Aortic Root Dimension Using Transthoracic Echocardiography: Results from the Copenhagen City Heart Study

Findings regarding the relation between aortic size and risk factors are heterogeneous. This study aimed to generate new insights from a population-based adult cohort on aortic root dimensions and their association with age, anthropometric measures, and cardiac risk factors and evaluate the incidence of acute aortic events. Participants from the fifth examination round of the Copenhagen City Heart study (aged 20 to 98 years) with applicable echocardiograms and no history of aortic disease or valve surgery were included. Aorta diameter was assessed at the annulus, sinus of Valsalva, sinotubular junction, and the tubular part of the ascending aorta. The study population comprised 1,796 men and 2,316 women; mean age: 56.4 ± 17.0 and 56.9 ± 18.1 years, respectively. Men had larger aortic root diameters than women regardless of height indexing (p <0.01). Age, height, weight, systolic and diastolic blood pressure, mean arterial pressure, pulse pressure, hypertension, diabetes, ischemic heart disease, and smoking were positively correlated with aortic sinus diameter in the crude and gender-adjusted analyses. However, after full adjustment, only height, weight, and diastolic blood pressure remained significantly positively correlated with aortic sinus diameter (p <0.001). For systolic blood pressure and pulse pressure, the correlation was inverse (p <0.001). During follow-up (median 5.4 [quartile 1 to quartile 3 4.5 to 6.3] years), the incidence rate of first-time acute aortic events was 13.6 (confidence interval 4.4 to 42.2) per 100,000 person-years. In conclusion, beyond anthropometric measures, age, and gender, diastolic blood pressure was the only cardiac risk factor that was independently correlated with aortic root dimensions. The number of aortic events during follow-up was low.

Trends in percutaneous left atrial appendage occlusion and 1-year mortality 2013-2021: A nationwide observational study

BACKGROUND

Percutaneous left atrial appendage occlusion (LAAO) is increasingly used for stroke prevention in patients with atrial fibrillation and anticoagulant-related complications. Yet, real-life studies evaluating changes in patient characteristics and indications for LAAO remain scarce.

METHODS

To evaluate changes in patient characteristics and indications for LAAO defined as 2-year history of intracerebral bleeding, any ischemic stroke/systemic embolism (SE), any non-intracerebral bleeding, other indication, and 1-year mortality. All patients undergoing percutaneous LAAO in Denmark from 2013 to 2021 were stratified into the following year groups: 2013-2015, 2016-2018, and 2019-2021.

RESULTS

In total, 1465 patients underwent LAAO. Age remained stable (2013-2015: 74 years versus 2019-2021: 75 years). Patients' comorbidity burden declined, exemplified by CHA2DS2-VASc ≥4 and HAS-BLED ≥3 decreased from 56.7% and 63.7% in 2013-2015 to 40.3% and 45.8% in 2019-2021. Indications for LAAO changed over time with other indication comprising 44.7% in 2019-2021; up from 26.9% in 2013-2015. Conversely, fewer patients had an indication of any ischemic stroke/SE (2013-2015: 30.8% vs 2019-2021: 20.3%) or any non-intracerebral bleeding (2013-2015: 29.4% vs 2019-2021: 23.4%). 1-year mortality was 11.3% for any non-intracerebral bleeding and 6.2% for other indication.

CONCLUSION

The LAAO patient-profile has changed considerably. Age remained stable, while comorbidity burden decreased during the period 2013-2021. LAAO is increasingly used in patients with no clinical event history and mortality differs according to indication. Selection of patients to LAAO should be done carefully, and contemporary real-life studies investigating clinical practice could add important insights.

Formation of Natural Magnesium Silica Hydrate (M-S-H) and Magnesium Alumina Silica Hydrate (M-A-S-H) Cement

Occurrences of natural magnesium alumina silicate hydrate (M-(A)-S-H) cement are present in Feragen and Leka, in eastern and western Trøndelag Norway, respectively. Both occurrences are in the subarctic climate zone and form in glacial till and moraine material deposited on ultramafic rock during the Weichselian glaciation. Weathering of serpentinized peridotite dissolves brucite and results in an alkaline fluid with a relatively high pH which subsequently reacts with the felsic minerals of the till (quartz, plagioclase, K-feldspar) to form a cement consisting of an amorphous material or a mixture of nanocrystalline Mg-rich phyllosilicates, including illite. The presence of plagioclase in the till results in the enrichment of alumina in the cement, i.e., forms M-A-S-H instead of the M-S-H cement. Dissolution of quartz results in numerous etch pits and negative quartz crystals filled with M-A-S-H cement. Where the quartz dissolution is faster than the cement precipitation, a honeycomb-like texture is formed. Compositionally, the cemented till (tillite) contains more MgO and has a higher loss of ignition than the till, suggesting that the cement is formed by a MgO fluid that previously reacted with the peridotite. The M-(A)-S-H cemented till represents a new type of duricrust, coined magsilcrete. The study of natural Mg cement provides information on peridotites as a Mg source for Mg cement and as a feedstock for CO2 sequestration.

Temporal Trends in Patient Characteristics and Outcomes of Transcatheter Aortic Valve Implantation and Surgical Aortic Valve Replacement: A Nationwide Study

With increased use of transcatheter aortic valve implantation (TAVI) in treatment of aortic stenosis, it is important to evaluate real life data trends in outcomes. This nationwide register-based study aimed to present an outlook on temporal trends in characteristics and outcomes, including mortality. First-time consecutive Danish patients who underwent TAVI from 2010 to 2019 were included in this study. The chi-square and Kruskal-Wallis tests were performed to assess the differences in the characteristics over time and Cochrane-Armitage trend tests were used to examine changes in complications and mortality. Between 2010 and 2019, 4,847 patients (54.6% men, median age 82 [quartile 1 to quartile 3: 77 to 85] years) underwent first-time TAVI. A statistically significant decrease over time was observed for preprocedural hypertension, ischemic heart disease, and heart failure, whereas preexisting chronic obstructive lung disease and preprocedural pacemaker remained stable. We observed a significant decrease in 30- and 90-day postoperative preprocedural pacemaker implantation from 2011 to 2017, with 15.1% and 15.9% in 2011 and 8.6% and 8.9% in 2017, respectively. The incidence of for 30- and 90-day heart failure significantly decreased from 19.3% and 20.3% to 8.5% and 9.1%, respectively. We observed significant changes for 30-day atrial fibrillation, whereas the changes over time for 90-day atrial fibrillation and 30- and 90-day stroke/transient ischemic attack remained insignificant. The all-cause mortality within 30- and 90 days significantly decreased over time from 6.7% and 9.2% in 2011 to 1.5% and 2.7% in 2019 and 2016, respectively. In conclusion, this national study provides general insight on the trends of complications and mortality of TAVI, demonstrating significant reductions over time.

Characteristics and Outcomes in Patients With Acute Aortic Dissection: A Nationwide Registry Study

BACKGROUND

We aimed to describe characteristics and outcomes in a nationwide population of patients with acute type A and type B aortic dissection.

METHODS

All patients in Denmark with a first-time diagnosis of acute aortic dissection between 2006 and 2015 were identified by national registries. The main outcomes were in-hospital mortality and long-term survival in hospital survivors.

RESULTS

The study population comprised 1157 (68%) patients with type A aortic dissection and 556 (32%) patients with type B aortic dissection, median age of 66 (57-74) years and 70 (61-79) years, respectively. Men accounted for 64%. Median follow-up was 8.9 (6.8-11.5) years. Of patients with type A aortic dissection, 74% were managed surgically, whereas 22% of the patients with type B aortic dissection were managed with surgery or endovascular technique. In-hospital mortality was 27% for type A aortic dissection overall (surgery, 18%; no surgery, 52%) and 16% for type B aortic dissection (surgery or endovascular treatment, 13%; conservative treatment, 17%; P < .001, type A vs type B). Of patients discharged alive, survival was persistently better for type A aortic dissection than for type B aortic dissection (P < .001). Unadjusted 1- and 3-year survival of patients with type A aortic dissection discharged alive was 96% and 91%, respectively, for surgically managed and 88% and 78% without surgery. For type B aortic dissection, the numbers were 89% and 83% for endovascular/surgically managed and 89% and 77% for conservatively managed.

CONCLUSIONS

We found higher in-hospital mortality for type A and type B aortic dissection than is reported from referral center registries. Type A aortic dissection had the highest mortality rate during the acute phase, whereas for patients who were discharged alive, the mortality rate was higher for patients with type B aortic dissection.

The Changing Face of Turner Syndrome

Turner syndrome (TS) is a condition in females missing the second sex chromosome (45,X) or parts thereof. It is considered a rare genetic condition and is associated with a wide range of clinical stigmata, such as short stature, ovarian dysgenesis, delayed puberty and infertility, congenital malformations, endocrine disorders, including a range of autoimmune conditions and type 2 diabetes, and neurocognitive deficits. Morbidity and mortality are clearly increased compared with the general population and the average age at diagnosis is quite delayed. During recent years it has become clear that a multidisciplinary approach is necessary toward the patient with TS. A number of clinical advances has been implemented, and these are reviewed. Our understanding of the genomic architecture of TS is advancing rapidly, and these latest developments are reviewed and discussed. Several candidate genes, genomic pathways and mechanisms, including an altered transcriptome and epigenome, are also presented.

Musculoskeletal diseases in Marfan syndrome: a nationwide registry study

Background

Marfan syndrome is associated with abnormalities in the musculoskeletal system including scoliosis, pectus deformities, protrusio acetabuli, and foot deformities. Over a life span, many patients with Marfan syndrome will need treatment; however, the musculoskeletal morbidity over a life span is not well described. The aim of the present study was to assess the overall burden of musculoskeletal disease in patients with Marfan syndrome.

Materials and methods

A registry-based, nationwide epidemiological study of patients with a Ghent II verified Marfan syndrome diagnosis from 1977 to 2014. Each patient was matched on age, and sex with up to 100 controls from the background population.

Results

We identified 407 patients with Marfan syndrome and 40,700 controls and compared their musculoskeletal diagnoses and surgical treatments using Cox proportional hazards ratio (HR). The risk of a registration of a musculoskeletal diagnosis in patients with Marfan syndrome was significantly increased compared to controls (HR: 1.94 (1.69–2.24). One out of six with Marfan syndrome was registered with scoliosis (HR: 36.7 (27.5–48.9). Scoliosis was more common in women with Marfan syndrome compared to men (HR: 4.30 (1.73–1.08)). One out of 11 were registered with a pectus deformity HR: 40.8 (28.1–59.3), and one out of six with a deformity of the foot. Primarily pes planus (HR: 26.0 (15.2–44.3). The proportion of patients with Marfan syndrome (94/407) that underwent musculoskeletal surgery was also significantly higher (HR: 1.76 (1.43–2.16)). The major areas of surgery were the spine, pectups correction, and surgery of the foot/ankle. Ten patients with Marfan syndrome had elective orthopedic surgery without being recognized and diagnosed with Marfan syndrome until later in life. None of these had scoliosis, pectus deformity or a foot deformity. Among patients with an aortic dissection, the age at dissection was 34.3 years in those with at least one major musculoskeletal abnormality. In patients without a major abnormality the age at dissection was 45.1 years (p < 0.01).

Conclusions

The extent of musculoskeletal disease is quite significant in Marfan syndrome, and many will need corrective surgery during their life span. Surgeons should be aware of undiagnosed patients with Marfan syndrome when treating patients with a Marfan syndrome like-phenotype.

Assessment of patients with a suspected cardioembolic ischemic stroke. A national consensus statement

OBJECTIVES

Several cardiovascular, structural, and functional abnormalities have been considered as potential causes of cardioembolic ischemic strokes. Beyond atrial fibrillation, other sources of embolism clearly exist and may warrant urgent action, but they are only a minor part of the many stroke mechanisms and strokes that seem to be of embolic origin remain without a determined source. The associations between stroke and findings like atrial fibrillation, valve calcification, or heart failure are confounded by co-existing risk factors for atherosclerosis and vascular disease. In addition, a patent foramen ovale which is a common abnormality in the general population is mostly an innocent bystander in patients with ischemic stroke. For these reasons, experts from the national Danish societies of cardiology, neurology, stroke, and neuroradiology sought to develop a consensus document to provide national recommendations on how to manage patients with a suspected cardioembolic stroke. Design: Comprehensive literature search and analyses were done by a panel of experts and presented at a consensus meeting. Evidence supporting each subject was vetted by open discussion and statements were adjusted thereafter. Results: The most common sources of embolic stroke were identified, and the statement provides advise on how neurologist can identify cases that need referral, and what is expected by the cardiologist. Conclusions: A primary neurological and neuroradiological assessment is mandatory and neurovascular specialists should manage the initiation of secondary prophylactic treatment. If a cardioembolic stroke is suspected, a dedicated cardiologist experienced in the management of cardioembolism should provide a tailored clinical and echocardiographic assessment.

Maternal health and pregnancy outcome in diagnosed and undiagnosed Marfan syndrome: A registry-based study

In Marfan syndrome (MFS), pregnancy is considered as high risk due to the deficiency of fibrillin in the connective tissue and increased risk of aortic dissection. The objective was to demonstrate the consequences on maternal health, in women with diagnosed and undiagnosed MFS at the time of pregnancy and childbirth. By using national health care registries, we identified all pregnancy related outcomes, from women with MFS (n = 183) and an age-matched background population (n = 18,300). We found 91 pregnancies during follow-up. Significantly fewer women with MFS gave birth, compared to the background population. No women with known MFS had a pregnancy related aortic dissection but complications related to the cervix were increased (HR:19.8 [95% CI:2.2-177.5]). Fifty women with MFS were undiagnosed at the time of their first pregnancy and/or childbirth. Among these, there were more birth canal related complications HR:27.2 (95% CI: 2.3-315.0), preeclampsia (HR:2.25 [95% CI: 1.11-4.60]), fetal deaths (HR:12.3 [95% CI: 1.51-99.8]), and all delivery-related dissections came from this subgroup. In conclusion, undiagnosed women with MFS experienced more pregnancy and childbirth related complications including fetal death, birth canal issues, preeclampsia, and aortic disease, which emphasizes the need for an early MFS diagnosis and special care during pregnancy and childbirth.

Bone Geometry, Density, and Microarchitecture in the Distal Radius and Tibia in Adults With Marfan Syndrome Assessed by HR-pQCT

Marfan syndrome (MFS) is a hereditary disorder of connective tissue caused by mutations in the fibrillin-1 gene. Studies have shown that patients with MFS have lower bone mass, but little is known about the other constituents of bone strength. We hypothesize that patients with MFS will have larger bone area and compromised cortical microarchitecture compared with non-MFS individuals. A total of 74 adult patients with MFS and 145 age- and sex-matched non-MFS reference individuals were included in this study. High-resolution peripheral quantitative computed tomography (HR-pQCT) at the distal radius and distal tibia and dual-energy X-ray absorptiometry of total hip and the lumbar spine were performed, and bone turnover and sex hormones were measured. Patients with MFS had significantly lower areal bone mineral density (BMD) at the total spine (-13%) and total hip (-7%) when compared with the reference group. Patients with MFS had significantly larger total bone area at both the radius (+27%) and tibia (+34%). Volumetric BMD at both measured sites showed significantly reduced total, trabecular, and cortical volumetric BMD in patients with MFS compared with the reference group. The microarchitectural parameters at the radius and tibia were compromised in patients with MFS with significantly reduced trabecular number and thickness, leading to a higher trabecular separation and significantly reduced cortical thickness and increased cortical porosity compared with the reference group. The differences in bone density, geometry, or microarchitecture were not explained by increased bone turnover markers or circulating levels of sex hormones. We conclude patients with MFS have altered bone geometry, altered bone microstructure, and lower bone mass (lower areal BMD and volumetric BMD at all sites) compared with healthy reference individuals. Future studies should focus on fracture rates and fracture risk in adult and aging patients with MFS. © 2020 American Society for Bone and Mineral Research (ASBMR).

Natural History of Hypertension in Turner Syndrome During a 12-Year Pragmatic Interventional Study

Turner syndrome is caused by complete or partial X monosomy in some or all cells. Cardiovascular complications are dominant, including increased blood pressure (BP), leading to early-onset hypertension. The aim is to describe the debut, development, and treatment of hypertension in Turner syndrome during a 12-year pragmatic interventional study to help identify risk factors associated with hypertension. One hundred and two women (aged 38±11 years, range: 18-62 years) with Turner syndrome verified by karyotyping (45, X: n=58 [57%]) were included consecutively. Ambulatory BPs were recorded over 24 hours with oscillometric measurements every 20 minutes. Antihypertensive treatment was recommended if the BP was above 135/85 mm Hg during the daytime. Overall, systolic BP, diastolic BP, and pulse pressure increased during the study, while heart rate decreased. The number of patients treated with antihypertensive medicine increased from 29 (28.71%) at baseline to 34 (53.13%) at the end of study. Twenty-four-hour systolic BP and 24-hour pulse pressure increased significantly with age, while 24-hour heart rate decreased with age, and diastolic BP was insignificantly affected by age. Antihypertensive treatment lowered systolic BP (24-hour: -5 mm Hg), diastolic BP (24-hour: -5 mm Hg), and diminished the pulse pressure (24-hour: -6 mm Hg) but did not affect nighttime systolic BP. Antihypertensive treatment did not affect heart rate. Our study showed that both systolic and diastolic BP increases significantly in women with Turner syndrome resulting in an increased risk of cardiovascular comorbidities. This increment should be considered of multifactorial origin with many contributing factors which is supported by our results.

Coronary plaque burden in Turner syndrome a coronary computed tomography angiography study

Turner syndrome (TS) is associated with coronary artery disease (CAD), an important cause of premature death in TS. However, the determinants of CAD in women with TS remain unknown. In a cross-sectional study design, 168 women without clinical evidence of CAD (115 with TS and 53 without TS) were assessed for the presence and volume of subclinical CAD using coronary CT angiography. Karyotype, the presence of congenital heart defects and conventional cardiovascular risk factors were also registered. Comparative analyses were performed (1) between women with and without TS and (2) in the TS group, between women with and without subclinical CAD. The prevalence of CAD, in crude and adjusted analyses, was not increased for women with TS (crude prevalence: 40 [35%] in TS vs. 25 [47%] in controls, p = 0.12). The volume of atherosclerosis was not higher in women with TS compared with controls (median and interquartile range 0 [0-92] in TS vs. 0 [0-81]mm³ in controls, p = 0.29). Among women with TS, women with subclinical CAD were older (46 ± 13 vs. 37 ± 11 years, p < 0.001), had higher blood pressure (systolic blood pressure 129 ± 16 vs. 121 ± 16 mmHg, p < 0.05) and were more frequently diagnosed with type 2 diabetes (5 [13%] vs. 2 [3%], p < 0.05). Karyotype or congenital heart defects were not associated with subclinical CAD. Some women with TS show early signs of CAD, however overall, not more than women without TS. Conventional cardiovascular risk factors were the principal determinants of CAD also in TS, and CAD prevention strategies should be observed.ClinicalTrial.gov Identifier: NCT01678261 ( https://clinicaltrials.gov/ct2/show/NCT01678261 ).

Sex Hormone Replacement Therapy in Turner Syndrome: Impact on Morbidity and Mortality

CONTEXT

The long-term effects of female hormone replacement therapy (HRT) in Turner syndrome (TS) are unknown.

OBJECTIVE

To examine morbidity, mortality and medicinal use in TS and the impact of HRT in 45,X women.

DESIGN AND SETTING

National cohort study, following all TS individuals ever diagnosed in Denmark from 1977 to 2014.

PATIENTS AND METHODS

In the Danish Cytogenetic Central Registry, we identified 1156 females diagnosed with TS from 1960 to 2014, and, subsequently, Statistics Denmark randomly identified 115 577 age-matched female controls. TS women and their matched controls were linked with person-level data from the National Patient Registry and the Medication Statistics Registry, and they were compared concerning mortality, hospitalizations, and medical prescriptions. Among 329 45,X women, 44 had never been HRT treated, and 285 had been treated at some point. HRT treated women were compared with untreated concerning mortality, hospitalizations, and medical prescriptions.

RESULTS

Endocrine and cardiovascular mortality and morbidity were significantly increased in TS compared with the matched controls. Comparing HRT treated with nontreated 45,X women, we found a similar mortality (hazard ratio 0.83, 95% confidence interval 0.38-1.79). Among the HRT-treated 45,X women, we found a significantly lower use of antihypertensives, antidiabetics, and thyroid hormones and significantly reduced hospitalization rates for stroke and osteoporotic fractures.

CONCLUSION

Women with TS have an increased overall mortality and morbidity. HRT seems to have a beneficial effect on endocrine conditions, hypertension, and stroke in women with 45,X karyotype, with no clear impact on mortality.

Detection and Characterization of a Novel Copper-Dependent Intermediate in a Lytic Polysaccharide Monooxygenase

Lytic polysaccharide monooxygenases (LPMOs) are copper-containing enzymes capable of oxidizing crystalline cellulose which have large practical application in the process of refining biomass. The catalytic mechanism of LPMOs still remains debated despite several proposed reaction mechanisms. Here, we report a long-lived intermediate (t_1/2 =6-8 minutes) observed in an LPMO from Thermoascus aurantiacus (TaLPMO9A). The intermediate with a strong absorption around 420 nm is formed when reduced LPMO-Cu^I reacts with sub-equimolar amounts of H₂ O₂ . UV/Vis absorption spectroscopy, electron paramagnetic resonance, resonance Raman and stopped-flow spectroscopy suggest that the observed long-lived intermediate involves the copper center and a nearby tyrosine (Tyr175). Additionally, activity assays in the presence of sub-equimolar amounts of H₂ O₂ showed an increase in the LPMO oxidation of phosphoric acid swollen cellulose. Accordingly, this suggests that the long-lived copper-dependent intermediate could be part of the catalytic mechanism for LPMOs. The observed intermediate offers a new perspective into the oxidative reaction mechanism of TaLPMO9A and hence for the biomass oxidation and the reactivity of copper in biological systems.

Turner syndrome: mechanisms and management

Turner syndrome is a rare condition in women that is associated with either complete or partial loss of one X chromosome, often in mosaic karyotypes. Turner syndrome is associated with short stature, delayed puberty, ovarian dysgenesis, hypergonadotropic hypogonadism, infertility, congenital malformations of the heart, endocrine disorders such as type 1 and type 2 diabetes mellitus, osteoporosis and autoimmune disorders. Morbidity and mortality are increased in women with Turner syndrome compared with the general population and the involvement of multiple organs through all stages of life necessitates a multidisciplinary approach to care. Despite an often conspicuous phenotype, the diagnostic delay can be substantial and the average age at diagnosis is around 15 years of age. However, numerous important clinical advances have been achieved, covering all specialty fields involved in the care of girls and women with Turner syndrome. Here, we present an updated Review of Turner syndrome, covering advances in genetic and genomic mechanisms of disease, associated disorders and multidisciplinary approaches to patient management, including growth hormone therapy and hormone replacement therapy.

Optimizing the fold stability of the circularly permuted Trp-cage motif

Through optimization of the linker region and key stabilizing mutations, it has been possible to improve the stability of the circularly permuted (cp) Trp-cage miniprotein. However, even the most stable Trp-cage circular permutants are still less stable than the analogous standard topology (std) Trp-cages. Extending mutational studies of Trp-cage fold stability to cp-species, including analogs lacking chain terminal charges, has uncovered and quantitated some additional stabilizing and destabilizing interactions. Upon protonation, the circular permutants are destabilized to a much greater extent than the standard topology series. End effects, particularly Coulombic interactions, appear to be more important for the cp-series while the Y10/P4 interaction in the cp-series is not as significant a stabilizing feature as the corresponding Y3/P19 in the standard topology series.

The adipokinetic hormones and their cognate receptor from the desert locust, Schistocerca gregaria: solution structure of endogenous peptides and models of their binding to the receptor

Background

Neuropeptides exert their activity through binding to G protein-coupled receptors (GPCRs). GPCRs are well-known drug targets in the pharmaceutical industry and are currently discussed as targets to control pest insects. Here, we investigate the neuropeptide adipokinetic hormone (AKH) system of the desert locust Schistocerca gregaria. The desert locust is known for its high reproduction, and for forming devastating swarms consisting of billions of individual insects. It is also known that S. gregaria produces three different AKHs as ligands but has only one AKH receptor (AKHR). The AKH system is known to be essential for metabolic regulation, which is necessary for reproduction and flight activity.

Methods

Nuclear magnetic resonance techniques (NMR) in a dodecylphosphocholin (DPC) micelle solution were used to determine the structure of the three AKHs. The primary sequence of the S. gregaria AKHR was used to construct a 3D molecular model. Next, the three AKHs were individually docked to the receptor, and dynamic simulation of the whole ligand–receptor complex in a model membrane was performed.

Results

Although the three endogenous AKHs of S. gregaria have quite different amino acids sequences and chain length (two octa- and one decapeptide), NMR experiments assigned a turn structure in DPC micelle solution for all. The GPCR-ModSim program identified human kappa opioid receptor to be the best template after which the S. gregaria AKHR was modeled. All three AKHs were found to have the same binding site on this receptor, interact with similar residues of the receptor and have comparable binding constants. Molecular switches were also identified; the movement of the receptor could be visually shown when ligands (AKHs) were docked and the receptor was activated.

Conclusions

The study proposes a model of binding of the three endogenous ligands to the one existing AKHR in the desert locust and paves the way to use such a model for the design of peptide analogs and finally, peptide mimetics, in the search for novel species-specific insecticides based on receptor–ligand interaction.

Recognition and management of adults with Turner syndrome: From the transition of adolescence through the senior years

Turner syndrome is recognized now as a syndrome familiar not only to pediatricians and pediatric specialists, medical geneticists, adult endocrinologists, and cardiologists, but also increasingly to primary care providers, internal medicine specialists, obstetricians, and reproductive medicine specialists. In addition, the care of women with Turner syndrome may involve social services, and various educational and neuropsychologic therapies. This article focuses on the recognition and management of Turner syndrome from adolescents in transition, through adulthood, and into another transition as older women. It can be viewed as an interpretation of recent international guidelines, complementary to those recommendations, and in some instances, an update. An attempt was made to provide an international perspective. Finally, the women and families who live with Turner syndrome and who inspired several sections, are themselves part of the broad readership that may benefit from this review.

Blood pressure, sympathovagal tone, exercise capacity and metabolic status are linked in Turner syndrome

OBJECTIVES

We studied cardiac autonomic changes in relation to metabolic factors, body composition and 24-hour ambulatory blood pressure measurements in Turner syndrome patients without known hypertension.

DESIGN

Cross sectional.

PATIENTS

Participants were 48 TS women and 24 healthy female controls aged over 18 years.

METHODS

Short-term power spectral analysis was obtained in supine-standing-supine position. Bedside tests included three conventional cardiovascular reflex tests of heart rate response to standing up, heart rate response to deep breathing and blood pressure response to standing up. Mean heart rate during the last 2 minutes of work was used to calculate the maximal aerobic power (VO_2max ).

RESULTS

We found a significantly higher mean reciprocal of the heart rate per second (RR) in TS. Testing for interaction between position and status (TS or control), there were highly significant differences between TS and controls in high-frequency (HF) power, the coefficient of component variation (square root of HF power/mean RR) and low-frequency (LF): HF ratio, with a dampened decline in vagal activity among TS during standing. Bedside test showed TS had a significantly higher diastolic BP in the supine position compared to controls, and the adaptive rise in BP, when changing to upright position was reduced. VO_2max and self-reported level of physical activity were significantly correlated to systolic ambulatory blood pressure both 24-hour and night diastolic ambulatory blood pressure.

CONCLUSION

Vagal tone and modulation of the sympathovagal balance during alteration in body position are impaired in TS. These changes can be risk factors for cardiovascular disease.

Aortic growth rates are not increased in Turner syndrome—a prospective CMR study

Background

Aortic disease is a key determinant of outcomes in Turner syndrome (TS). The present study characterized aortic growth rates and outcomes over nearly a decade in adult women with TS.

Methods and results

Prospective observational study assessing aortic diameters twice with cardiovascular magnetic resonance imaging in women with TS [N = 91; mean follow-up 8.8 ± 3.3 (range 1.6–12.6) years] and healthy age-matched female controls [N = 37; mean follow-up 6.7 ± 0.5 (range 5.9–8.1) years]. Follow-up also included aortic outcomes and mortality, antihypertensive treatment and ambulatory blood pressure. Aortic growth rates were similar or smaller in TS, but the variation was larger. The proximal aorta in TS grew by 0.20 ± 0.26 (mid-ascending) to 0.32 ± 0.36 (sinuses) mm/year. This compared to 0.26 ± 0.14 (mid-ascending) and 0.32 ± 0.17 (sinuses) mm/year in the controls. During 799 years at risk, 7 suffered an aortic outcome (1 aortic death, 2 aortic dissections, 2 aortic interventions, 2 surgical aortic listings) with further 2 aortic valve replacements. At baseline, two women were excluded. One died during subacute aortic surgery (severe dilatation) and one had a previously undetected type A dissection. The combined aortic outcome rate was 1126 per 100 000 observation years. The aortic and all-cause mortality rates were 1 per 799 years (125 deaths per 100 000 observation years) and 9 per 799 years (1126 deaths per 100 000 observation years). Aortic growth patterns were particularly perturbed in bicuspid aortic valves (BAV) and aortic coarctation (CoA).

Conclusion

Aortic growth rates in TS are not increased. BAVs and CoA are major factors that impact aortic growth. Aortic outcomes remain a concern.

Reversing the typical pH stability profile of the Trp-cage

The Trp-cage, an 18-20 residue miniprotein, has emerged as a primary test system for evaluating computational fold prediction and folding rate determination efforts. As it turns out, a number of stabilizing interactions in the Trp-cage folded state have a strong pH dependence; all prior Trp-cage mutants have been destabilized under carboxylate-protonating conditions. Notable among the pH dependent stabilizing interactions within the Trp-cage are: (1) an Asp as the helix N-cap, (2) an H-bonded Asp9/Arg16 salt bridge, (3) an interaction between the chain termini which are in close spatial proximity, and (4) additional side chain interactions with Asp9. In the present study, we have prepared Trp-cage species that are significantly more stable at pH 2.5 (rather than 7) and quantitated the contribution of each interaction listed above. The Trp-cage structure remains constant with the pH change. The study has also provided measures of the stabilizing contribution of indole ring shielding from surface exposure and the destabilizing effects of an ionized Asp at the C-terminus of an α-helix.

Fatal right-sided heart failure due to leukostasis in a patient with leukemic transformation of myelodysplastic syndrome

We document leukostasis leading to acute fatal right-sided heart failure. In patients presenting with leukostasis and cardiopulmonary symptoms, clinicians should aim to assess for cardiac involvement, that is, by ECG and acute echocardiogram, since early recognition of right ventricular disease may provide an opportunity to treat this potentially reversible condition.

Impaired aortic distensibility and elevated central blood pressure in Turner Syndrome: a cardiovascular magnetic resonance study

BACKGROUND

Women with Turner Syndrome have an increased risk for aortic dissection. Arterial stiffening is a risk factor for aortic dilatation and dissection. Here we investigate if arterial stiffening can be observed in Turner Syndrome patients and is an initial step in the development of aortic dilatation and subsequent dissection.

METHODS

Fifty-seven women with Turner Syndrome (48 years [29-66]) and thirty-six age- and sex-matched controls (49 years [26-68]) were included. Distensibility, blood pressure, carotid-femoral pulse wave velocity (PWV), the augmentation index (Aix) and central blood pressure were determined using cardiovascular magnetic resonance, a 24-h blood pressure measurement and applanation tonometry. Aortic distensibility was determined at three locations: ascending aorta, transverse aortic arch, and descending aorta.

RESULTS

Mean aortic distensibility in the descending aorta was significantly lower in Turner Syndrome compared to healthy controls (P = 0.02), however, this was due to a much lower distensibility among Turner Syndrome with coarctation, while Turner Syndrome without coarctation had similar distensibility as controls. Both the mean heart rate adjusted Aix (31.4% vs. 24.4%; P = 0.02) and central diastolic blood pressure (78.8 mmHg vs. 73.7 mmHg; P = 0.02) were higher in Turner Syndrome compared to controls, and these indices correlated significantly with ambulatory night-time diastolic blood pressure. The presence of aortic coarctation (r = - 0.44, P = 0.005) and a higher central systolic blood pressure (r = - 0.34, P = 0.03), age and presence of diabetes were inversely correlated with aortic distensibility in TS.

CONCLUSION

Aortic wall function in the descending aorta is impaired in Turner Syndrome with lower distensibility among those with coarctation of the aorta, and among all Turner Syndrome higher Aix, and elevated central diastolic blood pressure when compared to sex- and age-matched controls.

TRIAL REGISTRATION

The study was registered at ClinicalTrials.gov ( #NCT01678274 ) on September 3, 2012.

Causes of Mortality in the Marfan Syndrome(from a Nationwide Register Study)

The Marfan syndrome (MFS) is strongly associated with aortic disease causing a high prevalence of prophylactic aortic surgery, aortic dissection, and sudden death. The aim of the present study was to evaluate mortality in a nationwide Danish MFS population diagnosed by the Ghent II criteria. In a register-based setting, we identified all Danish patients with MFS (n = 412, men n = 215) by assessment of their medical records. We established a gender and age matched control cohort based on 41,000 control patients (men n = 21,500). MFS cases risk time was 6,669 patient years. We applied Cox regression using each case and his/her control as one stratum, adjusting for age and calendar time. We found a significantly decreased lifespan of 50years compared with 60years among controls. The mortality hazard ratio among MFS compared with controls was significantly increased to3.6 (CI 2.8-4.7, p < 0.001); men 4.0 (CI 2.8-5.7, p < 0.001); women 3.2 (CI 2.1-4.8,p < 0.001). Aorta disease represented the main reason for the overall increased mortality with a hazard ratio of 194.6 (CI 67.4-561.7, p < 0.0001); men 208.7 (CI 53.8-809.1, p < 0.001); women 173.4 (CI 31.5-954.5, p < 0.001). In addition, an unexplained mortality due to respiratory illness was not attributed to pneumothorax. Excluding cardiovascular and respiratory causes of death, we found no indication that MFS is associated with increased mortality for other reasons.

Biological consequences of improving the structural stability of hairpins that have antimicrobial activity

Designing new antimicrobial peptides (AMPs) focuses heavily on the activity of the peptide and less on the elements that stabilize the secondary structure of these peptides. Studies have shown that improving the structure of naturally occurring AMPs can affect activity and so here we explore the relationship between structure and activity of two non-naturally occurring AMPs. We have used a backbone-cyclized peptide as a template and designed an uncyclized analogue of this peptide that has antimicrobial activity. We focused on beta-hairpin-like structuring features. Improvements to the structure of this peptide reduced the activity of the peptide against gram-negative, Escherichia coli but improved the activity against gram-positive, Corynebacterium glutamicum. Distinctions in structuring effects on gram-negative versus gram-positive activity were also seen in a second peptide system. Structural improvements resulted in a peptide that was more active than the native against gram-positive bacterium but less active against gram-negative bacterium. Our results show that there is not always a correlation between improved hairpin-structuring and activity. Other factors such as the type of bacteria being targeted as well as net positive charge can play a role in the potency of AMPs. Copyright © 2017 European Peptide Society and John Wiley & Sons, Ltd.

Data for the homology modelling of the red pigment-concentrating hormone receptor (Dappu-RPCHR) of the crustacean Daphnia pulex, and docking of its cognate agonist (Dappu-RPCH)

The data presented in this article are related to the publication “Interaction of the red pigment-concentrating hormone of the crustacean Daphnia pulex, with its cognate receptor, Dappu-RPCHR: A nuclear magnetic resonance and modeling study” (Jackson et al., 2017) [1]. This article contains the data for homology modeling of the red pigment-concentrating hormone (RPCH) receptor of the water flea, Daphnia pulex (Dappu-RPCHR), which was constructed from its primary sequence. This is the first 3D model of a crustacean G-protein coupled receptor. Docking of the agonist, pGlu-Val-Asn-Phe-Ser-Thr-Ser-Trp amide (Dappu-RPCH), was used to find a binding pocket on the receptor and compared to the binding pocket of the adipokinetic hormone (AKH) receptor from the malaria mosquito. Data for the receptor, with and without loop refinement, together with the docked agonist, are presented.

Inhibition of Human Amylin Amyloidogenesis by Human Amylin-Fragment Peptides: Exploring the Effects of Serine Residues and Oligomerization upon Inhibitory Potency

To date, fragments from within the amyloidogenic-patch region of human amylin (hAM) have been shown to aggregate independently of the full-length peptide. In this study, we show that under certain conditions, both oligomers of NFGAILSS and the monomeric form are capable of inhibiting the aggregation of the full-length hAM sequence. The inhibition, rather than aggregate seeding, observed with the soluble portion of aged NFGAILSS solutions was particularly striking occurring at far substoichiometric levels. Apparently, the oligomer form of this fragment is responsible for inhibiting the transition from random coil to β-sheet or serves as a disaggregator of hAM β-oligomers. Sequential deletion of the serine residues from NFGAILSS results in a decrease of inhibition, indicating that these residues are important to the activity of this fragment. We, like others, observed instances of α-helix-like CD spectra prior to β-sheet formation as part of the amyloidogenesis pathway. The partially aggregated sample and the fragments studied display spectroscopic diagnostics, suggesting that they slow down the conversion of full-length hAM monomers to cytotoxic oligomers.

Clinical practice guidelines for the care of girls and women with Turner syndrome: proceedings from the 2016 Cincinnati International Turner Syndrome Meeting

Turner syndrome affects 25-50 per 100,000 females and can involve multiple organs through all stages of life, necessitating multidisciplinary approach to care. Previous guidelines have highlighted this, but numerous important advances have been noted recently. These advances cover all specialty fields involved in the care of girls and women with TS. This paper is based on an international effort that started with exploratory meetings in 2014 in both Europe and the USA, and culminated with a Consensus Meeting held in Cincinnati, Ohio, USA in July 2016. Prior to this meeting, five groups each addressed important areas in TS care: 1) diagnostic and genetic issues, 2) growth and development during childhood and adolescence, 3) congenital and acquired cardiovascular disease, 4) transition and adult care, and 5) other comorbidities and neurocognitive issues. These groups produced proposals for the present guidelines. Additionally, four pertinent questions were submitted for formal GRADE (Grading of Recommendations, Assessment, Development and Evaluation) evaluation with a separate systematic review of the literature. These four questions related to the efficacy and most optimal treatment of short stature, infertility, hypertension, and hormonal replacement therapy. The guidelines project was initiated by the European Society for Endocrinology and the Pediatric Endocrine Society, in collaboration with The European Society for Pediatric Endocrinology, The Endocrine Society, European Society of Human Reproduction and Embryology, The American Heart Association, The Society for Endocrinology, and the European Society of Cardiology. The guideline has been formally endorsed by the European Society for Endocrinology, the Pediatric Endocrine Society, the European Society for Pediatric Endocrinology, the European Society of Human Reproduction and Embryology and the Endocrine Society. Advocacy groups appointed representatives who participated in pre-meeting discussions and in the consensus meeting.

Interaction of the red pigment-concentrating hormone of the crustacean Daphnia pulex, with its cognate receptor, Dappu-RPCHR: A nuclear magnetic resonance and modeling study

The primary sequence of the red pigment-concentrating hormone (RPCH) receptor of the water flea, Daphnia pulex, was used in homology modeling to construct the first 3D model of a crustacean G-protein coupled receptor, Dappu-RPCHR. This receptor was found to belong to the class A subfamily of GPCRs with a disulfide bridge between Cys⁷² and Cys¹⁵⁰ and an ionic lock between Arg⁹⁷ and Thr²²⁴ and Thr²²⁰. NMR restrained molecular dynamics was used to determine the structure of an agonist, Dappu-RPCH, in a membrane-mimicking environment. The agonist was found to be flexible but has two main conformations in solution, both having β-turns. Docking of the predominant structure was used to find a binding pocket on the receptor. The pocket's spatial location was similar to that of the AKH receptor of Anopheles gambiae. The binding affinity was -69kcalmol^-1 with the N-terminus of Dappu-RPCH inserted between helices 4 and 6, and the C-terminus interacting with extra-cellular loop, ECL2. Upon binding, H-bonding to the peptide may activate the receptor. This development of the first Dappu-RPCH/Dappu-RPCHR model could be useful for understanding ligand-receptor interactions in crustaceans.

Computational and Experimental Evaluation of Designed β-Cap Hairpins Using Molecular Simulations and Kinetic Network Models

Molecular simulation has been used to model the detailed folding properties of peptides, yet prospective computational peptide design by such approaches remains challenging and nontrivial. To test the accuracy of simulation-based hairpin design, we characterized the folding properties of a series of so-called β-cap hairpin peptides designed to mimic a conserved hairpin of LapD, a bacterial intracellular signaling protein, both experimentally by NMR spectroscopy and computationally by implicit-solvent replica-exchange molecular dynamics using three different AMBER force fields (ff96, ff99sb-ildn, and ff99sb-ildn-NMR). A unique challenge presented by these designs is the presence of both a terminal Trp-Trp capping motif and a conserved GWxQ motif in the hairpin turn required for binding to LapG. Consistent with previous studies, we found AMBER ff96 to be the most accurate when used with the OBC GBSA implicit solvent model, despite its known bias toward β-sheet conformations when used in explicit-solvent simulations. To gain microscopic insight into the folding landscape of the hairpin designs, we additionally performed parallel simulations on the Folding@home distributed computing platform using AMBER ff99sb-ildn-NMR with TIP3P explicit solvent. Markov state models (MSMs) built from trajectory data reveal a number of non-native interactions between Trp and other amino acid side chains, creating potential problems in achieving well-folded hairpin structures in solution.

A pH Switch for β-Sheet Protein Folding

Protein design advancements have led to biotechnological strategies based on more stable and more specific structures. Herein we present a 6-residue sequence (HPATGK) that acts as a stable structure-nucleating turn at physiological and higher pH but is notably unfavorable for chain direction reversal at low pH. When placed into the turn of a β-sheet, this leads to a pH switch of folding. Using a standard 3-stranded β-sheet model, the WW domain, it was found that the pH switch sequence insertion caused minimal change at pH 8 but a ca. 50 °C drop in the melting temperature (Tm ) was observed at pH 2.5: ΔΔGF ≥11.3 kJ mol-1 . Using the strategies demonstrated in this article, the redesign of β-sheets to contain a global, or local, pH-dependent conformational switch should be possible.

New Iminodiacetate-Thiosemicarbazone Hybrids and Their Copper(II) Complexes Are Potential Ribonucleotide Reductase R2 Inhibitors with High Antiproliferative Activity

As ribonucleotide reductase (RNR) plays a crucial role in nucleic acid metabolism, it is an important target for anticancer therapy. The thiosemicarbazone Triapine is an efficient R2 inhibitor, which has entered ∼20 clinical trials. Thiosemicarbazones are supposed to exert their biological effects through effectively binding transition-metal ions. In this study, six iminodiacetate-thiosemicarbazones able to form transition-metal complexes, as well as six dicopper(II) complexes, were synthesized and fully characterized by analytical, spectroscopic techniques (IR, UV-vis; ¹H and ¹³C NMR), electrospray ionization mass spectrometry, and X-ray diffraction. The antiproliferative effects were examined in several human cancer and one noncancerous cell lines. Several of the compounds showed high cytotoxicity and marked selectivity for cancer cells. On the basis of this, and on molecular docking calculations one lead dicopper(II) complex and one thiosemicarbazone were chosen for in vitro analysis as potential R2 inhibitors. Their interaction with R2 and effect on the Fe(III)₂-Y· cofactor were characterized by microscale thermophoresis, and two spectroscopic techniques, namely, electron paramagnetic resonance and UV-vis spectroscopy. Our findings suggest that several of the synthesized proligands and copper(II) complexes are effective antiproliferative agents in several cancer cell lines, targeting RNR, which deserve further investigation as potential anticancer drugs.

Optimization of a β-sheet-cap for long loop closure

Protein loops make up a large portion of the secondary structure in nature. But very little is known concerning loop closure dynamics and the effects of loop composition on fold stability. We have designed a small system with stable β-sheet structures, including features that allow us to probe these questions. Using paired Trp residues that form aromatic clusters on folding, we are able to stabilize two β-strands connected by varying loop lengths and composition (an example sequence: RWITVTI - loop - KKIRVWE). Using NMR and CD, both fold stability and folding dynamics can be investigated for these systems. With the 16 residue loop peptide (sequence: RWITVTI-(GGGGKK)₂ GGGG-KKIRVWE) remaining folded (ΔG_U  = 1.6 kJ/mol at 295K). To increase stability and extend the series to longer loops, we added an additional Trp/Trp pair in the loop flanking position. With this addition to the strands, the 16 residue loop (sequence: RWITVRIW-(GGGGKK)₂ GGGG-WKTIRVWE) supports a remarkably stable β-sheet (ΔG_U  = 6.3 kJ/mol at 295 K, T_m  = ∼55°C). Given the abundance of loops in binding motifs and between secondary structures, these constructs can be powerful tools for peptide chemists to study loop effects; with the Trp/Trp pair providing spectroscopic probes for assessing both stability and dynamics by NMR.

Modulating the Amyloidogenesis of α-Synuclein

Alpha-Synuclein is found in the neuronal cells but its native function is not well known. While α -synuclein is an intrinsically disordered protein that adopts a helical conformation upon membrane binding, numerous studies have shown that oligomeric β-forms of this protein are cytotoxic. This response to misfolded species contributes to Parkinson's Disease etiology and symptoms. The resulting amyloid fibrils are an established diagnostic in Parkinson's Disease. In this review, we focus on strategies that have been used to inhibit the amyloidogenesis of α -synuclein either by stabilizing the native state, or by redirecting the pathway to less toxic aggregates. Small molecules such as polyphenols, peptides as well as large proteins have proven effective at protecting cells against the cytotoxicity of α-synuclein. These strategies may lead to the development of therapeutic agents that could prove useful in combating this disease.

Evaluating the quality of Marfan genotype-phenotype correlations in existing FBN1 databases

BACKGROUND

Genetic FBN1 testing is pivotal for confirming the clinical diagnosis of Marfan syndrome. In an effort to evaluate variant causality, FBN1 databases are often used. We evaluated the current databases regarding FBN1 variants and validated associated phenotype records with a new Marfan syndrome geno-phenotyping tool called the Marfan score.

METHODS AND RESULTS

We evaluated four databases (UMD-FBN1, ClinVar, the Human Gene Mutation Database (HGMD), and Uniprot) containing 2,250 FBN1 variants supported by 4,904 records presented in 307 references. The Marfan score calculated for phenotype data from the records quantified variant associations with Marfan syndrome phenotype. We calculated a Marfan score for 1,283 variants, of which we confirmed the database diagnosis of Marfan syndrome in 77.1%. This represented only 35.8% of the total registered variants; 18.5-33.3% (UMD-FBN1 versus HGMD) of variants associated with Marfan syndrome in the databases could not be confirmed by the recorded phenotype.

CONCLUSION

FBN1 databases can be imprecise and incomplete. Data should be used with caution when evaluating FBN1 variants. At present, the UMD-FBN1 database seems to be the biggest and best curated; therefore, it is the most comprehensive database. However, the need for better genotype-phenotype curated databases is evident, and we hereby present such a database.Genet Med advance online publication 01 December 2016.

Hairpin structure stability plays a role in the activity of two antimicrobial peptides

Many naturally occurring antimicrobial peptides (AMPs) are amphipathic with a β-hairpin conformation stabilized by cross-strand disulfides across the associated β-strands. Here, we show that the disulfides are not essential. Other structuring means such as better β-turns and noncovalent cross-strand interactions can, with proper design, replace the disulfides with no loss in antimicrobial activity. Our results also demonstrate that the hairpin turn region may play a role in membrane recognition for at least one member of this class, since a homodimeric turnless β-sheet analog showed no antimicrobial activity. We also examined the effects of N-terminal fatty acid adducts on AMPs. Surprisingly, the large hydrophobic carboxylic moieties examined completely eliminated the antimicrobial activity of previously active β-hairpin peptides.

Is it possible to cure childhood acute myeloid leukaemia without significant cardiotoxicity?

Since cardiotoxicity is a life threatening late effect, a reduction of cardiotoxicity in the treatment of acute myeloid leukaemia (AML) is essential. This review is a compilation of the current knowledge about cardiotoxicity after AML treatment and of how future directions in treatment may affect its incidence. A total of six studies concerning AML and cardiotoxicity were identified. The incidence of late subclinical cardiotoxicity varied between 1·3 and 15·3%, and late clinical cardiotoxicity varied between 1·3 and 9·3%. Cumulative dose of anthracyclines (ACs) and history of relapse were the most common risk factors identified. No conclusions could be drawn about new, potentially less toxic ACs. Differences in treatment data and variations in study populations made comparisons uncertain. The echocardiographic techniques used in the majority of the studies are inferior to more modern echocardiographic methods. This decreases reproducibility and may increase the risk of overestimation of cardiotoxicity. In summary, AML cannot be cured today without ACs. However, some ACs may cause less cardiotoxicity than others. Furthermore there is currently no consensus on equipotent doses of ACs and risk factors for cardiotoxicity. Further research including randomized trials is needed to evaluate whether or not the potentially less cardiotoxic agents fulfil their promise.

Peptide Inhibitors of the amyloidogenesis of IAPP: verification of the hairpin-binding geometry hypothesis

Versions of a previously discovered β-hairpin peptide inhibitor of IAPP aggregation that are stabilized in that conformation, or even forced to remain in the hairpin conformation by a backbone cyclization constraint, display superior activity as inhibitors. The cyclized hairpin, cyclo-WW2, displays inhibitory activity at substoichiometric concentrations relative to this amyloidogenic peptide. The hairpin-binding hypothesis stands confirmed.

Aryl-aryl interactions in designed peptide folds: Spectroscopic characteristics and optimal placement for structure stabilization

We have extended our studies of Trp/Trp to other Aryl/Aryl through-space interactions that stabilize hairpins and other small polypeptide folds. Herein we detail the NMR and CD spectroscopic features of these types of interactions. NMR data remains the best diagnostic for characterizing the common T-shape orientation. Designated as an edge-to-face (EtF or FtE) interaction, large ring current shifts are produced at the edge aryl ring hydrogens and, in most cases, large exciton couplets appear in the far UV circular dichroic (CD) spectrum. The preference for the face aryl in FtE clusters is W ≫ Y ≥ F (there are some exceptions in the Y/F order); this sequence corresponds to the order of fold stability enhancement and always predicts the amplitude of the lower energy feature of the exciton couplet in the CD spectrum. The CD spectra for FtE W/W, W/Y, Y/W, and Y/Y pairs all include an intense feature at 225-232 nm. An additional couplet feature seen for W/Y, W/F, Y/Y, and F/Y clusters, is a negative feature at 197-200 nm. Tyr/Tyr (as well as F/Y and F/F) interactions produce much smaller exciton couplet amplitudes. The Trp-cage fold was employed to search for the CD effects of other Trp/Trp and Trp/Tyr cluster geometries: several were identified. In this account, we provide additional examples of the application of cross-strand aryl/aryl clusters for the design of stable β-sheet models and a scale of fold stability increments associated with all possible FtE Ar/Ar clusters in several structural contexts. © 2016 Wiley Periodicals, Inc. Biopolymers 105: 337-356, 2016.

A Structuring Repeat for Peptide Design: Long Beta Ribbons

Beta sheets are inherently length-limited; adding residues to the ends of model β-sheets does not necessarily grow the β-sheet. Here, we present a method for extending β-sheets to any length with a stabilizing repeat unit containing cross-strand Trp residues. Beta ribbons as long as 35 residues (approaching 100 Å in length) are reported and characterized.

Prevalence, incidence, and age at diagnosis in Marfan Syndrome

BACKGROUND

Marfan syndrome is a genetic disorder with considerable morbidity and mortality. Presently, clinicians use the 2010 revised Ghent nosology, which includes optional genetic sequencing of the FBN1 gene, to diagnose patients. So far, only a few studies based on older diagnostic criteria have reported a wide range of prevalence and incidence. Our aim was to study prevalence, incidence, and age at diagnosis in patients with Marfan syndrome.

METHOD

Using unique Danish patient-registries, we identified all possible Marfan syndrome patients recorded by the Danish healthcare system (1977-2014). Following, we confirmed or rejected the diagnosis according to the 2010 revised Ghent nosology.

RESULTS

We identified a total of 1628 persons with possible Marfan syndrome. We confirmed the diagnosis in 412, whereof 46 were deceased, yielding a maximum prevalence of 6.5/100,000 at the end of 2014. The annual median incidence was 0.19/100,000 (range: 0.0-0.7) which increased significantly with an incidence rate ratio of 1.03 (95% CI: 1.02-1.04, p < 0.001). We found a median age at diagnose of 19.0 years (range: 0.0-74). The age at diagnosis increased during the study period, uninfluenced by the changes in diagnostic criteria. We found no gender differences.

CONCLUSION

The increasing prevalence of Marfan syndrome during the study period is possibly due to build-up of a registry. Since early diagnosis is essential in preventing aortic events, diagnosing Marfan syndrome remains a task for both pediatricians and physicians caring for adults.

Cardiac function in survivors of childhood acute myeloid leukemia treated with chemotherapy only: a NOPHO-AML study

OBJECTIVES

We report cardiac function of patients treated for Childhood acute myeloid leukemia with chemotherapy only according to three consecutive Nordic protocols.

METHODS

Ninety-eight of 138 eligible patients accepted examination with standardized echocardiography. Results were compared with age- and sex-matched controls.

RESULTS

The median age was 3 yr at diagnosis (range 0-15), and the median time from diagnosis to study was 11 yr (4-25). All but one patient had received doxorubicin and 90% had received mitoxantrone. The median cumulative dose of daunorubicin equivalents was 300 mg/m(2) (210-525). Left ventricular fractional shortening (LVFS) and ejection fraction (LVEF) were lower in patients than in controls (32.6% (SD 4.0) vs. 35.2% (SD 3.4), P = 0.002 and 59.9% (SD 5.5) vs. 64.2% (SD 4.4), P = 0.001). The myocardial performance index (MPI) was higher in patients than in controls (0.32 (SD 0.081) vs. 0.26 (SD 0.074), P < 0.0001). Cumulative dose of doxorubicin but not mitoxantrone was related to lower LVFS (P = 0.037) and LVEF (P = 0.016). Longer follow-up was associated with lower LVFS (P = 0.034). Higher MPI was associated with young age at diagnosis (P = 0.04) and longer follow-up (P = 0.031).

CONCLUSIONS

In this study, most patients had cardiac function within normal limits and reported very few cardiac symptoms. However, compared with healthy controls, they had significantly reduced left ventricular function.

Extreme mobility enhancement of two-dimensional electron gases at oxide interfaces by charge-transfer-induced modulation doping

Two-dimensional electron gases (2DEGs) formed at the interface of insulating complex oxides promise the development of all-oxide electronic devices. These 2DEGs involve many-body interactions that give rise to a variety of physical phenomena such as superconductivity, magnetism, tunable metal-insulator transitions and phase separation. Increasing the mobility of the 2DEG, however, remains a major challenge. Here, we show that the electron mobility is enhanced by more than two orders of magnitude by inserting a single-unit-cell insulating layer of polar La(1-x)Sr(x)MnO3 (x = 0, 1/8, and 1/3) at the interface between disordered LaAlO3 and crystalline SrTiO3 produced at room temperature. Resonant X-ray spectroscopy and transmission electron microscopy show that the manganite layer undergoes unambiguous electronic reconstruction, leading to modulation doping of such atomically engineered complex oxide heterointerfaces. At low temperatures, the modulation-doped 2DEG exhibits Shubnikov-de Haas oscillations and fingerprints of the quantum Hall effect, demonstrating unprecedented high mobility and low electron density.