Scaling laws in enzyme function reveal a new kind of biochemical universality.

All life on Earth is unified by its use of a shared set of component chemical compounds and reactions, providing a detailed model for universal biochemistry. However, this notion of universality is specific to known biochemistry and does not allow quantitative predictions about examples not yet observed. Here, we introduce a more generalizable concept of biochemical universality that is more akin to the kind of universality found in physics. Using annotated genomic datasets including an ensemble of 11,955 metagenomes, 1,282 archaea, 11,759 bacteria, and 200 eukaryotic taxa, we show how enzyme functions form universality classes with common scaling behavior in their relative abundances across the datasets. We verify that these scaling laws are not explained by the presence of compounds, reactions, and enzyme functions shared across known examples of life. We demonstrate how these scaling laws can be used as a tool for inferring properties of ancient life by comparing their predictions with a consensus model for the last universal common ancestor (LUCA). We also illustrate how network analyses shed light on the functional principles underlying the observed scaling behaviors. Together, our results establish the existence of a new kind of biochemical universality, independent of the details of life on Earth's component chemistry, with implications for guiding our search for missing biochemical diversity on Earth or for biochemistries that might deviate from the exact chemical makeup of life as we know it, such as at the origins of life, in alien environments, or in the design of synthetic life.

Nuclear introns help unravel the diversification history of the Australo-Pacific Petroica robins.

Australo-Pacific Petroica robins are known for their striking variability in sexual plumage coloration. Molecular studies in recent years have revised the taxonomy of species and subspecies boundaries across the southwest Pacific and New Guinea. However, these studies have not been able to resolve phylogenetic relationships within Petroica owing to limited sampling of the nuclear genome. Here, we sequence five nuclear introns across all species for which fresh tissue was available. Nuclear loci offer support for major geographic lineages that were first inferred from mtDNA. We find almost no shared nuclear alleles between currently recognized species within the New Zealand and Australian lineages, whereas the Pacific robin radiation has many shared alleles. Multilocus coalescent species trees based on nuclear loci support a sister relationship between the Australian lineage and the Pacific robin radiation-a node that is poorly supported by mtDNA. We also find discordance in support for a sister relationship between the similarly plumaged Rose Robin (P. rosea) and Pink Robin (P. rodinogaster). Our nuclear data complement previous mtDNA studies in suggesting that the phenotypically cryptic eastern and western populations of Australia's Scarlet Robin (P. boodang) are genetically distinct lineages at the early stages of divergence and speciation.

Tibiofibular bone-bridging osteoplasty in transtibial amputation: case report and description of technique.

Transtibial amputation osteoplasty procedures were originally designed as a technique for achieving a functional end-bearing limb in the post-World War I era; the Ertl procedure is now often used as a reconstructive procedure for failed primary amputations. Modifications of the original periosteal sleeve-covering technique include the tibiofibular bone-bridging osteoplasty. The theoretical advantages to this procedure are highly debated among trauma surgeons. For the patient with a lower extremity injury that necessitates a transtibial amputation, there are many psychologic and physiologic factors to consider, and a persistently painful residual limb postamputation may be mentally and physically disabling. Although the advantages of these techniques may be unproven, they are fairly simple and add little additional operative time to the primary transtibial amputation. A surgeon who performs transtibial amputations should at least be aware of the osteoplasty techniques and how to perform them. The decision to use these techniques may then be made by the surgeon on a case-by-case basis, given the individual demands of the patient. This article presents a case report and outlines the use of the fibular bone-bridging osteoplasty technique in transtibial amputations.

Seeding Biochemistry on Other Worlds: Enceladus as a Case Study.

The Solar System is becoming increasingly accessible to exploration by robotic missions to search for life. However, astrobiologists currently lack well-defined frameworks to quantitatively assess the chemical space accessible to life in these alien environments. Such frameworks will be critical for developing concrete predictions needed for future mission planning, both to determine the potential viability of life on other worlds and to anticipate the molecular biosignatures that life could produce. Here, we describe how uniting existing methods provides a framework to study the accessibility of biochemical space across diverse planetary environments. Our approach combines observational data from planetary missions with genomic data catalogued from across Earth and analyzed using computational methods from network theory. To demonstrate this, we use 307 biochemical networks generated from genomic data collected across Earth and "seed" these networks with molecules confirmed to be present on Saturn's moon Enceladus. By expanding through known biochemical reaction space starting from these seed compounds, we are able to determine which products of Earth's biochemistry are, in principle, reachable from compounds available in the environment on Enceladus, and how this varies across different examples of life from Earth (organisms, ecosystems, planetary-scale biochemistry). While we find that none of the 307 prokaryotes analyzed meet the threshold for viability, the reaction space covered by this process can provide a map of possible targets for detection of Earth-like life on Enceladus, as well as targets for synthetic biology approaches to seed life on Enceladus. In cases where biochemistry is not viable because key compounds are missing, we identify the environmental precursors required to make it viable, thus providing a set of compounds to prioritize for detection in future planetary exploration missions aimed at assessing the ability of Enceladus to sustain Earth-like life or directed panspermia.

Clinical Comparison of Surgical Constructs for Anterior Cervical Corpectomy and Fusion in Patients With Cervical Spondylotic Myelopathy or Ossified Posterior Longitudinal Ligament: A Systematic Review and Meta-Analysis.

STUDY DESIGN: This is a systematic review and meta-analysis. OBJECTIVE: To examine the differences in outcomes among current constructs and techniques for anterior cervical corpectomy and fusion (ACCF) in patients with single or multiple level cervical myelopathy (CM) secondary to cervical spondylosis or ossified posterior longitudinal ligament. SUMMARY OF BACKGROUND DATA: The natural history of CM can be a progressive disease process. In such cases, where surgical decompression is indicated to halt the progression, ACCF is typically chosen for pathology located posterior to the vertebral body. Numerous studies have shown that decompression with appropriate stabilization not only halts progression, but also improves patient outcomes. However, several constructs are available for this procedure, all with variable outcomes. MATERIALS AND METHODS: A systematic review was conducted using Cochrane Database, Medline, and PubMed. Only studies with a minimum patient population of 10, reporting on CM because of cervical spondylosis or ossified posterior longitudinal ligament were included; a minimum follow-up period of 12 months and 1 clinical and/or radiographic outcome were required. Studies examining patients with cervical trauma/fracture, tumor, and infection or revision cases were excluded. Data analysis was carried out with Microsoft Excel. RESULTS: A total of 30 studies met the inclusion criteria for qualitative analysis, while 26 studies were included for quantitative analysis. Constructs that were reported in these studies included titanium mesh cages, nano-hydroxyapatite/polyamide 66 composite struts, bone graft alone, expandable corpectomy cages, and polyetheretherketone cages. Clinical outcomes included Japanese Orthopaedic Association and modified Japanese Orthopaedic Association scores, Visual Analog Scale scores, Neck Disability Index scores, and Nurick grades. Radiographic outcomes included C2-C7 and segmental Cobb angles and pseudarthrosis rates. Each construct type had variable and unique benefits and shortcomings. CONCLUSIONS: ACCF is a common surgical option for CM, despite carrying certain risks expected of any anterior cervical approach. Several constructs are available for ACCF, all with variable clinical and radiographic outcomes.

Trends in cervical disc arthroplasty and revisions in the Medicare database.

BACKGROUND: Due to increased postoperative complications with anterior cervical discectomy and fusion (ACDF), there has been an increasing interest in the use of cervical disc arthroplasty (CDA). Advancements in prosthetic designs and techniques have improved patient reported outcome measurements and minimized revision rates. There is a paucity in the literature regarding recent trends in CDA utilization and revision rates. The purpose of this study was to determine annual primary and revision CDA trends with the use of an administrative database. METHODS: A retrospective review from 2005-2014 was performed using the Medicare Standard Analytical Files from the PearlDiver supercomputer (PearlDiver Technologies, Fort Wayne, IN, USA). Patients who underwent primary CDA were queried using International Classification of Disease, ninth revision (ICD-9) and current procedural terminology (CPT) code 84.62 and 22856, respectively. Revision CDAs were queried using ICD-9 procedure code 84.66. Primary outcomes of this study included annual primary procedures, annual revision incidence (RI), and additional demographic data such as age, gender, geographic location, Charlson-Comorbidity Index (CCI); in addition to length of stay (LOS), cost, and reimbursement. RESULTS: The query returned 2,016 and 517 primary CDA and revision CDA procedures were performed in the Medicare database, respectively. The data showed that the CAGR of primary and revision CDA procedures to be 20.54% and 5.84% (P<0.001), respectively. RI and RB demonstrated a CAGR of -12.22% and -9.61%, respectively. Patients younger than the age of 65 represented the majority of the patients undergoing this procedure. Demographically, primary and revision CDAs were found highest in the South. CONCLUSIONS: The data demonstrates a high rate of annual growth in CDA utilization (20.54%) and revision CDA (5.84%), indicating there is an increase demand for CDA in the United States. Compared to ACDF, patients who undergo CDA have improved patient reported outcome measurements and lower rates of postoperative complications.

Hypothyroidism increases 90-day postoperative complications in patients undergoing primary single level anterior cervical disectomy and fusion: a matched control analysis.

BACKGROUND: Anterior cervical discectomy and fusion (ACDF) is indicated for patients suffering from cervical radiculopathy, myelopathy, and degenerative disc disease, among other diseases. There is paucity in the literature regarding postoperative complications in patients undergoing primary ACDF with a diagnosis of hypothyroidism. The purpose of this study is to compare 90-day postoperative complications in patients with and without hypothyroidism undergoing primary ACDF. METHODS: A retrospective analysis was completed using a national administrative database known as Pearl Diver (Pearl Diver Technologies, Fort Wayne, Indiana) using the International Classification of Disease, ninth revision (ICD-9) codes. The study group consisted of patients having undergone ACDF with an active diagnosis of hypothyroidism 90 days prior to and on the day of surgery. Patients undergoing primary ACDF without hypothyroidism served as the control group. Patients in both groups were randomly matched according to age, gender, and Charlson-Comorbidity Index (CCI). The 90-day postoperative medical complications were assessed along with readmission rates and total cost of care. RESULTS: There were a total of 107,066 patients equally divided between the 2 cohorts. Patients with hypothyroidism had greater odds of developing complications such as non-healing surgical wound (OR: 2.27; P<0.001), pulmonary embolus (OR: 2.16; P<0.001), myocardial infarction (OR: 2.10; P<0.001), compared to patients in the control group after undergoing primary ACDF. Readmission rates were also higher in patients with hypothyroidism (OR: 1.45; P<0.001). Total cost of care was also greater in patients with hypothyroidism compared to patients without hypothyroidism undergoing primary ACDF. CONCLUSIONS: Hypothyroidism is a risk factor for worse postoperative outcomes in patients undergoing primary ACDF. Appropriate preoperative optimization with thyroid hormone supplementation could potentially minimize the incidence of developing numerous medical complications, in addition to potentially lowering readmission rates and the total cost of care.

Imaging the postoperative spine.

Imaging assessment of the postoperative spine is complex and depends on many factors. Postoperative imaging studies evaluate the position of implants, adequacy of decompression, fusion status, and potential complications. This article provides a review of various imaging techniques, with their advantages and disadvantages, for the evaluation of the postoperative spine. It also gives an overview of normal and abnormal postoperative appearances of the spine as seen via various modalities, with an emphasis on postoperative complications.