Social network analysis reveals the failure of between-farm movement restrictions to reduce Salmonella transmission.

An increasing number of countries are investigating options to stop the spread of the emerging zoonotic infection Salmonella (S.) Dublin, which mainly spreads among bovines and with cattle manure. Detailed surveillance and cattle movement data from an 11-year period in Denmark provided an opportunity to gain new knowledge for mitigation options through a combined social network and simulation modeling approach. The analysis revealed similar network trends for non-infected and infected cattle farms despite stringent cattle movement restrictions imposed on infected farms in the national control program. The strongest predictive factor for farms becoming infected was their cattle movement activities in the previous month, with twice the effect of local transmission. The simulation model indicated an endemic S. Dublin occurrence, with peaks in outbreak probabilities and sizes around observed cattle movement activities. Therefore, pre- and post-movement measures within a 1-mo time-window may help reduce S. Dublin spread.

Rare earth elements and select actinoids in the Canadian House Dust Study.

Nationally representative baseline data are presented for rare earth elements (REE), thorium (Th) and uranium (U) in house dust sampled from 1025 urban homes, in units of concentrations (µg g-1 ), loadings (µg m-2 ), and loading rates (ng m-2  d-1 ). Spearman rank correlations indicate that, in addition to outdoor sources, consumer products and building materials can influence indoor dust concentrations of REE, Th, and U. Correlations (P<.01) with numbers of occupants, dogs, and cats suggest soil track-in. Correlations (P<.01) with hardwood floors suggest release of REE additives used in pigments and coatings during daily wear and tear. Concentrations of light REE are elevated in smokers' homes compared to non-smokers' homes (P<.001), suggesting that a key source is "mischmetal," the REE alloy used in cigarette-lighter flints. Indoor sources include geological impurities in raw materials used in consumer products, such as U and Th impurities in bentonite clay used in cat litter, and REE impurities in phosphates used for a variety of applications including dog food and building materials. Median gastric bioaccessibility (pH 1.5) of most REE in dust ranges from about 20% to 29%. Household vacuum samples correlate with fresh dust samples from the same homes (P<.001 for all investigated elements).

Hypoxia increases exercise heart rate despite combined inhibition of ß-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 ß-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 ß-adrenergic transmission. A potential candidate is α-adrenergic transmission, which could also explain why a tachycardic effect of hypoxia persists during combined ß-adrenergic and muscarinic receptor inhibition.

Cardiac output during exercise: a comparison of four methods.

Several techniques assessing cardiac output (Q) during exercise are available. The extent to which the measurements obtained from each respective technique compares to one another, however, is unclear. We quantified Q simultaneously using four methods: the Fick method with blood obtained from the right atrium (Q(Fick-M)), Innocor (inert gas rebreathing; Q(Inn)), Physioflow (impedance cardiography; Q(Phys)), and Nexfin (pulse contour analysis; Q(Pulse)) in 12 male subjects during incremental cycling exercise to exhaustion in normoxia and hypoxia (FiO2 = 12%). While all four methods reported a progressive increase in Q with exercise intensity, the slopes of the Q/oxygen uptake (VO2) relationship differed by up to 50% between methods in both normoxia [4.9 ± 0.3, 3.9 ± 0.2, 6.0 ± 0.4, 4.8 ± 0.2 L/min per L/min (mean ± SE) for Q(Fick-M), Q(Inn), QP hys and Q(Pulse), respectively; P = 0.001] and hypoxia (7.2 ± 0.7, 4.9 ± 0.5, 6.4 ± 0.8 and 5.1 ± 0.4 L/min per L/min; P = 0.04). In hypoxia, the increase in the Q/VO2 slope was not detected by Nexfin. In normoxia, Q increases by 5-6 L/min per L/min increase in VO2, which is within the 95% confidence interval of the Q/VO2 slopes determined by the modified Fick method, Physioflow, and Nexfin apparatus while Innocor provided a lower value, potentially reflecting recirculation of the test gas into the pulmonary circulation. Thus, determination of Q during exercise depends significantly on the applied method.

External carotid artery flow maintains near infrared spectroscopy-determined frontal lobe oxygenation during ephedrine administration.

BACKGROUND: Phenylephrine and ephedrine affect frontal lobe oxygenation ([Formula: see text]) differently when assessed by spatially resolved near infrared spectroscopy. We evaluated the effect of phenylephrine and ephedrine on extra- vs intra-cerebral blood flow and on [Formula: see text]. METHODS: In 10 healthy males (age 20-54 yr), phenylephrine or ephedrine was infused for an ∼20 mm Hg increase in mean arterial pressure. Cerebral oxygenation (SavO2) was calculated from the arterial and jugular bulb oxygen saturations. Blood flow in the internal carotid artery (ICAf) and blood flow in the external carotid artery (ECAf) were assessed by duplex ultrasonography. Invos-5100c (SinvosO2) and Foresight (SforeO2) determined [Formula: see text] while forehead skin oxygenation (SskinO2) was assessed. RESULTS: Phenylephrine reduced SforeO2 by 6.9% (95% confidence interval: 4.8-9.0%; P<0.0001), SinvosO2 by 10.5 (8.2-12.9%; P<0.0001), and ECAf (6-28%; P=0.0001), but increased ICAf (5-21%; P=0.003) albeit with no consequence for SskinO2 or SavO2. In contrast, SforeO2 was maintained with administration of ephedrine while SinvosO2 and SavO2 decreased [by 3.1 (0.7-4.5%; P=0.017) and 2.1 (0.5-3.3%; P=0.012)] as arterial carbon dioxide pressure decreased (P=0.003). ICAf was stable and ECAf increased by 11 (4-18%; P=0.005) with administration of ephedrine while SskinO2 did not change. CONCLUSIONS: The effect of phenylephrine on ScO2 is governed by a decrease in external carotid blood flow since it increases cerebral blood flow as determined by flow in the internal carotid artery. In contrast, ScO2 is largely maintained with administration of ephedrine because blood flow to extracerebral tissue increases.

Health-related quality of life after surgery for advanced and recurrent rectal cancer: a nationwide prospective study.

AIM: Advances in the treatment of rectal cancer have made it possible to perform complex rectal cancer surgery (COMP-RCS) in patients with primary advanced rectal cancer penetrating beyond the total mesorectal excision planes and in patients with locally recurrent rectal cancer. The aim of this study was to examine health-related quality of life (HRQoL) before and during the first 2 years after COMP-RCS. METHOD: Between 2001 and 2008, 180 patients were treated with COMP-RCS at Aarhus University Hospital. HRQoL was assessed preoperatively and 3, 6, 12, 18 and 24 months after surgery using three questionnaires. The results were compared with those for patients treated with standard rectal cancer surgery (STAN-RCS) and with data from the general Danish population (NORM-data). RESULTS: One hundred and twenty-two (68%) patients responded to the questionnaires. Of these 80 (66%) with disease-free survival for 2 years after surgery were included in the main analysis. The lowest level of functioning and the highest degree of symptoms were reported preoperatively. The majority of the HRQoL scales improved or remained stable during the first postoperative year; a decrease was observed for body image only. One year after surgery, HRQoL in patients treated with COMP-RSC was comparable to that for patients treated with STAN-RCS. Lower levels were found for physical and emotional role functioning, compared with NORM-data. CONCLUSION: Patients treated with COMP-RCS experienced improvement in HRQoL in the first year after surgery. One year after surgery, HRQoL was similar to that of patients treated with STAN-RCS. Compared with NORM-data, lower levels were found for physical and emotional role functioning.

Value of laparoscopy before cytoreductive surgery and hyperthermic intraperitoneal chemotherapy for peritoneal carcinomatosis.

BACKGROUND: The outcome of cytoreductive surgery combined with hyperthermic intraperitoneal chemotherapy (HIPEC) depends on the extent of peritoneal carcinomatosis. The role of laparoscopy in the preoperative assessment of extent of peritoneal carcinomatosis in potential candidates for cytoreductive surgery and HIPEC was evaluated in a consecutive series. METHODS: Patients with peritoneal carcinomatosis from colorectal cancer or appendiceal cancer, pseudomyxoma peritonei or peritoneal mesothelioma referred to a single, national HIPEC centre were included prospectively between June 2006 and January 2012. From September 2010, preoperative evaluation also included a laparoscopy in patients deemed amenable to cytoreductive surgery and HIPEC after radiological evaluation, apart from those with pseudomyxoma peritonei with massive amounts of mucin. RESULTS: In the period before laparoscopic evaluation, 70 patients underwent laparotomy of whom 39 (56 per cent) completed cytoreductive surgery and HIPEC. After the introduction of laparoscopic assessment, diagnostic laparoscopy was planned in 45 patients and successful in 43. The laparoscopic evaluation excluded 18 patients from surgery because of extensive disease, among other reasons. Laparoscopy was uneventful and associated with no deaths. Twenty-seven patients were considered amenable to cytoreductive surgery and HIPEC based on laparoscopic findings, of whom 17 completed this treatment; the disease was unresectable in the remaining ten patients. Of 13 patients who were not eligible for laparoscopic evaluation and were subjected to cytoreductive surgery plus HIPEC, 11 completed the procedure. The overall completion rate of cytoreductive surgery and HIPEC increased to 70 per cent (28 of 40) after the introduction of laparoscopic evaluation. CONCLUSION: Diagnostic laparoscopy was valuable in preoperative evaluation of the extent of peritoneal carcinomatosis, and improved patient selection for cytoreductive surgery and HIPEC.

Cytoreductive surgery and hyperthermic intraperitoneal chemotherapy for peritoneal carcinomatosis: the Danish experience.

AIM: Cytoreductive surgery (CRS) combined with hyperthermic intraperitoneal chemotherapy (HIPEC) is a treatment option with curative intent for selected patients with peritoneal carcinomatosis (PC). CRS and HIPEC have been implemented in Denmark at a single centre since 2006. Six years of data on these patients were analysed. METHOD: Patients with PC from colorectal or appendiceal cancer, pseudomyxoma peritonei or malignant peritoneal mesothelioma referred to the single national HIPEC centre were prospectively registered from June 2006 to July 2012. Morbidity, 30-day mortality and long-term survival of patients who underwent CRS and HIPEC were analysed. RESULTS: In total, 80 patients underwent CRS and HIPEC. PC originated from colorectal cancer in 34 patients, pseudomyxoma peritonei in 29, appendiceal cancer in 13 and malignant peritoneal mesothelioma in four patients. Thirty-two patients had one or more complications during the hospital stay. The 30-day mortality rate was 1.3%. The predicted 2-, 3- and 5-year survival was 60%, 47% and 38% in patients with PC from colorectal cancer, and 100%, 93% and 73% in pseudomyxoma peritonei patients. CONCLUSION: CRS and HIPEC is a safe procedure when centralized as in Denmark. Favourable long-term outcome was achieved in selected patients with PC from colorectal cancer and pseudomyxoma peritonei. Short-term and long-term outcomes were comparable to results from international centres.

Chemical characterization of element 112.

The heaviest elements to have been chemically characterized are seaborgium (element 106), bohrium (element 107) and hassium (element 108). All three behave according to their respective positions in groups 6, 7 and 8 of the periodic table, which arranges elements according to their outermost electrons and hence their chemical properties. However, the chemical characterization results are not trivial: relativistic effects on the electronic structure of the heaviest elements can strongly influence chemical properties. The next heavy element targeted for chemical characterization is element 112; its closed-shell electronic structure with a filled outer s orbital suggests that it may be particularly susceptible to strong deviations from the chemical property trends expected within group 12. Indeed, first experiments concluded that element 112 does not behave like its lighter homologue mercury. However, the production and identification methods used cast doubt on the validity of this result. Here we report a more reliable chemical characterization of element 112, involving the production of two atoms of (283)112 through the alpha decay of the short-lived (287)114 (which itself forms in the nuclear fusion reaction of 48Ca with 242Pu) and the adsorption of the two atoms on a gold surface. By directly comparing the adsorption characteristics of (283)112 to that of mercury and the noble gas radon, we find that element 112 is very volatile and, unlike radon, reveals a metallic interaction with the gold surface. These adsorption characteristics establish element 112 as a typical element of group 12, and its successful production unambiguously establishes the approach to the island of stability of superheavy elements through 48Ca-induced nuclear fusion reactions with actinides.

Analysis of selected phthalates in Canadian indoor dust collected using household vacuum and standardized sampling techniques.

Phthalates have been used extensively as plasticizers to improve the flexibility of polymers, and they also have found many industrial applications. They are ubiquitous in the environment and have been detected in a variety of environmental and biological matrices. The goal of this study was to develop a method for the determination of 17 phthalate esters in house dust. This method involved sonication extraction, sample cleanup using solid phase extraction, and isotope dilution GC/MS/MS analysis. Method detection limits (MDLs) and recoveries ranged from 0.04 to 2.93 µg/g and from 84 to 117%, respectively. The method was applied to the analysis of phthalates in 38 paired household vacuum samples (HD) and fresh dust (FD) samples. HD and FD samples compared well for the majority of phthalates detected in house dust. Data obtained from 126 household dust samples confirmed the historical widespread use of bis(2-ethylhexyl) phthalate (DEHP), with a concentration range of 36 µg/g to 3840 µg/g. Dibutyl phthalate (DBP), benzyl butyl phthalate (BzBP), diisononyl phthalate (DINP), and diisodecyl phthalate (DIDP) were also found in most samples at relatively high concentrations. Another important phthalate, diisobutyl phthalate (DIBP), was detected at a frequency of 98.4% with concentrations ranging from below its MDL of 0.51 µg/g to 69 µg/g.

Genetic mapping of a second myotonic dystrophy locus.

We report the mapping of a second myotonic dystrophy locus, myotonic dystrophy type 2 (DM2). Myotonic dystrophy (DM) is a multi-system disease and the most common form of muscular dystrophy in adults. In 1992, DM was shown to be caused by an expanded CTG repeat in the 3' untranslated region of the dystrophia myotonica-protein kinase gene (DMPK) on chromosome 19 (refs 2-6). Although several theories have been put forth to explain how the CTG expansion causes the broad spectrum of clinical features associated with DM, it is not understood how this mutation, which does not alter the protein-coding region of a gene, causes an affect at the cellular level. We have identified a five-generation family (MN1) with a genetically distinct form of myotonic dystrophy. Affected members exhibit remarkable clinical similarity to DM (myotonia, proximal and distal limb weakness, frontal balding, cataracts and cardiac arrhythmias) but do not have the chromosome-19 D CTG expansion. We have mapped the disease locus (DM2) of the MN1 family to a 10-cM region of chromosome 3q. Understanding the common molecular features of two different forms of the disease should shed light on the mechanisms responsible for the broad constellation of seemingly unrelated clinical features present in both diseases.

Obesity is associated with high serotonin 4 receptor availability in the brain reward circuitry.

The neurobiology underlying obesity is not fully understood. The neurotransmitter serotonin (5-HT) is established as a satiety-generating signal, but its rewarding role in feeding is less well elucidated. From animal experiments there is now evidence that the 5-HT(4) receptor (5-HT(4)R) is involved in food intake, and that pharmacological or genetic manipulation of the receptor in reward-related brain areas alters food intake. Here, we used positron emission tomography in humans to examine the association between cerebral 5-HT(4)Rs and common obesity. We found in humans a strong positive association between body mass index and the 5-HT(4)R density bilaterally in the two reward 'hot spots' nucleus accumbens and ventral pallidum, and additionally in the left hippocampal region and orbitofrontal cortex. These findings suggest that the 5-HT(4)R is critically involved in reward circuits that regulate people's food intake. They also suggest that pharmacological stimulation of the cerebral 5-HT(4)R may reduce reward-related overeating in humans.

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.

A 10-year experience of total pelvic exenteration for primary advanced and locally recurrent rectal cancer based on a prospective database.

AIM: The study was conducted in a dedicated centre treating the majority of Danish patients with intended curative total pelvic exenteration for primary advanced (PARC) or locally recurrent (LRRC) rectal cancer. We compared PARC and LRRC and analysed postoperative morbidity and mortality, and long-term outcome. METHOD: There were 90 consecutive patients (PARC/LRRC 50/40) treated between January 2001 and October 2010, recorded on a prospectively maintained database. RESULTS: The median age was 63 (32-75) years with a gender ratio of 7 women to 83 men. All patients were American Society of Anesthesiologists level I or II. Sacral resection was performed in five patients with PARC and 15 with LRRC (P=0.002). R0 resection was achieved in 33 (66%) patients with PARC and in 15 (38%) with LRRC, R1 resection in 17 (34%) with PARC and 20 (50%) with LRRC and R2 resection in five (13%) with LRRC. R0 resection was more frequent in PARC (P=0.007). Forty-four (49%) patients had no postoperative complications. Fifty-five major complications were registered. Two (2.2%) patients died within 30 days, and the total in-hospital mortality was 5.6%. The median follow-up was 12 (0.4-91) months. The 5-year survival was 46% for PARC and 17% for LRRC (P=0.16). CONCLUSION: Pelvic exenteration is associated with considerable morbidity but low mortality in an experienced centre. Pelvic exenteration can improve long-term survival, especially for patients with PARC. However, pelvic exenteration is also justified for patients with LRRC.

International Olympic Committee consensus statement on thermoregulatory and altitude challenges for high-level athletes.

Challenging environmental conditions, including heat and humidity, cold, and altitude, pose particular risks to the health of Olympic and other high-level athletes. As a further commitment to athlete safety, the International Olympic Committee (IOC) Medical Commission convened a panel of experts to review the scientific evidence base, reach consensus, and underscore practical safety guidelines and new research priorities regarding the unique environmental challenges Olympic and other international-level athletes face. For non-aquatic events, external thermal load is dependent on ambient temperature, humidity, wind speed and solar radiation, while clothing and protective gear can measurably increase thermal strain and prompt premature fatigue. In swimmers, body heat loss is the direct result of convection at a rate that is proportional to the effective water velocity around the swimmer and the temperature difference between the skin and the water. Other cold exposure and conditions, such as during Alpine skiing, biathlon and other sliding sports, facilitate body heat transfer to the environment, potentially leading to hypothermia and/or frostbite; although metabolic heat production during these activities usually increases well above the rate of body heat loss, and protective clothing and limited exposure time in certain events reduces these clinical risks as well. Most athletic events are held at altitudes that pose little to no health risks; and training exposures are typically brief and well-tolerated. While these and other environment-related threats to performance and safety can be lessened or averted by implementing a variety of individual and event preventative measures, more research and evidence-based guidelines and recommendations are needed. In the mean time, the IOC Medical Commission and International Sport Federations have implemented new guidelines and taken additional steps to mitigate risk even further.

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.

Use of metformin before and during assisted reproductive technology in non-obese young infertile women with polycystic ovary syndrome: a prospective, randomized, double-blind, multi-centre study.

BACKGROUND: To study the effect of metformin before and during assisted reproductive technology (ART) on the clinical pregnancy rate (CPR) in non-obese women with polycystic ovary syndrome (PCOS). METHODS: A multi-centre, prospective, randomized, double-blind study was conducted in eight IVF clinics in four Nordic countries. We enrolled 150 PCOS women with a body mass index <28 kg/m(2), and treated them with 2000 mg/day metformin or identical placebo tablets for ≥ 12 weeks prior to and during long protocol IVF or ICSI and until the day of pregnancy testing. The primary outcome measure was CPR. Secondary outcome measures included spontaneous pregnancy rates during the pretreatment period, and the live birth rate (LBR). RESULTS: Among IVF treated women (n = 112), biochemical pregnancy rates were identical in both groups (42.9%), and there were no significant differences in the metformin versus the placebo group in CPR [39.3 versus 30.4%; 95% confidence interval (CI): -8.6 to 26.5]. The LBR was 37.5 versus 28.6% (95% CI: -8.4 to 26.3). However, prior to IVF there were 15 (20.3%) spontaneous pregnancies in the metformin group and eight (10.7%) in the placebo group (95% CI: -1.9 to 21.1; P = 0.1047). According to intention to treat analyses (n = 149); significantly higher overall CPR were observed in the metformin versus placebo group (50.0 versus 33.3%; 95% CI: -1.1 to 32.3; P = 0.0391). LBR was also significantly higher with use of metformin versus placebo (48.6 versus 32.0; 95% CI: 1.1 to 32.2; P = 0.0383). No major unexpected safety issues or multiple births were reported. More gastrointestinal side effects occurred in the metformin group (41 versus 12%; 95% CI: 0.15 to 0.42; P < 0.001). CONCLUSIONS: Metformin treatment for 12 weeks before and during IVF or ICSI in non-obese women with PCOS significantly increases pregnancy and LBRs compared with placebo. However, there was no effect on the outcome of ART per se. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT00159575.

Application of synchrotron microprobe methods to solid-phase speciation of metals and metalloids in house dust.

Determination of the source and form of metals in house dust is important to those working to understand human and particularly childhood exposure to metals in residential environments. We report the development of a synchrotron microprobe technique for characterization of multiple metal hosts in house dust. We have applied X-ray fluorescence for chemical characterization and X-ray diffraction for crystal structure identification using microfocused synchrotron X-rays at a less than 10 µm spot size. The technique has been evaluated by application to archived house dust samples containing elevated concentrations of Pb, Zn, and Ba in bedroom dust, and Pb and As in living room dust. The technique was also applied to a sample of soil from the corresponding garden to identify linkages between indoor and outdoor sources of metals. Paint pigments including white lead (hydrocerussite) and lithopone (wurtzite and barite) are the primary source of Pb, Zn, and Ba in bedroom dust, probably related to renovation activity in the home at the time of sampling. The much lower Pb content in the living room dust shows a relationship to the exterior soil and no specific evidence of Pb and Zn from the bedroom paint pigments. The technique was also successful at confirming the presence of chromated copper arsenate treated wood as a source of As in the living room dust. The results of the study have confirmed the utility of this approach in identifying specific metal forms within the dust.

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.

Multi-mycotoxin analysis of maize silage by LC-MS/MS.

This paper describes a method for determination of 27 mycotoxins and other secondary metabolites in maize silage. The method focuses on analytes which are known to be produced by common maize and maize-silage contaminants. A simple pH-buffered sample extraction was developed on the basis of a very fast and simple method for analysis of multiple pesticide residues in food known as QuEChERS. The buffering effectively ensured a stable pH in samples of both well-ensiled maize (pH < 4) and of hot spots with fungal infection (pH > 7). No further clean-up was performed before analysis using liquid chromatography-tandem mass spectrometry. The method was successfully validated for determination of eight analytes qualitatively and 19 quantitatively. Matrix-matched calibration standards were used giving recoveries ranging from 37% to 201% with the majority between 60% and 115%. Repeatability (5-27% RSD(r)) and intra-laboratory reproducibility (7-35% RSD(IR)) was determined. The limit of detection (LOD) for the quantitatively validated analytes ranged from 1 to 739 microg kg(-1). Validation results for citrinin, fumonisin B(1) and fumonisin B(2) were unsatisfying. The method was applied to 20 selected silage samples and alternariol monomethyl ether, andrastin A, alternariol, citreoisocoumarin, deoxynivalenol, enniatin B, fumigaclavine A, gliotoxin, marcfortine A and B, mycophenolic acid, nivalenol, roquefortine A and C and zearalenone were detected.