Toxicity of Metal Oxide Nanoparticles: Looking through the Lens of Toxicogenomics

The impact of solubility on the toxicity of metal oxide nanoparticles (MONPs) requires further exploration to ascertain the impact of the dissolved and particulate species on response. In this study, FE1 mouse lung epithelial cells were exposed for 2-48 h to 4 MONPs of varying solubility: zinc oxide, nickel oxide, aluminum oxide, and titanium dioxide, in addition to microparticle analogues and metal chloride equivalents. Previously published data from FE1 cells exposed for 2-48 h to copper oxide and copper chloride were examined in the context of exposures in the present study. Viability was assessed using Trypan Blue staining and transcriptomic responses via microarray analysis. Results indicate material solubility is not the sole property governing MONP toxicity. Transcriptional signaling through the 'HIF-1α Signaling' pathway describes the response to hypoxia, which also includes genes associated with processes such as oxidative stress and unfolded protein responses and represents a conserved response across all MONPs tested. The number of differentially expressed genes (DEGs) in this pathway correlated with apical toxicity, and a panel of the top ten ranked DEGs was constructed (Hmox1, Hspa1a, Hspa1b, Mmp10, Adm, Serpine1, Slc2a1, Egln1, Rasd1, Hk2), highlighting mechanistic differences among tested MONPs. The HIF-1α pathway is proposed as a biomarker of MONP exposure and toxicity that can help prioritize MONPs for further evaluation and guide specific testing strategies.

Dissolution Behaviour of Metal-Oxide Nanomaterials in Various Biological Media

Toxicological effects of metal-oxide-engineered nanomaterials (ENMs) are closely related to their distinct physical-chemical properties, especially solubility and surface reactivity. The present study used five metal-oxide ENMs (ZnO, MnO₂, CeO₂, Al₂O₃, and Fe₂O₃) to investigate how various biologically relevant media influenced dissolution behaviour. In both water and cell culture medium (DMEM), the metal-oxide ENMs were more soluble than their bulk analogues, with the exception that bulk-MnO₂ was slightly more soluble in water than nano-MnO₂ and Fe₂O₃ displayed negligible solubility across all tested media (regardless of particle size). Lowering the initial concentration (10 mg/L vs. 100 mg/L) significantly increased the relative solubility (% of total concentration) of nano-ZnO and nano-MnO₂ in both water and DMEM. Nano-Al₂O₃ and nano-CeO₂ were impacted differently by the two media (significantly higher % solubility at 10 mg/L in DMEM vs. water). Further evaluation of simulated interstitial lung fluid (Gamble's solution) and phagolysosomal simulant fluid (PSF) showed that the selection of aqueous media significantly affected agglomeration and dissolution behaviour. The solubility of all investigated ENMs was significantly higher in DMEM (pH = 7.4) compared to Gamble's (pH 7.4), attributable to the presence of amino acids and proteins in DMEM. All ENMs showed low solubility in Gamble's (pH = 7.4) compared with PSF (pH = 4.5), attributable to the difference in pH. These observations are relevant to nanotoxicology as increased nanomaterial solubility also affects toxicity. The results demonstrated that, for the purpose of grouping and read-across efforts, the dissolution behaviour of metal-oxide ENMs should be evaluated using aqueous media representative of the exposure pathway being considered.

Impact of copper oxide particle dissolution on lung epithelial cell toxicity: response characterization using global transcriptional analysis

The in vitro and in vivo toxicity of copper oxide nanoparticles (CuO NPs) is attributed to both particle and dissolved copper ion species. However, a clear understanding of (1) the specific cellular responses that are modulated by the two species and (2) the temporal dynamics in toxicity, as the proportional amount of particulate and ionic forms change over time, is lacking. In the current study, in vitro responses to microparticulate CuO (CuO MPs), CuO NPs, and dissolved Cu²⁺ were characterized in order to elucidate particle and ion-induced kinetic effects. Particle dissolution experiments were carried out in a relevant cell culture medium, using CuO NPs and MPs. Mouse lung epithelial cells were exposed for 2-48 h with 1-25 µg/mL CuO MPs, CuO NPs, or 7 and 54 µg/mL CuCl₂. Cellular viability and genome-wide transcriptional responses were assessed. Dose and time-dependent cytotoxicity were observed in CuO NP exposed cells, which was delayed and subtle in CuCl₂ and not observed in CuO MPs treated cells. Analyses of differentially expressed genes and associated pathway perturbations showed that dissolved ions released by CuO NPs in the extracellular medium are insufficient to account for the observed potency and cytotoxicity. Further organization of gene expression results in an Adverse Outcome Pathway (AOP) framework revealed a series of key events potentially involved in CuO NPs toxicity. The AOP is applicable to toxicity induced by metal oxide nanoparticles of varying solubility, and thus, can facilitate the development of in vitro alternative strategies to screen their toxicity.

Marine resource abundance drove pre-agricultural population increase in Stone Age Scandinavia

How climate and ecology affect key cultural transformations remains debated in the context of long-term socio-cultural development because of spatially and temporally disjunct climate and archaeological records. The introduction of agriculture triggered a major population increase across Europe. However, in Southern Scandinavia it was preceded by ~500 years of sustained population growth. Here we show that this growth was driven by long-term enhanced marine production conditioned by the Holocene Thermal Maximum, a time of elevated temperature, sea level and salinity across coastal waters. We identify two periods of increased marine production across trophic levels (P1 7600–7100 and P2 6400–5900 cal. yr BP) that coincide with markedly increased mollusc collection and accumulation of shell middens, indicating greater marine resource availability. Between ~7600–5900 BP, intense exploitation of a warmer, more productive marine environment by Mesolithic hunter-gatherers drove cultural development, including maritime technological innovation, and from ca. 6400–5900 BP, underpinned a ~four-fold human population growth.

How the development of human societies is influenced through their ecological environment and climatic conditions has been the subject of intensive debate. Here, the authors present multi-proxy data from southern Scandinavia which suggests that pre-agricultural population growth there was likely influenced by enhanced marine production.

2199Cardiovascular risk behaviour is an emerging health issue in developing countries

Background

Previously, cardiovascular disease (CVD) was considered the “Disease of the Rich”, however nowadays also populations with low socioeconomic status have been identified at increased risk of developing CVD. The global progress in CVD prevention is scarce particularly in developing countries, which are facing a high burden of CVD whilst there is limited availability of resources and evidence to educate and modify lifestyle behaviours in the population. Moreover, there is a lack of infrastructure and policy making in these countries.

Purpose

The goal of the study was to quantify the prevalence of different cardiovascular risk behaviours among patients with known cardiovascular conditions in a developing countries.

Methods

A hospital based cross-sectional survey was conducted in two referral hospitals in Ethiopia. Outpatient unit patients who had a confirmed diagnosis of CVD were eligible for participation in the study. Data were collected through face-to-face interviews with patients using validated tools; WHO STEPs instrument and international physical activity questionnaire.

Results

A total of 287 CVD patients were recruited, 56% were females and 90% were urban residents. All patients had inadequate consumption of fruit and vegetables, 20% were current khat chewers, 19% were current alcohol drinkers and only 1% were current smokers. The prevalence of low physical activity (defined as less than 600 MET-minutes per week) in the total population was 51.6% for both sexes; more than half of the total population were physically inactive. Moreover, females had a significantly higher prevalence of physical inactivity as compared to males, 58% vs 43.2%, P=0.017. Approximately one-third (30%) of patients had only one of these risk behaviours, more than half (52%) had two, 18% had three or more risk behaviours. The majority (70%) of the patients had multiple risk behaviours (Table 1), the prevalence of these did not significantly vary with sex, residence and educational level (p>0.05).

Conclusion

Patients with CVD maintain unhealthy lifestyles even though attending follow up care with a specific focus on risk management. The findings of this study demonstrate a high prevalence of physical inactivity, alcohol consumption and inadequate fruit and vegetable consumption in developing countries. The emerging increase of CVD and the continuation of unhealthy lifestyle in patients is somewhat comparable with western countries, demonstrating an emerging global problem. Moreover, this study shows the existing follow-up care is ineffective and provides evidence for policy makers that health services reform is required. Implementation of lifestyle support programs should be considered for the disease prevention policy agenda in developing countries.

The lived experience: Nurses' experience of caring for patients with a traumatic spinal cord injury

BACKGROUND

Nurses are involved in delivering care for patients following acute traumatic spinal cord injury throughout the entire care journey. An injury of this type is significant for the individual and their family and can be challenging for nurses delivering care for patients with life changing injuries, especially for nurses new to this setting. There is a lack of research that examines the experience of nurses caring for these patients in the acute setting.

METHOD

A hermeneutic phenomenological approach was used to understand the experience of nurses caring for patients in the acute setting who had sustained a traumatic spinal injury with associated neurological deficit. Using the phenomenological approach guided by the insight of Gadamer and Max Van Manen, participants with a broad range of experience were recruited and interviewed. The responses were transcribed into a text and subjected to hermeneutic analysis. Burnard's (1991) 14-step process and the hermeneutic approach were used to interpret and understand the phenomenon of interest.

CONCLUSION

The study highlights the experience and challenges of providing care to these individuals. Although patients had significant physical disabilities and were often dependent physically, the nurses' concerns were directed more towards fulfilling their psychological needs. Nurses identified grieving patients and felt their role was to provide realistic hope to motivate them. They felt an internal tension regarding desensitisation towards their patients, but this was often an internal protective mechanism to deal with the significance of the events surrounding these patients. Nurses new to this setting took time to learn the routines and manage the unique challenges effectively. Caring for these patients gave the nurses the opportunity to understand their patients and their families, and appreciate that both groups will fluctuate in their behavior throughout the acute process, as they adjust to grief and loss.

Parks After Dark Evaluation Brief

Parks after Dark is a Los Angeles County (County) program that began in 2010 as the primary prevention strategy of the County's Gang Violence Reduction Initiative. It has since evolved into a key County strategy to promote health, safety, equity, and community well-being. Led by the Department of Parks and Recreation (DPR), PAD is a collaboration of multiple County departments as well as community agencies. PAD was designed to be implemented in communities with higher rates of violence, economic hardship, and obesity. On average, PAD communities have greater levels of need across these three areas than Los Angeles County as a whole. PAD parks stay open late on Thursday, Friday, and Saturday evenings in the summer months to offer a variety of free activities for people of all ages. PAD provides recreational activities (e.g., sports clinics, exercise classes, and walking clubs), entertainment (concerts, movies, and talent shows), arts and educational programs (arts and crafts, computer classes, and cultural programs), teen clubs and activities, and health and social service resource fairs. Los Angeles County Sheriff’s Department (LASD) Deputy Sheriffs patrol the parks to ensure safety during PAD and participate in activities with community members. The PAD program began in three parks in 2010. In 2012, it expanded to six parks, and in 2015 to nine parks. In 2016, the program was being implemented in 21 parks throughout Los Angeles County.

Hemoglobin mass and intravascular volume kinetics during and after exposure to 3,454-m altitude

High altitude (HA) exposure facilitates a rapid contraction of plasma volume (PV) and a slower occurring expansion of hemoglobin mass (Hbmass). The kinetics of the Hbmass expansion has never been examined by multiple repeated measurements, and this was our primary study aim. The second aim was to investigate the mechanisms mediating the PV contraction. Nine healthy, normally trained sea-level (SL) residents (8 males, 1 female) sojourned for 28 days at 3,454 m. Hbmass was measured and PV was estimated by carbon monoxide rebreathing at SL, on every 4th day at HA, and 1 and 2 wk upon return to SL. Four weeks at HA increased Hbmass by 5.26% (range 2.5-11.1%; P < 0.001). The individual Hbmass increases commenced with up to 12 days of delay and reached a maximal rate of 4.04 ± 1.02 g/day after 14.9 ± 5.2 days. The probability for Hbmass to plateau increased steeply after 20–24 days. Upon return to SL Hbmass decayed by −2.46 ± 2.3 g/day, reaching values similar to baseline after 2 wk. PV, aldosterone concentration, and renin activity were reduced at HA ( P < 0.001) while the total circulating protein mass remained unaffected. In summary, the Hbmass response to HA exposure followed a sigmoidal pattern with a delayed onset and a plateau after ∼3 wk. The decay rate of Hbmass upon descent to SL did not indicate major changes in the rate of erythrolysis. Moreover, our data support that PV contraction at HA is regulated by the renin-angiotensin-aldosterone axis and not by changes in oncotic pressure.

Hypoxia increases exercise heart rate despite combined inhibition of β-adrenergic and muscarinic receptors

Hypoxia increases the heart rate response to exercise, but the mechanism(s) remains unclear. We tested the hypothesis that the tachycardic effect of hypoxia persists during separate, but not combined, inhibition of β-adrenergic and muscarinic receptors. Nine subjects performed incremental exercise to exhaustion in normoxia and hypoxia (fraction of inspired O2 = 12%) after intravenous administration of 1) no drugs (Cont), 2) propranolol (Prop), 3) glycopyrrolate (Glyc), or 4) Prop + Glyc. HR increased with exercise in all drug conditions ( P < 0.001) but was always higher at a given workload in hypoxia than normoxia ( P < 0.001). Averaged over all workloads, the difference between hypoxia and normoxia was 19.8 ± 13.8 beats/min during Cont and similar (17.2 ± 7.7 beats/min, P = 0.95) during Prop but smaller ( P < 0.001) during Glyc and Prop + Glyc (9.8 ± 9.6 and 8.1 ± 7.6 beats/min, respectively). Cardiac output was enhanced by hypoxia ( P < 0.002) to an extent that was similar between Cont, Glyc, and Prop + Glyc (2.3 ± 1.9, 1.7 ± 1.8, and 2.3 ± 1.2 l/min, respectively, P > 0.4) but larger during Prop (3.4 ± 1.6 l/min, P = 0.004). Our results demonstrate that the tachycardic effect of hypoxia during exercise partially relies on vagal withdrawal. Conversely, sympathoexcitation either does not contribute or increases heart rate through mechanisms other than β-adrenergic transmission. A potential candidate is α-adrenergic transmission, which could also explain why a tachycardic effect of hypoxia persists during combined β-adrenergic and muscarinic receptor inhibition.

Development of temporally refined land-use regression models predicting daily household-level air pollution in a panel study of lung function among asthmatic children

Regulatory monitoring data and land-use regression (LUR) models have been widely used for estimating individual exposure to ambient air pollution in epidemiologic studies. However, LUR models lack fine-scale temporal resolution for predicting acute exposure and regulatory monitoring provides daily concentrations, but fails to capture spatial variability within urban areas. This study coupled LUR models with continuous regulatory monitoring to predict daily ambient nitrogen dioxide (NO(2)) and particulate matter (PM(2.5)) at 50 homes in Windsor, Ontario. We compared predicted versus measured daily outdoor concentrations for 5 days in winter and 5 days in summer at each home. We also examined the implications of using modeled versus measured daily pollutant concentrations to predict daily lung function among asthmatic children living in those homes. Mixed effect analysis suggested that temporally refined LUR models explained a greater proportion of the spatial and temporal variance in daily household-level outdoor NO(2) measurements compared with daily concentrations based on regulatory monitoring. Temporally refined LUR models captured 40% (summer) and 10% (winter) more of the spatial variance compared with regulatory monitoring data. Ambient PM(2.5) showed little spatial variation; therefore, daily PM(2.5) models were similar to regulatory monitoring data in the proportion of variance explained. Furthermore, effect estimates for forced expiratory volume in 1 s (FEV(1)) and peak expiratory flow (PEF) based on modeled pollutant concentrations were consistent with effects based on household-level measurements for NO(2) and PM(2.5). These results suggest that LUR modeling can be combined with continuous regulatory monitoring data to predict daily household-level exposure to ambient air pollution. Temporally refined LUR models provided a modest improvement in estimating daily household-level NO(2) compared with regulatory monitoring data alone, suggesting that this approach could potentially improve exposure estimation for spatially heterogeneous pollutants. These findings have important implications for epidemiologic studies - in particular, for research focused on short-term exposure and health effects.

Four weeks of normobaric "live high-train low" do not alter muscular or systemic capacity for maintaining pH and K⁺ homeostasis during intense exercise

It was investigated if athletes subjected to 4 wk of living in normobaric hypoxia (3,000 m; 16 h/day) while training at 800-1,300 m ["live high-train low" (LHTL)] increase muscular and systemic capacity for maintaining pH and K(+) homeostasis as well as intense exercise performance. The design was double-blind and placebo controlled. Mean power during 30-s all-out cycling was similar before and immediately after LHTL (650 ± 31 vs. 628 ± 32 W; n = 10) and placebo exposure (658 ± 22 vs. 660 ± 23 W; n = 6). Supporting the performance data, arterial plasma pH, lactate, and K(+) during submaximal and maximal exercise were also unaffected by the intervention in both groups. In addition, muscle buffer capacity (in mmol H(+)·kg dry wt(-1)·pH(-1)) was similar before and after in both the LHTL (140 ± 12 vs. 140 ± 16) and placebo group (145 ± 2 vs. 140 ± 3). The expression of sarcolemmal H(+) transporters (Na(+)/H(+) exchanger 1, monocarboxylate transporters 1 and 4), as well as expression of Na(+)-K(+) pump subunits-α(1), -α(2), and -β(1) was also similar before and after the intervention. In conclusion, muscular and systemic capacity for maintaining pH and K(+) balance during exercise is similar before and after 4 wk of placebo-controlled normobaric LHTL. In accordance, 30-s all-out sprint ability was similar before and after LHTL.

Preliminary experience with external hemipelvectomy for locally advanced and recurrent pelvic carcinoma

AIM

Eight highly selected patients are reported, undergoing external hemipelvectomy (EHP) for malignant infiltration of the lumbosacral neural plexus.

METHOD

All patients were evaluated by positron emission tomography-computed tomography (PET-CT), CT and magnetic resonance imaging. No evidence of disseminated disease was found. With agreement by the multidisciplinary team, surgery was performed by a colorectal surgeon and an orthopaedic sarcoma surgeon and, if needed, by an urologist and vascular surgeon. Patients were reconstructed with either a femoral or a gluteal musculocutaneous flap.

RESULTS

Of the eight women [median age 54.5 (40-68) years], two had primary carcinoma and six local recurrence of a previously treated carcinoma. R0 was possible in six patients and R1 resection in two. The median duration of hospital stay was 29.5 (17-102) days. The median follow up was 8.3 (4.7-52.8) months. Three patients have died, one from postoperative complications at 5 months and two from recurrence at 5 and 52.8 months. Phantom-limb was experienced in six patients. Four patients received a prosthesis, one is considering this and one does not want a prosthesis.

CONCLUSION

Hemipelvectomy may be considered for a highly selected group of patients with locally advanced carcinoma or recurrence involving the lumbosacral neural plexus.

Determinants of time trial performance and maximal incremental exercise in highly trained endurance athletes

Human endurance performance can be predicted from maximal oxygen consumption (Vo(2max)), lactate threshold, and exercise efficiency. These physiological parameters, however, are not wholly exclusive from one another, and their interplay is complex. Accordingly, we sought to identify more specific measurements explaining the range of performance among athletes. Out of 150 separate variables we identified 10 principal factors responsible for hematological, cardiovascular, respiratory, musculoskeletal, and neurological variation in 16 highly trained cyclists. These principal factors were then correlated with a 26-km time trial and test of maximal incremental power output. Average power output during the 26-km time trial was attributed to, in order of importance, oxidative phosphorylation capacity of the vastus lateralis muscle (P = 0.0005), steady-state submaximal blood lactate concentrations (P = 0.0017), and maximal leg oxygenation (sO(2LEG)) (P = 0.0295), accounting for 78% of the variation in time trial performance. Variability in maximal power output, on the other hand, was attributed to total body hemoglobin mass (Hb(mass); P = 0.0038), Vo(2max) (P = 0.0213), and sO(2LEG) (P = 0.0463). In conclusion, 1) skeletal muscle oxidative capacity is the primary predictor of time trial performance in highly trained cyclists; 2) the strongest predictor for maximal incremental power output is Hb(mass); and 3) overall exercise performance (time trial performance + maximal incremental power output) correlates most strongly to measures regarding the capability for oxygen transport, high Vo(2max) and Hb(mass), in addition to measures of oxygen utilization, maximal oxidative phosphorylation, and electron transport system capacities in the skeletal muscle.

In humans IL-6 is released from the brain during and after exercise and paralleled by enhanced IL-6 mRNA expression in the hippocampus of mice

AIM

Plasma interleukin-6 (IL-6) increases during exercise by release from active muscles and during prolonged exercise also from the brain. The IL-6 release from muscles continues into recovery and we tested whether the brain also releases IL-6 in recovery from prolonged exercise in humans. Additionally, it was evaluated in mice whether brain release of IL-6 reflected enhanced IL-6 mRNA expression in the brain as modulated by brain glycogen levels.

METHODS

Nine healthy male subjects completed 4 h of ergometer rowing while the arterio-jugular venous difference (a-v diff) for IL-6 was determined. The IL-6 mRNA and the glycogen content were determined in mouse hippocampus, cerebellum and cortex before and after 2 h treadmill running (N = 8).

RESULTS

At rest, the IL-6 a-v diff was negligible but decreased to -2.2 ± 1.9 pg ml(-1) at the end of exercise and remained low (-2.1 ± 2.1 pg ml(-1) ) 1 h into the recovery (P < 0.05 vs. rest). IL-6 mRNA was expressed in the three parts of the brain with the lowest content in the hippocampus (P < 0.05) coupled to the highest glycogen content (3.2 ± 0.8 mmol kg(-1) ). Treadmill running increased the hippocampal IL-6 mRNA content 2-3-fold (P < 0.05), while the hippocampal glycogen content decreased to 2.6 ± 0.6 mmol kg(-1) (P < 0.05) with no significant changes in the two other parts of the brain.

CONCLUSION

Human brain releases IL-6 both during and in recovery from prolonged exercise and mouse data suggest that concurrent changes in IL-6 mRNA and glycogen levels make the hippocampus a likely source of the IL-6 release from the brain.

The carotid baroreflex is reset following prolonged exercise in humans

AIM

Alterations in the carotid baroreflex (CBR) control of arterial pressure may explain the reduction in arterial pressure and left ventricular (LV) function after prolonged exercise. We examined the CBR control of heart rate (HR) and mean arterial pressure (MAP), in addition to changes in LV function, pre- to post-exercise.

METHODS

Seven males (age, mean ± SEM; 29 ± 4 years) completed 4 h of ergometer rowing at a workload of 10-15% below the lactate threshold. The CBR control of HR and MAP was assessed via the rapid neck-suction/pressure protocol. LV systolic function was measured by echocardiography, where ejection fraction (EF), the ratio of systolic blood pressure to end systolic volume (SBP/ESV) and stroke volume (SV) were estimated.

RESULTS

Following exercise MAP was reduced (12 ± 3%) and HR was elevated (35 ± 5%; P < 0.05). Furthermore, CBR control of MAP was relocated to the left on the stimulus-response curve (P < 0.05) demonstrating that the CBR operated around a lower arterial pressure. Concomitantly, LV systolic function was reduced, indicated by a decrease in EF (22 ± 2%), SBP/ESV (32 ± 14%) and SV (25 ± 5%, P < 0.05). The reduced EF and SBP/ESV were associated with the decreased MAP operating point (r² = 0.71 and r² = 0.47, respectively, P < 0.05).

CONCLUSION

The CBR is reset after prolonged exercise to a lower prevailing arterial pressure. This resetting of the CBR may contribute to the reduction arterial pressure and LV function after exercise.

Plasma pH does not influence the cerebral metabolic ratio during maximal whole body exercise

Exercise lowers the cerebral metabolic ratio of O2 to carbohydrate (glucose+1/2 lactate) and metabolic acidosis appears to promote cerebral lactate uptake. However, the influence of pH on cerebral lactate uptake and, in turn, on the cerebral metabolic ratio during exercise is not known. Sodium bicarbonate (Bicarb, 1 M; 350-500 ml) or an equal volume of normal saline (Sal) was infused intravenously at a constant rate during a '2000 m' maximal ergometer row in six male oarsmen (23±2 years; mean±S.D.). During the Sal trial, pH decreased from 7.41±0.01 at rest to 7.02±0.02 but only to 7.36±0.02 (P <0.05) during the Bicarb trial. Arterial lactate increased to 21.4±0.8 and 32.7±2.3 mM during the Sal and Bicarb trials, respectively (P <0.05). Also, the arterial-jugular venous lactate difference increased from-0.03±0.01 mM at rest to 3.2±0.9 mM (P <0.05) and 3.4±1.4 mM (P <0.05) following the Sal and Bicarb trials, respectively. Accordingly, the cerebral metabolic ratio decreased equally during the Sal and Bicarb trials: from 5.8±0.6 at rest to 1.7±0.1 and 1.8±0.2, respectively. The enlarged blood-buffering capacity after infusion of Bicarb eliminated metabolic acidosis during maximal exercise but that did not affect the cerebral lactate uptake and, therefore, the decrease in the cerebral metabolic ratio.

Simultaneous quantitation of parabens, triclosan, and methyl triclosan in indoor house dust using solid phase extraction and gas chromatography-mass spectrometry

An integrated analytical method for the simultaneous determination of five parabens (methyl-, ethyl-, propyl-, butyl-, and benzyl-), triclosan, and methyl triclosan in indoor house dust was developed based on gas chromatographic-mass spectrometric technique (GC/MS). Analytes were extracted from dust samples by sonication. After sample cleanup by solid-phase extraction (SPE), the extracts were derivatized with N-methyl-N-(trimethylsilyl)trifluoroacetamide (MSTFA) and then analyzed by gas chromatography coupled with ion trap mass spectrometry operated in multiple reaction monitoring (MRM) mode. For quantitation, isotope-labelled internal standards were used for each corresponding target analyte. Only 0.05 g of dust sample was needed for the analysis. Method detection limits ranged from 6.5 to 10 ng/g, and absolute recoveries from 74% to 92%. The developed method demonstrated good repeatability and reproducibility, with relative standard deviations (RSDs) less than 16% for all the analytes. The analytes were determined in dust samples collected using two vacuum sampling methods from 63 Canadian homes: a sample of fresh or "active" dust (FD) collected using a Pullman-Holt vacuum sampler, and a composite sample taken from the household vacuum cleaner (HD). Methyl paraben, propyl paraben, and triclosan were detected in all HD and FD samples. HD samples yielded median values for methyl paraben, propyl paraben, and triclosan of 1080, 463, and 378 ng/g, respectively, which were comparable to the FD sample medians of 1120, 618 and 571 ng/g. Ethyl paraben was detected at frequencies of 89% in FD and 73% in HD samples, with median values of 52 and 25 ng/g, respectively. Butyl paraben was detected at frequencies of 44% in FD and 75% in HD samples, with median values of <10 and 59 ng/g, respectively. Benzyl paraben and methyl triclosan were not detected in any of the samples collected by either method. Samples collected according to the fresh dust protocol agreed with the household vacuum samples 90% of the time. Widely scattered concentration levels were observed for target analytes from this preliminary set of 63 Canadian samples, which suggests a wide variability in Canadian household exposures to these chemicals.

Effects of erythropoietin administration on cerebral metabolism and exercise capacity in men

Recombinant human erythropoietin (EPO) increases exercise capacity by stimulating erythropoiesis and subsequently enhancing oxygen delivery to the working muscles. In a large dose, EPO crosses the BBB and may reduce central fatigue and improve cognition. In turn, this would augment exercise capacity independent of erythropoiesis. To test this hypothesis, 15 healthy young men (18–34 years old, 74 ± 7 kg) received either 3 days of high-dose (30,000 IU/day; n = 7) double-blinded placebo controlled or 3 mo of low-dose (5,000 IU/wk; n = 8) counter-balanced open but controlled administration of EPO. We recorded exercise capacity, transcranial ultrasonography-derived middle cerebral artery blood velocity, and arterial-internal jugular venous concentration differences of glucose and lactate. In addition, cognitive function, ratings of perceived exertion, ventilation, and voluntary activation by transcranial magnetic stimulation-induced twitch force were evaluated. Although EPO in a high dose increased cerebrospinal fluid EPO concentration ∼20-fold and affected ventilation and cerebral glucose and lactate metabolism ( P < 0.05), 3 days of high-dose EPO administration had no effect on cognition, voluntary activation, or exercise capacity, but ratings of perceived exertion increased ( P < 0.05). We confirmed that 3 mo of administration of EPO increases exercise capacity, but the improvement could not be accounted for by other mechanisms than enhanced oxygen delivery. In conclusion, EPO does not attenuate central fatigue or change cognitive performance strategy, suggesting that EPO enhances exercise capacity exclusively by increased oxygen delivery to the working muscles.

Cerebral oxygenation is reduced during hyperthermic exercise in humans

AIM

Cerebral mitochondrial oxygen tension (P(mito)O(2)) is elevated during moderate exercise, while it is reduced when exercise becomes strenuous, reflecting an elevated cerebral metabolic rate for oxygen (CMRO(2)) combined with hyperventilation-induced attenuation of cerebral blood flow (CBF). Heat stress challenges exercise capacity as expressed by increased rating of perceived exertion (RPE).

METHODS

This study evaluated the effect of heat stress during exercise on P(mito)O(2) calculated based on a Kety-Schmidt-determined CBF and the arterial-to-jugular venous oxygen differences in eight males [27 +/- 6 years (mean +/- SD) and maximal oxygen uptake (VO(2max)) 63 +/- 6 mL kg(-1) min(-1)].

RESULTS

The CBF, CMRO(2) and P(mito)O(2) remained stable during 1 h of moderate cycling (170 +/- 11 W, approximately 50% of VO(2max), RPE 9-12) in normothermia (core temperature of 37.8 +/- 0.4 degrees C). In contrast, when hyperthermia was provoked by dressing the subjects in watertight clothing during exercise (core temperature 39.5 +/- 0.2 degrees C), P(mito)O(2) declined by 4.8 +/- 3.8 mmHg (P < 0.05 compared to normothermia) because CMRO(2) increased by 8 +/- 7% at the same time as CBF was reduced by 15 +/- 13% (P < 0.05). During exercise with heat stress, RPE increased to 19 (19-20; P < 0.05); the RPE correlated inversely with P(mito)O(2) (r(2) = 0.42, P < 0.05).

CONCLUSION

These data indicate that strenuous exercise in the heat lowers cerebral P(mito)O(2), and that exercise capacity in this condition may be dependent on maintained cerebral oxygenation.

Reduced muscle activation during exercise related to brain oxygenation and metabolism in humans

Maximal exercise may be limited by central fatigue defined as an inability of the central nervous system to fully recruit the involved muscles. This study evaluated whether a reduction in the cerebral oxygen-to-carbohydrate index (OCI) and in the cerebral mitochondrial oxygen tension relate to the ability to generate a maximal voluntary contraction and to the transcranial magnetic stimulated force generation. To determine the role of a reduced OCI and in central fatigue, 16 males performed low intensity, maximal intensity and hypoxic cycling exercise. Exercise fatigue was evaluated by ratings of perceived exertion (RPE), arm maximal voluntary force (MVC), and voluntary activation of elbow flexor muscles assessed with transcranial magnetic stimulation. Low intensity exercise did not produce any indication of central fatigue or marked cerebral metabolic deviations. Exercise in hypoxia (0.10) reduced cerebral oxygen delivery 25% and decreased 11+/-4 mmHg (P<0.001) together with OCI (6.2+/-0.7 to 4.8+/-0.5, P<0.001). RPE increased while MVC and voluntary activation were reduced (P<0.05). During maximal exercise declined 8+/-4 mmHg (P<0.05) and OCI to 3.8+/-0.5 (P<0.001). RPE was 18.5, and MVC and voluntary activation were reduced (P<0.05). We observed no signs of muscular fatigue in the elbow flexors and all control MVCs were similar to resting values. Exhaustive exercise provoked cerebral deoxygenation, metabolic changes and indices of fatigue similar to those observed during exercise in hypoxia indicating that reduced cerebral oxygenation may play a role in the development of central fatigue and may be an exercise capacity limiting factor.

Reporting standards for endovascular repair of saccular intracranial cerebral aneurysms

BACKGROUND AND PURPOSE

The goal of this article is to provide consensus recommendations for reporting standards, terminology, and written definitions when reporting on the radiological evaluation and endovascular treatment of intracranial, cerebral aneurysms. These criteria can be used to design clinical trials, to provide uniformity of definitions for appropriate selection and stratification of patients, and to allow analysis and meta-analysis of reported data.

METHODS

This article was written under the auspices of the Joint Writing Group of the Technology Assessment Committee, Society of NeuroInterventional Surgery, Society of Interventional Radiology; Joint Section on Cerebrovascular Neurosurgery of the American Association of Neurological Surgeons and Congress of Neurological Surgeons; and Section of Stroke and Interventional Neurology of the American Academy of Neurology. A computerized search of the National Library of Medicine database of literature (PubMed) from January 1991 to December 2007 was conducted with the goal to identify published endovascular cerebrovascular interventional data about the assessment and endovascular treatment of cerebral aneurysms useful as benchmarks for quality assessment. We sought to identify those risk adjustment variables that affect the likelihood of success and complications. This article offers the rationale for different clinical and technical considerations that may be important during the design of clinical trials for endovascular treatment of cerebral aneurysms. Included in this guidance article are suggestions for uniform reporting standards for such trials. These definitions and standards are primarily intended for research purposes; however, they should also be helpful in clinical practice and applicable to all publications.

CONCLUSIONS

The evaluation and treatment of brain aneurysms often involve multiple medical specialties. Recent reviews by the American Heart Association have surveyed the medical literature to develop guidelines for the clinical management of ruptured and unruptured cerebral aneurysms. Despite efforts to synthesize existing knowledge on cerebral aneurysm evaluation and treatment, significant inconsistencies remain in nomenclature and definition for research and reporting purposes. These operational definitions were selected by consensus of a multidisciplinary writing group to provide consistency for reporting on imaging in clinical trials and observational studies involving cerebral aneurysms. These definitions should help different groups to publish results that are directly comparable.

Relationship between stroke volume, cardiac output and filling of the heart during tilt

BACKGROUND

Cardiac function curves are widely accepted to apply to humans but are not established for the entire range of filling of the heart that can be elicited during head-up (HUT) and head-down tilt (HDT), taken to represent minimal and maximal physiological filling of the heart, respectively. With the supine resting position as a reference, we assessed stroke volume (SV), cardiac output (CO) and filling of the heart during graded tilt to evaluate whether SV and CO are maintained during an assumed maximal physiological filling of the heart elicited by 90 degrees HDT in healthy resting humans.

METHODS

In 26 subjects, central blood volume was manipulated with graded tilt from 60 degrees HUT to 90 degrees HDT. We measured SV, CO (Finometer) and cardiac filling by echocardiography of the left ventricular end-diastolic volume (LVEDV; n=12).

RESULTS

From supine rest to 60 degrees HUT, SV and CO decreased 23 ml [confidence intervals (CI): 16-30; P<0.001; 23%] and 0.9 l/min (0.4-1.4; P<0.0001; 14%), respectively, but neither SV nor CO changed during HDT up to 70 degrees . However, during 90 degrees HDT, SV decreased 12 ml (CI: 6-19; P<0.0001; 12%), with an increase of 21 ml (9-33; P=0.002; 16%) in LVEDV because HR increased 3 bpm and CO decreased 0.5 l/min (ns).

CONCLUSION

This study confirmed that SV and CO are maximal in resting, supine, healthy humans and decrease during HUT. However, 90 degrees HDT was associated with increased LVEDV and induced a reduction in SV.

Cerebral oxygenation and metabolism during exercise following three months of endurance training in healthy overweight males

Endurance training improves muscular and cardiovascular fitness, but the effect on cerebral oxygenation and metabolism remains unknown. We hypothesized that 3 mo of endurance training would reduce cerebral carbohydrate uptake with maintained cerebral oxygenation during submaximal exercise. Healthy overweight males were included in a randomized, controlled study (training: n = 10; control: n = 7). Arterial and internal jugular venous catheterization was used to determine concentration differences for oxygen, glucose, and lactate across the brain and the oxygen-carbohydrate index [molar uptake of oxygen/(glucose + (1/2) lactate); OCI], changes in mitochondrial oxygen tension (DeltaP(Mito)O(2)) and the cerebral metabolic rate of oxygen (CMRO(2)) were calculated. For all subjects, resting OCI was higher at the 3-mo follow-up (6.3 +/- 1.3 compared with 4.7 +/- 0.9 at baseline, mean +/- SD; P < 0.05) and coincided with a lower plasma epinephrine concentration (P < 0.05). Cerebral adaptations to endurance training manifested when exercising at 70% of maximal oxygen uptake (approximately 211 W). Before training, both OCI (3.9 +/- 0.9) and DeltaP(Mito)O(2) (-22 mmHg) decreased (P < 0.05), whereas CMRO(2) increased by 79 +/- 53 micromol x 100 x g(-1) min(-1) (P < 0.05). At the 3-mo follow-up, OCI (4.9 +/- 1.0) and DeltaP(Mito)O(2) (-7 +/- 13 mmHg) did not decrease significantly from rest and when compared with values before training (P < 0.05), CMRO(2) did not increase. This study demonstrates that endurance training attenuates the cerebral metabolic response to submaximal exercise, as reflected in a lower carbohydrate uptake and maintained cerebral oxygenation.

Cerebral oxygenation decreases during exercise in humans with beta-adrenergic blockade

AIM

Beta-blockers reduce exercise capacity by attenuated increase in cardiac output, but it remains unknown whether performance also relates to attenuated cerebral oxygenation.

METHODS

Acting as their own controls, eight healthy subjects performed a continuous incremental cycle test to exhaustion with or without administration of the non-selective beta-blocker propranolol. Changes in cerebral blood flow velocity were measured with transcranial Doppler ultrasound and those in cerebral oxygenation were evaluated using near-infrared spectroscopy and the calculated cerebral mitochondrial oxygen tension derived from arterial to internal jugular venous concentration differences.

RESULTS

Arterial lactate and cardiac output increased to 15.3 +/- 4.2 mM and 20.8 +/- 1.5 L min(-1) respectively (mean +/- SD). Frontal lobe oxygenation remained unaffected but the calculated cerebral mitochondrial oxygen tension decreased by 29 +/- 7 mmHg (P < 0.05). Propranolol reduced resting heart rate (58 +/- 6 vs. 69 +/- 8 beats min(-1)) and at exercise exhaustion, cardiac output (16.6 +/- 3.6 L min(-1)) and arterial lactate (9.4 +/- 3.7 mM) were attenuated with a reduction in exercise capacity from 239 +/- 42 to 209 +/- 31 W (all P < 0.05). Propranolol also attenuated the increase in cerebral blood flow velocity and frontal lobe oxygenation (P < 0.05) whereas the cerebral mitochondrial oxygen tension decreased to a similar degree as during control exercise (delta 28 +/- 10 mmHg; P < 0.05).

CONCLUSION

Propranolol attenuated the increase in cardiac output of consequence for cerebral perfusion and oxygenation. We suggest that a decrease in cerebral oxygenation limits exercise capacity.

Mantle cell lymphoma in the orbital and adnexal region

AIMS

To characterise clinicopathological features of mantle cell lymphoma (MCL) in the orbital and adnexal region.

METHODS

Data on lymphoid lesions were retrieved searching the Danish Ocular Lymphoma Database 1980-2005. Specimens were collected from Danish pathological departments and re-evaluated with a panel of monoclonal antibodies. For all patients with confirmed MCL the complete clinical files were collected and reviewed.

RESULTS

Twenty-one patients with MCL in the orbital and adnexal region were identified comprising 9% (21/230) of all lymphoma in the ocular region. There were 18 male patients and three female patients with an age range from 60 to 90 years (median 75 years). Orbital and adnexal region MCL as first presenting symptom comprised 67% of the patients. Of these, 71% had bilateral involvement. The orbit (71%) and eyelids (64%) were the most commonly affected sites. All but two presented in stage III/IV. Secondary MCL comprised 33% of the patients. Bilateral affection (29%) was less common in this patient group. The median survival was not different between the two presentation groups. Patients receiving anti-CD20 (rituximab)-containing chemotherapy had a significantly better 5-year overall survival (OS) rate (83%) than patients in treatment regimes without rituximab (5-year OS rate, 8%).

CONCLUSIONS

Orbital and adnexal region MCL presents in elderly males. The orbit and eyelid are frequently involved. There is a very high proportion of systemic involvement in general with MCL of the orbital and adnexal region. Most patients presented with stage IV disease and had multiple relapses and short survival time. Treatment with rituximab-containing chemotherapy improved survival significantly compared with combination chemotherapy without rituximab.

Does recombinant human Epo increase exercise capacity by means other than augmenting oxygen transport?

This study was performed to test the hypothesis that administration of recombinant human erythropoietin (rHuEpo) in humans increases maximal oxygen consumption by augmenting the maximal oxygen carrying capacity of blood. Systemic and leg oxygen delivery and oxygen uptake were studied during exercise in eight subjects before and after 13 wk of rHuEpo treatment and after isovolemic hemodilution to the same hemoglobin concentration observed before the start of rHuEpo administration. At peak exercise, leg oxygen delivery was increased from 1,777.0 ± 102.0 ml/min before rHuEpo treatment to 2,079.8 ± 120.7 ml/min after treatment. After hemodilution, oxygen delivery was decreased to the pretreatment value (1,710.3 ± 138.1 ml/min). Fractional leg arterial oxygen extraction was unaffected at maximal exercise; hence, maximal leg oxygen uptake increased from 1,511.0 ± 130.1 ml/min before treatment to 1,793.0 ± 148.7 ml/min with rHuEpo and decreased after hemodilution to 1,428.0 ± 111.6 ml/min. Pulmonary oxygen uptake at peak exercise increased from 3,950.0 ± 160.7 before administration to 4,254.5 ± 178.4 ml/min with rHuEpo and decreased to 4,059.0 ± 161.1 ml/min with hemodilution ( P = 0.22, compared with values before rHuEpo treatment). Blood buffer capacity remained unaffected by rHuEpo treatment and hemodilution. The augmented hematocrit did not compromise peak cardiac output. In summary, in healthy humans, rHuEpo increases maximal oxygen consumption due to augmented systemic and muscular peak oxygen delivery.