Pulmonary artery pressure monitoring in chronic heart failure: effects across clinically relevant subgroups in the MONITOR-HF trial.

BACKGROUND AND AIMS: In patients with chronic heart failure (HF), the MONITOR-HF trial demonstrated the efficacy of pulmonary artery (PA)-guided HF therapy over standard of care in improving quality of life and reducing HF hospitalizations and mean PA pressure. This study aimed to evaluate the consistency of these benefits in relation to clinically relevant subgroups. METHODS: The effect of PA-guided HF therapy was evaluated in the MONITOR-HF trial among predefined subgroups based on age, sex, atrial fibrillation, diabetes mellitus, left ventricular ejection fraction, HF aetiology, cardiac resynchronisation therapy, and implantable cardioverter defibrillator. Outcome measures were based upon significance in the main trial and included quality of life, clinical, and PA pressure endpoints, and were assessed for each subgroup. Differential effects in relation to the subgroups were assessed with interaction terms. Both unadjusted and multiple testing adjusted interaction terms were presented. RESULTS: The effects of PA monitoring on quality of life, clinical events, and PA pressure were consistent in the predefined subgroups, without any clinically relevant heterogeneity within or across all endpoint categories (all adjusted interaction P-values were nonsignificant). In the unadjusted analysis of the primary endpoint quality-of-life change, weak trends towards a less pronounced effect in older patients (Pinteraction = 0.03; adjusted Pinteraction = 0.33) and diabetics (Pinteraction = 0.01; adjusted Pinteraction = 0.06) were observed. However, these interaction effects did not persist after adjusting for multiple testing. CONCLUSIONS: This subgroup analysis confirmed the consistent benefits of PA-guided HF therapy observed in the MONITOR-HF trial across clinically relevant subgroups, highlighting its efficacy in improving quality of life, clinical, and PA pressure endpoints in chronic HF patients.

Tolerance development in cow's milk-allergic children receiving amino acid-based formula with synbiotics: 36-Months follow-up of a randomized controlled trial (PRESTO Study).

The objective of the present study is to assess the rates of acquired tolerance to cow's milk (CM) after 36 months in subjects who consumed amino acid-based formula with synbiotics (AAF-S) or amino acid-based formula without synbiotics (AAF) during a 1-year intervention period in early life as part of the PRESTO study (Netherlands Trial Register number NTR3725). Differences in CM tolerance development between groups were analysed using a logistic regression model. Results show that the proportion of subjects (mean [±SD] age, 3.8 ± 0.27 years) who developed CM tolerance after 36 months was similar in the group receiving AAF-S (47/60 [78%]) and in the group receiving AAF (49/66 [74%]) (p = 0.253), that is, figures comparable to natural outgrowth of CM allergy. Our data suggest that the consumption of AAF and absence of exposure to CM peptides do not slow down CM tolerance acquisition.

SARS-CoV-2 Vaccination Safety in Guillain-Barré Syndrome, Chronic Inflammatory Demyelinating Polyneuropathy, and Multifocal Motor Neuropathy.

BACKGROUND AND OBJECTIVES: There are concerns on the safety of SARS-CoV-2 vaccination in patients with a history of Guillain-Barré syndrome (GBS), chronic inflammatory demyelinating polyneuropathy (CIDP), and multifocal motor neuropathy (MMN). The aim of this study was to determine the risk of recurrence of GBS and exacerbations of CIDP or MMN after SARS-CoV-2 vaccination. METHODS: We conducted a prospective, multicenter cohort study from January 2021 to August 2021. Patients known in 1 of 3 Dutch University Medical Centers with research focus on immune-mediated neuropathy and members of the Dutch Patient Association for Neuromuscular Diseases were invited to participate if they were 18 years or older and diagnosed with GBS, CIDP, or MMN. Participants completed a series of questionnaires at 4 different time points: study baseline (1), within 48 hours before any SARS-CoV-2 vaccination (2 and 3, if applicable), and 6 weeks after their last vaccination (4). Participants unwilling to get vaccinated completed the last questionnaire (4) 4 months after study baseline. We assessed recurrences of GBS, any worsening of CIDP or MMN-related symptoms, treatment alterations, and hospitalization. RESULTS: Of 1,152 individuals to whom we sent the questionnaires, 674 (59%) signed informed consent. We excluded 153 individuals, most often because they had already received a SARS-CoV-2 vaccination or had had the infection (84%) before study baseline. Of 521 participants included in analyses, 403 (81%) completed the last questionnaire (time point 4). None of 162 participants with a history of GBS had a recurrence after vaccination. Of 188 participants with CIDP, 10 participants (5%) reported a worsening of symptoms within 6 weeks after vaccination. In 5 (3%) of these patients, maintenance treatment was modified. Two of 53 participants with MMN (4%) reported a worsening of symptoms, and treatment modification was reported by 1 participant. DISCUSSION: We found no increased risk of GBS recurrence and a low to negligible risk of worsening of CIDP or MMN-related symptoms after SARS-CoV-2 vaccination. Based on our data, SARS-CoV-2 vaccination in patients with these immune-mediated neuropathies seems to be safe.

Helical structure in cyclic peptides: effect of N-methyl amides versus esters.

An alpha helical turn can be reproduced in a cyclic pentapeptide if the first and fifth amino acid sidechains are correctly joined. Here structural studies (CD, NMR, in silico) reveal why N-methylation at positions not involved in hydrogen bonds disrupts helicity whereas ester bonds can maintain helicity and promote greater cell uptake.

Mild hypothermia during cardiopulmonary bypass assisted CABG is associated with improved short- and long-term survival, a 18-year cohort study.

Data substantiating the optimal patient body temperature during cooling procedures in cardiac operations are currently unavailable. To explore the optimal temperature strategy, we examined the association between temperature management and survival among patients during cardiopulmonary bypass assisted coronary artery bypass grafting (CABG) procedures on 30-days and 5-year postoperative survival. Adult patients (n = 5,672, 23.6% female and mean (SD) age of 66 (10) years) operated between 1997 and 2015 were included, with continuous measured intraoperative nasopharyngeal temperatures. The association between mortality and patient characteristics, laboratory parameters, the lowest intraoperative plateau temperature and intraoperative cooling/rewarming rates were examined by multivariate Cox regression analysis. Machine learning-based cluster analysis was used to identify patient subgroups based on pre-cooling parameters and explore whether specific subgroups benefitted from a particular temperature management. Mild hypothermia (32-35°C) was independently associated with improved 30-days and 5-year survival compared to patients in other temperature categories regardless of operation year. 30 days and 5-year survival were 98% and 88% in the mild hypothermia group, whereas it amounted 93% and 80% in the severe hypothermia (<30°C). Normothermia (35-37°C) showed the lowest survival after 30 days and 5 years amounting 93% and 72%, respectively. Cluster analysis identified 8 distinct patient subgroups principally defined by gender, age, kidney function and weight. The full cohort and all patient subgroups displayed the highest survival at a temperature of 32°C. Given these associations, further prospective randomized controlled trials are needed to ascertain optimal patient temperatures during CPB.

Validation of the ELAN-HF Score and self-care behaviour on the nurse-led heart failure clinic after admission for heart failure.

AIM: To validate the predictive value of the European coLlaboration on Acute decompeNsated Heart Failure (ELAN-HF) score, and to assess the effect of self-care behaviour on readmission and mortality in patients after admission with acute decompensated heart failure (ADHF). DESIGN: Quantitative, prospective, single centre, cohort study. METHODS: N-Terminal pro-B-type natriuretic peptide (NT-proBNP) levels were measured on admission and discharge, and were used together with clinical and laboratory parameters to calculate the ELAN-HF score. Patients were stratified into four risk groups (low, intermediate, high, very high) according to their ELAN-HF score. The performance of the ELAN-HF score was evaluated and compared to the original study. Self-care behaviour was assessed by the European Heart Failure Self-care Behaviour Scale (EHFScBS-9). Survival analysis was used to estimate the association between both scores and re-admission for HF and/or all-cause mortality within 180 days. RESULTS: 88 patients were included. The median age of the study population was 75 years (IQR 69-83), 43% was female. NYHA III/IV functional class was present at discharge in 68 patients (85%) and 27 patients (34%) had a left ventricular ejection fraction < 40%. Complete data and 180 day follow up was available for 80 patients. 55% reached the endpoint of readmission and/or all-cause mortality. There was a significant association between the ELAN-HF score and re-admission and/or mortality < 180 days (HR = 1.25, 95% CI 1.08-1.45, p = 0.003). The median EHFScBS-9 score was 68.1 (IQR 58.3 - 77.8). There was no significant association between the EHFScBS-9 score and readmission and/or mortality < 180 days (HR = 1.01, 95% CI 0.99-1.03, p = 0.174). CONCLUSION: This study confirms the validity and therefore the potential of the ELAN-HF score to triage patients with ADHF before discharge. Using this score may optimize the follow-up treatment on the nurse-led heart failure clinic in order to decrease readmission and mortality. Self-care behaviour was non-significantly associated with readmission and/or mortality in our study population. TRIAL REGISTRATION: This study has been registered with the ethics committee MEC-U (Nieuwegein, The Netherlands), registration nr: V.160999/W18.208/HG/mk.

The association between polypharmacy and malnutrition(risk) in older people: A systematic review.

BACKGROUND & AIM: Malnutrition adversely influences a broad range of physical and psychological symptoms. Although polypharmacy is often mentioned to be associated with malnutrition, especially in older people it is unclear to what extent. The aim of this systematic review was to investigate the extent of the association between polypharmacy and malnutrition in older people. METHODS: The methodology followed the guidelines of the Cochrane Collaboration. Literature search was performed in PubMed, CINAHL and Embase. The population of interest for this systematic review were people of 65 years and older with polypharmacy. Because there is ambiguity with regard to the actual definition of malnutrition and polypharmacy, in this systematic review all articles describing malnutrition prevalence rates were included, regardless of the criteria used. Both observational and intervention studies were screened for eligibility. Selection and quality assessment of the included full text studies was assessed by two reviewers independently. A level of evidence and methodological quality score was adjudged to each article based on this assessment. RESULTS: A total of 3126 studies were retrieved by the literature search, of which seven studies were included in this systematic review. There was considerable variation in the definition of polypharmacy between studies. Two studies defined polypharmacy as the use of five or more drugs, two studies as the use of six or more drugs, two studies provided a mean and standard deviation that corresponded to the minimum of five drugs, and one study distinguished between polypharmacy (five or more drugs) and excessive polypharmacy (ten or more drugs). However, all studies showed a statistically significant association between (the risk) of becoming malnourished and polypharmacy regardless the instrument or criterion used to define risk of malnutrition. Studies presented the associations respectively as OR ≥ 1.177, p-value ≤ 0.028, ß ≥ -0.62 and r  ≥ -0.31. CONCLUSION: This review demonstrated a statistically significant association between polypharmacy and malnutrition. Further research is required to determine the magnitude of the effect by increased number of drugs in combination with the type of drugs, on the risk of malnutrition.

Perioperative anaphylaxis: A five-year review in a tertiary paediatric hospital.

Making a diagnosis of perioperative anaphylaxis and identifying culprit drugs are diagnostic challenges. The aim of this study is to describe the perioperative presentation of anaphylaxis and results of patients who underwent allergy evaluation. This is a retrospective review of perioperative anaphylaxis of severity Grade 2 and above based on the Australian and New Zealand Anaesthetic Allergy Group criteria from 2015 to 2019 in a tertiary paediatric hospital. Data collected were demographics, clinical features, investigations and management. Of the 35,361 cases of paediatric anaesthesia, there were 15 cases of perioperative anaphylaxis, giving an incidence of four in 10,000. The median age was seven years (interquartile range four-15 years) with a male predominance of 86.7% (13/15). The severity of anaphylaxis was Grade 2 in 33.3% (5/15) and Grade 3 in 66.7% (10/15). The commonest presenting feature was hypotension (13/15, 86.7%) while the earliest symptom was respiratory change (9/15, 60.0%). Dynamic tryptase was raised in 75% (6/8) of the patients with adequate tryptase samples. Eight patients (53.3%) completed allergy testing, of whom five patients (62.5%) had IgE-mediated anaphylaxis with skin test positive to cefazolin (n = 3), atracurium (n = 1) and rocuronium (n = 1). Three patients (25.0%) had non-IgE-mediated reactions with negative skin tests. Although only half the patients completed allergy evaluation, a culprit drug could be identified in 62.5%, with antibiotics being the commonest. This emphasises the need for appropriate evaluation in cases of suspected perioperative anaphylaxis.

Long-term risk of stroke and myocardial infarction in middle-aged men with a hypertensive response to exercise: a 44-year follow-up study.

INTRODUCTION: Data on the prognostic value of hypertensive response to exercise in cardiovascular disease are limited. The aim was to determine whether SBP reactions during exercise have any prognostic value in relation to the long-term risk of stroke and myocardial infarction (MI). PATIENTS AND METHODS: A representative cohort of men from Gothenburg, Sweden, born in 1913, who performed a maximum exercise test at age 54 years, (n = 604), was followed-up for a maximum of 44 years with regard to stroke and MI. RESULTS: Among the 604 men, the mean resting and maximum SBP was 141.5 (SD 18.8) and 212.1 (SD 24.6) mmHg, respectively. For maximum SBP, the risk of stroke increased by 34% (hazard ratio 1.34, 95% confidence interval 1.11-1.61) per 1-SD increase, while no risk increase was observed for MI. The highest risk of stroke among blood pressure groups was observed among men with a resting SBP of at least 140 mmHg and a maximum SBP of at least 210 mmHg with an hazard ratio of 2.09 (95% confidence interval 1.29-3.40), compared with men with a resting SBP of less than 140 mmHg and a maximum SBP of less than 210 mmHg, independent of smoking, blood glucose, cholesterol and BMI. CONCLUSION: Among middle-aged men with high resting and maximum blood pressure during maximum exercise workload, an increased risk of stroke was observed but not for MI. Further studies with larger sample sizes are needed to investigate the underlying mechanisms of the increased risk of stroke among individuals with hypertensive response to exercise.

[Second-degree atrioventricular block caused by Lyme disease]. / Tweedegraads atrioventriculair blok door lymeziekte.

BACKGROUND: Tick-borne diseases, including Lyme disease, are becoming increasingly common in Europe. Lyme disease has a wide variety of clinical manifestations, as a result of which physicians of diverse disciplines are coming into contact with such patients. CASE DESCRIPTION: A 58-year-old man was seen at the emergency room with a symptomatic Wenckebach-type second-degree atrioventricular (AV) block and periods of 2:1 AV block. Four weeks previously the patient had noticed a red skin lesion on his left lower leg. Under the working diagnosis of early disseminated Lyme disease with cardiac involvement, treatment with ceftriaxone was started. This diagnosis was supported by a positive Borrelia PCR and culture of a skin biopsy and positive Borreliaserology. The AV conduction disorders resolved completely after 2 weeks of treatment with antibiotics and it was not necessary to implant a pacemaker. CONCLUSION: A Borrelia infection is a reversible but rare cause of AV conduction disorders. In the event of sudden onset of symptoms or a severe or progressive AV conduction disorder, Lyme carditis should be considered, especially if the medical history or physical examination provides clues for Lyme disease.

TrimetaziDine as a Performance-enhancING drug in heart failure with preserved ejection fraction (DoPING-HFpEF): rationale and design of a placebo-controlled cross-over intervention study.

BACKGROUND: Currently, no specific treatment exists for heart failure with preserved ejection fraction (HFpEF). Left ventricular (LV) relaxation during diastole is a highly energy-demanding process, while energy homeostasis is known to be compromised in HFpEF. We hypothesise that trimetazidine - a fatty acid ß­oxidation inhibitor - improves LV diastolic function in HFpEF, by altering myocardial substrate use and improving the myocardial energy status. OBJECTIVES: To assess whether trimetazidine improves LV diastolic function by improving myocardial energy metabolism in HFpEF. METHODS: The DoPING-HFpEF trial is a randomised, double-blind, placebo-controlled cross-over intervention trial comparing the efficacy of trimetazidine and placebo in 25 patients with stable HFpEF. The main inclusion criteria are: New York Heart Association functional class II to IV, LV ejection fraction ≥50%, and evidence of LV diastolic dysfunction. Patients are treated with one 20-mg trimetazidine tablet or placebo thrice daily (twice daily in the case of moderate renal dysfunction) for two periods of 3 months separated by a 2-week washout period. The primary endpoint is the change in pulmonary capillary wedge pressure during different intensities of exercise measured by right heart catheterisation. Our key secondary endpoint is the myocardial phosphocreatine (PCr)/ATP ratio measured by phosphorus-31 magnetic resonance spectroscopy and its relation to the primary endpoint. Exploratory endpoints are 6­min walk distance, N-terminal pro-brain natriuretic peptide levels, and quality of life. CONCLUSION: The DoPING-HFpEF is a phase-II trial that evaluates the effect of trimetazidine, a metabolic modulator, on diastolic function and myocardial energy status in HFpEF. [EU Clinical Trial Register: 2018-002170-52; NTR registration: NL7830].

A randomised comparison of the effect of haemodynamic monitoring with CardioMEMS in addition to standard care on quality of life and hospitalisations in patients with chronic heart failure : Design and rationale of the MONITOR HF multicentre randomised clinical trial.

BACKGROUND: Assessing haemodynamic congestion based on filling pressures instead of clinical congestion can be a way to further improve quality of life (QoL) and clinical outcome by intervening before symptoms or weight gain occur in heart failure (HF) patients. The clinical efficacy of remote monitoring of pulmonary artery (PA) pressures (CardioMEMS; Abbott Inc., Atlanta, GA, USA) has been demonstrated in the USA. Currently, the PA sensor is not reimbursed in the European Union as its benefit when applied in addition to standard HF care is unknown in Western European countries, including the Netherlands. AIMS: To demonstrate the efficacy and cost-effectiveness of haemodynamic PA monitoring in addition to contemporary standard HF care in a high-quality Western European health care system. METHODS: The current study is a prospective, multi-centre, randomised clinical trial in 340 patients with chronic HF (New York Heart Association functional class III) randomised to HF care including remote monitoring with the CardioMEMS PA sensor or standard HF care alone. Eligible patients have at least one hospitalisation for HF in 12 months before enrolment and will be randomised in a 1:1 ratio. Minimum follow-up will be 1 year. The primary endpoint is the change in QoL as measured by the Kansas City Cardiomyopathy Questionnaire (KCCQ). Secondary endpoints are the number of HF hospital admissions and changes in health status assessed by EQ-5D-5L questionnaire including health care utilisation and formal cost-effectiveness analysis. CONCLUSION: The MONITOR HF trial will evaluate the efficacy and cost-effectiveness of haemodynamic monitoring by CardioMEMS in addition to standard HF care in patients with chronic HF. Clinical Trial Registration number NTR7672.

Mirror image pairs of cyclic hexapeptides have different oral bioavailabilities and metabolic stabilities.

Rule-of-five parameters and membrane permeabilities have been routinely used to guide development of orally bioavailabile drugs. Here we compare enantiomeric pairs of cyclic hexapeptides with identical rule-of-five parameters and membrane permeabilities. For each enantiomeric pair, the isomer with more l- than d-amino acids is much more orally bioavailable in rats, more metabolically stable to rat liver microsomes, and cleared more slowly in vivo.

Establishing Signature Fragments for Identification and Sequencing of Dityrosine Cross-Linked Peptides Using Ultraviolet Photodissociation Mass Spectrometry.

Dityrosine cross-linking of Aß peptides and α-synuclein is increasingly becoming recognized as a biomarker of neuropathological diseases. However, there remains a need for the development of analytical methods that enable the specific and selective identification of dityrosine cross-linked proteins and peptides in complex biological samples. Here, we report that the gas-phase fragmentation of protonated dityrosine cross-linked peptides under ultraviolet photodissociation (UVPD) tandem mass spectrometry (MS/MS) conditions results in the cleavage across Cα and Cß atoms of the dityrosine residue. This Cα-Cß cleavage in UVPD-MS/MS results in the formation of diagnostic pairs of product ions, providing information on the two individual peptides involved in the cross-linking, resolving the intrinsic "n2 problem" plaguing the identification of this post-translational modification (PTM) by tandem mass spectrometry. Sequencing of a heterodimeric dityrosine cross-linked peptide was demonstrated using hybrid UVPD-MS/MS and CID-MS3 on a diagnostic pair of product ions. In combination with dedicated MS-cleavable MSn software, UVPD-MSn therefore provides an avenue to selectively discover and describe dityrosine cross-linked peptides. Additionally, observation of dityrosine-specific "reporter ions" at m/z 240.1019 and m/z 223.0752 in UVPD-MS/MS will be useful for the validation of the dityrosine cross-linked peptides.

Notch Coordinates Periodontal Ligament Maturation through Regulating Lamin A.

Tooth eruption is a continuous biological process with dynamic changes at cellular and tissue levels, particularly within the periodontal ligament (PDL). Occlusion completion is a significant physiological landmark of dentition establishment. However, the importance of the involvement of molecular networks engaging in occlusion establishment on the final PDL maturation is still largely unknown. In this study, using rat and mouse molar teeth and a human PDL cell line for RNAseq and proteomic analysis, we systematically screened the key molecular links in regulating PDL maturation before and after occlusion establishment. We discovered Notch, a key molecular pathway in regulating stem cell fate and differentiation, is a major player in the event. Intercepting the Notch pathway by deleting its key canonical transcriptional factor, RBP-Jkappa, using a conditional knockout strategy in the mice delayed PDL maturation. We also identified that Lamin A, a cell nuclear lamina member, is a unique marker of PDL maturation, and its expression is under the control of Notch signaling. Our study therefore provides a deep insight of how PDL maturation is regulated at the molecular level, and we expect the outcomes to be applied for a better understanding of the molecular regulation networks in physiological conditions such as tooth eruption and movement and also for periodontal diseases.

Vaccine-induced immune thrombocytopaenia purpura in autologous haematopoietic stem cell transplantation.

Immune Thrombocytopenia Purpura (ITP) secondary to vaccinations is rare, especially after autologous hematopoietic stem cell transplantation (HSCT). A 31-yearold female received autologous HSCT for relapsed Hodgkin Disease, with platelet engraftment at Day+14. One week after receiving second scheduled vaccinations, she developed severe thrombocytopenia (3x109/L) associated with pharyngeal hematoma. Bone marrow (BM) examinations were consistent with ITP, possibly secondary to Influenza vaccine. Platelet increment was poor despite high dose corticosteroids, intravenous immunoglobulin (IVIG), Danazol and Eltrombopag. A repeated BM biopsy was in agreement with ITP. Re-treatment with tapering doses of prednisolone resulted in stable platelet counts at 120x109/L a year later.

Nonlinear Metasurface for Simultaneous Control of Spin and Orbital Angular Momentum in Second Harmonic Generation.

The spin and orbital angular momentum (SAM and OAM) of light is providing a new gateway toward high capacity and robust optical communications. While the generation of light with angular momentum is well studied in linear optics, its further integration into nonlinear optical devices will open new avenues for increasing the capacity of optical communications through additional information channels at new frequencies. However, it has been challenging to manipulate the both SAM and OAM of nonlinear signals in harmonic generation processes with conventional nonlinear materials. Here, we report the generation of spin-controlled OAM of light in harmonic generations by using ultrathin photonic metasurfaces. The spin manipulation of OAM mode of harmonic waves is experimentally verified by using second harmonic generation (SHG) from gold meta-atom with 3-fold rotational symmetry. By introducing nonlinear phase singularity into the metasurface devices, we successfully generate and measure the topological charges of spin-controlled OAM mode of SHG through an on-chip metasurface interferometer. The nonlinear photonic metasurface proposed in this work not only opens new avenues for manipulating the OAM of nonlinear optical signals but also benefits the understanding of the nonlinear spin-orbit interaction of light in nanoscale devices.

Downsizing Proto-oncogene cFos to Short Helix-Constrained Peptides That Bind Jun.

The oncogenic transcription factor activator protein-1 (AP-1) is a DNA-binding protein that assembles through dimerization of Fos and Jun protein subunits, their leucine-rich helical sequences entwining into a coiled-coil structure. This study reports on downsizing the proto-oncogene cFos protein (380 residues) to shorter peptides (37-25 residues) modified with helix-inducing constraints to enhance binding to Jun. A crystal structure is reported for a 37-residue Fos-derived peptide (FosW) bound to Jun. This guided iterative downsizing of FosW to shorter peptide sequences that were constrained into stable water-soluble α-helices by connecting amino acid side chains to form cyclic pentapeptide components. Structural integrity in the presence and absence of Jun was assessed by circular dichroism spectroscopy, while the thermodynamics of binding to cFos was measured by isothermal titration calorimetry. A 25-residue constrained peptide, one-third shorter yet 25% more helical than the structurally characterized 37-residue Fos-derived peptide, retained 80% of the binding free energy as a result of preorganization in a Jun-binding helix conformation, with the entropy gain (TΔS = +3.2 kcal/mol) compensating for the enthalpy loss. Attaching a cell-penetrating peptide (TAT48-57) and a nuclear localization signal (SV40) promoted cell uptake, localization to the nucleus, and inhibition of the proliferation of two breast cancer cell lines.

Characterization and Identification of Dityrosine Cross-Linked Peptides Using Tandem Mass Spectrometry.

The use of mass spectrometry coupled with chemical cross-linking of proteins has become a powerful tool for proteins structure and interactions studies. Unlike structural analysis of proteins using chemical reagents specific for lysine or cysteine residues, identification of gas-phase fragmentation patterns of endogenous dityrosine cross-linked peptides have not been investigated. Dityrosine cross-linking in proteins and peptides are clinical markers of oxidative stress, aging, and neurodegenerative diseases including Alzheimer's disease and Parkinson's disease. In this study, we investigated and characterized the fragmentation pattern of a synthetically prepared dityrosine cross-linked dimer of Aß(1-16) using ESI tandem mass spectrometry. We then detailed the fragmentation pattern of dityrosine cross-linked Aß(1-16), using collision induced dissociation (CID), higher-energy collision induced dissociation (HCD), electron transfer dissociation (ETD), and electron capture dissociation (ECD). Application of these generic fragmentation rules of dityrosine cross-linked peptides allowed for the identification of dityrosine cross-links in peptides of Aß and α-synuclein generated in vitro by enzymatic peroxidation. We report, for the first time, the dityrosine cross-linked residues in human hemoglobin and α-synuclein under oxidative conditions. Together these tools open up the potential for automated analysis of this naturally occurring post-translation modification in neurodegenerative diseases as well as other pathological conditions.