Brood parasitic songbirds are a natural system in which developing birds are isolated from species-typical song and therefore present a unique opportunity to compare neural plasticity in song learners raised with and without conspecific tutors. We compared perineuronal nets (PNN) and parvalbumin (PV) in song control nuclei in juveniles and adults of two closely related Icterid species (i.e. blackbirds): brown-headed cowbirds (Molothrus ater; brood parasite) and red-winged blackbirds (Agelaius phoeniceus; non-parasite). The number of PV cells per nucleus was significantly higher in adults compared to juveniles in HVC and RA, whereas no significant species difference appeared in any region of interest. The PNN per nuclei was significantly higher in adults compared to juveniles in HVC, RA and Area X but only RA exhibited a significant difference between species. PV cells surrounded by PNN (PV+PNN) also exhibited age-related differences in HVC, RA and Area X but RA was the only region in which PV+PNN exhibited significant species differences. Furthermore, a significant interaction existed in RA between age and species with respect to PNN and PV+PNN, revealing RA as a region displaying differing plasticity patterns across age and species. Additional comparisons of PNN and PV between adult male and female cowbirds revealed that males have greater numbers of all three measures in RA compared to females. Species-, sex- and age-related differences in RA suggest species differences in neural plasticity are related to differences in song production rather than sensitivity to song learning despite stark contrast in early exposure to conspecific male tutors.

Intervertebral cage mispositioning is an uncommon complication of a posterior lumbar corpectomy. Most frequently, cages are placed obliquely, laterally, or protruding. However, there are few reports of implanted cages that fail to contact the adjacent vertebral endplate and thus no descriptions of successful revisions. The objective of this case report is to report a unique case of minimally invasive rescue vertebroplasty with cement augmentation following a lumbar corpectomy that resulted in graft-endplate noncontact in a medically complicated patient A 60-year-old male with a history of active intravenous (IV) drug use, untreated hepatitis C virus (HCV) infection, and chronic malnourishment presented with low back pain. He had a history of vertebral osteomyelitis managed with intravenous antibiotics, although he was noncompliant with infusions. The diagnosis of L2-L3 discitis-osteomyelitis with intradiscal abscess causing cord compression was made using inpatient lumbar imaging. The initial intervention was accomplished with L2 and L3 vertebral corpectomy with decompression and expandable cage placement as well as a T10-pelvis posterior fixation. Despite the resolution of presenting symptoms, routine postoperative radiographs identified noncontact between the inferior surface of the cage and the superior endplate of the L4 vertebral body. Salvage therapy was pursued via fluoroscopy-guided vertebroplasty with cement augmentation to correct cage malposition. Secondary surgical intervention was successful in bringing the intervertebral cage into contact with the adjacent vertebral body. Lower extremity strength improved, and back pain was resolved. The postoperative motor examination remained unchanged after the rescue procedure. Accurate intraoperative cage placement can be difficult in patients with poor bone quality, especially in the setting of ongoing infection and cachexia. For this reason, routine postoperative imaging is crucial to assessing graft complications. In patients who are poor candidates for revision surgery, we demonstrate that an interventional radiology-based approach may be successful in correcting cage mispositioning and preventing further changes during healing and fusion.

OBJECTIVE Lymphopenia is often seen in advanced metastatic disease and has been associated with poor postoperative outcomes. Limited research has been done to validate this metric in patients with spinal metastases. The objective of this study was to evaluate the capability of preoperative lymphopenia to predict 30-day mortality, overall survival (OS), and major complications in patients undergoing surgery for metastatic spine tumors. METHODS A total of 153 patients who underwent surgery for metastatic spine tumor between 2012 and 2022 and met the inclusion criteria were examined. Electronic medical record chart review was conducted to obtain patient demographics, comorbidities, preoperative laboratory values, survival time, and postoperative complications. Preoperative lymphopenia was defined as < 1.0 K/μL based on the institution’s laboratory cutoff value and within 30 days prior to surgery. The primary outcome was 30-day mortality. Secondary outcomes were OS up to 2 years and 30-day postoperative major complications. Outcomes were assessed with logistic regression. Survival analyses were done using the Kaplan-Meier method with log-rank test and Cox regression. Receiver operating characteristic curves were plotted to classify the predictive ability of lymphocyte count as a continuous variable on outcome measures. RESULTS Lymphopenia was identified in 47% of patients (72 of 153). The overall 30-day mortality rate was 9% (13 of 153). In logistic regression analysis, lymphopenia was not associated with 30-day mortality (OR 1.35, 95% CI 0.43–4.21; p = 0.609). The mean OS in this sample was 15.6 months (95% CI 13.9–17.3 months), with no significant difference between patients with lymphopenia and those with no lymphopenia (p = 0.157). Cox regression analysis did not show an association between lymphopenia and survival (HR 1.44, 95% CI 0.87–2.39; p = 0.161). The major complication rate was 26% (39 of 153). In univariable logistic regression analysis, lymphopenia was not associated with the development of a major complication (OR 1.44, 95% CI 0.70–3.00; p = 0.326). Finally, receiver operating characteristic curves generated poor discrimination between lymphocyte count and all outcomes, including 30-day mortality (area under the curve 0.600, p = 0.232). CONCLUSIONS This study does not support prior research that had shown an independent association between low preoperative lymphocyte level and poor postoperative outcomes following surgery for metastatic spine tumors. Although lymphopenia may be used to predict outcomes in other tumor-related surgeries, this metric may not hold a similar predictive capability in the population undergoing surgery for metastatic spine tumors. Further research into reliable prognostic tools is needed.

Protein export pathways are important for bacterial physiology among pathogens and non-pathogens alike. This includes the Twin-Arginine Translocation (Tat) pathway, which transports fully folded proteins across the bacterial cytoplasmic membrane. Some Tat substrates are virulence factors, while others are important for cellular processes like peptidoglycan remodeling. Some bacteria encode more than one copy of each Tat component, including the Gram-negative soil isolate Acinetobacter baylyi. One of these Tat pathways is essential for growth, while the other is not. We constructed a loss-of-function mutation to disrupt the non-essential tatC2 gene and assessed its contribution to cell growth under different environmental conditions. While the tatC2 mutant grew well under standard laboratory conditions, it displayed a growth defect and an aberrant cellular morphology when subjected to high temperature stress including an aberrant cellular morphology. Furthermore, increased sensitivities to detergent suggested a compromised cell envelope. Lastly, using an in vitro co-culture system, we demonstrate that the non-essential Tat pathway provides a growth advantage. The findings of this study establish the importance of the non-essential Tat pathway for optimal growth of A. baylyi in stressful environmental conditions.