Environmental drivers of increased ecosystem respiration in a warming tundra.

Arctic and alpine tundra ecosystems are large reservoirs of organic carbon1,2. Climate warming may stimulate ecosystem respiration and release carbon into the atmosphere3,4. The magnitude and persistency of this stimulation and the environmental mechanisms that drive its variation remain uncertain5-7. This hampers the accuracy of global land carbon-climate feedback projections7,8. Here we synthesize 136 datasets from 56 open-top chamber in situ warming experiments located at 28 arctic and alpine tundra sites which have been running for less than 1 year up to 25 years. We show that a mean rise of 1.4 °C [confidence interval (CI) 0.9-2.0 °C] in air and 0.4 °C [CI 0.2-0.7 °C] in soil temperature results in an increase in growing season ecosystem respiration by 30% [CI 22-38%] (n = 136). Our findings indicate that the stimulation of ecosystem respiration was due to increases in both plant-related and microbial respiration (n = 9) and continued for at least 25 years (n = 136). The magnitude of the warming effects on respiration was driven by variation in warming-induced changes in local soil conditions, that is, changes in total nitrogen concentration and pH and by context-dependent spatial variation in these conditions, in particular total nitrogen concentration and the carbon:nitrogen ratio. Tundra sites with stronger nitrogen limitations and sites in which warming had stimulated plant and microbial nutrient turnover seemed particularly sensitive in their respiration response to warming. The results highlight the importance of local soil conditions and warming-induced changes therein for future climatic impacts on respiration.

Robot-assisted nephroureterectomy for upper tract urothelial carcinoma-feasibility and complications: a single center experience.

BACKGROUND: Robot-assisted nephroureterectomy (RANU) is the primary treatment for upper tract urothelial carcinoma (UTUC) at our hospital for patients with clinical stage less than T2, and for patients with invasive tumours, but unfit for major surgery. OBJECTIVE: To assess peri-operative conditions and outcomes of RANU at our unit, and to evaluate the safety of the procedure. METHODS: The medical records of all 166 patients undergoing RANU for suspected UTUC and followed for more than three months in a large university hospital in Sweden were reviewed retrospectively. After the exclusion of twenty patients because of previous cystectomy, simultaneous surgical procedure, or other tumour types than UTUC in the pathological report, 146 patients remained for the analyses. The primary endpoint was complication rate according to Clavien-Dindo at 90 days. Secondary endpoints were perioperative bleeding, violation of oncological surgical principles, hospital stay, and re-admission within 90 days. RESULTS: The median age was 75 [(Inter Quartile Range) IQR 70-80] years and 57% of the patients had an ASA score above 2. According to Clavien-Dindo, one patient had a grade 3 complication, and no patient had a grade 4-5 complication. The median blood loss was 50 (IQR 20-100) ml and the median hospital stay was 6 (IQR 5-7) days. Twelve patients were re-admitted to the hospital within 90 days (eight with urinary tract infection/haematuria, one with hematoma, and three with other diseases). CONCLUSION: Robot-assisted nephroureterectomy is a safe procedure for patients with upper tract urothelial carcinoma, with a low risk of major surgical complications.

Single institution followed by national implementation of systematic surgical quality control and feedback for radical prostatectomy: a 20-year journey.

PURPOSE: The demand for objective and outcome-based facts about surgical results after radical prostatectomy (RP) is increasing. Systematic feedback is also essential for each surgeon to improve his/her performance. METHODS: RP outcome data (e.g., pT-stage and margin status) have been registered at Sahlgrenska University Hospital (SUH) since 1988 and patient-related outcome measures (PROM) have been registered since 2001. The National Prostate Cancer Registry (NPCR) has covered all Regions in Sweden since 1998 and includes PROM-data from 2008. Initially PROM was on-paper questionnaires but due since 2018 all PROMs are collected electronically. In 2014 an on-line "dashboard" panel was introduced, showing the results for ten quality-control variables in real-time. Since 2017 all RP data on hospital, regional, and national levels are publicly accessible on-line on "www.npcr.se/RATTEN". RESULTS: The early PROM-data from SUH have been used for internal quality control. As national clinical and PROM-data from the NPCR have been made accessible on-line and in real-time we have incorporated this into our pre-existing protocol. Our data are now internally available as real-time NPCR reports on the individual surgeons' results, as well as ePROM data. We can compare the results of each surgeon internally and to other departments' aggregated data. The public can access data and compare hospital level data on "RATTEN". CONCLUSIONS: The process of quality control of RP locally at SUH, and nationally through the NPCR, has been long but fruitful. The online design, with direct real-time feedback to the institutions that report the data, is essential.

Aerobic exercise training lowers platelet reactivity and improves platelet sensitivity to prostacyclin in pre- and postmenopausal women.

Essentials It is unknown how regular exercise affects platelet function after menopause. We studied the effect of 3-months of high-intensity exercise in pre- and postmenopausal women. Platelet sensitivity to the inhibitory effect of arterially infused prostacyclin was increased. Reduced basal platelet reactivity was seen in the premenopausal women only. SUMMARY: Background The risk of atherothrombotic events increases after the menopause. Regular physical activity has been shown to reduce platelet reactivity in younger women, but it is unknown how regular exercise affects platelet function after the menopause. Objectives To examine the effects of regular aerobic exercise in late premenopausal and recent postmenopausal women by testing basal platelet reactivity and platelet sensitivity to prostacyclin and nitric oxide. Methods Twenty-five sedentary, but healthy, late premenopausal and 24 matched recently postmenopausal women, mean (95% confidence interval) 49.1 (48.2-49.9) and 53.7 (52.5-55.0) years old, participated in an intervention study: 3-month high-intensity supervised aerobic spinning-cycle training (1 h, × 3/week). Basal platelet reactivity was analyzed in platelet-rich plasma from venous blood as agonist-induced % aggregation. In a subgroup of 13 premenopausal and 14 postmenopausal women, platelet reactivity was tested ex vivo after femoral arterial infusion of prostacyclin, acetylcholine, a cyclooxygenase inhibitor, and after acute one-leg knee extensor exercise. Results Basal platelet reactivity (%aggregation) to TRAP-6 (1 µm) was higher in the postmenopausal, 59% (50-68), than the premenopausal women, 45% (35-55). Exercise training reduced basal platelet reactivity to collagen (1 µg mL-1 ) in the premenopausal women only: from 63% (55-71%) to 51% (41-62%). After the training intervention, platelet aggregation was more inhibited by the arterial prostacyclin infusion and the acute exercise in both premenopausal and postmenopausal women. Conclusions These results highlight previously unknown cardioprotective aspects of regular aerobic exercise in premenopausal and postmenopausal women, improving their regulation of platelet reactivity through an increased platelet sensitivity to prostacyclin, which may counterbalance the increased atherothrombotic risk associated with the menopause.

Vascular function in health, hypertension, and diabetes: effect of physical activity on skeletal muscle microcirculation.

Regulation of skeletal muscle blood flow is a complex process, which involves an integration of multiple mechanisms and a number of vasoactive compounds. Overall, muscle blood flow is regulated through a balance between vasoconstrictor and vasodilator signals. In a healthy cardiovascular system, the increase in muscle blood flow required for oxygen supply during exercise is achieved through a substantial increase in vasodilators locally formed in the active muscle tissue that overcome the vasoconstrictor signals. Most of the vasodilator signals are mediated via endothelial cells, which lead to the formation of vasodilators such as nitric oxide (NO) and prostacyclin. In essential hypertension and type II diabetes, the endothelial function and regulation of vascular tone is impaired with consequent increases in peripheral vascular resistance and inadequate regulation of oxygen supply to the skeletal muscle, which can affect muscle function. Central aspects in the vascular impairments are alterations in the formation of prostacyclin, the bioavailability of NO and an increased formation of vasoconstrictors and reactive oxygen species (ROS). Regular physical activity effectively improves vascular function by enhancing vasodilator formation and reducing the levels of vasoconstrictors and ROS.

Capillary growth, ultrastructure remodelling and exercise training in skeletal muscle of essential hypertensive patients.

AIM: The aim was to elucidate whether essential hypertension is associated with altered capillary morphology and density and to what extent exercise training can normalize these parameters. METHODS: To investigate angiogenesis and capillary morphology in essential hypertension, muscle biopsies were obtained from m. vastus lateralis in subjects with essential hypertension (n = 10) and normotensive controls (n = 11) before and after 8 weeks of aerobic exercise training. Morphometry was performed after transmission electron microscopy, and protein levels of several angioregulatory factors were determined. RESULTS: At baseline, capillary density and capillary-to-fibre ratio were not different between the two groups. However, the hypertensive subjects had 9% lower capillary area (12.7 ± 0.4 vs. 13.9 ± 0.2 µm(2)) and tended to have thicker capillary basement membranes (399 ± 16 vs. 358 ± 13 nm; P = 0.094) than controls. Protein expression of vascular endothelial growth factor (VEGF), VEGF receptor-2 and thrombospondin-1 were similar in normotensive and hypertensive subjects, but tissue inhibitor of matrix metalloproteinase was 69% lower in the hypertensive group. After training, angiogenesis was evident by 15% increased capillary-to-fibre ratio in the hypertensive subjects only. Capillary area and capillary lumen area were increased by 7 and 15% in the hypertensive patients, whereas capillary basement membrane thickness was decreased by 17% (P < 0.05). VEGF expression after training was increased in both groups, whereas VEGF receptor-2 was decreased by 25% in the hypertensive patients(P < 0.05). CONCLUSION: Essential hypertension is associated with decreased lumen area and a tendency for increased basement membrane thickening in capillaries of skeletal muscle. Exercise training may improve the diffusion conditions in essential hypertension by altering capillary structure and capillary number.

Dual-modality probe intended for prostate cancer detection combining Raman spectroscopy and tactile resonance technology--discrimination of normal human prostate tissues ex vivo.

Prostate cancer is the most common cancer for men in the western world. For the first time, a dual-modality probe, combining Raman spectroscopy and tactile resonance technology, has been used for assessment of fresh human prostate tissue. The study investigates the potential of the dual-modality probe by testing its ability to differentiate prostate tissue types ex vivo. Measurements on four prostates show that the tactile resonance modality was able to discriminate soft epithelial tissue and stiff stroma (p < 0.05). The Raman spectra exhibited a strong fluorescent background at the current experimental settings. However, stroma could be discerned from epithelia by integrating the value of the spectral background. Combining both parameters by a stepwise analysis resulted in 100% sensitivity and 91% specificity. Although no cancer tissue was analysed, the results are promising for further development of the instrument and method for discriminating prostate tissues and cancer.

Nitric oxide and reactive oxygen species in limb vascular function: what is the effect of physical activity?

Nitric oxide (NO) is known to be one of the most important regulatory compounds within the cardiovascular system where it is central for functions such as regulation of blood pressure, blood flow, and vascular growth. The bioavailability of NO is determined by a balance between, on one hand, the extent of enzymatic and non-enzymatic formation of NO and on the other hand, removal of NO, which in part is dependent on the reaction of NO with reactive oxygen species (ROS). The presence of ROS is dependent on the extent of ROS formation via mitochondria and/or enzymes such as NAD(P)H oxidase (NOX) and xanthine oxidase (XO) and the degree of ROS removal through the antioxidant defense system or other reactions. The development of cardiovascular disease has been proposed to be closely related to a reduced bioavailability of NO in parallel with an increased presence of ROS. Excessive levels of ROS not only lower the bioavailability of NO but may also cause cellular damage in the cardiovascular system. Physical activity has been shown to greatly improve cardiovascular function, in part through improved bioavailability of NO, enhanced endogenous antioxidant defense and a lowering of the expression of ROS-forming enzymes. Regular physical activity is therefore likely to be a highly useful tool in the treatment of cardiovascular disease. Future studies should focus on which form of exercise may be most optimal for enhancing NO bioavailability and improving cardiovascular health.

Influence of nitrate supplementation on VO2 kinetics and endurance of elite cyclists.

The present study examined if an elevated nitrate intake would improve VO(2) kinetics, endurance, and repeated sprint capacity in elite endurance athletes. Ten highly trained cyclists (72 ± 4 mL O(2) /kg/min, mean ± standard deviation) underwent testing for VO(2) kinetics (3 × 6 min at 298 ± 28 W), endurance (120 min preload followed by a 400-kcal time trial), and repeated sprint capacity (6 × 20 s sprints, recovery 100 s) during two 6-day periods in randomized order with a daily ingestion of either 0.5 L beetroot (BR) juice to increase nitrate levels or a 0.5 L placebo (PLA) drink with blackcurrant juice. Plasma NOx (nitrate + nitrite) levels were higher (P < 0.01) in BR (147 ± 102 and 159 ± 103 µM after 4 and 6 days of beverage intake, respectively) compared with PLA (41 ± 10 and 40 ± 7 µM). VO(2) kinetics and exercise economy were the same in BR and PLA. Time-trial performance was similar with an average completion time of 18:20 and 18:37 min:s in BR and PLA, respectively, with average power outputs of 290 ± 43 W in BR and 285 ± 44 W in PLA. Peak and mean power during repeated sprinting were similar in BR and PLA. In contrast to observations in moderately trained subjects intake of BR juice had no effect on VO(2) kinetics and performance in elite cyclists.

Physical activity opposes the age-related increase in skeletal muscle and plasma endothelin-1 levels and normalizes plasma endothelin-1 levels in individuals with essential hypertension.

AIMS: Endothelin-1 has potent constrictor and proliferative activity in vascular smooth muscle, and essential hypertension and aging are associated with increased endothelin-1-mediated vasoconstrictor tone. The aim of this study was to investigate the effect of physical activity, hypertension and age on endothelin-1 levels in plasma and skeletal muscle and endothelin receptors in skeletal muscle in human subjects. METHODS: In study 1, normotensive (46 ± 1 years, n = 11) and hypertensive (47 ± 1 years, n = 10) subjects were studied before and after 8 weeks of aerobic exercise training. In study 2, young (23 ± 1 years, n = 8), older lifelong sedentary (66 ± 2 years, n = 8) and older lifelong endurance-trained (62 ± 2 years, n = 8) subjects were studied in a cross-sectional design. RESULTS: Skeletal muscle and plasma endothelin-1 levels were increased with age and plasma endothelin-1 levels were higher in hypertensive than normotensive individuals. Eight weeks of exercise training normalized plasma endothelin-1 levels in the hypertensive subjects and increased the protein expression of the ET(A) receptor in skeletal muscle of normotensive subjects. Similarly, individuals that had performed lifelong physical activity had similar plasma and muscle endothelin-1 levels as the young controls and had higher ET(A) receptor levels. CONCLUSION: Our findings suggest that aerobic exercise training opposes the age-related increase in skeletal muscle and plasma endothelin-1 levels and normalizes plasma endothelin-1 levels in individuals with essential hypertension. This effect may explain some of the beneficial effects of training on the cardiovascular system in older and hypertensive subjects.

Vasodilator interactions in skeletal muscle blood flow regulation.

During exercise, oxygen delivery to skeletal muscle is elevated to meet the increased oxygen demand. The increase in blood flow to skeletal muscle is achieved by vasodilators formed locally in the muscle tissue, either on the intraluminal or on the extraluminal side of the blood vessels. A number of vasodilators have been shown to bring about this increase in blood flow and, importantly, interactions between these compounds seem to be essential for the precise regulation of blood flow. Two compounds stand out as central in these vasodilator interactions: nitric oxide (NO) and prostacyclin. These two vasodilators are both stimulated by several compounds, e.g. adenosine, ATP, acetylcholine and bradykinin, and are affected by mechanically induced signals, such as shear stress. NO and prostacyclin have also been shown to interact in a redundant manner where one system can take over when formation of the other is compromised. Although numerous studies have examined the role of single and multiple pharmacological inhibition of different vasodilator systems, and important vasodilators and interactions have been identified, a large part of the exercise hyperaemic response remains unexplained. It is plausible that this remaining hyperaemia may be explained by cAMP- and cGMP-independent smooth muscle relaxation, such as effects of endothelial derived hyperpolarization factors (EDHFs) or through metabolic modulation of sympathetic effects. The nature and role of EDHF as well as potential novel mechanisms in muscle blood flow regulation remain to be further explored to fully elucidate the regulation of exercise hyperaemia.

Lifelong physical activity preserves functional sympatholysis and purinergic signalling in the ageing human leg.

Ageing is associated with an impaired ability to modulate sympathetic vasoconstrictor activity (functional sympatholysis) and a reduced exercise hyperaemia. The purpose of this study was to investigate whether a physically active lifestyle can offset the impaired functional sympatholysis and exercise hyperaemia in the leg and whether ATP signalling is altered by ageing and physical activity. Leg haemodynamics, interstitial [ATP] and P2Y(2) receptor content was determined in eight young (23 ± 1 years), eight lifelong sedentary elderly (66 ± 2 years) and eight lifelong active elderly (62 ± 2 years) men at rest and during one-legged knee extensions (12 W and 45% maximal workload (WL(max))) and arterial infusion of ACh and ATP with and without tyramine. The vasodilatory response to ACh was lowest in the sedentary elderly, higher in active elderly (P < 0.05) and highest in the young men (P < 0.05), whereas ATP-induced vasodilatation was lower in the sedentary elderly (P < 0.05). During exercise (12 W), leg blood flow, vascular conductance and VO2 was lower and leg lactate release higher in the sedentary elderly compared to the young (P < 0.05), whereas there was no difference between the active elderly and young. Interstitial [ATP] during exercise and P2Y(2) receptor content were higher in the active elderly compared to the sedentary elderly (P < 0.05). Tyramine infusion lowered resting vascular conductance in all groups, but only in the sedentary elderly during exercise (P < 0.05). Tyramine did not alter the vasodilator response to ATP infusion in any of the three groups. Plasma [noradrenaline] increased more during tyramine infusion in both elderly groups compared to young (P < 0.05). A lifelong physically active lifestyle can maintain an intact functional sympatholysis during exercise and vasodilator response to ATP despite a reduction in endothelial nitric oxide function. A physically active lifestyle increases interstitial ATP levels and skeletal muscle P2Y(2) receptor content.

Combining scanning haptic microscopy and fibre optic Raman spectroscopy for tissue characterization.

The tactile resonance method (TRM) and Raman spectroscopy (RS) are promising for tissue characterization in vivo. Our goal is to combine these techniques into one instrument, to use TRM for swift scanning, and RS for increasing the diagnostic power. The aim of this study was to determine the classification accuracy, using support vector machines, for measurements on porcine tissue and also produce preliminary data on human prostate tissue. This was done by developing a new experimental set-up combining micro-scale TRM-scanning haptic microscopy (SHM)-for assessing stiffness on a micro-scale, with fibre optic RS measurements for assessing biochemical content. We compared the accuracy using SHM alone versus SHM combined with RS, for different degrees of tissue homogeneity. The cross-validation classification accuracy for healthy porcine tissue types using SHM alone was 65-81%, and when RS was added it increased to 81-87%. The accuracy for healthy and cancerous human tissue was 67-70% when only SHM was used, and increased to 72-77% for the combined measurements. This shows that the potential for swift and accurate classification of healthy and cancerous prostate tissue is high. This is promising for developing a tool for probing the surgical margins during prostate cancer surgery.

Contribution of intravascular versus interstitial purines and nitric oxide in the regulation of exercise hyperaemia in humans.

The regulation of blood flow to skeletal muscle involves a complex interaction between several locally formed vasodilators that are produced both in the skeletal muscle interstitium and intravascularly. The gas nitric oxide (NO) and the purines ATP and adenosine, are potent vasodilators that are formed by multiple cell types and released into the skeletal muscle interstitium and in plasma in response to muscle contraction. Cellular sources of ATP and NO in plasma are erythrocytes and endothelial cells, whereas interstitial sources are skeletal muscle cells and endothelial cells. Adenosine originates primarily from extracellular degradation of ATP. During exercise the concentrations of ATP and adenosine increase markedly in the interstitium with smaller increases occurring in plasma, and thus the interstitial concentration during exercise is severalfold higher than in plasma. The concentration of NO metabolites (NOx) in interstitium and plasma does not change during exercise and is similar in the two compartments. Adenosine and NO have been shown to contribute to exercise hyperaemia whereas the role of ATP remains unclear due to lack of specific purinergic receptor blockers. The relative role of intravascular versus interstitial vasodilators is not known but evidence suggests that both compartments are important. In cardiovascular disease, a reduced capacity to form adenosine in the muscle interstitium may be a contributing factor in increased peripheral vascular resistance.

Blood flow in the foetal superior vena cava and the effect of foetal breathing movements.

OBJECTIVES: The superior vena cava (SVC) drains venous blood from the upper foetal body, mainly the head. Data on the human foetus is scarce. Here we present reference values for the blood flow during the second half of pregnancy, and test the hypothesis that foetal breathing movements (FBM) enhance this flow. METHODS: Based on a power calculation, 110 women with low-risk singleton pregnancies were recruited to a longitudinal study that included three sets of observations during the second half of pregnancy. Ultrasound was used to determine inner diameter, peak systolic blood velocity and time-average maximum velocities in the SVC during rest and respiratory activity. RESULTS: During the second half of pregnancy, SVC blood flow increased from 57.8 mL/min (95% CI 51.7-64.3) to 221.5 (204.5-239.3). Based on 558 sets of observations obtained during foetal rest and FBM, we found an overall increase in diameter from 0.41 cm (0.40-0.42) to 0.46 (0.44-0.48), peak systolic velocity from 35.9 cm/s (34.9-37.0) to 62.2 (59.1-65.5), and time-averaged maximum velocity from 20.3 cm/s (19.7-20.8) to 27.3 (26.1-28.6). This resulted in an overall 90% increase in mean SVC blood flow, from 108.1 mL/min (98.8-117.9) at rest to 205.9 (183.2-230.5) during FBM. CONCLUSION: The blood flow in the SVC increases during the second half of pregnancy and is substantially augmented during FBM. Since high-amplitude FBM additionally reduces flow in the inferior vena cava, the net effect is a prioritised venous drainage from the foetal head enhancing the washout of CO(2) in that area, which also contains the chemoreceptors.

Hemodynamics of fetal breathing movements: the inferior vena cava.

OBJECTIVE: Based on the hypothesis that fetal breathing movements (FBM) enhance sections of the circulation to meet the needs of gas transport, we studied the effects of FBM on the fetal inferior vena cava (IVC), which transports blood with the lowest oxygen saturation in the fetal body. METHODS: One-hundred and ten women with low-risk singleton pregnancies were included in a longitudinal study during the second half of pregnancy. Inner diameter, peak systolic velocity and time-averaged maximum blood velocity were measured in the IVC below the ductus venosus outlet during rest and FBM. Volume flow and pressure gradient were estimated in 55 observations of forced inspiratory movements at 36 weeks of gestation. The results are presented as mean and 95% CI of the mean. RESULTS: Based on 585 observations obtained during fetal rest and FBM, we found no difference in diameter, 0.42 (95% CI, 0.41-0.43) cm vs. 0.41 (95% CI, 0.39-0.42) cm, respectively, apart from during high-amplitude inspiratory movement, when the diameter was 0.15 (95% CI, 0.13-0.17) cm. The peak systolic velocity was different during rest and FBM, 34.0 (95% CI, 32.7-35.3) cm/s vs. 81.5 (95% CI, 76.2-87.5) cm/s, respectively, and correspondingly for time-averaged maximum velocity, 19.7 (95% CI, 18.9-20.5) cm/s vs. 37.2 (95% CI, 34.9-39.9) cm/s, respectively. Forced inspiratory movements at 36 weeks significantly reduced flow in the IVC compared with rest, 63.6 (95% CI, 44.4-88.1) mL/min vs. 186.0 (95% CI, 142.8-238.1) mL/min, respectively. The pressure gradient increased 14-fold during forced inspiration, from 0.64 to 8.76 mmHg. CONCLUSIONS: High-amplitude fetal inspiration substantially constricts the abdominal IVC and creates a negative pressure in the chest. The IVC constriction withholds abdominal blood, thus temporarily giving way to other flows.

Fetal breathing is associated with increased umbilical blood flow.

OBJECTIVES: In humans, fetal breathing movements affect blood velocities in the umbilical vein and artery, but it is not known whether fetal respiratory activity is associated with increased fetal blood flow through the placenta. We therefore tested this hypothesis in the present study. METHODS: One-hundred and ten women with low-risk singleton pregnancies were each examined three times by ultrasound during the second half of pregnancy. Fetal heart rate, umbilical artery blood velocity, umbilical vein diameter and blood velocity, and umbilical blood flow at the placental end were determined during fetal rest and fetal respiratory movements. RESULTS: Based on 330 observations obtained during fetal rest or breathing activity, no difference was found in the mean fetal heart rate (beats per minute (bpm)) during rest compared with breathing (142 bpm vs. 142 bpm, respectively). Although fetal breathing affected the umbilical artery waveform, there was no difference in the mean time-averaged maximum velocity between rest and breathing: 26.6 (95% CI, 25.1-28.3) cm/s vs. 28.9 (95% CI, 27.2-30.7) cm/s, respectively. The umbilical vein was 27% greater in cross-sectional area and the blood velocity 9% higher during breathing, resulting in a 42% increase in mean umbilical blood flow: 121.8 (95% CI, 109.5-135.0) mL/min at rest vs. 173.0 (95% CI, 158.0-188.6) mL/min during breathing. Venous velocity was calculated from recordings of mean duration 3.7 s at rest and 6.2 s of respiratory activity. Gestational age did not influence the relationship. CONCLUSION: Fetal breathing is associated with increased umbilical blood flow during the second half of pregnancy. Umbilical vein distension during breathing suggests active endocrine regulation.

Moulds and mycotoxins in rice from the Swedish retail market.

A survey of moulds and mycotoxins was performed on 99 rice samples taken from the Swedish retail market. The main objective was to study the mould and mycotoxin content in basmati rice and rice with a high content of fibre. Samples of jasmine rice as well as long-grain rice were also included. The samples were analysed for their content of ochratoxin A (high-performance liquid chromatography (HPLC)), aflatoxin B(1), B(2), G(1), and G(2) (HPLC, RIDA(R)QUICK), and mould (traditional cultivation methods in combination with morphological analysis). The majority of samples were sampled according to European Commission Regulation 401/2006. Subsamples were pooled and mixed before milling and both mould and mycotoxin analyses were performed on milled rice. The results showed that the majority of basmati rice (71%) and many jasmine rice samples (20%) contained detectable levels of aflatoxin B(1) (level of quantification = 0.1 microg aflatoxin kg(-1) rice). Two samples of jasmine rice and ten basmati rice samples contained levels over the regulated European maximum limits of 2 microg kg(-1) for aflatoxin B(1) or 4 microg kg(-1) for total aflatoxins. Aspergillus was the most common mould genus isolated, but also Penicillium, Eurotium, Wallemia, Cladosporium, Epicoccum, Alternaria, and Trichotecium were found. The presence of Aspergillus flavus in 21% of the samples indicates that incorrect management of rice during production and storage implies a risk of mould growth and subsequent production of aflatoxin. Rough estimates showed that high rice consumers may have an intake of 2-3 ng aflatoxin kg(-1) bodyweight and day(-1) from rice alone. This survey shows that aflatoxin is a common contaminant in rice imported to Europe.

Electronic structure of a vapor-deposited metal-free phthalocyanine thin film.

The electronic structure of a vapor-sublimated thin film of metal-free phthalocyanine (H2Pc) is studied experimentally and theoretically. An atom-specific picture of the occupied and unoccupied electronic states is obtained using x-ray-absorption spectroscopy (XAS), core- and valence-level x-ray photoelectron spectroscopy (XPS), and density-functional theory (DFT) calculations. The DFT calculations allow for an identification of the contributions from individual nitrogen atoms to the experimental N1s XAS and valence XPS spectra. This comprehensive study of metal-free phthalocyanine is relevant for the application of such molecules in molecular electronics and provides a solid foundation for identifying modifications in the electronic structure induced by various substituent groups.

The hydrogen bond in ice probed by soft x-ray spectroscopy and density functional theory.

We combine photoelectron and x-ray absorption spectroscopy with density functional theory to derive a molecular orbital picture of the hydrogen bond in ice. We find that the hydrogen bond involves donation and back-donation of charge between the oxygen lone pair and the O-H antibonding orbitals on neighboring molecules. Together with internal s-p rehybridization this minimizes the repulsive charge overlap of the connecting oxygen and hydrogen atoms, which is essential for a strong attractive electrostatic interaction. Our joint experimental and theoretical results demonstrate that an electrostatic model based on only charge induction from the surrounding medium fails to properly describe the internal charge redistributions upon hydrogen bonding.