risk for cardiovascular events. Nailfold Video Capillaroscopy (NVC) is a non-invasive and reproducible imaging technique of the capillary vascular bed, used in the evaluation of microvascular involvement in SSc. Previous data on the association between micro- and macrovascular damage are scarce.

Objectives:

The aim of this study was to examine the association between micro- and macrovascular involvement in patients with SSc.

Methods:

This is a cross-sectional study including consecutive SSc patients attending to a Scleroderma Outpatient Clinic between March and September 2018. All the study participants underwent NVC and the findings were classified in one of the following qualitative patterns: early, active, and late NVC pattern. Capillary’s density was evaluated in the distal row of each finger, based on the number of capillaries per 1 mm and the mean capillaroscopic skin ulcer risk index (CSURI) was automatically calculated with software image analysis. Carotid intima-media thickness (cIMT) was measured in the common carotid artery bilaterally, according to the relevant guidelines. Aortic blood pressure (BP), heart rate adjusted augmentation index [AIx(75)] and carotid-femoral pulse wave velocity (PWV) were evaluated with applanation tonometry (Sphygmocor).

Results:

Sixty-four (95,3% women) SSc individuals with mean age 57.54±12.99 years were included in this analysis. AIx(75) was significantly associated with CSURI (r=0.261; p=0.038) and inversely associated with the number of capillaries (r=-0.271; p=0.030) suggesting a link between the degree of microvascular disease and arterial stiffening. Regarding SSc-specific NVC patterns, AIx(75) were marginally lower in patients with early compared to active or late patterns (25.95±11.27 vs 32.50±11.17 vs 31.62±10.32%; p=0.081 and p=0.083) confirming a trend between progressive microvasculopathy and arterial stiffness. Mean cIMT was negatively correlated with enlarged capillary loops. Brachial or aortic systolic BP (SBP) and pulse pressure (PP) levels were not correlated with any of the studied NVC parameters.

Conclusion:

Microvascular vasculopathy is associated with higher wave reflections, indicating an association between atherosclerotic disease and microvascular injury in SSc patients. Such observations may provide possible explanations for the excessive cardiovascular and mortality risk in this population.

References:

[1]Soulaidopoulos, S., Pagkopoulou, E., Katsiki, N. et al. Arterial stiffness correlates with progressive nailfold capillary microscopic changes in systemic sclerosis: results from a cross-sectional study. Arthritis Res Ther 21, 253 (2019)

[2]Jung K-H, Lim MJ, Kwon SR, Kim D, Joo K, Park W. Nailfold capillary microscopic changes and arterial stiffness in Korean systemic sclerosis patients. Mod Rheumatol. 2015;25:328–31.

[3]Aviña-zubieta JA, Man A, Yurkovich M, Huang K, Sayre EC. Early cardiovascular disease after the diagnosis of systemic sclerosis. Am J Med. 2015;129:324–31

Disclosure of Interests:

Eleni Pagkopoulou: None declared, Stergios Soulaidopoulos: None declared, Eva Triantafyllidou: None declared, Niki Katsiki: None declared, Georeg Kitas: None declared, Asterios Karagiannis: None declared, Alexandros Garyfallos Grant/research support from: MSD, Aenorasis SA, Speakers bureau: MSD, Novartis, gsk, Theodoros Dimitroulas: None declared

The effect of general anaesthetics on brain lactate release

The effects of anaesthetic agents on brain energy metabolism may explain their shared neurophysiological actions but remain poorly understood. The brain lactate shuttle hypothesis proposes that lactate, provided by astrocytes, is an important neuronal energy substrate. Here we tested the hypothesis that anaesthetic agents impair the brain lactate shuttle by interfering with astrocytic glycolysis. Lactate biosensors were used to record changes in lactate release by adult rat brainstem and cortical slices in response to thiopental, propofol and etomidate. Changes in cytosolic nicotinamide adenine dinucleotide reduced (NADH) and oxidized (NAD⁺) ratio as a measure of glycolytic rate were recorded in cultured astrocytes. It was found that in brainstem slices thiopental, propofol and etomidate reduced lactate release by 7.4 ± 3.6% (P < 0.001), 9.7 ± 6.6% (P < 0.001) and 8.0 ± 7.8% (P = 0.04), respectively. In cortical slices, thiopental reduced lactate release by 8.2 ± 5.6% (P = 0.002) and propofol by 6.0 ± 4.5% (P = 0.009). Lactate release in cortical slices measured during the light phase (period of sleep/low activity) was ~25% lower than that measured during the dark phase (period of wakefulness) (326 ± 83 μM vs 430 ± 118 μM, n = 10; P = 0.04). Thiopental and etomidate induced proportionally similar decreases in cytosolic [NADH]:[NAD⁺] ratio in astrocytes, indicative of a reduction in glycolytic rate. These data suggest that anaesthetic agents inhibit astrocytic glycolysis and reduce the level of extracellular lactate in the brain. Similar reductions in brain lactate release occur during natural state of sleep, suggesting that general anaesthesia may recapitulate some of the effects of sleep on brain energy metabolism.

P869Predictive value of the endothelial shear stress distribution in three-dimensional quantitative coronary angiography models in detecting vulnerable plaques

Background

Low Endothelial shear stress (ESS) is a well-known instigator of coronary atherosclerosis. Prospective intravascular ultrasound (IVUS)-based imaging studies with computational fluid dynamic analysis revealed its predictive merit in-vivo. However, whether coronary modelling derived from quantitative coronary angiography (QCA) is equally effective in detecting high-risk plaques remains to be established.

Purpose

To examine the value of endothelial shear stress (ESS) estimated in three-dimensional (3D) QCA models in detecting plaques that are likely to progress and cause events.

Method

We analysed the baseline intravascular ultrasound virtual histology (IVUS-VH) and angiographic data from 28 non-culprit lesions with a vulnerable phenotype (i.e., fibroatheroma or thin cap fibroatheroma) that caused major adverse cardiac events or required revascularization (nc-MACE-R) at 5-year follow-up and from a control group of 119 vulnerable plaques that remained quiescent. The segments studied by IVUS-VH at baseline were reconstructed using 3D-QCA software and in the obtained geometries blood flow simulation was performed and we estimated the resting Pd/Pa across the vulnerable plaque and the mean ESS values in 3mm sub-segments. A propensity score was built by the baseline plaque characteristics and the hemodynamic indices and its efficacy in detecting nc-MACE-R lesions was examined.

Results

Nc-MACE-R lesions were longer (32.5mm [18.0, 41.6], vs. 19.6mm [12.7, 31.3], p=0.03), had smaller minimum lumen area (MLA) (3.65mm2 [3.26, 4.36] vs. 5.03mm2 [3.98, 6.66], p<0.01), increased plaque burden (PB) (69.4% [63.5, 72.0] vs. 60.8% [53.7, 66.5], p<0.01), were exposed to higher ESS (9.40Pa [6.3, 12.5] vs. 4.1Pa [3.0, 6.9], p<0.01), and exhibited a lower resting Pd/Pa (0.97 [0.95, 0.98] vs. 0.98 [0.97, 0.99], p<0.01]. In multivariable analysis the only independent predictor of nc-MACE-R was the maximum 3mm ESS value (hazard ratio: 1.08 [1.02, 1.16], P=0.016). Lesions exposed to high ESS (>4.95Pa) with a high-risk anatomy (MLA<4mm2and PB>70%) had a higher nc-MACE-R rate (53.8%) than those with a low-risk anatomy exposed to high ESS (31.6%) or those exposed to low ESS that had high (20.0%) or low-risk anatomy (7.1%, P<0.001).

Conclusion

In the present study, 3D-QCA-derived local hemodynamic variables provided useful prognostic information and in combination with lesion anatomy enabled more accurate identification of nc-MACE-R lesions. Further research in a larger number of patients is need to confirm these findings before the conduction of large scale prospective studies that will combine intravascular imaging and 3D-QCA modelling to more accurately detect vulnerable plaques.

P5500Acute coronary syndrome in young patients: frequency, mechanisms and clinical outcomes following percutaneous coronary intervention

Introduction

Acute coronary syndromes (ACS) mainly affect older patients and little is known on the frequency, the underlying causes and outcomes following ACS in young.

Purpose

To investigate the frequency, mechanisms and clinical outcomes of young patients suffering from ACS and undergoing percutaneous coronary intervention (PCI).

Methods

Between February 2009 and December 2016, 6720 consecutive patients undergoing PCI for an ACS were prospectively enrolled. We defined young patients as male <45 years or female <50 years. The primary endpoint was the patient-oriented composite endpoint (POCE) defined as the composite of all-cause death, myocardial infarction or any revascularization at 12 months. The mechanisms of ACS in young patients (atherosclerotic vs. embolic vs. spontaneous coronary artery dissection) were retrospectively assessed by an adjudication committee based on clinical and angiographic criteria.

Results

Among 6720 ACS patients, 378 (5.6%) patients were young (41±5 years, 73% male). Young patients, as compared to old patients, presented more frequently with STEMI (64% vs. 45%; p<0.001) and single vessel disease (85% vs. 74%; p<0.001). Cardiovascular risk factors were more frequent in young patients including BMI>30 kg/m2 (34% vs. 22%; p<0.001), smoking (68% vs. 31%; p<0.001), positive family history of coronary artery disease (35% vs. 23%; p<0.001) and baseline LDL-C levels (3.3±1.1 mmol/l vs. 2.9±1.1 mmol/l; p<0.001). Diabetes mellitus was less frequent in the young patient group (10% vs. 21%; p<0.001). The mechanisms of ACS in young patients were atherosclerotic in 87%, coronary embolism in 9%, and spontaneous coronary artery dissection in 4%. At 12 months, the primary endpoint POCE occurred less frequently in young patients (9.3% vs. 17%; HR 0.52, 95% CI 0.37–0.73; p<0.001). The rates of the individual components of the primary endpoint were lower in young patients including all-cause death (3.4% vs. 9.4%; HR 0.36, 95% CI 0.21–0.62; p<0.001), myocardial infarction (1.9% vs. 3.7%; HR 0.48, 95% CI 0.22–1.01; p=0.053) and any revascularization (5.6% vs. 7.7%; HR 0.68, 95% CI 0.44–1.05; p=0.083). Young patients with coronary embolism or spontaneous coronary artery dissection had a higher rate of cardiac death at 12 months as compared to young patients with atherosclerotic disease (embolic vs. atherosclerotic: 9.4% vs. 2.2%; HR 4.3, 95% CI 1.11–16.71; p=0.02; spontaneous coronary artery dissection vs. atherosclerotic: 17.6% vs. 2.2%; HR 8.1, 95% CI 2.1–31.1; p<0.001).

Conclusions

Approximately one out of 20 ACS patients undergoing PCI was young and the main presumed mechanism of ACS was atherosclerosis (87%) followed by coronary embolism (9%) and spontaneous coronary artery dissection (4%). While young ACS patients carry a lower risk for future cardiovascular events as compared with older patients, the high cardiac death rates following embolic disease or spontaneous coronary artery dissections deserves particular attention.

Ammonia mediates cortical hemichannel dysfunction in rodent models of chronic liver disease

The pathogenesis of hepatic encephalopathy (HE) in cirrhosis is multifactorial and ammonia is thought to play a key role. Astroglial dysfunction is known to be present in HE. Astrocytes are extensively connected by gap junctions formed of connexins, which also exist as functional hemichannels allowing exchange of molecules between the cytoplasm and the extracellular milieu. The astrocyte-neuron lactate shuttle hypothesis suggests that neuronal activity is fueled (at least in part) by lactate provided by neighboring astrocytes. We hypothesized that in HE, astroglial dysfunction could impair metabolic communication between astrocytes and neurons. In this study, we determined whether hyperammonemia leads to hemichannel dysfunction and impairs lactate transport in the cerebral cortex using rat models of HE (bile duct ligation [BDL] and induced hyperammonemia) and also evaluated the effect of ammonia-lowering treatment (ornithine phenylacetate [OP]). Plasma ammonia concentration in BDL rats was significantly reduced by OP treatment. Biosensor recordings demonstrated that HE is associated with a significant reduction in both tonic and hypoxia-induced lactate release in the cerebral cortex, which was normalized by OP treatment. Cortical dye loading experiments revealed hemichannel dysfunction in HE with improvement following OP treatment, while the expression of key connexins was unaffected.

CONCLUSION

The results of the present study demonstrate that HE is associated with central nervous system hemichannel dysfunction, with ammonia playing a key role. The data provide evidence of a potential neuronal energy deficit due to impaired hemichannel-mediated lactate transport between astrocytes and neurons as a possible mechanism underlying pathogenesis of HE. (Hepatology 2017;65:1306-1318).

Epidemiology and outcome of elderly admitted to the ward for sepsis

BACKGROUND

The elderly represent a significant cohort of patients presenting at the emergency department, especially in the developed countries. They are characterized by impaired physical condition, comorbidities, and little immune system resources and make frequent use of the healthcare system and its facilities. This study aimed to describe the features and prognostic factors of sepsis in elderly patients (>60 years old) admitted to an internal medicine ward.

MATERIAL AND METHODS

Two hundred eighty eight consecutively patients aged >60 years who were admitted with sepsis during a two-year-period were retrospectively included in the study. Clinical and laboratory parameters at presentation were analyzed. Causes of sepsis and biochemical markers were compared between the healthcare facility-naïve and the healthcare facility-exposed groups. The effect of comorbidities and previous exposure to the healthcare system on clinical course and outcome of the patients was analyzed.

RESULTS

Among the comorbidities that were recorded and included in the analysis, the presence of chronic and acute renal impairment and neurologic disabilities were associated with a worse outcome of sepsis in the elderly. In the same cohort, a previous contact with the healthcare system was found to affect the duration of hospital stay, but not the outcome per se. Sepsis-related markers, such as inflammatory markers were not found to be associated with clinical progression and outcome.

CONCLUSIONS

Timely diagnosis and accurate evaluation of the severity of sepsis is required to ensure a better outcome for the patients. Sensitive markers and accurate prognostic models are constantly pursued. The impact of living characteristics of the modern aging society is additionally addressed and their effect on sepsis outcome assessed. Hippokratia 2016, 20(4): 274-278.

Effectiveness of perindopril/amlodipine fixed dose combination in everyday clinical practice: results from the EMERALD study

OBJECTIVE

The rates of blood pressure (BP) control worldwide are discouraging. This study had the purpose of assessing the effectiveness of perindopril/amlodipine fixed dose combination on BP-lowering efficacy, and recording adherence, safety and tolerability during a 4 month treatment period.

RESEARCH DESIGN AND METHODS

In this multicenter, observational study 2269 hypertensive patients were prospectively enrolled. The data were recorded at 1 and 4 months of treatment.

MAIN OUTCOME MEASURES AND RESULTS

Between the first and third visits mean BP values (systolic/diastolic) decreased from 158.4 ± 13.6/89.9 ± 8.7 mmHg to 130.0 ± 7.9/77.7 ± 6.3 mmHg (P < 0.001). The magnitude of BP reduction depended on baseline blood pressure levels and total cardiovascular (CV) risk (P < 0.001). Patients with grade 1, 2 and 3 showed a BP reduction of 21.9/10.0 mmHg, 34.4/14.2 mmHg and 51.4/21.2 mmHg, accordingly (P < 0.001). Patients with very high, high, moderate and low added CV risk showed a BP reduction of 35.7/14.9 mmHg, 27.5/12.1 mmHg, 28.6/12.2 mmHg and 14.5/5.8 mmHg respectively (P < 0.001). Adherence to treatment was high: 98.3% of the sample was taking the treatment "every day" or "quite often", while only 15 patients (0.7% of the sample) prematurely discontinued treatment. Study interpretation may be limited by the fact that this is an observational study with no comparator and a short follow-up period.

CONCLUSIONS

A perindopril/amlodipine fixed dose combination significantly decreases BP levels. The degree of BP reduction is related to baseline BP levels and total CV risk.

Hemichannel-mediated release of lactate

In the central nervous system lactate contributes to the extracellular pool of readily available energy substrates and may also function as a signaling molecule which mediates communication between glial cells and neurons. Monocarboxylate transporters are believed to provide the main pathway for lactate transport across the membranes. Here we tested the hypothesis that lactate could also be released via opening of pannexin and/or functional connexin hemichannels. In acute slices prepared from the brainstem, hippocampus, hypothalamus and cortex of adult rats, enzymatic amperometric biosensors detected significant tonic lactate release inhibited by compounds, which block pannexin/connexin hemichannels and facilitated by lowering extracellular [Ca(2+)] or increased PCO2 Enhanced lactate release triggered by hypoxia was reduced by ∼50% by either connexin or monocarboxylate transporter blockers. Stimulation of Schaffer collateral fibers triggered lactate release in CA1 area of the hippocampus, which was facilitated in conditions of low extracellular [Ca(2+)], markedly reduced by blockade of connexin hemichannels and abolished by lactate dehydrogenase inhibitor oxamate. These results indicate that lactate transport across the membranes may occur via mechanisms other than monocarboxylate transporters. In the central nervous system, hemichannels may function as a conduit of lactate release, and this mechanism is recruited during hypoxia and periods of enhanced neuronal activity.

Impaired CO2 sensitivity of astrocytes in a mouse model of Rett syndrome

Rett syndrome, a prototypical neurological disorder caused by loss of function of the transcriptional regulator methyl-CpG-binding protein 2 (MeCP2) gene, is associated with a severely disordered breathing pattern and reduced ventilatory CO2 sensitivity. In a mouse model of Rett syndrome (MeCP2 knockout), re-introduction of the MeCP2 gene selectively in astrocytes rescues normal respiratory phenotype. In the present study we determined whether the metabolic and/or signalling functions of astrocytes are affected by testing the hypotheses that in conditions of MeCP2 deficiency, medullary astrocytes are unable to produce/release appropriate amounts of lactate or detect changes in PCO2/[H(+) ], or both. No differences in tonic or hypoxia-induced release of lactate from the ventral surface of the medulla oblongata or cerebral cortex in brain slices of MeCP2-knockout and wild-type mice were found. In brainstem slices of wild-type mice, respiratory acidosis triggered robust elevations in [Ca(2+) ]i in astrocytes residing near the ventral surface of the medulla oblongata. The magnitude of CO2 -induced [Ca(2+) ]i responses in medullary astrocytes was markedly reduced in conditions of MeCP2 deficiency, whereas [Ca(2+) ]i responses to ATP were unaffected. These data suggest that (i) metabolic function of astrocytes in releasing lactate into the extracellular space is not affected by MeCP2 deficiency, and (ii) MeCP2 deficiency impairs the ability of medullary astrocytes to sense changes in PCO2/[H(+) ]. Taken together with the evidence of severely blunted ventilatory sensitivity to CO2 in mice with conditional MeCP2 deletion in astroglia, these data support the hypothesis of an important role played by astrocytes in central respiratory CO2 /pH chemosensitivity.

Brainstem hypoxia contributes to the development of hypertension in the spontaneously hypertensive rat

Systemic arterial hypertension has been previously suggested to develop as a compensatory condition when central nervous perfusion/oxygenation is compromised. Principal sympathoexcitatory C1 neurons of the rostral ventrolateral medulla oblongata (whose activation increases sympathetic drive and the arterial blood pressure) are highly sensitive to hypoxia, but the mechanisms of this O2 sensitivity remain unknown. Here, we investigated potential mechanisms linking brainstem hypoxia and high systemic arterial blood pressure in the spontaneously hypertensive rat. Brainstem parenchymal PO2 in the spontaneously hypertensive rat was found to be ≈15 mm Hg lower than in the normotensive Wistar rat at the same level of arterial oxygenation and systemic arterial blood pressure. Hypoxia-induced activation of rostral ventrolateral medulla oblongata neurons was suppressed in the presence of either an ATP receptor antagonist MRS2179 or a glycogenolysis inhibitor 1,4-dideoxy-1,4-imino-d-arabinitol, suggesting that sensitivity of these neurons to low PO2 is mediated by actions of extracellular ATP and lactate. Brainstem hypoxia triggers release of lactate and ATP which produce excitation of C1 neurons in vitro and increases sympathetic nerve activity and arterial blood pressure in vivo. Facilitated breakdown of extracellular ATP in the rostral ventrolateral medulla oblongata by virally-driven overexpression of a potent ectonucleotidase transmembrane prostatic acid phosphatase results in a significant reduction in the arterial blood pressure in the spontaneously hypertensive rats (but not in normotensive animals). These results suggest that in the spontaneously hypertensive rat, lower PO2 of brainstem parenchyma may be associated with higher levels of ambient ATP and l-lactate within the presympathetic circuits, leading to increased central sympathetic drive and concomitant sustained increases in systemic arterial blood pressure.

The Effect of Antihypertensive Drugs on Arterial Stiffness and Central Hemodynamics: Not All Fingers are Made the Same

Arterial stiffness and central hemodynamics attract increasing scientific interest within the hypertensive community during the last decade. Accumulating evidence indicates that aortic stiffness is a strong and independent predictor of cardiovascular events and all-cause mortality in hypertensive patients, and its predictive value extends beyond traditional risk factors. The role of central hemodynamics and augmentation index (a marker of reflected waves), remains less established and requires further investigation. Several lines of evidence indicate that antihypertensive therapy results in significant reductions of pulse wave velocity and central hemodynamics. However, beta-blockers seem to be the only exception with significant within-class differences. Conventional beta-blockers, although equally effective in reducing pulse wave velocity, seem to be less beneficial on central hemodynamics and augmentation index than the other antihypertensive drug categories, whereas the newer vasodilating beta-blockers seem to share the benefits of the other antihypertensive drugs. In conclusion, aortic stiffness seems ready for ‘prime-time’ in the management of essential hypertension, while further research is needed for central hemodynamics and augmentation index.

The clinical utility of bone turnover markers in the evaluation of bone disease in patients with haemophilia A and B

Haemophilia A and B have been associated with increased prevalence of low bone mineral density (BMD). However, the utility of bone turnover markers (BTM) remains unknown. The aim of this study was to evaluate bone metabolism in men with haemophilia and to investigate associations between BTM and bone disease. Serum N- (NTX-I), C-terminal telopeptide of type I collagen (CTX-I) and tartrate-resistant acid phosphatase band-5b (TRAP-5b), as bone resorption markers, and osteocalcin (OC) and bone-specific alkaline phosphatase (b-ALP), as bone formation markers, were assessed. Seventy men with haemophilia A (n = 59) or B (n = 11) were studied. Patients with low BMD had significantly higher b-ALP concentrations compared with those with normal BMD (12.8 ± 1.60 vs. 9.72 ± 0.58 μg/L, P = 0.009), without any differences in the other BTM. NTX-I and CTX-I concentrations were negatively associated with oestradiol levels and hip BMD and positively with human immunodeficiency virus infection, number of affected joints and arthropathy scores. B-ALP and OC concentrations were negatively associated with hip BMD, severity of haemophilia and fracture history, and positively with the number of affected joints and testosterone concentrations. After multivariate analysis, NTX-I levels remained negatively associated with oestradiol levels, whereas b-ALP concentrations negatively correlated with the level of physical activity and positively with the number of affected joints. Increased bone metabolism exists in men with haemophilia and low BMD. Increased b-ALP levels may identify patients at high risk for fracture. Increased number of target joints, low physical activity and low oestradiol concentrations are independently associated with increased bone metabolism.

Simple variables predict miserable outcome after intravenous thrombolysis

BACKGROUND AND PURPOSE

To test the predictability of miserable outcome amongst ischaemic stroke patients receiving intravenous thrombolysis (IVT) based on a simple variables model (SVM) and to compare the model's predictive performance with that of an existing score which includes imaging and laboratory parameters (DRAGON).

METHODS

The SVM consists of the parameters age, independence before stroke, normal Glasgow coma verbal score, able to lift arms and able to walk. In a derivation cohort (n = 1346) and a validation cohort (n = 638) of consecutive IVT-treated stroke patients, the probability estimated by SVM and the observed occurrence of miserable 3-month outcome (modified Rankin score 5-6) were compared. The performances of SVM and the DRAGON score were compared. The area under the receiver operating curve (AUC) (95% confidence interval, CI) and the bootstrapping approach were used to compare the predictive performance.

RESULTS

The AUCs to predict miserable outcome in the derivation cohort were 0.807 (95% CI 0.774-0.838) using the SVM and 0.822 (0.790-0.850) using the DRAGON score (P = 0.3). For the validation cohort, AUCs were 0.786 (0.742-0.829) for the SVM and 0.809 (0.774-0.845) for the DRAGON score (P = 0.23). Only one patient with an SVM probability of >70% for miserable outcome in either cohort had a good outcome whilst 83% had a miserable outcome. An online SVM calculator to estimate the probability of miserable outcome for individual patients is available under http://www.unispital-basel.ch/SVM-Tool.

CONCLUSION

The SVM was similar in accuracy to the DRAGON score for predicting miserable outcome after IVT. As these simple variables are available already at the pre-hospital stage, the SVM may facilitate and accelerate pre-hospital triage of patients at high risk for miserable outcome after IVT towards endovascular treatment.

Characterization and distribution of Reelin-positive interneuron subtypes in the rat barrel cortex

GABAergic inhibitory interneurons (IN) represent a heterogeneous population with different electrophysiological, morphological, and molecular properties. The correct balance between interneuronal subtypes is important for brain function and is impaired in several neurological and psychiatric disorders. Here we show the data of 123 molecularly and electrophysiologically characterized neurons of juvenile rat barrel cortex acute slices, 48 of which expressed Reelin (Reln). Reln mRNA was exclusively detected in Gad65/67-positive cells but was found in interneuronal subtypes in different proportions: all cells of the adapting-Somatostatin (SST) cluster expressed Reln, whereas 63% of the adapting-neuropeptide Y (NPY, 50% of the fast-spiking Parvalbumin (PVALB), and 27% of the adapting/bursting-Vasoactive Intestinal Peptide (VIP) cluster were Reln-positive. Silhouette analysis revealed a high impact of the parameter Reln on cluster quality. By analyzing the co-localization of RELN immunoreactivity with those of different IN-markers, we found that RELN is produced layer-independently in SST-, NPY-, and NOS1-expressing INs, whereas co-localization of RELN and VIP was mostly absent. Of note, RELN co-localized with PVALB, predominantly in INs of layers IV/V (>30%). Our findings emphasize RELN's role as an important IN-marker protein and provide a basis for the functional characterization of Reln-expressing INs and its role in the regulation of inhibitory IN networks.

Diabetes, bilirubin and amputations: is there a link?

A study by Chan et al in this issue of Diabetologia (DOI: 10.1007/s00125-012-2818-4 ) reports that low plasma bilirubin levels are associated with an increased risk of amputation in patients with type 2 diabetes mellitus participating in the Fenofibrate Intervention and Event Lowering in Diabetes (FIELD) study. These findings raise the interesting and clinically relevant hypothesis that bilirubin protects against risk of amputation in patients with type 2 diabetes. This commentary considers some of the limitations associated with research aiming to define any link between circulating bilirubin levels and vascular disease. Numerous confounding factors (several of which may be present in patients with type 2 diabetes) may explain why the literature regarding this potentially protective role of bilirubin remains controversial.

Beyond the frontiers of neuronal types

Cortical neurons and, particularly, inhibitory interneurons display a large diversity of morphological, synaptic, electrophysiological, and molecular properties, as well as diverse embryonic origins. Various authors have proposed alternative classification schemes that rely on the concomitant observation of several multimodal features. However, a broad variability is generally observed even among cells that are grouped into a same class. Furthermore, the attribution of specific neurons to a single defined class is often difficult, because individual properties vary in a highly graded fashion, suggestive of continua of features between types. Going beyond the description of representative traits of distinct classes, we focus here on the analysis of atypical cells. We introduce a novel paradigm for neuronal type classification, assuming explicitly the existence of a structured continuum of diversity. Our approach, grounded on the theory of fuzzy sets, identifies a small optimal number of model archetypes. At the same time, it quantifies the degree of similarity between these archetypes and each considered neuron. This allows highlighting archetypal cells, which bear a clear similarity to a single model archetype, and edge cells, which manifest a convergence of traits from multiple archetypes.

Cardiovascular benefits of bariatric surgery in morbidly obese patients

Morbid obesity is associated with increased morbidity and represents a major healthcare problem with increasing incidence worldwide. Bariatric surgery is considered an effective option for the management of morbid obesity. We searched MEDLINE, Current Contents and the Cochrane Library for papers published on bariatric surgery in English from 1 January 1990 to 20 July 2010. We also manually checked the references of retrieved articles for any pertinent material. Bariatric surgery results in resolution of major comorbidities including type 2 diabetes mellitus, hypertension, dyslipidemia, metabolic syndrome, non-alcoholic fatty liver disease, nephropathy, left ventricular hypertrophy and obstructive sleep apnea in the majority of morbidly obese patients. Through these effects and possibly other independent mechanisms bariatric surgery appears to reduce cardiovascular morbidity and mortality. Laparoscopic Roux-en-Y gastric bypass (LRYGB) appears to be more effective than laparoscopic adjustable gastric banding (LAGB) in terms of weight loss and resolution of comorbidities. Operation-associated mortality rates after bariatric surgery are low and LAGB is safer than LRYGB. In morbidly obese patients bariatric surgery is safe and appears to reduce cardiovascular morbidity and mortality.

Comparative effects of rosuvastatin and atorvastatin on glucose metabolism and adipokine levels in non-diabetic patients with dyslipidaemia: a prospective randomised open-label study

AIMS

The impact of statins on glucose metabolism and adipokines remains controversial. We compared the effects of rosuvastatin and atorvastatin on glucose homeostasis, insulin sensitivity (IS), adiponectin and leptin levels as well as systemic inflammation in non-diabetic patients with dyslipidaemia.

METHODS

Thirty-six patients were randomly assigned to 10 mg/day of rosuvastatin (n = 18) or 20 mg/day of atorvastatin (n = 18) for 12 weeks. Total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), non-HDL-C, triglycerides (TG), fasting plasma glucose, insulin, homeostasis model assessment-insulin resistance (HOMA-IR), quantitative IS check index (QUICKI), adiponectin, leptin and high-sensitivity C-reactive protein (hsCRP) were measured at baseline and after 4 and 12 weeks.

RESULTS

Both statins significantly lowered TC, LDL-C, non-HDL-C and TG compared with baseline. Only rosuvastatin caused a significant reduction in insulin and HOMA-IR levels (-35%, p = 0.005 and -33%, p = 0.011 respectively) and a significant increase in QUICKI (+11%, p = 0.003) at 12 weeks. In terms of adipokines and hsCRP, no difference was observed after 4 and 12 weeks of treatment with either statin.

CONCLUSIONS

Rosuvastatin compared with atorvastatin resulted in significant improvements in IS indices. No significant changes in adiponectin, leptin or hsCRP levels were observed at 4 and 12 weeks of treatment with either statin.

Glucagon-like peptide-1-based therapies and cardiovascular disease: looking beyond glycaemic control

Type 2 diabetes mellitus is a well-established risk factor for cardiovascular disease (CVD). New therapeutic approaches have been developed recently based on the incretin phenomenon, such as the degradation-resistant incretin mimetic exenatide and the glucagon-like peptide-1 (GLP-1) analogue liraglutide, as well as the dipeptidyl dipeptidase (DPP)-4 inhibitors, such as sitagliptin, vildagliptin, saxagliptin, which increase the circulating bioactive GLP-1. GLP-1 exerts its glucose-regulatory action via stimulation of insulin secretion and glucagon suppression by a glucose-dependent way, as well as by weight loss via inhibition of gastric emptying and reduction of appetite and food intake. These actions are mediated through GLP-1 receptors (GLP-1Rs), although GLP-1R-independent pathways have been reported. Except for the pancreatic islets, GLP-1Rs are also present in several other tissues including central and peripheral nervous systems, gastrointestinal tract, heart and vasculature, suggesting a pleiotropic activity of GLP-1. Indeed, accumulating data from both animal and human studies suggest a beneficial effect of GLP-1 and its metabolites on myocardium, endothelium and vasculature, as well as potential anti-inflammatory and antiatherogenic actions. Growing lines of evidence have also confirmed these actions for exenatide and to a lesser extent for liraglutide and DPP-4 inhibitors compared with placebo or standard diabetes therapies. This suggests a potential cardioprotective effect beyond glucose control and weight loss. Whether these agents actually decrease CVD outcomes remains to be confirmed by large randomized placebo-controlled trials. This review discusses the role of GLP-1 on the cardiovascular system and addresses the impact of GLP-1-based therapies on CVD outcomes.

Effect of a plant stanol ester-containing spread, placebo spread, or Mediterranean diet on estimated cardiovascular risk and lipid, inflammatory and haemostatic factors

BACKGROUND AND AIMS

Mediterranean diet is associated with a reduced risk for cardiovascular disease (CVD). Use of plant stanols decreases low density lipoprotein cholesterol (LDL-C) concentrations. We compared the effects of the Mediterranean diet and plant stanol esters on vascular risk factors and estimated CVD (eCVD) risk.

METHODS AND RESULTS

In this prospective, randomized, placebo-controlled study, 150 mildly hypercholesterolaemic subjects were randomized to Mediterranean diet, a spread containing plant stanol esters (2 g/day) or a placebo spread. Vascular risk factors were assessed every month for 4 months and the eCVD risk was calculated using the PROspective- Cardiovascular-Munster (PROCAM), Framingham, and Reynolds risk engines. Placebo had no significant effect on risk factors or eCVD risk. Mediterranean diet gradually induced a significant reduction in total cholesterol (TC), LDL-C, triglycerides, high sensitivity C-reactive protein (hsCRP), blood pressure and eCVD risk (24-32%). The plant stanol ester spread reduced (by 1 month) TC (-14%), LDL-C (-16%), hsCRP (-17%), and estimated CVD risk (26-30%). eCVD risk reduction was sustained at 4th months when the gradual Mediterranean diet eCVD risk reduction became comparable to that of the stanol group.

CONCLUSIONS

Plant stanol esters yielded an early, by 1st treatment month, reduction of eCVD risk that resulted from a TC, LDL-C, and hsCRP decrease. eCVD risk reduction on the Mediterranean diet resulted from a change in several CVD risk factors and equaled that of plant stanol at 4 months. The consumption of plant stanol esters by moderately hypercholesterolaemic patients may be a useful option to reduce CVD risk in those who do not adopt a Mediterranean diet.

Paraganglioma in a young patient with asymptomatic severe hypertension: a case report and review of the literature

We present a case of a 19-year old woman who was admitted to our department with a recently, and incidentally, diagnosed severe hypertension [220/140 mmHg systolic/diastolic blood pressure (BP)]. The patient was asymptomatic. The laboratory investigation demonstrated both elevated plasma norepinephrine (1807 pg/ml, normal range 120-350 pg/ml) and 24h urinary free catecholamines (483 µg/24h, normal range <150 µg/24h), making the diagnosis of a catecholamineproducing tumor highly probable. Although magnetic resonance imaging of the abdomen showed normal adrenal glands, it revealed a mass (4x4 cm) anterior to the inferior vena cava. The diagnosis of paraganglioma was confirmed by the (131)Imeta- iodobenzylguanidine scintigraphy. Preoperatively, α- and β-adrenergic receptor blockers were administered. After successful resection of the tumor, the patient's BP was restored to normal and remained stable during the 3-month follow up. Plasma and 24h urinary catecholamine levels were also normalized. In conclusion, it is important to consider paragangliomas as a possible cause of secondary hypertension and proceed to diagnosis and treatment as described above, since surgical removal of the tumor, especially in sporadic cases, may cure the patient.

Implementation of responsible care in the chemical industry: evidence from Greece

The chemical industry can be held accountable for numerous large-scale accidents which have led to the release of dangerous hazardous materials, pollutants and toxic chemicals into the environment, two well-known examples being the Union Carbide Bhopal disaster and the Three Mile Island tragedy). To ensure environmental protection and the Health and Safety (H&S) of communities, the chemical industry has voluntarily adopted integrated management programs such as the Responsible Care Program. The theoretical body of relevant literature attempts to explain the origin of the Responsible Care Program (RCP) through socio-political and economic theories. At the same time, the empirical research examines the ways in which various factors affect the choice of the chemical industry in their adoption of the RCP. This paper contributes to the debate by examining the challenges and barriers faced by the Greek chemical industry when adopting RCP, the environmental and H&S issues that prevail and finally, the extent of participation of stakeholders in the planning of RCP in the sector.

Brain natriuretic peptide and the athlete's heart: a pilot study

BACKGROUND

The role of brain natriuretic peptide (BNP) in differentiating the athlete's heart from maladaptive cardiac hypertrophy is unclear.

METHODS

To address this issue, an integrated M mode, two-dimensional B mode and Doppler echocardiographical study were performed and plasma BNP levels were measured in 25 strength athletes, 25 patients with established hypertrophic cardiomyopathy (HCM) and 25 healthy volunteers.

RESULTS

Among athletes, BNP levels correlated negatively with the total training time (r = -0.79, p = 0.002) and positively with ejection fraction (r = 0.58, p = 0.049) and fractional shortening (r = 0.57, p = 0.049). A BNP cut-off value of 11.8 pg/ml had 88% specificity and 74% negative predictive value for the exclusion of HCM.

CONCLUSIONS

Brain natriuretic peptide might be useful as a preparticipation screening test in athletes.

Endothelial dysfunction in metabolic syndrome: prevalence, pathogenesis and management

The metabolic syndrome (MetS) is characterized by the presence of central obesity, impaired glucose metabolism, dyslipidemia and hypertension. Several studies showed that MetS is associated with increased risk for type 2 diabetes mellitus (T2DM) and vascular events. All components of MetS have adverse effects on the endothelium. Endothelial dysfunction plays a role in the pathogenesis of atherosclerosis and might also increase the risk for insulin resistance and T2DM. We review the prevalence and pathogenesis of endothelial dysfunction in MetS. We also discuss the potential effects of lifestyle measures and pharmacological interventions on endothelial function in these patients. It remains to be established whether improving endothelial function in MetS will reduce the risk for T2DM and vascular events.

Initiative for a new diabetes therapeutic approach in a Mediterranean country: the INDEED study

AIM

To assess the efficacy of a strategy to improve vascular risk management in patients with type 2 diabetes mellitus (T2DM).

METHODS

This was a pilot best practice implementation enhancement programme that enrolled 578 patients with T2DM. A baseline visit was followed by a concerted effort from previously trained physicians to improve adherence to lifestyle advice and optimise drug treatment for all vascular risk factors. The patients were followed-up for 6 months. The UKPDS risk engine was used to estimate vascular risk in patients without established coronary heart disease (CHD) (n = 279).

RESULTS

There was an improvement in compliance to lifestyle measures and increased prescription of evidence-based medication. In patients without established CHD there was a 37% reduction in estimated risk for CHD, 44% for fatal CHD, 10% for stroke and 25% for fatal stroke (p < or = 0.003 for all comparisons vs. baseline). There was also a substantial increase in the proportion of patients with established CHD who achieved their vascular risk factor targets.

CONCLUSIONS

This is the first study to increase the adherence to multiple interventions in patients with T2DM in both primary care and hospital settings. Education of physicians and patients, distribution of guidelines/brochures, and the completion of a one-page form, motivated both physicians and patients to achieve multiple vascular risk factor goals.