A rat model of orthopedic injury-induced hypercoagulability and fibrinolytic shutdown.

BACKGROUND: Postinjury hypercoagulability occurs in >25% of injured patients, increasing risk of thromboembolic complications despite chemoprophylaxis. However, few clinically relevant animal models of posttraumatic hypercoagulability exist. We aimed to evaluate a rodent model of bilateral hindlimb injury as a preclinical model of postinjury hypercoagulability. METHODS: Forty Wistar rats were anesthetized with isoflurane: 20 underwent bilateral hindlimb fibula fracture, soft tissue and muscular crush injury, and bone homogenate injection intended to mimic the physiological severity of bilateral femur fracture. Twenty sham rats underwent anesthesia only. Terminal citrated blood samples were drawn at 0, 6, 12, and 24 hours (n = 5 per timed group) for analysis by native thromboelastography in the presence and absence of taurocholic acid to augment fibrinolysis. Plasminogen activator inhibitor 1 and α-2 antiplasmin levels in plasma were assessed via enzyme-linked immunosorbent assay. RESULTS: Injured rats became hypercoagulable relative to baseline by 6 hours based on thromboelastography maximal amplitude (MA) and G (p < 0.005); sham rats became hypercoagulable to a lesser degree by 24 hours (p < 0.005). Compared with sham animals, injured rats were hypercoagulable by MA and G within 6 hours of injury, remained hypercoagulable by MA and G through at least 24 hours (all p < 0.01), and showed impaired fibrinolysis by taurocholic acid LY30 at 12 hours (p = 0.019) and native LY30 at 24 hours (p = 0.045). In terms of antifibrinolytic mediators, α-2 antiplasmin was elevated in trauma animals at 24 hours (p = 0.009), and plasminogen activator inhibitor 1 was elevated in trauma animals at 6 hours (p = 0.004) and 12 hours (p < 0.001) when compared with sham. CONCLUSIONS: Orthopedic injury in rodents induced platelet and overall hypercoagulability within 6 hours and fibrinolytic impairment by 12 to 24 hours, mimicking postinjury hypercoagulability in injured patients. This rodent model of orthopedic injury may serve as a preclinical testing ground for potential therapies to mitigate hypercoagulability, maintain normal fibrinolysis, and prevent thromboembolic complications.

Anatomy of a dinosaur-Clarification of vertebrae in vertebrate anatomy.

The flat-end surfaces of dinosaur vertebral centra led to the presumption that intervertebral discs occupied the space between their vertebrae. A set of fused hadrosaur vertebrae allowed that hypothesis to be tested. The Tyrannosaurus rex responsible for this pathology did not escape unscathed. It left behind a tooth crown that had fractured. Fragments of that tooth were scattered through the intervertebral space, evidencing that there was no solid structure to impede its movement. That eliminates the possibility of an intervertebral disc and instead proves the presence of an articular space, similar to that in modern reptiles, but at variance to what is noted in birds. While avian cervical vertebral centra appear to be separated by diarthrodial joints, the preponderance of their thoracic vertebral centra is not separated by synovial joints.

Laser-stimulated fluorescence in paleontology.

Fluorescence using ultraviolet (UV) light has seen increased use as a tool in paleontology over the last decade. Laser-stimulated fluorescence (LSF) is a next generation technique that is emerging as a way to fluoresce paleontological specimens that remain dark under typical UV. A laser's ability to concentrate very high flux rates both at the macroscopic and microscopic levels results in specimens fluorescing in ways a standard UV bulb cannot induce. Presented here are five paleontological case histories that illustrate the technique across a broad range of specimens and scales. Novel uses such as back-lighting opaque specimens to reveal detail and detection of specimens completely obscured by matrix are highlighted in these examples. The recent cost reductions in medium-power short wavelength lasers and use of standard photographic filters has now made this technique widely accessible to researchers. This technology has the potential to automate multiple aspects of paleontology, including preparation and sorting of microfossils. This represents a highly cost-effective way to address paleontology's preparatory bottleneck.

Failure events in transition of care for surgical patients.

BACKGROUND: Unexpected clinical deterioration (failure events) in surgical patients on standard nursing units (WARDs) could have a significant impact on eventual survival. We sought to investigate failure events requiring intensive care (surgical ICU [SICU]) transfer of surgical patients on WARDs in a single-center academic setting. STUDY DESIGN: Surgical patients admitted to WARDs over a 12-month period, who developed failure events, were retrospectively reviewed. Time to deterioration since WARD arrival, clinical factors, notification chain, and outcomes were identified. A physician review panel determined the preventability of failure events. RESULTS: Ninety-eight patients experienced 111 failure events requiring SICU transfer. Most patients (85%) were emergency admissions. Of 111 events, 90% had been previously discharged from an SICU or a postanesthesia care unit (PACU). Recognition of failure was by nursing (54%) and on routine physician rounds (34%). Rapid response or code blue alone was less common (12%). A second physician notification was needed in 29%, with delays due to failure to identify severity of illness. Most commonly, respiratory events prompted notification (77 of 111, 69%). Overall mortality was 26 of 98 (27%). Median time to failure was 2 days and was associated with early transfer from the SICU or PACU. Rapid response or code blue activation was associated with higher mortality than physician notification. CONCLUSIONS: Patients most at risk for WARD failures were those with acute surgical emergencies or recently discharged from the SICU or PACU. Respiratory complications were the most common cause of WARD failure events. Many early failures may have been due to premature transfer from the SICU or PACU. Failure events on WARDs can have lethal consequences. Awareness, monitoring, and communication are important components of preventative measures.

The power of the claw.

Scratches on bones have routinely been attributed to tooth marks (a predominantly untested speculation), ignoring the effects of claws, perhaps because of the general assumption that claws are too soft to damage bone. However, some pathologies appears to be more compatible with claw rather than tooth impacts. Therefore, it is critical to determine if the claws of any animal are capable of scratching into the surface of any bone--a test and proof of concept. A tiger enrichment program was used to document actual bone damage unequivocally caused by claws, by assuring that the tiger had access to bones only by using its paws (claws). The spectrum of mechanisms causing bone damage was expanded by evidentiary analysis of claw-induced pathology. While static studies suggested that nails/claws could not disrupt bone, specific tiger enrichment activities documented that bones were susceptible to damage from the kinetic energy effect of the striking claw. This documents an expanded differential consideration for scratch marks on bone and evidences the power of the claw.

Raman spectroscopic documentation of Oligocene bladder stone.

Discovery of a fossil (30-35 million-year-old) urolith from Early Oligocene deposits in northeastern Colorado provides the earliest evidence for the antiquity of bladder stones. These are spherical objects with a layered phosphatic structure and a hollow center. Each layer is composed of parallel crystals oriented perpendicular to the surface. Macroscopic and microscopic examination and X-ray diffraction analysis, along with comparison with 1,000 contemporary uroliths, were used as evidence in the confirmation of this diagnosis. Raman microspectroscopy verified the presence of organic material between layers, confirming its biologic origin.

Physical evidence of predatory behavior in Tyrannosaurus rex.

Feeding strategies of the large theropod, Tyrannosaurus rex, either as a predator or a scavenger, have been a topic of debate previously compromised by lack of definitive physical evidence. Tooth drag and bone puncture marks have been documented on suggested prey items, but are often difficult to attribute to a specific theropod. Further, postmortem damage cannot be distinguished from intravital occurrences, unless evidence of healing is present. Here we report definitive evidence of predation by T. rex: a tooth crown embedded in a hadrosaurid caudal centrum, surrounded by healed bone growth. This indicates that the prey escaped and lived for some time after the injury, providing direct evidence of predatory behavior by T. rex. The two traumatically fused hadrosaur vertebrae partially enclosing a T. rex tooth were discovered in the Hell Creek Formation of South Dakota.

Mycobacterium tuberculosis complex lipid virulence factors preserved in the 17,000-year-old skeleton of an extinct bison, Bison antiquus.

Tracing the evolution of ancient diseases depends on the availability and accessibility of suitable biomarkers in archaeological specimens. DNA is potentially information-rich but it depends on a favourable environment for preservation. In the case of the major mycobacterial pathogens, Mycobacterium tuberculosis and Mycobacterium leprae, robust lipid biomarkers are established as alternatives or complements to DNA analyses. A DNA report, a decade ago, suggested that a 17,000-year-old skeleton of extinct Bison antiquus, from Natural Trap Cave, Wyoming, was the oldest known case of tuberculosis. In the current study, key mycobacterial lipid virulence factor biomarkers were detected in the same two samples from this bison. Fluorescence high-performance liquid chromatography (HPLC) indicated the presence of mycolic acids of the mycobacterial type, but they were degraded and could not be precisely correlated with tuberculosis. However, pristine profiles of C(29), C(30) and C(32) mycocerosates and C(27) mycolipenates, typical of the Mycobacterium tuberculosis complex, were recorded by negative ion chemical ionization gas chromatography mass spectrometry of pentafluorobenzyl ester derivatives. These findings were supported by the detection of C(34) and C(36) phthiocerols, which are usually esterified to the mycocerosates. The existence of Pleistocene tuberculosis in the Americas is confirmed and there are many even older animal bones with well-characterised tuberculous lesions similar to those on the analysed sample. In the absence of any evidence of tuberculosis in human skeletons older than 9,000 years BP, the hypothesis that this disease evolved as a zoonosis, before transfer to humans, is given detailed consideration and discussion.

No association of time from surgery with functional deficits in athletes after anterior cruciate ligament reconstruction: evidence for objective return-to-sport criteria.

BACKGROUND: Release for full activity and return to sport after anterior cruciate ligament reconstruction (ACLR) is often dictated by time from surgery and subjective opinion by the medical team. Temporal guidelines for return to sport may not accurately identify impaired strength and neuromuscular control, which are associated with increased risk for second injury (contralateral and/or ipsilateral limb) after ACLR in athletes. HYPOTHESES: Athletes undergoing ACLR and returning to sport would demonstrate functional deficits that would not be associated with time from surgery. STUDY DESIGN: Controlled laboratory study. METHODS: Thirty-three male (n = 10) and female (n = 23) athletes with unilateral ACLR, who were cleared by a physician to return to their sport after surgery and rehabilitation, performed the single-legged vertical hop test for 10 seconds on a portable force plate. Matched teammates of each patient were recruited to serve as sex-, sport-, and age-matched controls (CTRL; n = 67). Maximum vertical ground-reaction force (VGRF) was measured during each single-limb landing. Single-limb symmetry index (LSI) was calculated as the ratio of the involved divided by uninvolved limb, expressed as a percentage. RESULTS: The single-limb vertical jump height LSI was reduced in the ACLR group, 89% (95% confidence interval [CI], 83%-95%), compared with the matched CTRL group, 101% (95% CI, 96%-105%; P < .01). The LSI for VGRF normalized to potential energy achieved during flight of the hop was increased in ACLR at 112% (95% CI, 106%-117%) relative to the CTRL group at 102% (95% CI, 98%-106%; P < .01). Linear regression analysis indicated that time from surgery was not associated with limb symmetry deficits in the ACLR group (P > .05; R (2) = .002-.01). CONCLUSION: Deficits in unilateral force development (vertical jump height) and absorption (normalized VGRF) persist in an athlete's single-limb performance after ACLR and full return to sports. These symmetry deficits appear to be independent of time after reconstruction. CLINICAL RELEVANCE: On the basis of these results, clinicians should consider assessment of single-limb power performance in the decision-making process for return-to-sport release. Persistent side-to-side asymmetries may increase the risk of contralateral and/or ipsilateral injury.

Species-specific responses of Late Quaternary megafauna to climate and humans.

Despite decades of research, the roles of climate and humans in driving the dramatic extinctions of large-bodied mammals during the Late Quaternary period remain contentious. Here we use ancient DNA, species distribution models and the human fossil record to elucidate how climate and humans shaped the demographic history of woolly rhinoceros, woolly mammoth, wild horse, reindeer, bison and musk ox. We show that climate has been a major driver of population change over the past 50,000 years. However, each species responds differently to the effects of climatic shifts, habitat redistribution and human encroachment. Although climate change alone can explain the extinction of some species, such as Eurasian musk ox and woolly rhinoceros, a combination of climatic and anthropogenic effects appears to be responsible for the extinction of others, including Eurasian steppe bison and wild horse. We find no genetic signature or any distinctive range dynamics distinguishing extinct from surviving species, emphasizing the challenges associated with predicting future responses of extant mammals to climate and human-mediated habitat change.

Microfluidics-based capture of human neutrophils for expression analysis in blood and bronchoalveolar lavage.

Gene expression analysis can be a powerful tool in predicting patient outcomes and identifying patients who may benefit from targeted therapies. However, isolating human blood polymorphonuclear cells (PMNs) for genomic analysis has been challenging. We used a novel microfluidic technique that isolates PMNs by capturing CD66b(+) cells and compared it with dextran-Ficoll gradient isolation. We also used microfluidic isolation techniques for blood and bronchoalveolar lavage (BAL) samples of patients with acute respiratory distress syndrome (ARDS) to evaluate PMN genomic alterations secondary to pulmonary sequestration. PMNs obtained from ex vivo lipopolysaccharide (LPS)-stimulated or -unstimulated whole blood from five healthy volunteers were isolated by either dextran-Ficoll gradient, microfluidics capture, or a combination of the two techniques. Blood and BAL fluid PMNs were also isolated using microfluidics from seven hospitalized patients with ARDS. Gene expression was inferred from extracted RNA using Affymetrix U133 Plus 2.0 GeneChips. All methods of PMN isolation produced similar quantities of high-quality RNA, when adjusted for recovered cell number. Unsupervised analysis and hierarchical clustering indicated that LPS stimulation was the primary factor affecting gene expression patterns among all ex vivo samples. Patterns of gene expression from blood and BAL PMNs differed significantly from each other in the patients with ARDS. Isolation of PMNs by microfluidics can be applied to both blood and BAL specimens from critically ill, hospitalized patients. Unique genomic expression patterns are obtained from the blood and BAL fluid of critically ill patients with ARDS, and these differ significantly from genomic patterns seen after ex vivo LPS stimulation.

Fossil evidence of avian crops from the Early Cretaceous of China.

The crop is characteristic of seed-eating birds today, yet little is known about its early history despite remarkable discoveries of many Mesozoic seed-eating birds in the past decade. Here we report the discovery of some early fossil evidence for the presence of a crop in birds. Two Early Cretaceous birds, the basal ornithurine Hongshanornis and a basal avian Sapeornis, demonstrate that an essentially modern avian digestive system formed early in avian evolution. The discovery of a crop in two phylogenetically remote lineages of Early Cretaceous birds and its absence in most intervening forms indicates that it was independently acquired as a specialized seed-eating adaptation. Finally, the reduction or loss of teeth in the forms showing seed-filled crops suggests that granivory was possibly one of the factors that resulted in the reduction of teeth in early birds.

Lipooligosaccharide Structure is an Important Determinant in the Resistance of Neisseria Gonorrhoeae to Antimicrobial Agents of Innate Host Defense.

The strict human pathogen Neisseria gonorrhoeae has caused the sexually transmitted infection termed gonorrhea for thousands of years. Over the millennia, the gonococcus has likely evolved mechanisms to evade host defense systems that operate on the genital mucosal surfaces in both males and females. Past research has shown that the presence or modification of certain cell envelope structures can significantly impact levels of gonococcal susceptibility to host-derived antimicrobial compounds that bathe genital mucosal surfaces and participate in innate host defense against invading pathogens. In order to facilitate the identification of gonococcal genes that are important in determining levels of bacterial susceptibility to mediators of innate host defense, we used the Himar I mariner in vitro mutagenesis system to construct a transposon insertion library in strain F62. As proof of principle that this strategy would be suitable for this purpose, we screened the library for mutants expressing decreased susceptibility to the bacteriolytic action of normal human serum (NHS). We found that a transposon insertion in the lgtD gene, which encodes an N-acetylgalactosamine transferase involved in the extension of the α-chain of lipooligosaccharide (LOS), could confer decreased susceptibility of strain F62 to complement-mediated killing by NHS. By complementation and chemical analyses, we demonstrated both linkage of the transposon insertion to the NHS-resistance phenotype and chemical changes in LOS structure that resulted from loss of LgtD production. Further truncation of the LOS α-chain or loss of phosphoethanolamine (PEA) from the lipid A region of LOS also impacted levels of NHS-resistance. PEA decoration of lipid A also increased gonococcal resistance to the model cationic antimicrobial polymyxin B. Taken together, we conclude that the Himar I mariner in vitro mutagenesis procedure can facilitate studies on structures involved in gonococcal pathogenesis.

All-terrain vehicle safety in Florida: is legislation really the answer?

Florida is among the nation's leaders in all-terrain vehicle (ATV)-related injuries and fatalities. We hypothesized that patients sustaining injuries while in compliance with ATV laws would demonstrate less severe injury patterns and improved outcomes when compared with noncompliant patients. We reviewed patients treated for ATV-related injuries over a 36-month period. We grouped patients according to conformity with Florida statutes and compared demographics, admission status, injuries sustained, and outcome measures. Three hundred seventy-seven patients were treated for ATV-related injuries. In 294 cases, sufficient data existed to assess compliance with Florida's statutes regarding ATV rider safety: safety helmet use for persons younger than age 16 years and prohibition of ATV operation on roadways. Forty-three per cent (n = 126) had violated one or both statutes; 57 per cent (n = 168) had violated neither. The group in violation was younger (15 vs 24 years, P < 0.001) and wore helmets less often (6 vs 34%, P < 0.001). Groups required admission at similar rates (62% violators vs 60% nonviolators, P = 0.770), showed similar injury patterns, and had comparable mortality rates (2% violators vs 5% nonviolators, P = 0.451). Current Florida laws are inadequate to prevent ATV-related injuries and their sequelae. This issue should be addressed through an increased focus on safety education for ATV operators.

Model tests of gliding with different hindwing configurations in the four-winged dromaeosaurid Microraptor gui.

Fossils of the remarkable dromaeosaurid Microraptor gui and relatives clearly show well-developed flight feathers on the hind limbs as well as the front limbs. No modern vertebrate has hind limbs functioning as independent, fully developed wings; so, lacking a living example, little agreement exists on the functional morphology or likely flight configuration of the hindwing. Using a detailed reconstruction based on the actual skeleton of one individual, cast in the round, we developed light-weight, three-dimensional physical models and performed glide tests with anatomically reasonable hindwing configurations. Models were tested with hindwings abducted and extended laterally, as well as with a previously described biplane configuration. Although the hip joint requires the hindwing to have at least 20 degrees of negative dihedral (anhedral), all configurations were quite stable gliders. Glide angles ranged from 3 degrees to 21 degrees with a mean estimated equilibrium angle of 13.7 degrees, giving a lift to drag ratio of 4.1:1 and a lift coefficient of 0.64. The abducted hindwing model's equilibrium glide speed corresponds to a glide speed in the living animal of 10.6 m x s(-1). Although the biplane model glided almost as well as the other models, it was structurally deficient and required an unlikely weight distribution (very heavy head) for stable gliding. Our model with laterally abducted hindwings represents a biologically and aerodynamically reasonable configuration for this four-winged gliding animal. M. gui's feathered hindwings, although effective for gliding, would have seriously hampered terrestrial locomotion.

100-million-year dynasty of giant planktivorous bony fishes in the Mesozoic seas.

Large-bodied suspension feeders (planktivores), which include the most massive animals to have ever lived, are conspicuously absent from Mesozoic marine environments. The only clear representatives of this trophic guild in the Mesozoic have been an enigmatic and apparently short-lived Jurassic group of extinct pachycormid fishes. Here, we report several new examples of these giant bony fishes from Asia, Europe, and North America. These fossils provide the first detailed anatomical information on this poorly understood clade and extend its range from the lower Middle Jurassic to the end of the Cretaceous, showing that this group persisted for more than 100 million years. Modern large-bodied, planktivorous vertebrates diversified after the extinction of pachycormids at the Cretaceous-Paleogene boundary, which is consistent with an opportunistic refilling of vacated ecospace.

The birdlike raptor Sinornithosaurus was venomous.

We suggest that some of the most avian dromaeosaurs, such as Sinornithosaurus, were venomous, and propose an ecological model for that taxon based on its unusual dentition and other cranial features including grooved teeth, a possible pocket for venom glands, and a groove leading from that pocket to the exposed bases of the teeth. These features are all analogous to the venomous morphology of lizards. Sinornithosaurus and related dromaeosaurs probably fed on the abundant birds of the Jehol forests during the Early Cretaceous in northeastern China.