Impact of proportionate versus disproportionate mitral regurgitation on acute procedural changes and clinical outcomes following transcatheter mitral valve repair

Background

Transcatheter mitral edge-to-edge repair (TEER) with MitraClip offers a less invasive alternative for patients with severe, symptomatic mitral regurgitation (MR) who are considered high risk for surgery. However, patient selection for TEER remains challenging given the variability in underlying MR pathology and current discordance among studies regarding predictors of procedural efficacy and clinical outcomes.

Purpose

This study aimed to assess acute procedural changes and long-term outcomes in patients who underwent TEER according to the proportionality of MR, defined as the ratio of the effective regurgitant orifice area (EROA) and left ventricular end-diastolic volume (LVEDV).

Methods

We analyzed patients who underwent TEER at our institution between 2014 and 2020 with available biplane left ventricular volume measurement. Relevant clinical comorbidities, demographics, and anthropometrics, along with pertinent pre- and post-procedural echocardiogram measurements, were obtained by review of the electronic medical record. The EROA to LVEDV index was calculated for all patients who were then stratified by quartiles. Patients with an EROA/LVEDV index in the lowest quartile were defined as having the most proportionate MR and those with an index in the highest quartile were defined as the most disproportionate MR. Baseline and post-TEER parameters were used to assess acute procedural and longitudinal outcomes.

Results

Baseline clinical and echocardiographic parameters of the 230 subjects according to quartile are shown in the table. Following TEER, there was a larger reduction in the left ventricular end-diastolic diameter and increased MR reduction with increasingly disproportionate MR (p=0.03 and p=0.05, respectively). The change in ejection fraction pre- versus post-TEER did not significantly differ across groups (p=0.64). Median follow up time was 1.7 (0.7–3.5) years; mortality occurred in 77 patients (33.5%) and heart failure hospitalizations occurred in 20 patients (8.7%) during follow up. No significant difference in all-cause mortality or post-procedural heart failure hospitalizations was identified across groups.

Conclusions

In our series, patients with proportionate MR were similarly symptomatic to those with disproportionate MR but had less severe MR with increased comorbidities. Post-TEER MR grade was similar between groups. Longer-term follow up in larger groups of patients is needed to determine the clinical implications.

Funding Acknowledgement

Type of funding sources: None.

4 year outcomes in a prospective evaluation of transcatheter mitral valve-in-valve, valve-in-ring and valve-in-mitral annular calcification: results from the MITRAL trial

Background

The MITRAL Trial (Mitral Implantation of TRAnscatheter vaLves) evaluates the safety and feasibility of balloon-expandable aortic transcatheter heart valves in patients with severe mitral valve disease with mitral annular calcification (MAC), failed surgical rings or failed bioprostheses.

Purpose

We sought to evaluate 4-year outcomes of patients enrolled in the MITRAL trial.

Methods

This is a prospective study that enrolled 91 high surgical risk patients at 13 sites in the U.S. 30 patients underwent Mitral Valve-in-Valve (MViV), 30 Valve-in-Ring (MViR) and 31 Valve-in-MAC (ViMAC). 4-year outcomes of these patients were evaluated in this analysis. Primary endpoints and key serious adverse events including deaths were adjudicated by an independent Clinical Events Committee. Cardiac computed tomography (CT) and echocardiographic images were evaluated by independent CT and Echocardiographic Core Laboratories.

Results

Mean age was 74.3±8.9 years. Most patients undergoing MViV and ViMAC were female (MVIV=63.3%, MViR=36.7% and ViMAC=71%). Mean STS score was 9.2±6.6% (MViV 10.2±6.5%, MViR 8.7±4.7%, ViMAC=8.6±8.2%). All-cause mortality at 4 years was higher for ViMAC and MViR: MViV=6.9% (cardiovascular 3.4%), MViR=48.1% (cardiovascular 18.5%), ViMAC=51.9% (cardiovascular 29.6%), p=0.002 (Figure 1). At 4 years, all survivors had ≤1+ mitral regurgitation and most had none or trace mitral regurgitation (MViV=87.5, MViR=33.3% and ViMAC=100%). Mean mitral valve gradients remained stable (MViV=5.9±2.2 mmHg, MViR= 6.6±5.1 mmHg, ViMAC=5.1±1.0 mmHg), Figure 2. Most survivors experienced significant improvement of symptoms and were in NYHA class I-II at 4-year follow-up (MViV=78.9%, MViR=66.7% and ViMAC=66.7%).

Conclusions

MViV is associated with excellent outcomes at 4 years. MViR and ViMAC were associated with higher mortality at 4 years. However, most survivors in all groups experienced sustained improvement of symptoms and stable THV performance at 4 years. Whether survival bias had an impact on THV performance and improved symptoms at follow-up is not known and deserves further evaluation.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): Unrestricted Research Grant from Edwards Lifesciences.

Abstract P098: Association Between Postpartum Sleep Characteristics And Twenty-four Hour Blood Pressure Patterns In Women With And Without A History Of Preeclampsia

Introduction: Women with a history of preeclampsia (hxPE), a hypertensive pregnancy disorder, are at a four-fold elevated risk of chronic hypertension postpartum compared with healthy pregnancy. The postpartum period is particularly vulnerable to adverse sleep characteristics such as poor sleep quality and frequent sleep disturbances, which are associated with hypertension risk. However, the relation between postpartum sleep characteristics, nighttime blood pressure (BP) and diurnal BP variation assessed by twenty-four hour ambulatory BP monitoring is not well-studied.

Methods: Women with a hxPE (N=13, age 37 ± 5 years) and healthy pregnancy controls (N=12, 36 ± 3 years) without history of sleep disorders were enrolled between 1-5 years postpartum (2.9 ± 1.3 years). Subjective sleep characteristics were reported using the Pittsburgh Sleep Quality Index (PSQI). Ambulatory BP monitoring was conducted to measure 24-hour, day and night BP as well as nocturnal BP dipping and morning BP surge quantified by sleep-trough surge.

Results: Women with a hxPE tended to report poorer global sleep quality (7 ± 3 vs 5 ± 3 PSQI score, P=0.09) related to more frequent sleep disturbance (8 ± 4 vs 5 ± 3 score, P=0.053) without differences in habitual sleep duration (7 ± 1 vs 7 ± 1 hours, P=0.37) or sleep latency (18 ± 11 vs 17 ± 9 min, P=0.89). In the entire group, frequency of sleep disturbance was associated with greater 24-hour BP (systolic: r = 0.42, P=0.046; diastolic: r = 0.43, P=0.04) but not night BP (systolic: r = 0.19, P=0.40; diastolic: r = 0.19, P=0.40). Only sleep latency was related to blunted nocturnal BP dipping % (r = -0.38, P=0.08), and no sleep characteristics were associated with augmented morning BP surge.

Conclusions: Women with a hxPE reported poorer overall sleep quality compared with healthy pregnancy controls 1-5 years postpartum, particularly frequent sleep disturbances. Frequency of sleep disturbance was associated with elevated 24-hour BP, but not higher nighttime BP or attenuated nocturnal BP dipping, indicating that the impact of postpartum sleep characteristics on BP is not attributable to diurnal BP variation.

Axonal quantification of the white matter association fasciculi in cerebral hemispheres of cow (Bos taurus), pig (Sus scrofa domesticus) and rabbit (Oryctolagus cuniculus)

BACKGROUND

Cerebral white matter consists mainly of axons surrounded by myelin sheaths, which are grouped to form association, commissural, and projection fasciculi. The aim of our work was to quantify and compare under the microscope the axons of the white matter association fasciculi in the cerebral hemispheres of cow (Bos taurus), pig (Sus scrofa domesticus) and rabbit (Oryctolagus cuniculus) indirectly by identification of their myelin sheaths.

MATERIALS AND METHODS

The samples were taken from 30 cerebral hemispheres: 10 cow, 10 pig and 10 rabbit (15 right and 15 left). They were obtained following a protocol based on the Talairach-Tournoux coordinate system for human and primate brains. The slides were stained with Luxol Fast Blue, observed by optical microscopy, and photographed at 600×. Samples were also prepared for observation in scanning transmission electron microscopy with osmium tetroxide. The myelin sheaths/axons were counted with the ImageJ software.

RESULTS

Statistically significant differences in the number of myelin sheaths per 410 μm² were found in the inferior and superior longitudinal fasciculi between the left and right hemispheres of cows, with predominance of the right hemisphere; and in the inferior occipitofrontal fasciculus of the rabbit with predominance of the left hemisphere.

CONCLUSIONS

The use of animal models for experiments in the cerebral fasciculi, especially pig, could give us a greater understanding of the behaviour of demyelinating and neurodegenerative diseases in humans.

Life after incarceration: The impact of stability on formerly imprisoned Oxford House residents

According to the National Institute on Drug Abuse, roughly 65% of the US prison population is diagnosed with a substance use disorder (SUD) and over 600,000 individuals are released from incarceration yearly. Thus, it is important to better understand the factors that allow individuals recovering from SUD to reintegrate into communities after incarceration. This study sought to understand the relationship between a personality mediator (stability) and quality of life (QOL) and belonging support (BS), as well as the relationship between this mediator and QOL and psychological sense of community (PSOC) for 131 individuals living in Oxford House (OH) recovery homes. Stability was found to mediate the relationship between BS and QOL, as well as PSOC and QOL. The findings suggest that OH is a supportive and positive recovery community for those with criminal justice backgrounds, particularly those with higher stability.

The prevalence and natural history of mitral annulus calcification

Background

There is a paucity of data about the prevalence and natural history of mitral annular calcification (MAC).

Purposes

In a large cohort of patients undergoing clinically-indicated echocardiography, we aimed to evaluate the prevalence and the natural history of MAC, and the frequency of associated mitral valve dysfunction (MVD).

Methods

Retrospective review of all patients who underwent echocardiographic evaluation at our institution between January 1st and December 31st 2015. The patients were stratified into 3 groups: MAC with MVD, MAC without MVD, no MAC. MVD was defined as moderate or greater mitral regurgitation (MR) or stenosis (MS). The 3 groups were compared for baseline clinical and echocardiographic characteristics and all-cause mortality during follow-up.

Results

Of 24,415 evaluated patients, 5478 (22%) had MAC. Patients with MAC were older (75±10 vs. 60±16 years, p<0.01) and more often female (46% vs. 43%, p<0.01). MVD was more frequently observed in patients with MAC (16% vs. 7%, p<0.01); moderate or greater MR was found in 10% of patients with MAC vs. 6% without MAC (p<0.01) and MS in 7% vs. 0.5% (p<0.01). In patients with MAC, those with MVD were more often female and more frequently had creatinine ≥2mg/dl and moderate or greater aortic stenosis (AS) than those without MVD (Fig. A). Kaplan-Meier survivals at 1 year were 75% in patients with MAC and MVD, 87% in those with MAC without MVD, and 92% in those without MAC (Fig B). Adjusted for age, sex, diabetes, creatinine ≥2 mg/dl, coronary artery disease, left ventricular ejection fraction <50%, and AS, MAC was associated with higher all-cause mortality (adjusted hazard ratio1.4, 95% confidence interval: 1.3–1.5, p<0.01); combined MAC and MVD was associated with the highest mortality during follow-up of 2.5±1.8 years.

Conclusion

In a large cohort of patients undergoing echocardiographic evaluation, the prevalence of MAC was 22%. MV dysfunction was more than twice as prevalent in patients with MAC as without. Patients with MAC had higher all-cause mortality than patients without MAC. Among patients with MAC and mitral valvular dysfunction, adjusted mortality was two-fold higher compared to those without MAC.

Funding Acknowledgement

Type of funding source: None

Symptoms and natural history in patients with isolated severe calcific mitral stenosis

Background

Prevalence of calcific mitral stenosis (MS) increases with age. Mitral valve interventions for calcific MS are often delayed until symptoms are severely limiting because the natural history of calcific MS and its relation to cardiac symptoms or comorbidities have not been well assessed.

Objectives

We assessed the prevalence of symptoms, comorbidities and determinants of all-cause mortality in patients with severe calcific MS.

Methods

We retrospectively investigated adults with echocardiographic isolated severe MS, defined as mitral valve area (MVA by the continuity equation) ≤1.5 cm2, from July 2003 to December 2017. Among them, calcific MS was identified as obstruction of left ventricular inflow due to degenerative calcification of the mitral annulus using echocardiography and, whenever available, operative findings including histopathological examination. Inactivity was defined as requirement for assistance with activities of daily living. Follow up was obtained by review of medical records.

Results

Of 491 patients with isolated severe MS, calcific MS was present in 200 (41%; age 78±11 years, 18% men, 32% with atrial fibrillation). Charlson Comorbidity Index (CCI) was 5.1±1.7 and 14 (7%) were inactive. MVA and transmitral gradient (TMG) were 1.26±0.19 cm2 and 8.1±3.8 mmHg, respectively. Symptoms were present at baseline in 120 (60%) including dyspnea in 97, chest discomfort in 12, syncope in 3, lower extremity edema in 3, thrombosis in 3 and fatigue in 2. Of them, mitral valve interventions including surgical or transcatheter mitral valve replacement and mitral valve bypass were performed in 27 (23%): within 1 year after index TTE in 23 (19%) and at 2, 4, 5 and 6 years in 1 each. Of 80 patients without symptoms at index TTE, 20 (25%) developed symptoms at mean 2.9±3.2 years and interventions were performed in 5 (6%). Of 168 who did not receive interventions, 60 (36%) did not develop symptoms during follow up, 58 (35%) were considered to have moderate MS, 46 (27%) were not offered surgery because of high risk due to advanced age, multiple comorbidities or heavy calcification, and 2 (1%) declined interventions. During follow-up of 2.8±3.0 years, Kaplan-Meier survival at 1 and 3 years without intervention were 72% and 52%, respectively (Fig. A). Inactivity, CCI >5, left ventricular ejection fraction (LVEF) <50%, TMG ≥8 mmHg (the mean TMG) and right ventricular systolic pressure (RVSP) ≥50 mmHg were independently associated with mortality (Fig. B). Symptoms were associated with referral for interventions (OR 3.43, 95% CI 1.22–9.65; p=0.019), but not with mortality.

Conclusion

Patients with isolated severe calcific MS had a high burden of comorbidities and had high mortality without intervention. Symptoms were common (60%), but were not associated with mortality. TMG ≥8 mmHg, RVSP ≥50 mmHg, LVEF<50%, CCI >5 and inactivity were independently associated with mortality.

Funding Acknowledgement

Type of funding source: None

Effects of Climate Variability on Queen Production and Pollen Preferences of Neotropical Bumblebee Bombus atratus in a High Andean Suburban Condition

Bombus atratus Franklin is a widely distributed bumblebee of South America. In Colombia, this species is recognized for its ability to adapt to highly disturbed habitats. However, knowledge of its ecology is poorly known, in particular conditions to ensure the long-term conservation of its populations. Identification of pollen resources is an important issue that could be used as a tool to manage and conserve bumblebees. In tropical areas, rainfall patterns could affect floral phenology and therefore the availability of pollen resources. Considering this, the present work aimed to establish the effect of extreme weather conditions (El Niño) in pollen availability, use of pollinic sources, and gyne production in B. atratus colonies. We reared and located 14 B. atratus colonies in a suburban area during a dry season (ENSO "El Niño") and a rainy season (ENSO "La Niña"). We registered time to gyne production and numbers of gynes produced per colony. We extracted pollen samples to establish both its floral origin and its relative abundance. We measured floral offer for each season. The data of pollen use per colony were utilized to perform Bipartite networks. We analyzed the production of gynes and pollen use per season with correlation models and generalized linear models. Colonies of the rainy season produced more gynes and faster. The floral diversity and offer were higher during the rainy season. Successful colonies used specific pollen sources in two seasons, independently of the floral offer. Extreme dry season affected development of B. atratus colonies.

4D-Dynamic Contrast-Enhanced MRI for Preoperative Localization in Patients with Primary Hyperparathyroidism

BACKGROUND AND PURPOSE

Our aim was to test the hypothesis that our recently introduced 4D-dynamic contrast-enhanced MR imaging with high spatial and temporal resolution has equivalent accuracy to 4D-CT for preoperative gland localization in primary hyperparathyroidism without requiring exposure to ionizing radiation.

MATERIALS AND METHODS

Inclusion criteria were the following: 1) confirmed biochemical diagnosis of primary hyperparathyroidism, 2) preoperative 4D-dynamic contrast-enhanced MR imaging, and 3) surgical cure with >50% decrease in serum parathyroid hormone intraoperatively. 4D-dynamic contrast-enhanced studies were reviewed independently by 2 neuroradiologists to identify the side, quadrant, and number of abnormal glands, and compared with surgical and pathologic results.

RESULTS

Fifty-four patients met the inclusion criteria: 37 had single-gland disease, and 17, multigland disease (9 with double-gland hyperplasia; 3 with 3-gland hyperplasia; and 5 with 4-gland hyperplasia). Interobserver agreement (κ) for the side (right versus left) was 0.92 for single-gland disease and 0.70 for multigland disease. Interobserver agreement for the quadrant (superior versus inferior) was 0.70 for single-gland disease and 0.69 for multigland disease. For single-gland disease, the gland was correctly located in 34/37 (92%) patients, with correct identification of the side in 37/37 (100%) and the quadrant in 34/37 (92%) patients. For multigland disease, the glands were correctly located in 35/47 (74%) patients, with correct identification of the side in 35/47 (74%) and the quadrant in 36/47 (77%).

CONCLUSIONS

The proposed high spatial and temporal resolution 4D-dynamic contrast-enhanced MR imaging provides excellent diagnostic performance for preoperative localization in primary hyperparathyroidism, with correct gland localization of 92% for single-gland disease and 74% in multigland disease, superior to 4D-CT studies.

P1798 Determinants of increased mitral mean diastolic gradient after transcatheter edge-to-edge mitral valve repair

Background

Transcatheter edge-to-edge mitral valve repair (TMVR; MitraClip, Abbott Vascular) is clinically approved for treatment of severe, symptomatic mitral regurgitation (MR) in high or prohibitive surgical risk patients. Iatrogenic mitral stenosis is a known complication of TMVR, but determinants of increased post-procedure mean diastolic gradient are not well defined.

Purpose

We aimed to investigate the determinants of increased mitral mean diastolic gradient after TMVR.

Methods

We retrospectively reviewed 59 patients. 2D and 3D TEE data sets acquired before and immediately after procedure were analyzed. 4D Cardio-View and 4D MV-Assessment (TomTec, Germany) were used for the analysis of the 3D volume data set. Quantitative mitral valve analysis was done at the end of systole. Increased mitral mean diastolic gradient after TMVR was correlated with pre-procedure 2D and 3D echocardiographic data.

Results

34 patients had primary MR, 25 patients had mixed/secondary MR. Baseline mean mitral diastolic gradient was 2.0 ± 0.9mmHg and increased to 3.9 ± 1.8mmHg post-TMVR and the mean 3D planimetric mitral valve area decreased from 5.3 ± 1.5cm2 to 2.6 ± 1.0cm2. Implantation of multiple clips was performed less frequently in patients with smaller baseline mitral valve area; 8% vs 47% in the lowest quartile vs all others (p = 0.006). 12(20%) of patients had a mean diastolic gradient >5mmHg post-TMVR and 15(25%) of patients had a post-TMVR mitral valve area <2.0 cm2. There was no significant difference in post-procedure heart rate between patients with mean diastolic gradient ≤5mmHg vs >5mmHg (p = 0.08). Patient characteristics according to post-TMVR mean diastolic gradient are shown in the Table. Post-TMVR mean diastolic gradient >5mmHg was more common in patients with increased pre-procedure mean diastolic gradient(p = 0.006), post-TMVR mitral valve area <2.0 cm2(40% vs 14%, p = 0.03), and ≥moderate residual mitral regurgitation(38% vs 11%, p = 0.02). Post-TMVR mitral valve area <2.0cm2 was present in 50% vs 19% of patients with vs without a mean gradient >5mmHg(p = 0.04).

Conclusions

Elevated post-TMVR mean diastolic gradient is multifactorial and related to mitral stenosis, but residual mitral regurgitation also appears to be an important contributor to increased gradients in some patients. Larger cohorts are likely needed to assess the concurrent impact of mitral annular calcification, leaflet calcification, and other variables on post-TMVR mean gradient.

Abstract P1798 Figure. 2D and 3D Echocardiographic Parameters

Maternal fasting glycemia and adverse pregnancy outcomes in a Mediterranean population

AIMS

The hyperglycemia and adverse pregnancy outcome study demonstrated a continuous association between fasting plasma glucose (FPG) levels below those diagnostic of diabetes and adverse neonatal outcomes. We aimed to investigate whether the same association was found in a Mediterranean population.

METHODS

A retrospective analysis of singleton pregnancies attended at our Hospital between 2008 and 2015 (n = 5203). FPG was evaluated in the second trimester, and it was divided into 7 categories (1 < 75, 2 75-79, 3 80-84, 4 85-89, 5 90-94, 6 95-99 and 7 100-124 mg/dL). Pregnancy outcomes included elective cesarean delivery, gestational hypertensive disorders (GHD), large for gestational age (LGA), small for gestational age (SGA), macrosomia, prematurity, severe prematurity and APGAR at 1 min <7.

RESULTS

Maternal age was 33.8 ± 3.8 years, and BMI at first antenatal visit was 22.9 ± 3.5 kg/m²; mean FPG was 79 ± 7 mg/dL. A positive association was observed between FPG and LGA (p < 0.001), GHD (p = 0.004) and prematurity both <37 and <34 weeks of gestation (p = 0.001 and p = 0.004). FPG and SGA were inversely related (p = 0,038). FPG was not significantly related to rate of C-section or APGAR. Adjusted odds ratios associated with 1 standard deviation increase in the fasting plasma glucose (7 mg/dL) were 1.26 (1.15 to 1.37) for LGA, 1.28 (1.09 to 1.49) for GHD and 0.83 (0.74-0.93) for SGA. In a multivariate analysis controlling for confounders, FPG remained associated with LGA.

CONCLUSIONS

We found an association between FPG levels, below those diagnostic of gestational diabetes according to our guidelines, and adverse maternal and neonatal outcomes in a Mediterranean population.

Drying in Pharmaceutical and Biotechnological Industries

The process used for drying pharmaceuticals has a high impact on the final product characteristics, both on the active ingredient (high chemical purity product) and the end drug product (complexgalenic formulation). For example, it is well-known that there is a direct relation between the absorption of the active ingredient and its characteristic crystalline or polymorphic form. In some cases, the latter is related to the procedure and conditions of drying. The consequences of the process used to dry a pharmaceutical product may be different depending on the development phase: pre-clinical studies or manufacture (production). The drying process may greatly influence the quality of the drug substances in several aspects: the polymorphic form of the active ingredient, the structural changes that may have an effect on the activity of the substance, the degradation products formed due to the drying conditions and the presence of residual solvents undesirable or above the permitted limits after drying. Consequently, it is important to know the influence of all the factors and to establish the product specifications, as well as the nature and limits of residual solvents, in agreement with current regulations.

Toxic consumption among patients suffering delusional disorder

Introduction

Several epidemiological studies describe the association between substance abuse and appearance of psychotic symptoms. There is a higher prevalence of psychotic symptoms among cannabis and cocaine consumers compared to the general population.

The cannabinoid receptors regulate the release of dopamine and cocaine has a strong inhibitory action on reuptake of the same. This may explain the greater proportion of subjects moderately or heavily dependent on cocaine or cannabis experience symptoms of psychotic sphere.

Objectives/Aims

Describing the profile of drug consumption among a group of patients diagnosed with delusional disorder.

Methods

Our data come from a case register study of delusional disorder in Andalucía (Spanish largest region). By accessing digital health data, we selected 1927 cases who meet criteria DSM 5 for delusional disorder collecting different toxic consumption habits.

Results

It was found that 1070 (93.4%) of patients diagnosed as delusional disorder according DSM 5 did not consume cannabis, compared to 75 (6.6%) who do so. Among patients diagnosed as “other psychoses”, 243 (85%) did not use drugs and 43 (15%) consume other drugs of different types of cannabis.

Conclusion

In our sample, we found that the use of drugs such as cannabis and cocaine is less common among patients diagnosed with delusional disorder compared with other individuals diagnosed as “other psychosis”.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

Electrochemically synthesized amorphous and crystalline nanowires: dissimilar nanomechanical behavior in comparison with homologous flat films

The effects of constrained sample dimensions on the mechanical behavior of crystalline materials have been extensively investigated. However, there is no clear understanding of these effects in nano-sized amorphous samples. Herein, nanoindentation together with finite element simulations are used to compare the properties of crystalline and glassy CoNi(Re)P electrodeposited nanowires (ϕ ≈ 100 nm) with films (3 μm thick) of analogous composition and structure. The results reveal that amorphous nanowires exhibit a larger hardness, lower Young's modulus and higher plasticity index than glassy films. Conversely, the very large hardness and higher Young's modulus of crystalline nanowires are accompanied by a decrease in plasticity with respect to the homologous crystalline films. Remarkably, proper interpretation of the mechanical properties of the nanowires requires taking the curved geometry of the indented surface and sink-in effects into account. These findings are of high relevance for optimizing the performance of new, mechanically-robust, nanoscale materials for increasingly complex miniaturized devices.

Polymer versus phosphine stabilized Rh nanoparticles as components of supported catalysts: implication in the hydrogenation of cyclohexene model molecule

The influence of stabilizers on the catalytic performance of small rhodium nanoparticles was studied through a model hydrogenation reaction.

Dynamic 4D MRI for Characterization of Parathyroid Adenomas: Multiparametric Analysis

BACKGROUND AND PURPOSE

The hypervascular nature of parathyroid adenomas can be explored by proper dynamic imaging to narrow the target lesions for surgical exploration. The purpose of this study was to establish MR perfusion characteristics of parathyroid adenomas to differentiate them from their mimics, such as subjacent thyroid tissue and cervical lymph nodes.

MATERIALS AND METHODS

Preoperative high-spatial and -temporal resolution dynamic 4D contrast-enhanced MR imaging in 30 patients with surgically proved parathyroid adenomas was evaluated retrospectively. Using coregistered images, we placed ROIs over the parathyroid adenoma, thyroid gland, and a cervical lymph node (jugulodigastric) to obtain peak enhancement, time-to-peak, wash-in, and washout in each patient. Data were analyzed by logistic regression and analysis of variance. Receiver operating characteristic analysis was performed to determine the optimal parameters for determination of parathyroid adenomas versus thyroid tissue and cervical lymph nodes.

RESULTS

Parathyroid adenomas showed significantly (P < .05) faster time-to-peak, higher wash-in, and higher washout compared with cervical lymph nodes and significantly (P < .05) higher peak enhancement, faster time-to-peak, higher wash-in, and higher washout compared with thyroid tissue. Logistic regression analysis indicated significant contribution from time-to-peak (P = .02), wash-in (P = .03), and washout (P = .008) for differentiation of parathyroid adenomas from thyroid and cervical lymph nodes. Using receiver operating characteristic analysis, we obtained the best diagnostic accuracy from a combination of time-to-peak/wash-in/washout in the differentiation of parathyroid adenomas versus lymph nodes (area under the curve, 0.96; sensitivity/specificity, 88%/90%) and in distinguishing parathyroid adenomas versus thyroid tissue (area under the curve, 0.96; sensitivity/specificity, 91%/95%).

CONCLUSIONS

Dynamic 4D contrast-enhanced MR imaging can be used to exploit the hypervascular nature of parathyroid adenomas. Multiparametric MR perfusion can distinguish parathyroid adenomas from subjacent thyroid tissue or lymph nodes with diagnostic accuracies of 96%.

Muscle enzyme and fiber type-specific sarcomere protein increases in serum after inertial concentric-eccentric exercise

Muscle damage induced by inertial exercise performed on a flywheel device was assessed through the serum evolution of muscle enzymes, interleukin 6, and fiber type-specific sarcomere proteins such as fast myosin (FM) and slow myosin (SM). We hypothesized that a model of muscle damage could be constructed by measuring the evolution of serum concentration of muscle proteins following inertial exercise, according to their molecular weight and the fiber compartment in which they are located. Moreover, by measuring FM and SM, the type of fibers that are affected could be assessed. Serum profiles were registered before and 24, 48, and 144 h after exercise in 10 healthy and recreationally active young men. Creatine kinase (CK) and CK-myocardial band isoenzyme increased in serum early (24 h) and returned to baseline values after 48 h. FM increased in serum late (48 h) and remained elevated 144 h post-exercise. The increase in serum muscle enzymes suggests increased membrane permeability of both fast and slow fibers, and the increase in FM reveals sarcomere disruption as well as increased membrane permeability of fast fibers. Consequently, FM could be adopted as a fiber type-specific biomarker of muscle damage.

Effect of varying dose-per-pulse and average dose rate in X-ray beam irradiation on cultured cell survival

Characterizing the biological effects of flattening filter-free (FFF) X-ray beams from linear accelerators is of importance, due to their increasing clinical availability. The purpose of this work is to determine whether in vitro cell survival is affected by the higher dose-per-pulse present in FFF beams in comparison with flattened X-ray beams. A Varian TrueBeam(®) linear accelerator was used to irradiate the T98G, V79-4 and U87-MG cell lines with a single fraction of 5 Gy or 10 Gy doses of X-rays. Beams with energies of 6 MegaVolt (MV), 6 MV FFF and 10 MV FFF were used, with doses-per-pulse as measured at the monitor chamber of 0.28, 0.78 and 1.31 mGy/pulse for 6 MV, 6 MV FFF and 10 MV FFF, respectively. The dose delivered to each Petri dish was verified by means of ionization chamber measurements. No statistically significant effects on survival fraction were observed for any of the cell lines considered, either as a function of dose-per-pulse, average dose rate or total dose delivered. Biological effects of higher instantaneous rates should not be excluded on the basis of in vitro experimental results such as the ones presented in this work. The next step toward an assessment of the biological impact of FFF beams will require in vivo studies.