A Proteolytic Site-Directed Affinity Label to Inhibit the Human ATP-Dependent Protease Caseinolytic Complex XP.

Human caseinolytic protease component X and P (hClpXP) is a heterooligomeric ATP-dependent protease. The hClpX subunit catalyzes ATP hydrolysis whereas the hClpP subunit catalyzes peptide bond cleavage. In this study, we generated a peptidyl chloromethyl ketone (dansyl-FAPAL-CMK) that inhibited the hClpP subunit through alkylation of the catalytic His122, which was detected by LC-MS. This inhibitor is composed of a peptide sequence derived from a hydrolyzed peptide product of a substrate cleaved by hClpXP. Binding of FAPAL positions the electrophilic chloromethyl ketone moiety near His122 where alkylation occurs. Dansyl FAPAL-CMK exhibits selectivity for hClpXP over other ATP-dependent proteases such as hLon and the 26S proteasome and abolishes hClpXP activity in HeLa cell lysate. Using the fluorogenic peptide substrate FR-Cleptide as reporter, we detected biphasic inhibition time courses; this supports a slow-binding, time-dependent, covalent inhibition mechanism that is often found in active-site directed affinity labels. Because this inhibitor reacts only with hClpXP but not hLon or the proteasome, it has the potential to serve as a chemical tool to help validate endogenous protein substrates of hClpXP in cell lysate, thereby benefiting investigation of the physiological functions of hClpXP in different cell types or tissue samples.

Safety and efficacy of minimally invasive posterior cervical fusion: a single center, single surgeon retrospective review.

Standard posterior cervical fusion is a common surgical technique that utilizes lateral mass screws and rods for fixation. A relatively new, minimally invasive technique involving interfacet decortication and placement of spacers has shown promise in terms of outcomes. We sought to determine fusion rates and complications of this new technique at our institution to bolster current literature. We retrospectively reviewed all patients that underwent a 3-level or less minimally invasive posterior cervical fusions by a single surgeon. Patients were evaluated to determine fusion rates and postoperative complications. Twenty-eight patients underwent minimally invasive posterior cervical fusion. Twenty-seven demonstrated fusion (96%). One patient that underwent the procedure for juxta-fusional disease required additional surgery for pseudoarthrosis. The minimally invasive posterior cervical technique results in favorable fusion rates and has low complication rates. Our study strengthens current literature that this minimally invasive technique is a safe and effective alternative.

Safety and timing of early therapeutic anticoagulation therapy after craniotomy.

Background: To date, there are few guidelines and studies to guide the timing of initiation of therapeutic anticoagulation (AC) after craniotomy. The goal of this study was to assess the timing, safety, and outcomes of patients following the administration of therapeutic AC after craniotomy. Methods: A retrospective case-control study was performed evaluating all craniotomy patients from August 2017 to July 2021. Cases were selected if they received therapeutic AC within ten days of craniotomy. Nineteen out of 1013 craniotomy patients met the inclusion criteria. Indications for therapeutic AC were diverse, including deep venous thrombosis, pulmonary embolism, dural venous sinus thrombosis, mechanical heart valve, and left ventricular thrombus. Results: The mean and median time to therapeutic AC were 5.35 and 5 days, respectively. Three patients developed intracerebral hemorrhage (ICH) that was stable on repeat imaging and did not require any surgical intervention or result in new neurologic deficits. There was no significant association between therapeutic AC and postoperative ICH (P = 0.067). Conclusion: This study demonstrated that the initiation of therapeutic AC in postoperative craniotomy patients from postoperative days 2 to 10 did not result in any major complications. A prospective study is warranted to clarify the indications and safety of therapeutic AC after craniotomy.

Arachnoid webs with spinal cord compression: insights from three cases.

Spinal arachnoid webs are intradural bands of abnormally formed arachnoid tissue, located within the subarachnoid space and causing compression of the dorsal aspect of the spinal cord. Arachnoid webs are uncommon and can be difficult to treat. We report 3 patients presenting with a spinal arachnoid web within a 6-month period. All of them exhibited signs of thoracic myelopathy and the MRI showed the pathognomonic 'scalpel sign'. Two of the patients underwent surgery for removal of their spinal arachnoid web, whereas the third patient case is currently being managed conservatively. We also present our 2D intraoperative video for arachnoid web removal and spinal cord decompression.

Persistent brainstem abscess requiring repeat microsurgical drainage: case report.

In this paper, we present a patient who was treated for a pontine abscess at our institution. This patient underwent sub-occipital craniotomy for microscopic abscess drainage after which cultures grew Streptococcus intermedius. She was treated with antibiotics but failed to show clinical improvement and was taken back to the operating room for repeat abscess drainage. Clinical improvement was seen after the second operation. This case report describes open surgical technique as a safe and effective way of treating brainstem abscess.

Low-Dose Intravenous Heparin Infusion After Aneurysmal Subarachnoid Hemorrhage is Associated With Decreased Risk of Delayed Neurological Deficit and Cerebral Infarction.

BACKGROUND: Patients who survive aneurysmal subarachnoid hemorrhage (aSAH) are at risk for delayed neurological deficits (DND) and cerebral infarction. In this exploratory cohort comparison analysis, we compared in-hospital outcomes of aSAH patients administered a low-dose intravenous heparin (LDIVH) infusion (12 U/kg/h) vs those administered standard subcutaneous heparin (SQH) prophylaxis for deep vein thrombosis (DVT; 5000 U, 3 × daily). OBJECTIVE: To assess the safety and efficacy of LDIVH in aSAH patients. METHODS: We retrospectively analyzed 556 consecutive cases of aSAH patients whose aneurysm was secured by clipping or coiling at a single institution over a 10-yr period, including 233 administered the LDIVH protocol and 323 administered the SQH protocol. Radiological and outcome data were compared between the 2 cohorts using multivariable logistic regression and propensity score-based inverse probability of treatment weighting (IPTW). RESULTS: The unadjusted rate of cerebral infarction in the LDIVH cohort was half that in SQH cohort (9 vs 18%; P = .004). Multivariable logistic regression showed that patients in the LDIVH cohort were significantly less likely than those in the SQH cohort to have DND (odds ratio (OR) 0.53 [95% CI: 0.33, 0.85]) or cerebral infarction (OR 0.40 [95% CI: 0.23, 0.71]). Analysis following IPTW showed similar results. Rates of hemorrhagic complications, heparin-induced thrombocytopenia and DVT were not different between cohorts. CONCLUSION: This cohort comparison analysis suggests that LDIVH infusion may favorably influence the outcome of patients after aSAH. Prospective studies are required to further assess the benefit of LDIVH infusion in patients with aSAH.

Mechanisms regulating PD-L1 expression on tumor and immune cells.

BACKGROUND: The PD-1/PD-L1 checkpoint is a central mediator of immunosuppression in the tumor immune microenvironment (TME) and is primarily associated with IFN-g signaling. To characterize other factors regulating PD-L1 expression on tumor and/or immune cells, we investigated TME-resident cytokines and the role of transcription factors in constitutive and cytokine-induced PD-L1 expression. METHODS: Thirty-four cultured human tumor lines [18 melanomas (MEL), 12 renal cell carcinomas (RCC), 3 squamous cell carcinomas of the head and neck (SCCHN), and 1 non-small-cell lung carcinoma (NSCLC)] and peripheral blood monocytes (Monos) were treated with cytokines that we detected in the PD-L1+ TME by gene expression profiling, including IFN-g, IL-1a, IL-10, IL-27 and IL-32g. PD-L1 cell surface protein expression was detected by flow cytometry, and mRNA by quantitative real-time PCR. Total and phosphorylated STAT1, STAT3, and p65 proteins were detected by Western blotting, and the genes encoding these proteins were knocked down with siRNAs. Additionally, the proximal promoter region of PDL1 (CD274) was sequenced in 33 cultured tumors. RESULTS: PD-L1 was constitutively expressed on 1/17 cultured MELs, 8/11 RCCs, 3/3 SCCHNs, and on Monos. Brief IFN-g exposure rapidly induced PD-L1 on all tumor cell lines and Monos regardless of constitutive PD-L1 expression. PD-L1 mRNA levels were associated with protein expression, which was diminished by exposure to transcriptional inhibitors. siRNA knockdown of STAT1 but not STAT3 reduced IFN-g- and IL-27-induced PD-L1 protein expression on tumor cells. In contrast, STAT3 knockdown in Monos reduced IL-10-induced PD-L1 protein expression, and p65 knockdown in tumor cells reduced IL-1a-induced PD-L1 expression. Notably, constitutive PD-L1 expression was not affected by knocking down STAT1, STAT3, or p65. Differential effects of IFN-g, IL-1a, and IL-27 on individual tumor cell lines were not due to PDL1 promoter polymorphisms. CONCLUSIONS: Multiple cytokines found in an immune-reactive TME may induce PD-L1 expression on tumor and/or immune cells through distinct signaling mechanisms. Factors driving constitutive PD-L1 expression were not identified in this study. Understanding complex mechanisms underlying PD-L1 display in the TME may allow treatment approaches mitigating expression of this immunosuppressive ligand, to enhance the impact of PD-1 blockade.

Investigating the Gender Pay Gap in Industry Contributions to Academic Neurosurgeons.

BACKGROUND: A large gender gap exists in industry funding for academic neurosurgeons. Selection criteria for funding distribution remain unclear. However, academic rank, scholarly productivity, and experience have been suggested as determining factors. METHODS: We conducted a cross-sectional study of industry payments to US academic neurosurgeons. We used online faculty listings to determine academic rank and gender, then used the Center for Medicare and Medicaid Services Open Payment Database to identify industry contributions. Details were collected on H-index and length of time in practice was used as a proxy for experience. RESULTS: Of the 1481 academic neurosurgeons included, men were in the majority (91% vs. 9%, P = 0.0001). Relative to their male colleagues, female assistant and associate professors received fewer payments (4 vs. 8, P = 0.0040; 2 vs. 7, P = 0.0067) at lower median values ($409 vs. $437, P = 0.0490; $163 vs. $260, P = 0.0089). H-index was more strongly associated with general payment receipt for women academic neurosurgeons (r = 0.20, P = 0.0201) than men academic neurosurgeons (r = 0.06, P = 0.0301). Experience trended toward a significant association with industry funding in men (r = 0.05, P = 0.0601). After adjustment for scholarly productivity and experience, gender-based funding inequalities became insignificant. CONCLUSIONS: In academic neurosurgery, substantial gender disparities exist in industry payments and metrics of academic success. There may be an industry selection bias toward recruitment of key opinion and thought leaders, as identified by scholarly productivity and experience. Despite the objective gender inequalities, industry funding to academic neurosurgeons appears to be equitable when metrics of academic success are considered.