The effects of menstrual cycle phase on the incidence of plateau at and associated cardiorespiratory dynamics

The purpose of this study was to examine the effect of menstrual cycle phase on maximal oxygen uptake () and associated cardiodynamic responses. A total of 16 active females volunteered of which n = 10 formed the non‐oral contraceptive pill group (n‐OCP), displaying a regular menstrual cycle of 28·4 ± 2·2 days (age 20·6 ± 1·6 years, height 169·9 ± 6·4 cm, mass 68·7 ± 7·9 kg) and n = 6 formed the oral contraceptive pill group (OCP) (monophasic pill) (age 21·7 years ± 2·16, height 168·1 cm ± 6·8 cm, mass 61·6 ± 6·8 kg). Each completed four incremental exercise tests for determination of , cardiac output, stroke volume and heart rate. Each test was completed according to the phases of the menstrual cycle as determined through salivary analysis of 17‐β oestrodiol and progesterone. Non‐significant differences were observed for across phases and between groups (P>0·05) with additional non‐significant differences for , HR_max and SV_max between groups. For ? during the final 60 s of the trial, significant differences were observed between OCP and n‐OCP (P<0·05) with OCP showing zero plateaus in three pseudo‐phases. Significant difference observed for a‐vO_2dif n‐OCP between premenstruation and menstruation at 30–100% (P<0·05). Data suggest that the ‐plateau is effected by monophasic oral contraceptive pill, furthermore these data imply that test outcome is independent of menstrual cycle phase but caution should be applied when evaluating maximal oxygen uptake in females who are administered a monophasic oral contraceptive pill.     

The effects of exercise modality on the incidence of plateau at V·O2max

The purpose of this study was to determine the effect of exercise modality on the incidence of plateau at . Twelve recreationally active men (age, 21·7 ± 2·3 year; mass, 74·8 ± 6·5 kg; height, 177·6 ± 5·6 cm) completed four incremental tests to volitional exhaustion, of which two were completed on a treadmill (TRE) and two were completed using a cycle ergometer (CYC). The work rate employed for CYC was 1 W·2 s^?1 from an initial loading of 100 W with cadence being maintained at 60 rpm. For TRE, the workload (gradient) increased at a rate of 0·5% · 30 s^?1while maintaining a constant running speed of 10 kph. Throughout all the trials, was determined on a breath‐by‐breath basis using a precalibrated metabolic cart. The criteria adopted for determination of a plateau was a Δ over the final two consecutive 30‐s sampling periods of ≤50 ml · min^?1. Averaging across the two trials per each exercise modality showed a significant difference for plateau incidence between CYC (8%) and TRE (58%) (P = 0·017). This was aligned with a significant difference in the slope of the regression line during the final 60 s of the test, CYC (99·9 ± 49·7 ml · min^?1) and TRE (49·6 ± 42·6 ml · min^?1) (P = 0·017). Repeat measures ANOVA of these data suggests that plateau incidence rates at differ between treadmill‐ and cycle ergometry‐based exercises. Future studies need to address whether these response rates are replicated in well‐trained athletes.     

Whole body,regional fat accumulation,and appetite‐related hormonal response after hypoxic training

The present study was conducted to determine change in regional fat accumulation and appetite‐related hormonal response following hypoxic training. Twenty sedentary subjects underwent hypoxic (n = 9, HYPO, FiO₂ = 15%) or normoxic training (n = 11, NOR, FiO₂ = 20·9%) during a 4‐week period (3 days per week). They performed a 4‐week training at 55% of maximal oxygen uptake (O_2max) for each condition. Before and after the training period, O_2max, whole body fat mass, abdominal fat area, intramyocellular lipid content (IMCL), fasting and postprandial appetite‐related hormonal responses were determined. Both groups showed a significant increase in O_2max following training (P<0·05). Whole body and segmental fat mass, abdominal fat area, IMCL did not change in either group. Fasting glucose and insulin concentrations significantly reduced in both groups (P<0·05). Although area under the curve for the postprandial blood glucose concentrations significantly decreased in both groups (P<0·05), the change was significantly greater in the HYPO group than in the NOR group (P<0·05). Changes in postprandial plasma ghrelin were similar in both groups. A significant reduction of postprandial leptin response was observed in both groups (P<0·05), while postprandial glucagon‐like peptide‐1 (GLP‐1) concentrations increased significantly in the NOR group only (P<0·05). In conclusion, hypoxic training for 4 weeks resulted in greater improvement in glucose tolerance without loss of whole body fat mass, abdominal fat area or IMCL. However, hypoxic training did not have synergistic effect on the regulation of appetite‐related hormones.     

Effects of anatomical differences on electromagnetic fields,SAR, and temperature change

Electromagnetic field simulations are increasingly used to assure RF safety of patients during MRI exams. In practice, however, tissue property distribution of the patient being imaged is not known, but may be represented with a pre‐existing model. Repeatedly, agreement in transmit magnetic ( ) field distributions between two geometries has been used to suggest agreement in heating distributions. Here we examine relative effects of anatomical differences on distribution, specific absorption rate (SAR), and temperature change (ΔT). Numerical simulations were performed for a single surface coil positioned adjacent a homogeneous phantom and bovine phantom, each with slight geometric variations, and adjacent two different human body models. Experimental demonstration was performed on a bovine phantom using MR thermometry and mapping. Simulations and experiments demonstrate that distributions in different samples can be well correlated, while notable difference in maximum SAR and ΔT occur. This work illustrates challenges associated with utilizing simulations or experiments for RF safety assurance purposes. Reliance on distributions alone for validation of simulations and/or experiments with a sample or subject for assurance of safety in another should be performed with caution. © 2015 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 46B: 8–18, 2016     

Relationship between cardioventilatory coupling and pulmonary gas exchange

Cardioventilatory coupling (CVC) is a temporal alignment between the heartbeat and inspiratory activity caused by pulsatile baroreceptor afferent activity. However, although first described over a century ago, the functional significance of CVC has yet to be established. One hypothesis is that baroreceptor triggering of inspiration positions heartbeats into phases of the respiratory cycle that may optimize pulmonary gas exchange efficiency. To test this hypothesis, we recruited ten patients with permanently implanted fixed‐rate cardiac pacemakers and instructed them to pace breathe at heart rate‐to‐respiratory rate (HR/f) ratios of 3·8, 4·0 and 4·2. This breathing protocol enabled us to simulate heartbeat distributions similar to those seen in the presence (4·0) and complete absence (3·8, 4·2) of CVC. Results showed that heart rate, mean arterial pressure, end‐tidal carbon dioxide and tidal volume remained unchanged across the three conditions (P>0·05). Pulmonary gas exchange efficiency, as determined by the ventilatory equivalents of carbon dioxide () and oxygen () did not differ significantly by HR/f ratio (P = 0·29 and P = 0·70, respectively). These data suggest that CVC does not play a significant role in optimizing pulmonary gas exchange efficiency in humans.     

Allometric scaling of flow‐mediated dilation: is it always helpful?

Flow‐mediated dilation (FMD) is calculated as the greatest percent change in arterial diameter following an ischaemic challenge. This Traditional %FMD calculation is thought to have statistical bias towards baseline diameter (D_base), which is reduced by allometric scaling. This study examined whether allometric scaling FMD influenced the difference between a group of healthy young and older adults compared to the Traditional %FMD, and to determine whether a New (allometric) scaling %FMD improved the ability to obtain individually scaled FMD. Popliteal artery FMD was assessed in 18 young (26 ± 3 years) and 17 older adults (77 ± 5 years). ‘Corrected’ mean FMD was generated from a log‐linked ANCOVA model. Individual %FMD was evaluated using three calculations: (1) Traditional %FMD calculation; (2) Atkinson (allometric) scaling %FMD (peak diameter ); and (3) New scaling %FMD . Traditional %FMD was significantly larger in young (5·82 ± 2·58%) versus old (3·72 ± 1·26%). ‘Corrected’ FMD means (Y: 5·97 ± 2·12%; O: 3·98 ± 2·06%) were similar to Traditional %FMD; however, the logarithmic transformation prevents statistical interpretation of group differences. Individually scaled %FMD using the Atkinson scaling resulted in values that were corrected for variations in D_base but that were twofold to threefold larger than those of the Traditional calculation. New scaling %FMD resulted in values that were similar to values expected (Y: 6·21 ± 2·75%; O: 3·98 ± 1·36%); however, it did not effectively correct for variation in D_base. Recommendations regarding the advantages of allometrically scaling %FMD should be made with caution until research clearly establishes the benefits of this approach.     

Dependence of and field patterns of surface coils on the electrical properties of the sample and the MR operating frequency

In high field MRI, the spatial distribution of the radiofrequency magnetic ( ) field is usually affected by the presence of the sample. For hardware design and to aid interpretation of experimental results, it is important both to anticipate and to accurately simulate the behavior of these fields. Fields generated by a radiofrequency surface coil were simulated using dyadic Green's functions, or experimentally measured over a range of frequencies inside an object whose electrical properties were varied to illustrate a variety of transmit ( ) and receive ( ) field patterns. In this work, we examine how changes in polarization of the field and interference of propagating waves in an object can affect the spatial distribution. Results are explained conceptually using Maxwell's equations and intuitive illustrations. We demonstrate that the electrical conductivity alters the spatial distribution of distinct polarized components of the field, causing “twisted” transmit and receive field patterns, and asymmetries between and . Additionally, interference patterns due to wavelength effects are observed at high field in samples with high relative permittivity and near‐zero conductivity, but are not present in lossy samples due to the attenuation of propagating EM fields. This work provides a conceptual framework for understanding spatial distributions for surface coils and can provide guidance for RF engineers. © 2016 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 46B: 25–40, 2016     

Cosleeping,sleep disturbances,children's behavioral problems,and parenting self‐efficacy among Korean American families

The purpose of this study was to compare sleep disturbances of children and their mothers, children's behavioral problems, and parenting self‐efficacy between Korean American families who coslept and those who did not cosleep. Forty‐eight mothers of children between 3 and 8 years of age completed the following surveys: Children's Sleep Habits Questionnaire, Pediatric Symptom Checklist, Pittsburgh Sleep Quality Index, Parenting Self‐Efficacy Questionnaire, and Acculturation Rating Scale for Mexican Americans II. Overall, 48% (n = 23) of families coslept, and families with younger children coslept more than families with older children (). When the families were divided into non‐cosleeping (i.e., rarely) and cosleeping (i.e., sometimes and usually) groups, 100% of the cosleeping children had sleep disturbances compared to 56% of the non‐cosleeping children (). For mothers, 28% (n = 7) of the non‐cosleeping mothers reported sleep disturbances, compared to 52% (n = 12) of the cosleeping mothers ). Children's behavioral problems were not different between the two groups (F = 1.78, p = NS). Cosleeping mothers reported lower parenting self‐efficacy than non‐cosleeping mothers (F = 6.26, p < .05). When providing care to Korean American families with young children, their cosleeping, sleep disturbances, and parenting self‐efficacy need to be addressed.     

A comparison of rectal,oesophageal and gastro‐intestinal tract temperatures during moderate‐intensity cycling in temperate and hot conditions

The purpose of this study was to compare three of the most commonly used methods of core temperature (T_core) measurement during cycling under different environmental conditions as there are practical problems associated with each method and, sometimes, uncertainty as to which is the appropriate measure. Eight trained males (O₂max: 60 ± 7 ml kg^?1 min^?1) completed two 60‐min cycling trials at ~70% O₂max at 20°C (MOD) and 35°C (HOT). Measures of T_core were made every 5 min with oesophageal (T_oes) and rectal (T_rec) thermistors and of the gastro‐intestinal tract temperature (T_gi) with a temperature‐sensitive disposable radio pill. During MOD T_oes initially plateaued after 10 min, T_gi after 25 min and T_rec after 50 min, whereas during HOT these times had increased to 25 min for T_oes and 55 min for both T_gi and T_rec. T_oes consistently provided lower readings than T_rec (0·24–0·26°C) and T_gi (0·26–0·28°C) with T_gi and T_rec similar (0·02°C). Readings for T_gi displayed closer agreement with T_rec (ICC = 0·92) than T_oes (ICC = 0·86) with less agreement between T_rec and T_oes (ICC = 0·84). 95% of all T_gi readings were within ±0·5°C of T_rec and within ±0·6°C of T_oes with 95% of all T_oes readings being within ±0·7°C of T_rec. These results demonstrate distinct response times, absolute values and agreement between T_core measured at different body locations under different ambient conditions. Implications and considerations are discussed.     

Quadrature birdcage coil with distributed capacitors for 7.0 T magnetic resonance data acquisition of small animals

High static magnetic field magnetic resonance imaging (MRI) is commonly used for preclinical studies in rodents. In this context, minimization of coil losses is mandatory to scan samples that are small compared to the radiofrequency wavelength in the medium. In this study we construct a radiofrequency (RF) birdcage probe with distributed capacitors, operating in quadrature, tailored for 7.0T ¹H MRI of small animals. The design eliminates the need for extra electrical components on the probe structure and affords a high SNR, a uniform field (homogeneity of 93% in the axial plain of the phantom) and a coil sensitivity of 9.8 . Feasibility experiments of mouse imaging are conducted and the competitive capability of a 7.0 T human system equipped with the proposed coil is demonstrated in both body and brain preclinical imaging. © 2015 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 44B: 83–88, 2015     

Twenty‐four hour variation in heart rate variability indices derived from fractional differintegration

Assuming that RR time‐series behave as a fractionally differintegrated Gaussian process, García‐González et al. (2003) recently proposed new indices for quantifying variability and structure in RR data. One of these was the ‘fractional noise quantifier’ (fnQ), measuring the departure of an RR time‐series from a monofractal structure (i.e. a measure of its multifractality). Sixty‐nine participants (aged = 34·5 ± 12·4 years, body mass index (BMI) = 23·9 ± 2·9 kg m^?2, maximal oxygen uptake rate (O_2peak) = 42·4 ± 10·9 ml min^?1 kg^?1, 39 males) provided continuous beat‐to‐beat ECG recordings for a 24‐h period. Fractional differintegration was used to quantify fnQ, and heart rate variability was calculated in the time domain. All variables were evaluated during consecutive 1‐h periods and also during four 6‐h blocks corresponding to morning, afternoon, evening and night periods. Apart from RR, circadian trends in all variables were independent of gender (P = 0·11–0·59). Apart from fnQ, all variables exhibited circadian variation (0·0005<P<0·012). Although fnQ was statistically uniform during the 24‐h period, it showed a trend towards elevated values during evening and night. The main finding of this study was that fnQ was elevated by around 10% during the evening and night, although this was not statistically significant. This suggests that the structure of RR time‐series in healthy individuals is most strongly ‘multifractal’ during evening and night periods. fnQ appears to be a plausible surrogate measure of multifractality in RR time‐series.     

Protective effect of N,N’‐dimethylthiourea against stress‐induced gastric mucosal lesions in rats

In the present study, we examined the protective effect of N,N’‐dimethylthiourea (DMTU), a scavenger of hydroxyl radical (), against water‐immersion restraint stress (WIRS)‐induced gastric mucosal lesions in rats. When male Wistar rats fasted for 24 h were exposed to WIRS for 3 h, gastric mucosal lesions occurred with increases in the levels of gastric mucosal myeloperoxidase (MPO), an index of tissue neutrophil infiltration, pro‐inflammatory cytokines (tumor necrosis factor alpha and interleukin 1beta), lipid peroxide (LPO), and nitrite/nitrate (NOx), an index of nitric oxide synthesis, and decreases in the levels of gastric mucosal nonprotein SH and vitamin C and gastric adherent mucus. DMTU (1, 2.5, or 5 mmol/kg) administered orally at 0.5 h before the onset of WIRS reduced the severity of gastric mucosal lesions with attenuation of the changes in the levels of gastric mucosal MPO, pro‐inflammatory cytokines, LPO, NOx, nonprotein SH, and vitamin C and gastric adherent mucus found at 3 h after the onset of WIRS in a dose‐dependent manner. Serum levels of corticosterone and glucose, which are indices of stress responses, increased in rats exposed to WIRS for 3 h, but DMTU pre‐administered at any dose had no effect on these increases. These results indicate that DMTU protects against WIRS‐induced gastric mucosal lesions in rats by exerting its antioxidant action including scavenging and its anti‐inflammatory action without affecting the stress response.     

Internalization of annexin A5‐functionalized iron oxide particles by apoptotic Jurkat cells

Apoptosis plays an important role in the etiology of various diseases. Several studies have reported on the use of annexin A5‐functionalized iron oxide particles for the detection of apoptosis with MRI, both in vitro and in vivo. The protein annexin A5 binds with high affinity to the phospholipid phosphatidylserine, which is exposed in the outer leaflet of the apoptotic cell membrane. When co‐exposed to apoptotic stimuli, this protein was shown to internalize into endocytic vesicles. Therefore in the present study we investigated the possible internalization of commercially available annexin A5‐functionalized iron oxide particles (r₁ = 34.0 ± 2.1 and r₂ = 205.0 ± 10.4 mm ^?1 s^?1 at 20 MHz), and the effects of their spatial distribution on relaxation rates R, R₂ and R₁. Two different incubation procedures were performed, where (1) Jurkat cells were either incubated with the contrast agent after induction of apoptosis or (2) Jurkat cells were simultaneously incubated with the apoptotic stimulus and the contrast agent. Transmission electron microscopy images and relaxation rates showed that the first incubation strategy mainly resulted in binding of the annexin A5‐iron oxide particles to the cell membrane, whereas the second procedure allowed extensive membrane‐association as well as a small amount of internalization. Owing to the small extent of internalization, only minor differences were observed between the ΔR/ΔR₂ and ΔR₂/ΔR₁ ratios of cell pellets with membrane‐associated or internalized annexin A5 particles. Only the increase in R₁ (ΔR₁) appeared to be diminished by the internalization. Internalization of annexin A5‐iron oxide particles is also expected to occur in vivo, where the apoptotic stimulus and the contrast agent are simultaneously present. Where the extent of internalization in vivo is similar to that observed in the present study, both T₂‐ and T‐weighted MR sequences are considered suitable for the detection of these particles in vivo. Copyright © 2009 John Wiley & Sons, Ltd.     

Propofol attenuates high glucose‐induced superoxide anion accumulation in human umbilical vein endothelial cells

Perioperative hyperglycemia is a common clinical metabolic disorder. Hyperglycemia could induce endothelial apoptosis, dysfunction, and inflammation, resulting in endothelial injury. Propofol is a widely used anesthetic drug in clinical settings. Our previous studies indicated that propofol attenuated high glucose‐induced endothelial apoptosis, dysfunction, and inflammation via inhibiting reactive oxygen species (ROS) accumulation. However, the mechanisms by which propofol reduces high glucose‐induced endothelial ROS accumulation are still obscure. In this study, we examined how propofol attenuates high glucose‐induced endothelial ROS accumulation. Compared with 5 mm glucose treatment, 15 mm glucose upregulated the expression of pin‐1, phosphatase A2 (PP2A), p66^shc and mitochondrial p66^shc expression, increased p66^shc‐Ser³⁶ phosphorylation, and accumulation. More importantly, although propofol had no effect on 15 mm glucose‐induced p66^shc‐Ser³⁶ phosphorylation and pin‐1 expression, propofol could downregulated PP2A expression and p66^shc expression in whole‐cell and mitochondrion, resulting in the reduction of accumulation. Moreover, we demonstrated that the antioxidative effect of propofol was similar to that of calyculin A, an inhibitor of PP2A. In contrast, FTY720, an activator of PP2A, antagonized the effect of propofol. Our data indicated that the antioxidative effect of propofol was achieved by downregulating PP2A expression, resulting in the inhibition of p66^shc‐Ser³⁶ dephosphorylation and mitochondrial p66^shc expression.     

Attenuation Coefficient Measurement in the Thyroid

Objective . To assess the feasibility of a novel method of measuring the attenuation coefficient in the thyroid, which offers less variability of results than the conventional method. Methods . In our new method, the attenuation coefficient was evaluated on the basis of the following equation with sound field correction: In our system, the attenuation coefficient was also evaluated by the spectral shift central frequency method at the same time. In this study, we used 32 cases of normal thyroid, 26 cases of Graves disease, and 11 cases of Hashimoto thyroiditis in the system. Results . With this novel method, attenuation coefficient values of the thyroid (mean ± SD) were 1.50 ± 0.26 dB ? cm^?1 ? MHz^?1 in the normal group, 0.91 ± 0.23 dB ? cm^?1 ? MHz^?1 in the Graves disease group, and 1.10 ± 0.27 dB ? cm^?1 ? MHz^?1 in the Hashimoto thyroiditis group. The novel method recorded a statistically significant difference between normal and diseased thyroids (P < .0001) and between Graves disease and Hashimoto thyroiditis groups (P = .0035). Statistical variation of the attenuation coefficient values obtained using the novel method was much smaller than that of those obtained by the spectral shift central frequency method in every group. Conclusions . This new method is considered usable for evaluating the attenuation coefficient of the thyroid in vivo.     

Converting FENO by different flows to standard flow FENO

In clinical practice, assessment of expiratory nitric oxide (F_ENO) may reveal eosinophilic airway inflammation in asthmatic and other pulmonary diseases. Currently, measuring of F_ENO is standardized to exhaled flow level of 50 ml s^?1, since the expiratory flow rate affects the F_ENO results. To enable the comparison of F_ENO measured with different expiratory flows, we firstly aimed to establish a conversion model to estimate F_ENO at the standard flow level, and secondly, validate it in five external populations. F_ENO measurements were obtained from 30 volunteers (mixed adult population) at the following multiple expiratory flow rates: 50, 30, 100 and 300 ml s^?1, after different mouthwash settings, and a conversion model was developed. We tested the conversion model in five populations: healthy adults, healthy children, and patients with COPD, asthma and alveolitis. F_ENO conversions in the mixed adult population, in healthy adults and in children, showed the lowest deviation between estimated from 100 ml s^?1 and measured F_ENO at 50 mL s^?1: ?0·28 ppb, ?0·44 ppb and 0·27 ppb, respectively. In patients with COPD, asthma and alveolitis, the deviation was ?1·16 ppb, ?1·68 ppb and 1·47 ppb, respectively. We proposed a valid model to convert F_ENO in healthy or mixed populations, as well as in subjects with obstructive pulmonary diseases and found it suitable for converting F_ENO measured with different expiratory flows to the standard flow in large epidemiological data, but not on individual level. In conclusion, a model to convert F_ENO from different flows to the standard flow was established and validated.     

Influence of work rate on the determinants of oxygen deficit during short-term submaximal exercise: implications for clinical research

Objective: The effect of increasing work rate was studied on the determinants of the oxygen deficit. Methods: Exercise testing was performed on a treadmill and gas exchange was measured on a breath‐by‐breath basis. Eleven healthy subjects, aged 18–25 years, performed three square wave exercise tests of different intensity. Before exercise, gas exchange was measured at rest in the standing position for 3 min, followed by a 6‐min square wave exercise test, randomly assigned at 4, 8 or 12% inclination. Immediately after exercise the recovery gas exchange was determined for 3 min. To calculate oxygen deficit, the oxygen uptake (O₂) values at onset of exercise were subtracted from the steady‐state value, the differences were cumulated and expressed as a percentage of the total oxygen cost for the 6‐min exercise. Results: The oxygen deficit increased significantly (P<0·001) with increasing work rate (6·1 ± 1·4% for 4%, 8·4 ± 2·1% for 8% and 9·4 ± 1·7% at 12% inclination). This resulted from a somewhat slower increase of O₂ at the onset of exercise at the highest work rate, reflected by a significantly higher time constant for O₂ at 8 and 12% (24·6 ± 7·3 s at 8% and 24·1 ± 6·3 s at 12% versus 20·2 ± 8·1 s at 4%). More importantly a significantly higher steady‐state value for O₂ was found at the highest exercise level, compared with the other exercise intensities. Conclusion: The higher oxygen deficit at the highest level of exercise is determined by a slower time constant and a higher asymptote value for O₂.     

Surface functionalization of superparamagnetic nanoparticles for the development of highly efficient magnetic resonance probe for macrophages

In vivo magnetic resonance imaging (MRI) tracking of macrophages plays an important role in monitoring and understanding numerous human diseases with high macrophage activity. In this work, superparamagnetic iron oxide nanoparticles (SPIONs) of ～12 nm were surface‐functionalized with poly(DL ‐lactic acid‐co‐malic acid) copolymer (PLMA) via a nanoprecipitation method. The r₁, r₂ and r₂/r₁ values of the PLMA‐SPIONs obtained at a magnetic field of 3 T were 0.38, 196 and 516 mM ^?1 s^?1, respectively. The high r₂/r₁ ratio can be expected to provide enhanced MR contrast. The PLMA‐SPIONs were readily taken in by macrophages and the high iron uptake was confirmed via Prussian Blue staining and quantified by inductively coupled plasma mass spectrometry (ICP‐MS). No significant cytotoxicity was found even at a high nanoparticle loading of 67.7 pg Fe per cell. A linear relationship between R₂ and R values and the number of PLMA‐SPIONs labeled cells was observed in vitro. As a result of the significantly higher R than R₂ effects, an in vitro detection threshold of about 2820 labeled cells was achieved with short labeling time and low nanoparticle concentration using a clinical 3 T MRI scanner. Thus, the PLMA‐SPIONs can be potentially useful as magnetic resonance probes for targeting and tracking macrophages. Copyright © 2011 John Wiley & Sons, Ltd.     

Peak cardiac power output in healthy,trained men

Previous investigations into peak cardiac power output (CPO peak) have been limited to clinical populations and healthy, but non‐athletic adults, and normative data on trained individuals would allow a greater understanding of this parameter. Therefore, we recruited eight healthy, well‐trained male cyclists. Peak oxygen consumption ( peak) was assessed using an incremental ergometer test, and following a 40‐min recovery period, peak cardiac output (T peak) was measured during a constant load test that elicited peak (±5%) using the Defares CO₂ rebreathing technique. CPO peak was calculated as described by Cooke et al. (1998) . Mean (±SD) values during the constant load test were: peak, 4·94 ± 0·41 l min^?1; T peak, 36·5 ± 3·7 l min^?1; mean arterial pressure, 123 ± 8 mmHg and CPO peak, 9·9 ± 1·0 W. These results demonstrate CPO peak in a well‐trained population to be approximately twice those observed in healthy, but non‐athletic adults. The current data provide useful information regarding the upper limits and possible ‘trainability’ of cardiac pumping capacity for sedentary and clinically compromised individuals.     

An Emerging Role: The Nurse Content Curator

A new phenomenon, the inverted or “flipped” classroom, assumes that students are no longer acquiring knowledge exclusively through textbooks or lectures. Instead, they are seeking out the vast amount of free information available to them online (the very essence of open source) to supplement learning gleaned in textbooks and lectures. With so much open‐source content available to nursing faculty, it benefits the faculty to use readily available, technologically advanced content. The nurse content curator supports nursing faculty in its use of such content. Even more importantly, the highly paid, time‐strapped faculty is not spending an inordinate amount of effort surfing for and evaluating content. The nurse content curator does that work, while the faculty uses its time more effectively to help students vet the truth, make meaning of the content, and learn to problem‐solve.

Brooks