Does Traction Decrease the Need for Open Reduction in Femoral Shaft Fractures Treated Within 24 Hours?

This study evaluates whether preoperative skeletal traction reduces the need for open reduction in femoral shaft fractures treated with intramedullary nailing (IMN) within 24 hours. A retrospective review was conducted of femoral shaft fractures undergoing IMN within 1 day of admission. Primary outcome was an open reduction at the time of IMN. Secondary outcomes were blood loss and transfusion requirements. One hundred eighty-four patients were analyzed, 106 in the knee immobilizer group and 78 in the skeletal traction group. Skeletal traction did not reduce the need for an open reduction. The knee immobilizer group required open reduction in 13% (14/106) compared with 14% (11/78) in the skeletal traction group, which was not significant (p $=$ .89). Blood loss and transfusion rates were similar between groups. Skeletal traction does not appear to reduce the need for open reduction at the time of IMN for femoral shaft fractures treated within 1 day of admission. (Journal of Surgical Orthopaedic Advances 27(4):303-306, 2018).

Aging-associated inflammation promotes selection for adaptive oncogenic events in B cell progenitors.

The incidence of cancer is higher in the elderly; however, many of the underlying mechanisms for this association remain unexplored. Here, we have shown that B cell progenitors in old mice exhibit marked signaling, gene expression, and metabolic defects. Moreover, B cell progenitors that developed from hematopoietic stem cells (HSCs) transferred from young mice into aged animals exhibited similar fitness defects. We further demonstrated that ectopic expression of the oncogenes BCR-ABL, NRAS(V12), or Myc restored B cell progenitor fitness, leading to selection for oncogenically initiated cells and leukemogenesis specifically in the context of an aged hematopoietic system. Aging was associated with increased inflammation in the BM microenvironment, and induction of inflammation in young mice phenocopied aging-associated B lymphopoiesis. Conversely, a reduction of inflammation in aged mice via transgenic expression of α-1-antitrypsin or IL-37 preserved the function of B cell progenitors and prevented NRAS(V12)-mediated oncogenesis. We conclude that chronic inflammatory microenvironments in old age lead to reductions in the fitness of B cell progenitor populations. This reduced progenitor pool fitness engenders selection for cells harboring oncogenic mutations, in part due to their ability to correct aging-associated functional defects. Thus, modulation of inflammation--a common feature of aging--has the potential to limit aging-associated oncogenesis.

Allometry and evolution in the galago skull.

To probe the ontogenetic bases of morphological diversity across galagos, we performed the first clade-wide analyses of growth allometries in 564 adult and non-adult crania from 12 galagid taxa. In addition to evaluating if variation in galago skull form results from the differential extension/truncation of common ontogenetic patterns, scaling trajectories were employed as a criterion of subtraction to identify putative morphological adaptations in the feeding complex. A pervasive pattern of ontogenetic scaling is observed for facial dimensions across galagids, with 2 genera also sharing relative growth trajectories for masticatory proportions (Galago, Galagoides). As the facial growth series and adult data are largely coincidental, interspecific variation may result from character displacement and consequent selection for size differentiation among sister taxa. Derived configurations of the jaw joint and jaw muscle mechanical advantage in Otolemur and Euoticus appear to facilitate increased gape during scraping behaviors. Differences in aspects of masticatory growth and form characterizing these 2 genera highlight selection to uncouple shared ontogenetic patterns, which occurred via transpositions that retained ancestral scaling patterns. Due to the lack of increased robusticity of load-resisting mandibular elements in Otolemur and Euoticus, there is little evidence to suggest that exudativory in galagos results in correspondingly higher masticatory stresses.

Masticatory loading, function, and plasticity: a microanatomical analysis of mammalian circumorbital soft-tissue structures.

In contrast to experimental evidence regarding the postorbital bar, postorbital septum, and browridge, there is exceedingly little evidence regarding the load-bearing nature of soft-tissue structures of the mammalian circumorbital region. This hinders our understanding of pronounced transformations during primate origins, in which euprimates evolved a postorbital bar from an ancestor with the primitive mammalian condition where only soft tissues spanned the lateral orbital margin between frontal bone and zygomatic arch. To address this significant gap, we investigated the postorbital microanatomy of rabbits subjected to long-term variation in diet-induced masticatory stresses. Rabbits exhibit a masticatory complex and feeding behaviors similar to primates, yet retain a more primitive mammalian circumorbital region. Three cohorts were obtained as weanlings and raised on different diets until adult. Following euthanasia, postorbital soft tissues were dissected away, fixed, and decalcified. These soft tissues were divided into inferior, intermediate, and superior units and then dehydrated, embedded, and sectioned. H&E staining was used to characterize overall architecture. Collagen orientation and complexity were evaluated via picrosirius-red staining. Safranin-O identified proteoglycan content with additional immunostaining performed to assess Type-II collagen expression. Surprisingly, the ligament along the lateral orbital wall was composed of elastic fibrocartilage. A more degraded organization of collagen fibers in this postorbital fibrocartilage is correlated with increased masticatory forces due to a more fracture-resistant diet. Furthermore, the lack of marked changes in the extracellular composition of the lateral orbital wall related to tissue viscoelasticity suggests it is unlikely that long-term exposure to elevated masticatory stresses underlies the development of a bony postorbital bar.

Ontogeny and phyletic size change in living and fossil lemurs.

Lemurs are notable for encompassing the range of body-size variation for all primates past and present-close to four orders of magnitude. Benefiting from the phylogenetic proximity of subfossil lemurs to smaller-bodied living forms, we employ allometric data from the skull to probe the ontogenetic bases of size differentiation and morphological diversity across these clades. Building upon prior pairwise comparisons between sister taxa, we performed the first clade-wide analyses of craniomandibular growth allometries in 359 specimens from 10 lemuroids and 176 specimens from 8 indrioids. Ontogenetic trajectories for extant forms were used as a criterion of subtraction to evaluate morphological variation, and putative adaptations among sister taxa. In other words, do species-level differences in skull form result from the differential extension of common patterns of relative growth?In lemuroids, a pervasive pattern of ontogenetic scaling is observed for facial dimensions in all genera, with three genera also sharing relative growth trajectories for jaw proportions (Lemur, Eulemur, Varecia). Differences in masticatory growth and form characterizing Hapalemur and fossil Pachylemur likely reflect dietary factors. Pervasive ontogenetic scaling characterizes the facial skull in extant Indri, Avahi, and Propithecus, as well as their larger, extinct sister taxa Mesopropithecus and Babakotia. Significant interspecific differences are observed in the allometry of indrioid masticatory proportions, with variation in the mechanical advantage of the jaw adductors and stress-resisting elements correlated with diet. As the growth series and adult data are largely coincidental in each clade, interspecific variation in facial form may result from selection for body-size differentiation among sister taxa. Those cases where trajectories are discordant identify potential dietary adaptations linked to variation in masticatory forces during chewing and biting. Although such dissociations highlight selection to uncouple shared ancestral growth patterns, they occur largely via transpositions and retention of primitive size-shape covariation patterns or relative growth coefficients.