Emergency department prediction model for 30-day mortality after hip fracture: the Spanish National Hip Fracture Registry (RNFC) cohort.

INTRODUCTION: The aim of this study was to design and validate a predictive model for 30-day mortality in a cohort of patients from the Spanish National Hip Fracture Registry (RNFC) with variables collected at the Emergency Department. METHODS: Retrospective study of a prospective database of hip fracture patients ⩾75 years old between 1 January 2017 and 30 September 2019. Patient characteristics, type of fracture and osteoprotective medication were collected at the Emergency Department. Univariate analysis compared the results between patients alive and deceased 30 days after hospital discharge. The variables associated with 30-day mortality in the regression analysis were age >85 years, male sex, indoors pre-fracture mobility, dementia, ASA score >3, pathological fracture, and vitamin D intake. A score scale was created with these variables. Discriminative performance was assessed using the area under the curve (AUC), calibration was assessed by applying Hosmer-Lemeshow goodness-of-fit test and predicted-to-observed mortality was compared. RESULTS: A total of 29,875 hip fracture cases were included in the study. The 30-day mortality of the overall cohort was 7.7%. A scale of 0-9 points was created, with a cut-off point of 4 points for the determination of patients at high risk of mortality. The AUC was 0.886. RNFC score presented good level of calibration (p = 0.139). The predicted-to-observed ratio was 1.09. CONCLUSIONS: The RNFC predictive model with variables collected at the Emergency Department showed an excellent predictive capacity for 30-day mortality in patients after hip fracture.

Integrin α6ß4 Recognition of a Linear Motif of Bullous Pemphigoid Antigen BP230 Controls Its Recruitment to Hemidesmosomes.

Mechanical stability of epithelia requires firm attachment to the basement membrane via hemidesmosomes. Dysfunction of hemidesmosomal proteins causes severe skin-blistering diseases. Two plakins, plectin and BP230 (BPAG1e), link the integrin α6ß4 to intermediate filaments in epidermal hemidesmosomes. Here, we show that a linear sequence within the isoform-specific N-terminal region of BP230 binds to the third and fourth FnIII domains of ß4. The crystal structure of the complex and mutagenesis analysis revealed that BP230 binds between the two domains of ß4. BP230 induces closing of the two FnIII domains that are locked in place by an interdomain ionic clasp required for binding. Disruption of BP230-ß4 binding prevents recruitment of BP230 to hemidesmosomes in human keratinocytes, revealing a key role of this interaction for hemidesmosome assembly. Phosphomimetic substitutions in ß4 and BP230 destabilize the complex. Thus, our study provides insights into the architecture of hemidesmosomes and potential mechanisms of regulation.

Efficacy, cost, and aspects to take into account in the treatment of osteoporosis in the elderly.

Age is one of the principal risk factors for development of frailty fractures. Age pyramids show a population that is becoming increasingly more elderly, with an increasing incidence of fractures, and the forecasts for the future are truly alarming. Adequate handling of these patients who are especially at risk, at both the preventive and care levels, with a well-defined orthogeriatric model is necessary to respond to this clinical challenge. The objective of this review is to analyze the efficacy of the different strategies for the handling of geriatric patients with fracture risk.

Tyrosine sulfation modulates activity of tick-derived thrombin inhibitors.

Madanin-1 and chimadanin are two small cysteine-free thrombin inhibitors that facilitate blood feeding in the tick Haemaphysalis longicornis. Here, we report a post-translational modification-tyrosine sulfation-of these two proteins that is critical for potent anti-thrombotic and anticoagulant activity. Inhibitors produced in baculovirus-infected insect cells displayed heterogeneous sulfation of two tyrosine residues within each of the proteins. One-pot ligation-desulfurization chemistry enabled access to homogeneous samples of all possible sulfated variants of the proteins. Tyrosine sulfation of madanin-1 and chimadanin proved crucial for thrombin inhibitory activity, with the doubly sulfated variants three orders of magnitude more potent than the unmodified inhibitors. The three-dimensional structure of madanin-1 in complex with thrombin revealed a unique mode of inhibition, with the sulfated tyrosine residues binding to the basic exosite II of the protease. The importance of tyrosine sulfation within this family of thrombin inhibitors, together with their unique binding mode, paves the way for the development of anti-thrombotic drug leads based on these privileged scaffolds.

[Orthogeriatrics: The First multicentre regional register of hip fractures in Castilla y León (Spain)]. / Ortogeriatría: primer registro multicéntrico autonómico de fracturas de cadera en Castilla y León (España).

OBJECTIVE: The objective of this study is to describe the characteristics of the patients with hip fracture admitted to the Public Hospitals of Castilla y León during three monthly periods (November 2014, and October and November 2015). MATERIAL AND METHOD: The Castilla y León orthogeriatrics work group created a common register to collect data on hip fractures. The study included patients 75 years-old and over hospitalised with hip fractures in the 13 public hospitals in the community during November 2014, and October and November 2015. A multicentre, prospective, and observational study was conducted, in which clinical, functional, and social variables, as well as in-hospital mortality, were collected. RESULTS: The analysis included data from a total of 776 patients with a mean age of 86 (±6) years. The surgical delay was 4±2.8 days, and the mean hospital stay was 10±4.7 days. The anaesthesia risk was ASA 3±0.6. Around two-thirds (66.5%) of the patients had medical complications while in hospital, and 55.5% required a transfusion. In-hospital mortality was 4.6%. The mean pre-surgical stay was related to the overall stay: P<.001. CONCLUSIONS: Hip fracture registers are an essential tool for evaluating the process and for improving the treatment quality of these patients. This is the first multicentre register of hip fracture in the elderly created in a Spanish region, and could be a good precedent reference for a future national register.

Purification and Structural Analysis of Plectin and BPAG1e.

Plectin and BPAG1e belong to the plakin family of high-molecular-weight proteins that interconnect the cytoskeletal systems and anchor them to junctional complexes. Plectin and BPAG1e are prototypical plakins with a similar tripartite modular structure. The N- and C-terminal regions are built of multiple discrete structural domains, while the central rod domain mediates dimerization by coiled-coil interactions. Owing to the mosaic organization of plakins, the structure of their constituent individual domains or small multi-domain segments can be analyzed isolated. Yet, understanding the integrated function of large regions, oligomers, and heterocomplexes of plakins is difficult due to the large and segmented structure. Here, we describe methods for the production of plectin and BPAG1e samples suitable for structural and biophysical analysis. In addition, we discuss the combination of hybrid methods that yield information at several resolution levels to study the complex, multi-domain, and flexible structure of plakins.

Combination of X-ray crystallography, SAXS and DEER to obtain the structure of the FnIII-3,4 domains of integrin α6ß4.

Integrin α6ß4 is a major component of hemidesmosomes that mediate the stable anchorage of epithelial cells to the underlying basement membrane. Integrin α6ß4 has also been implicated in cell proliferation and migration and in carcinoma progression. The third and fourth fibronectin type III domains (FnIII-3,4) of integrin ß4 mediate binding to the hemidesmosomal proteins BPAG1e and BPAG2, and participate in signalling. Here, it is demonstrated that X-ray crystallography, small-angle X-ray scattering and double electron-electron resonance (DEER) complement each other to solve the structure of the FnIII-3,4 region. The crystal structures of the individual FnIII-3 and FnIII-4 domains were solved and the relative arrangement of the FnIII domains was elucidated by combining DEER with site-directed spin labelling. Multiple structures of the interdomain linker were modelled by Monte Carlo methods complying with DEER constraints, and the final structures were selected against experimental scattering data. FnIII-3,4 has a compact and cambered flat structure with an evolutionary conserved surface that is likely to correspond to a protein-interaction site. Finally, this hybrid method is of general application for the study of other macromolecules and complexes.

[Clinical pathway for hip fracture patients]. / Utilidad de una vía clínica en el manejo del anciano con fractura de cadera.

INTRODUCTION: Hip fracture in the elderly often occurs in patients with high co-morbidity. Effective management requires a comprehensive and multidisciplinary approach. PURPOSE: To evaluate the effect of a quality improvement intervention in the detection and treatment of complications in elderly patients admitted for hip fracture. MATERIAL AND METHODS: A comparative study was conducted between two groups of patients admitted for hip fracture prior to 2010, and after a quality improvement intervention in 2013. The intervention consisted of implementing improved multidisciplinary measures in accordance with recent scientific evidence. The degree of compliance of the implemented measures was quantified. RESULTS: Patients admitted due to hip fracture in 2010 (216 patients) and 2013 (196 patients) were similar in age, sex, Barthel Index, and a reduced Charlson Index, although there were more comorbidities in 2013. After implementation of the protocols, the detection of delirium, malnutrition, anemia, and electrolyte disturbances increased. A larger number of patients in 2013 were precribed intravenous iron (24% more) and osteoporosis treatment (61.3% more). The average stay was reduced by 45.3% and surgical delay by 29.4%, achieving better functional efficiency. CONCLUSION: The implementation of a clinical pathway in geriatric patients with hip fracture is useful to detect and treat complications at an early stage, and to reduce pre-operative and overall stay, all without a negative clinical or functional impact.

Trifluoroethanethiol: an additive for efficient one-pot peptide ligation-desulfurization chemistry.

Native chemical ligation followed by desulfurization is a powerful strategy for the assembly of proteins. Here we describe the development of a high-yielding, one-pot ligation-desulfurization protocol that uses trifluoroethanethiol (TFET) as a novel thiol additive. The synthetic utility of this TFET-enabled methodology is demonstrated by the efficient multi-step one-pot syntheses of two tick-derived proteins, chimadanin and madanin-1, without the need for any intermediary purification.

The unique regulation of iron-sulfur cluster biogenesis in a Gram-positive bacterium.

Iron-sulfur clusters function as cofactors of a wide range of proteins, with diverse molecular roles in both prokaryotic and eukaryotic cells. Dedicated machineries assemble the clusters and deliver them to the final acceptor molecules in a tightly regulated process. In the prototypical Gram-negative bacterium Escherichia coli, the two existing iron-sulfur cluster assembly systems, iron-sulfur cluster (ISC) and sulfur assimilation (SUF) pathways, are closely interconnected. The ISC pathway regulator, IscR, is a transcription factor of the helix-turn-helix type that can coordinate a [2Fe-2S] cluster. Redox conditions and iron or sulfur availability modulate the ligation status of the labile IscR cluster, which in turn determines a switch in DNA sequence specificity of the regulator: cluster-containing IscR can bind to a family of gene promoters (type-1) whereas the clusterless form recognizes only a second group of sequences (type-2). However, iron-sulfur cluster biogenesis in Gram-positive bacteria is not so well characterized, and most organisms of this group display only one of the iron-sulfur cluster assembly systems. A notable exception is the unique Gram-positive dissimilatory metal reducing bacterium Thermincola potens, where genes from both systems could be identified, albeit with a diverging organization from that of Gram-negative bacteria. We demonstrated that one of these genes encodes a functional IscR homolog and is likely involved in the regulation of iron-sulfur cluster biogenesis in T. potens. Structural and biochemical characterization of T. potens and E. coli IscR revealed a strikingly similar architecture and unveiled an unforeseen conservation of the unique mechanism of sequence discrimination characteristic of this distinctive group of transcription regulators.

Advances and perspectives of the architecture of hemidesmosomes: lessons from structural biology.

Hemidesmosomes (HD) are adhesive protein complexes that mediate stable attachment of basal epithelial cells to the underlying basement membrane. The organization of HDs relies on a complex network of protein-protein interactions, in which integrin alpha6beta4 and plectin play an essential role. Here we summarize the current knowledge of the structure of hemidesmosomal proteins, which includes the structures of the first and second fibronectin type III (FnIII) domains and the calx-beta domain of the integrin beta4 subunit, the actin binding domain of plectin, and two non-overlapping pairs of spectrin repeats of plectin and BPAG1e. Binding of plectin to the beta4 subunit is critical for the formation and the stability of HDs. The recent 3D structure of the primary complex between the integrin beta4 subunit and plectin has provided a first insight into the macromolecular recognition mechanisms responsible for HD assembly. Two missense mutations in beta4 linked to non lethal forms of epidermolysis bullosa map on the plectin-binding surface. Finally, the formation of the beta4-plectin complex induces conformational changes in beta4 and plectin, suggesting that their interaction may be subject to allosteric regulation.

Structure of the Calx-beta domain of the integrin beta4 subunit: insights into function and cation-independent stability.

The integrin alpha6beta4 is a receptor for laminins and provides stable adhesion of epithelial cells to the basement membranes. In addition, alpha6beta4 is important for keratinocyte migration during wound healing and favours the invasion of carcinomas into surrounding tissue. The cytoplasmic domain of the beta4 subunit is responsible for most of the intracellular interactions of the integrin; it contains four fibronectin type III domains and a Calx-beta motif. The crystal structure of the Calx-beta domain of beta4 was determined to 1.48 A resolution. The structure does not contain cations and biophysical data support the supposition that the Calx-beta domain of beta4 does not bind calcium. Comparison of the Calx-beta domain of beta4 with the calcium-binding domains of Na(+)/Ca(2+)-exchanger 1 reveals that in beta4 Arg1003 occupies a position equivalent to that of the calcium ions in the Na(+)/Ca(2+)-exchanger. By combining mutagenesis and thermally induced unfolding, it is shown that Arg1003 contributes to the stability of the Calx-beta domain. The structure of the Calx-beta domain is discussed in the context of the function and intracellular interactions of the integrin beta4 subunit and a putative functional site is proposed.