The Low Fall as a Surrogate Marker of Frailty Predicts Long-Term Mortality in Older Trauma Patients

Background

Frailty is associated with adverse outcomes including disability, mortality and risk of falls. Trauma registries capture a broad range of injuries. However, frail patients who fall comprise a large proportion of the injuries occurring in ageing populations and are likely to have different outcomes compared to non-frail injured patients. The effect of frail fallers on mortality is under-explored but potentially significant. Currently, many trauma registries define low falls as less than three metres, a height that is likely to include non-frailty falls. We hypothesized that the low fall from less than 0.5 metres, including same-level falls, is a surrogate marker of frailty and predicts long-term mortality in older trauma patients.

Methods

Using data from the Singapore National Trauma Registry, 2011–2013, matched till September 2014 to the death registry, we analysed adults aged over 45 admitted via the emergency department in public hospitals sustaining blunt injuries with an injury severity score (ISS) of 9 or more, excluding isolated hip fractures from same-level falls in the over 65. Patients injured by a low fall were compared to patients injured by high fall and other blunt mechanisms. Logistic regression was used to analyze 12-month mortality, controlling for mechanism of injury, ISS, revised trauma score (RTS), co-morbidities, gender, age and age-gender interaction. Different low fall height definitions, adjusting for injury regions, and analyzing the entire adult cohort were used in sensitivity analyses and did not change our findings.

Results

Of the 8111 adults in our cohort, patients who suffered low falls were more likely to die of causes unrelated to their injuries (p<0.001), compared to other blunt trauma and higher fall heights. They were at higher risk of 12-month mortality (OR 1.75, 95% CI 1.18–2.58, p = 0.005), independent of ISS, RTS, age, gender, age-gender interaction and co-morbidities. Falls that were higher than 0.5m did not show this pattern. Males were at higher risk of mortality after low falls. The effect of age on mortality started at age 55 for males, and age 70 for females, and the difference was attributable to the additional mortality in male low-fallers.

Conclusions

The low fall mechanism can optimize prediction of long-term mortality after moderate and severe injury, and may be a surrogate marker of frailty, complementing broader-based studies on aging.     

HtrA1 is upregulated during RANKL-induced osteoclastogenesis,and negatively regulates osteoblast differentiation and BMP2-induced Smad1/5/8, ERK and p38 phosphorylation

Bone remodeling is regulated by secreted factors in the bone microenvironment. However, data regarding osteoclast-derived factors that influence osteoblast differentiation are lacking. Here, we show that HtrA1 is produced as a secreted protein during osteoclastogenesis, and negatively regulates osteoblast differentiation. Exogenous addition of recombinant HtrA1 attenuates osteoblast differentiation and BMP2-induced Smad1/5/8, ERK1/2 and p38 phosphorylation in pre-osteoblasts. Our studies imply a unique mode of crosstalk in which HtrA1 is produced by both osteoclasts and osteoblasts and negatively regulates osteoblast differentiation, suggesting that HtrA1 may mediate the fine tuning of paracrine and autocrine regulations during bone remodeling processes.     

Arterial Extracellular Matrix: A Mechanobiological Study of the Contributions and Interactions of Elastin and Collagen

The complex network structure of elastin and collagen extracellular matrix (ECM) forms the primary load bearing components in the arterial wall. The structural and mechanobiological interactions between elastin and collagen are important for properly functioning arteries. Here, we examined the elastin and collagen organization, realignment, and recruitment by coupling mechanical loading and multiphoton imaging. Two-photon excitation fluorescence and second harmonic generation methods were performed with a multiphoton video-rate microscope to capture real time changes to the elastin and collagen structure during biaxial deformation. Enzymatic removal of elastin was performed to assess the structural changes of the remaining collagen structure. Quantitative analysis of the structural changes to elastin and collagen was made using a combination of two-dimensional fast Fourier transform and fractal analysis, which allows for a more complete understanding of structural changes. Our study provides new quantitative evidence, to our knowledge on the sequential engagement of different arterial ECM components in response to mechanical loading. The adventitial collagen exists as large wavy bundles of fibers that exhibit fiber engagement after 20% strain. The medial collagen is engaged throughout the stretching process, and prominent elastic fiber engagement is observed up to 20% strain after which the engagement plateaus. The fiber orientation distribution functions show remarkably different changes in the ECM structure in response to mechanical loading. The medial collagen shows an evident preferred circumferential distribution, however the fiber families of adventitial collagen are obscured by their waviness at no or low mechanical strains. Collagen fibers in both layers exhibit significant realignment in response to unequal biaxial loading. The elastic fibers are much more uniformly distributed and remained relatively unchanged due to loading. Removal of elastin produces similar structural changes in collagen as mechanical loading. Our study suggests that the elastic fibers are under tension and impart an intrinsic compressive stress on the collagen.     

Recognition intensities of submolecular structures,mammalian glyco-structural units,ligand cluster and polyvalency in abrin-a-carbohydrate interactions

Abrin-a is the most toxic fraction of lectins isolated from Abrus precatorius seeds and belongs to the family of type 2 ribosome inactivating proteins (RIP). This toxin may act as a defense molecule in plants against viruses, fungi and insects, where attachment of abrin-a to the exposed glycans on the surface of target cells is the crucial and initial step of its cytotoxicity. Although it has been studied for over four decades, the recognition factors involved in abrin-a-carbohydrate interaction remains to be clarified. In this study, roles of mammalian glyco-structural units, ligand clusters and polyvalency in abrin-a recognition were comprehensively analyzed by enzyme-linked lectinosorbent binding and inhibition assays. The results indicate that: (i) this toxin prefers oligosaccharides having α-anomer of galactose (Gal) at the non-reducing terminal than the corresponding β-anomer; (ii) Galα1-3Galα1- (B_α), Galα1-4Gal (E), Galβ1-3GalNAc (T) and Galβ1-3/4GlcNAc (I/II) related oligosaccharides were the active glyco-structural units; (iii) tri-antennary II_β, prepared from N-glycan of asialo fetuin, played a dominant role in recognition; (iv) many high-density polyvalent I_β/II_β and E_β glycotopes enhanced the reactivity; (v) the carbohydrate recognition domain of abrin-a is proposed to be a combination of a small cavity type of Gal as major site and a groove type of additional one to tetrasaccharides as subsites with a preference of α1-3/4/6Gal, β1-3GalNAc, β1-3/4/6GlcNAc, β1-4/6Glc, β1-3DAra and β1-4Man as subterminal sugars; (vi) size of the carbohydrate recognition domain may be as large enough to accommodate a linear pentasaccharide and complementary to Galα1-3Galβ1-4GlcNAc β1-3Galβ1-4Glc (gailipenta) sequence. A comparison of the recognition factors and combining sites of abrin-a with ricin, another highly toxic lectin, was also performed to further understand the differences in recognition factors between these two type 2 RIPs.     

Invasive three-dimensional organotypic neoplasia from multiple normal human epithelia

Refined cancer models are required if researchers are to assess the burgeoning number of potential targets for cancer therapeutics in a clinically relevant context that allows a fast turnaround. Here we use tumor-associated genetic pathways to transform primary human epithelial cells from the epidermis, oropharynx, esophagus and cervix into genetically defined tumors in a human three-dimensional (3D) tissue environment that incorporates cell-populated stroma and intact basement membrane. These engineered organotypic tissues recapitulated natural features of tumor progression, including epithelial invasion through basement membrane, a complex process that is necessary for biological malignancy in 90% of human cancers. Invasion was rapid and was potentiated by stromal cells. Oncogenic signals in 3D tissue, but not 2D culture, resembled gene expression profiles from spontaneous human cancers. We screened 3D organotypic neoplasia with well-characterized signaling pathway inhibitors to distill a clinically faithful cancer gene signature. Multitissue 3D human tissue cancer models may provide an efficient and relevant complement to current approaches to characterizing cancer progression.     

Mycobacterium tuberculosis CYP125A1, a steroid C27 monooxygenase that detoxifies intracellularly generated cholest‐4‐en‐3‐one

The infectivity and persistence of Mycobacterium tuberculosis requires the utilization of host cell cholesterol. We have examined the specific role of cytochrome P450 CYP125A1 in the cholesterol degradation pathway using genetic, biochemical and high‐resolution mass spectrometric approaches. The analysis of lipid profiles from cells grown on cholesterol revealed that CYP125A1 is required to incorporate the cholesterol side‐chain carbon atoms into cellular lipids, as evidenced by an increase in the mass of the methyl‐branched phthiocerol dimycocerosates. We observed that cholesterol‐exposed cells lacking CYP125A1 accumulate cholest‐4‐en‐3‐one, suggesting that this is a physiological substrate for this enzyme. Reconstitution of enzymatic activity with spinach ferredoxin and ferredoxin reductase revealed that recombinant CYP125A1 indeed binds both cholest‐4‐en‐3‐one and cholesterol, efficiently hydroxylates both of them at C‐27, and then further oxidizes 27‐hydroxycholest‐4‐en‐3‐one to cholest‐4‐en‐3‐one‐27‐oic acid. We determined the X‐ray structure of cholest‐4‐en‐3‐one‐bound CYP125A1 at a resolution of 1.58 Å. CYP125A1 is essential for growth of CDC1551 in media containing cholesterol or cholest‐4‐en‐3‐one. In its absence, the latter compound is toxic for both CDC1551 and H37Rv when added with glycerol as a second carbon source. CYP125A1 is a key enzyme in cholesterol metabolism and plays a crucial role in circumventing the deleterious effect of cholest‐4‐en‐3‐one.     

Proteome mining for novel IgE-binding proteins from the German cockroach (Blattella germanica) and allergen profiling of patients

Although cockroaches are known to produce allergens that can cause IgE-mediated hypersensitivity reactions, including perennial rhinitis and asthma, the various cockroach allergens have not yet been fully studied. Many proteins from the German cockroach show high IgE reactivity, but have never been comprehensively characterized. To identify these potential allergens, proteins were separated by 2-DE and IgE-binding proteins were analyzed by nanoLC-MS/MS or N-terminal sequencing analysis. Using a combination of proteomic techniques and bioinformatic allergen database analysis, we identified a total of ten new B. germanica IgE-binding proteins. Of these, aldolase, arginine kinase, enolase, Hsp70, triosephosphate isomerase, and vitellogenin have been reported as allergens in species other than B. germanica. Analysis of the Food Allergy Research and Resource Program allergen database indicated that arginine kinase, enolase, and triosephosphate isomerase showed significant potential cross-reactivity with other related allergens. This study revealed that vitellogenin is an important novel B. germanica allergen. Personalized profiling and reactivity of IgE Abs against the panel of IgE-binding proteins varied between cockroach-allergic individuals. These findings make it possible to monitor the individual IgE reactivity profile of each patient and facilitate personalized immunotherapies for German cockroach allergy disorders.     

Deletion 17q12 is a recurrent copy number variant that confers high risk of autism and schizophrenia

Autism spectrum disorders (ASD) and schizophrenia are neurodevelopmental disorders for which recent evidence indicates an important etiologic role for rare copy number variants (CNVs) and suggests common genetic mechanisms. We performed cytogenomic array analysis in a discovery sample of patients with neurodevelopmental disorders referred for clinical testing. We detected a recurrent 1.4 Mb deletion at 17q12, which harbors HNF1B, the gene responsible for renal cysts and diabetes syndrome (RCAD), in 18/15,749 patients, including several with ASD, but 0/4,519 controls. We identified additional shared phenotypic features among nine patients available for clinical assessment, including macrocephaly, characteristic facial features, renal anomalies, and neurocognitive impairments. In a large follow-up sample, the same deletion was identified in 2/1,182 ASD/neurocognitive impairment and in 4/6,340 schizophrenia patients, but in 0/47,929 controls (corrected p = 7.37 × 10⁻⁵). These data demonstrate that deletion 17q12 is a recurrent, pathogenic CNV that confers a very high risk for ASD and schizophrenia and show that one or more of the 15 genes in the deleted interval is dosage sensitive and essential for normal brain development and function. In addition, the phenotypic features of patients with this CNV are consistent with a contiguous gene syndrome that extends beyond RCAD, which is caused by HNF1B mutations only.