Comparative Analysis of the Subventricular Zone in Rat, Ferret and Macaque: Evidence for an Outer Subventricular Zone in Rodents

The mammalian cerebral cortex arises from precursor cells that reside in a proliferative region surrounding the lateral ventricles of the developing brain. Recent work has shown that precursor cells in the subventricular zone (SVZ) provide a major contribution to prenatal cortical neurogenesis, and that the SVZ is significantly thicker in gyrencephalic mammals such as primates than it is in lissencephalic mammals including rodents. Identifying characteristics that are shared by or that distinguish cortical precursor cells across mammalian species will shed light on factors that regulate cortical neurogenesis and may point toward mechanisms that underlie the evolutionary expansion of the neocortex in gyrencephalic mammals. We immunostained sections of the developing cerebral cortex from lissencephalic rats, and from gyrencephalic ferrets and macaques to compare the distribution of precursor cell types in each species. We also performed time-lapse imaging of precursor cells in the developing rat neocortex. We show that the distribution of Pax6+ and Tbr2+ precursor cells is similar in lissencephalic rat and gyrencephalic ferret, and different in the gyrencephalic cortex of macaque. We show that mitotic Pax6+ translocating radial glial cells (tRG) are present in the cerebral cortex of each species during and after neurogenesis, demonstrating that the function of Pax6+ tRG cells is not restricted to neurogenesis. Furthermore, we show that Olig2 expression distinguishes two distinct subtypes of Pax6+ tRG cells. Finally we present a novel method for discriminating the inner and outer SVZ across mammalian species and show that the key cytoarchitectural features and cell types that define the outer SVZ in developing primates are present in the developing rat neocortex. Our data demonstrate that the developing rat cerebral cortex possesses an outer subventricular zone during late stages of cortical neurogenesis and that the developing rodent cortex shares important features with that of primates

Trends in Utilization and Patient Demographics for Shoulder Instability Procedures from 2010 to 2019

INTRODUCTION: Improved technique and increased surgeon experience has optimized surgical care in patients with recurrent shoulder instability. Several techniques are used for surgical repair of shoulder instability, yet there is limited data on how utilization has changed over the past decade. The aim of this study was to assess trends in the utilization rate and patient demographics (age and gender) from 2010-2019 for four shoulder instability procedures: coracoid transfer/Latarjet procedure (LP), anterior bone block (ABB), open Bankart repair (OBR), and arthroscopic Bankart repair (ABR). METHODS: We identified over 87,00 patients using an all-payer claims database. The utilization rate was defined as the number of cases for a procedure divided by the total number surgical cases for shoulder instability for any given year. Age was divided into three groups: \u3c25, 25-35, \u3e35-years-old. Trends were reported in terms of compounded annual growth rates (CAGR). RESULTS: While ABR was the most common shoulder instability procedure overall (91% utilization rate), LP had the greatest increase in utilization from 2010-2019 (2.0% to 4.5%; CAGR: +9.8%). In comparison, the utilization for ABB increased +4.3% annually while OBR declined -6.9% annually. The utilization of ABR showed minimal change. Notably, LP was performed more frequently on younger patients over time. The percentage of patients \u3c25-years-old who underwent LP increased from 30% to 41% from 2010-2019 (+3.4%). There was a trend toward performing more LP on men versus women (+1.2% vs. -3.5%, P \u3c 0.05), although most cases (68%) were still performed on men. CONCLUSION: ABR continues to account for most shoulder instability procedures. LP had the greatest increase in utilization rate from 2010-2019 and has now surpassed OBR in utilization rate. ABB is also being more frequently performed but only represents a minority of stabilization cases. During the course of the study period, a greater percentage of patients undergoing shoulder instability procedure were male and \u3c25-years-old

Catastrophic acute failure of pelvic fixation in adult spinal deformity requiring revision surgery: a multicenter review of incidence, failure mechanisms, and risk factors

OBJECTIVE: There are few prior reports of acute pelvic instrumentation failure in spinal deformity surgery. The objective of this study was to determine if a previously identified mechanism and rate of pelvic fixation failure were present across multiple institutions, and to determine risk factors for these types of failures. METHODS: Thirteen academic medical centers performed a retrospective review of 18 months of consecutive adult spinal fusions extending 3 or more levels, which included new pelvic screws at the time of surgery. Acute pelvic fixation failure was defined as occurring within 6 months of the index surgery and requiring surgical revision. RESULTS: Failure occurred in 37 (5%) of 779 cases and consisted of either slippage of the rods or displacement of the set screws from the screw tulip head (17 cases), screw shaft fracture (9 cases), screw loosening (9 cases), and/or resultant kyphotic fracture of the sacrum (6 cases). Revision strategies involved new pelvic fixation and/or multiple rod constructs. Six patients (16%) who underwent revision with fewer than 4 rods to the pelvis sustained a second acute failure, but no secondary failures occurred when at least 4 rods were used. In the univariate analysis, the magnitude of surgical correction was higher in the failure cohort (higher preoperative T1-pelvic angle [T1PA], presence of a 3-column osteotomy; p \u3c 0.05). Uncorrected postoperative deformity increased failure risk (pelvic incidence-lumbar lordosis mismatch \u3e 10°, higher postoperative T1PA; p \u3c 0.05). Use of pelvic screws less than 8.5 mm in diameter also increased the likelihood of failure (p \u3c 0.05). In the multivariate analysis, a larger preoperative global deformity as measured by T1PA was associated with failure, male patients were more likely to experience failure than female patients, and there was a strong association with implant manufacturer (p \u3c 0.05). Anterior column support with an L5-S1 interbody fusion was protective against failure (p \u3c 0.05). CONCLUSIONS: Acute catastrophic failures involved large-magnitude surgical corrections and likely resulted from high mechanical strain on the pelvic instrumentation. Patients with large corrections may benefit from anterior structural support placed at the most caudal motion segment and multiple rods connecting to more than 2 pelvic fixation points. If failure occurs, salvage with a minimum of 4 rods and 4 pelvic fixation points can be successful

Yersinia enterocolitica Inhibits Salmonella enterica Serovar Typhimurium and Listeria monocytogenes Cellular Uptake

Yersinia enterocolitica biovar 1B employs two type three secretion systems (T3SS), Ysa and Ysc, which inject effector proteins into macrophages to prevent phagocytosis. Conversely, Salmonella enterica serovar Typhimurium uses a T3SS encoded by Salmonella pathogenicity island 1 (SPI1) to actively invade cells that are normally nonphagocytic and a second T3SS encoded by SPI2 to survive within macrophages. Given the distinctly different outcomes that occur with regard to host cell uptake of S. Typhimurium and Y. enterocolitica, we investigated how each pathogen influences the internalization outcome of the other. Y. enterocolitica reduces S. Typhimurium invasion of HeLa and Caco-2 cells to a level similar to that observed using an S. Typhimurium SPI1 mutant alone. However, Y. enterocolitica had no effect on S. Typhimurium uptake by J774.1 or RAW264.7 macrophage-like cells. Y. enterocolitica was also able to inhibit the invasion of epithelial and macrophage-like cells by Listeria monocytogenes. Y. enterocolitica mutants lacking either the Ysa or Ysc T3SS were partially defective, while double mutants were completely defective, in blocking S. Typhimurium uptake by epithelial cells. S. Typhimurium encodes a LuxR homolog, SdiA, which detects N-acylhomoserine lactones (AHLs) produced by Y. enterocolitica and upregulates the expression of an invasin (Rck) and a putative T3SS effector (SrgE). Two different methods of constitutively activating the S. Typhimurium SdiA regulon failed to reverse the uptake blockade imposed by Y. enterocolitica