Prognostic role of global work efficiency in patients undergoing transcatheter aortic valve implantation

Background

Non-invasive myocardial work (MW) quantification has emerged in the last years as an alternative echocardiographic tool for myocardial function assessment. Its role in patients with severe aortic stenosis (AS) after aortic valve implantation (TAVI) has not been adequately investigated.

Purpose

We aimed to evaluate MW indices as early echocardiographic markers of LV reverse remodeling within a month after TAVI and their prognostic value.

Methods and results

We conducted a single-centre prospective study, enrolling 88 consecutive patients (mean age 79.9±6.4 years, 35% males) with AS undergoing TAVI between April 2018 and 2021, selected from the EffecTAVI registry. Exclusion criteria were prior valve surgery, atrial fibrillation, left bundle branch block (LBBB) at baseline and and suboptimal quality of imaging. Echocardiographic assessment was performed before TAVI and at 30-day follow-up, including quantification of 2D global longitudinal strain (GLS), global work index (GWI), global constructive work (GCW), global wasted work (GWW) and global work efficiency (GWE). LV peak systolic pressure was estimated non-invasively from the sum of systolic blood pressure and trans-aortic mean gradient. One month after the procedure, there was a significant improvement of LV GLS (−18.4±4.2 vs −19.5±4.2%, before and after TAVI respectively, p=0.006), a significant reduction of GWI (2406±567 vs 1908±479 mmHg%, p<0.001), GCW (2783±616 vs 2202±463 mmHg%, p<0.001), and GWW (238±203 vs 173±127 mmHg%, p=0.002). Conversely, MWE did not change early after intervention (90.4±6.2 vs 91.4±5.1%, p=0.113). After TAVI, 32 patients (36.4%) developed LV dyssynchrony due to LBBB or pacemaker implantation. When the population was divided according to the presence or absence of LV dyssynchrony at 30-day follow-up, a significant reduction in GWW was found only in the those without dyssynchrony (241±229 vs 142±103 mmHg% before and after TAVI, p<0.001). Consistently, in this subgroup, MWE significantly improved after TAVI (90±7 vs 93±5%, p=0.001), while a trend of MWE reduction was observed in patients who developed dyssynchrony after TAVI (91±5 vs 89±5%, p=0.110). In the overall population, a 30-day value of MWE≤92% was associated with an increased rate of cardiovascular events (composite of all-cause death and rehospitalization for heart failure) at 1-year follow-up (29.5% vs 4.8%, long rank p=0.003). In multivariable Cox-regression analysis, adjusted for confounders, GWE after TAVI (HR: 0.892, CI: 0.817–0.974; p=0.011) was independently associated with events at 1-year follow-up.

Conclusions

In patients with severe AS undergoing TAVI a significant reduction of GWW and improvement of MWE can be detected only in those who do not develop LV dyssynchrony. In this setting, MWE≤92% early after TAVI is associated with poor outcome. Thus, MWE could represent an alternative tool for myocardial function assessment and prognostic evaluation in patients receiving TAVI.

Funding Acknowledgement

Type of funding sources: None.

Comparative Assessment of the Structural Features of Originator Recombinant Human Follitropin Alfa Versus Recombinant Human Follitropin Alfa Biosimilar Preparations Approved in Non-European Regions

Although the full primary structures of the alfa and beta subunits of reference r-hFSH-alfa and its biosimilars are identical, cell context-dependent differences in the expressing cell lines and manufacturing process can lead to variations in glycosylation profiles. In the present study, we compared the structural features of reference r-hFSH-alfa with those of five biosimilar preparations approved in different global regions outside Europe (Primapur^®, Jin Sai Heng^®, Follitrope^®, Folisurge^®, and Corneumon^®) with respect to glycosylation, macro- and microheterogeneity, and other post-translational modifications and higher order structure. The mean proportion of N-glycosylation-site occupancy was highest in reference r-hFSH-alfa, decreasing sequentially in Primapur, Jin Sai Heng, Corneumon, Follisurge and Follitrope, respectively. The level of antennarity showed slightly higher complexity in Corneumon, Primapur and Follitrope versus reference r-hFSH-alfa, whereas Jin Sai Heng and Folisurge were aligned with reference r-hFSH-alfa across all N-glycosylation sites. Sialylation level was higher in Corneumon and Follitrope, but small differences were detected in other biosimilar preparations compared with reference r-hFSH-alfa. Jin Sai Heng showed higher levels of N-glyconeuramic acid than the other preparations. Minor differences in oxidation levels were seen among the different products. Therefore, in summary, we identified var ious differences in N-glycosylation occupancy, antennarity, sialylation and oxidation between reference r-hFSH-alfa and the biosimilar preparations analyzed.

P–661 Comparative assessment of the structural features of human follicle-stimulating hormone in products from multiple markets

Study question

The aim of the study is to explore the structural differences occurring in recombinant human follicle-stimulating hormone alfa (r-hFSH- α), originator and its biosimilars, from various countries.

Summary answer

When compared with r-hFSH-α originator (Gonal-f), its biosimilars presented structural differences, namely Primapur showed a significant different glycosylation profile.

What is known already

FSH is part of cystine knot growth factor superfamily and plays a central role in reproduction, as FSH stimulates follicular development and estrogen synthesis. R-hFSH- α is commonly used in assisted reproductive technologies to achieve multifollicular development. At the present r-hFSH- α biosimilars are available in Europe and other regions. R-hFSH-α is a complex glycoprotein, that possesses several structural features critical for its efficacy and safety1–2. Glycosylation profile is one of the most impactful attributes of the molecule defining a moiety of FSH isoforms with impact on its biological net effect3. Efficacy and safety of r-hFSH- α are strictly correlated with glycoforms’ composition3–8.

Study design, size, duration

At least two different batches of each r-hFSH- α originator and its biosimilars have been included in the study.

Participants/materials, setting, methods

The structural features of products from six different marketed r-hFSH α (Gonal-f, Primapur, Folisurge Intas, Corneumon, Jin Sai Heng, Follitrope LG) have been investigated with a variety of analytical techniques in order to evaluate the presence of molecular differences, which could have a severe impact on the efficacy and safety of the product. The attributes which have been investigated in-depth include primary, secondary and tertiary structure as well as post-translational modifications (PTMs), including glycosylation and contaminants.

Main results and the role of chance

All r-hFSH- α biosimilars analyzed presented differences compared to the originator. We firstly investigated Primapur and found significant differences regarding multiple structural attributes, particularly in the glycosylation profile. Gonal-f exhibited lower glycan branching, expressed by an A-index* of 2.5, while Primapur showed an A-index of 2.4. Furthermore, Primapur showed a lower level of sialylation in comparison with Gonal-f, as measured by their respective S-index* of 1.8 and 2.1. FSH glycosylation exhibits both macroheterogeneity and microheterogeneity, impacting both FSH protein’s half-life and affinity with the follicle-stimulating hormone receptor (FSHR). Antennarity, representing FSH microheterogeneity, influence r-hFSH-α activity since it has been shown that bulky and extended glycans may take longer to fit into the FSHR cavity compared to less sterically hindering glycans, resulting in a delayed response 7,8.Additionaly, sialylation has been shown in-vivo to correlate with plasma half-life and effect on granulosa cells proliferation 1,2,3. The slower clearance of highly sialylated r-hFSH has been shown to lead to a higher in-vivo activity, despite the lower in-vitro bioactivity 1,2,3.

*A-index and S-index express respectively a measure of the number of antennae and sialic acid per glycan. Final values are generated from many relative abundances normalized to 100, highlighting the significance of small numerical differences.

Limitations, reasons for caution

More batches should be tested for each product. The authors are presenting full characterization of only one of the biosimilars since the rest of the products are under characterization.

Wider implications of the findings: r-hFSH-α originator and its biosimilar showed differences in terms of glycosylation profile that is well known as the major protein characteristic impacting FSH activity as extensively demonstrated in in-vivo and in-vitro models. This structural difference could have impact also on product efficacy and safety.

Trial registration number

‘not applicable’

Structural basis for chain release from the enacyloxin polyketide synthase

Modular polyketide synthases and non-ribosomal peptide synthetases are molecular assembly lines that consist of several multienzyme subunits that undergo dynamic self-assembly to form a functional megacomplex. N- and C-terminal docking domains are usually responsible for mediating the interactions between subunits. Here we show that communication between two non-ribosomal peptide synthetase subunits responsible for chain release from the enacyloxin polyketide synthase, which assembles an antibiotic with promising activity against Acinetobacter baumannii, is mediated by an intrinsically disordered short linear motif and a β-hairpin docking domain. The structures, interactions and dynamics of these subunits were characterized using several complementary biophysical techniques to provide extensive insights into binding and catalysis. Bioinformatics analyses reveal that short linear motif/β-hairpin docking domain pairs mediate subunit interactions in numerous non-ribosomal peptide and hybrid polyketide-non-ribosomal peptide synthetases, including those responsible for assembling several important drugs. Short linear motifs and β-hairpin docking domains from heterologous systems are shown to interact productively, highlighting the potential of such interfaces as tools for biosynthetic engineering.

Thermal ablation combined with high ligation of sapheno-femoral junction for lower limb primary varicosity

AIM

For long time the traditional surgical treatment for lower limb varicose veins has been high ligation of sapheno-femoral junction and stripping of great saphenous vein. Surgery, however, has been frustrated by postoperative pains, discomfort and recurrences so that it has been challenged by minimally invasive endovenous techniques such as laser treatment and radiofrequency ablation. The aim of the article is to assess the feasibility of a combined approach to greater saphenous vein reflux: high ligation of sapheno-femoral junction and thermal treatment of the great saphenous vein.

METHODS

A retrospective analysis on 95 patients treated with high ligation and thermal ablation at our institution was performed, assessing duration of surgery, post-operative pain and analgesics requirements, early complications and resumption of activities.

RESULTS

Two patients (5,4%), in the laser group experienced skin burns in the course of the GSV. Moderate ecchymosis, by laser fibre-Romainduced perforation of the vein wall, were observed in another two patients (5.4%). Four limbs (10.8%) in the EVLT group developed transient paraesthesias. Analgesic requirement on POD 3 was nil for RFA group; conversely half of the EVLT patients did take analgesics, either 2 or 3 tabs were required. On POD 7, the patients of RFA group continued to not ask for any analgesics, but the same half of the patients in EVLT group still needed 1-2 tabs to carry out their normal activities smoothly. On POD 15, no patient did require analgesics. Resumption of routine activities was earlier for RFA group patients than for those in the EVLT group. The RFA group resumed their activities within 3 days, whereas EVLT group in 8-9 days. High ligation of the SFJ didn't add too much time or morbidities.

CONCLUSION

High ligation of saphenous femoral arc combined with catheter delivered thermal energies for saphenous ablation, even when combined with high ligation of saphenous femoral arc, demonstrated to be minimally invasive, easy to learn and easy to perform, with early resumption and return to normal activity. EVLT achieved similar results to RFA and both techniques were considered equally effective and safe; the results we obtained were not statistically significant but RFA showed less pain, ecchymosis and haematomas, as well as provided better short-term quality of life.

Mechanism of intersubunit ketosynthase-dehydratase interaction in polyketide synthases

Modular polyketide synthases (PKSs) produce numerous structurally complex natural products that have diverse applications in medicine and agriculture. PKSs typically consist of several multienzyme subunits that utilize structurally defined docking domains (DDs) at their N and C termini to ensure correct assembly into functional multiprotein complexes. Here we report a fundamentally different mechanism for subunit assembly in trans-acyltransferase (trans-AT) modular PKSs at the junction between ketosynthase (KS) and dehydratase (DH) domains. This mechanism involves direct interaction of a largely unstructured docking domain (DD) at the C terminus of the KS with the surface of the downstream DH. Acyl transfer assays and mechanism-based crosslinking established that the DD is required for the KS to communicate with the acyl carrier protein appended to the DH. Two distinct regions for binding of the DD to the DH were identified using NMR spectroscopy, carbene footprinting, and mutagenesis, providing a foundation for future elucidation of the molecular basis for interaction specificity.

Highly versatile nanohydrogel platform based on riboflavin-polysaccharide derivatives useful in the development of intrinsically fluorescent and cytocompatible drug carriers

In this work we describe a new nanohydrogel platform, based on polysaccharides modified with the hydrophobic and fluorescent molecule riboflavin tetrabutyrate, which leads to innovative structures useful for drug delivery applications. Hyaluronic acid and pullulan were chosen as representative of anionic and neutral polysaccharides, respectively, and the bromohexyl derivative of riboflavin tetrabutyrate was chemically linked to these polymer chains. Because of such derivatization, polymer chains were able to self-assemble in aqueous environment thus forming nanohydrogels, with mean diameters of about 312 and 210 nm, for hyaluronan and pullulan, respectively. These new nanohydrogels showed low polydispersity index, and negative ζ-potential. Moreover, the nanohydrogels, which can be easily loaded with model drugs, showed long-term stability in water and physiological conditions and excellent cytocompatibility. All these properties allow to consider these intrinsically fluorescent nanohydrogels suitable for the formulation of innovative drug dosage forms.

[Notes on respiratory and cardiac pathology in an unpublished letter of Maurizio Bufalini]

An unpublished letter written by Maurizio Bufalini on 8th January 1820 describes a clinical case of considerable gravity characterized by asthma with pleural effusion and "dilatation of the vena cava". On this basis, the state of knowledge of asthma in that period, particularly in relation to heart diseases, is reviewed. Following a careful examination of the letter, the possibility that M. Bufalini may have been a forerunner of the modern concept of cor pulmonale is suggested.

Formation of acetoacetate from 3-hydroxy-3-methylglutarate by rat liver and isolation of a mitochondrial coenzyme A-transferase activity involved

1. Formation of acetoacetate from 3-hydroxy-3-methylglutarate was observed in the perfused rat liver. Production of 3.5mumol of acetoacetate/h per g of tissue was obtained. 2. Formation of acetoacetate was catalysed mainly by the mitochondrial fraction of the homogenized liver, at a rate of 62nmol/h per mg of protein. 3. Experiments with hydroxy-[3-(14)C]methylglutarate demonstrated that the acetoacetate formed was derived mainly from this compound. 4. A mitochondrial transferase activity catalysing the transfer of a CoA molecule from succinyl-CoA (3-carboxypropionyl-CoA) to hydroxymethylglutarate was shown. The K(m) value for hydroxymethylglutarate was 5x10(-3)m.