Carissa Chu

Phosphorylation of Rpt6 Regulates Synaptic Strength in Hippocampal Neurons

It has become increasingly evident that protein degradation via the ubiquitin proteasome system plays a fundamental role in the development, maintenance and remodeling of synaptic connections in the CNS. We and others have recently described the activity-dependent regulation of proteasome activity and recruitment of proteasomes into spine compartments involving the phosphorylation of the 19S ATPase subunit, Rpt6, by the plasticity kinase Ca2+/calmodulin-dependent protein kinase II α (CaMKIIα) (Bingol and Schuman, 2006; Djakovic et al., 2009; Bingol et al, 2010). Here, we investigated the role of Rpt6 phosphorylation on proteasome function and synaptic strength. Utilizing a phospho-specific antibody we verified that Rpt6 is phosphorylated at Serine 120 (S120) by CaMKIIα. In addition, we found that Rpt6 is phosphorylated by CaMKIIα in an activity-dependent manner. Furthermore, we showed that a serine 120 to aspartic acid phospho-mimetic mutant of Rpt6 (S120D) increases its resistance to detergent extraction in rat hippocampal dendrites, indicating phosphorylated Rpt6 may promote the tethering of proteasomes to scaffolds and cytoskeletal components. Expression of Rpt6 S120D decreased miniature EPSC (mEPSC) amplitude, while expression of a phospho-dead mutant (S120A) increased mEPSC amplitude. Surprisingly, homeostatic scaling of mEPSC amplitude produced by chronic application of bicuculline or tetrodotoxin is both mimicked and occluded by altered Rpt6 phosphorylation. Together, these data suggest that CaMKII-dependent phosphorylation of Rpt6 at S120 may be an important regulatory mechanism for proteasome-dependent control of synaptic remodeling in slow homeostatic plasticity.

Generation of a Pain Memory in the Primary Afferent Nociceptor Triggered by PKCε Activation of CPEB

Isolectin B4-positive [IB4(+)] primary afferent nociceptors challenged with an inflammatory or neuropathic insult develop a PKCε-dependent long-lasting hyperalgesic response to a subsequent challenge by the proinflammatory cytokine prostaglandin E2 (PGE2), a phenomenon known as hyperalgesic priming. Here we demonstrate that the neuroplasticity underlying nociceptor priming requires 72 h to be established; rats that have been challenged with the inflammatory mediator TNFα 24 or 48 h ahead of PGE2 do not show the enhanced and prolonged hyperalgesic response by which primed IB4(+)-nociceptors are being characterized. Moreover, as the underlying plasticity can be interrupted by the peripheral administration of the protein translation inhibitor anisomycin it is reflected by changes in the peripheral protein expression pattern. Finally, the induction of priming by the selective PKCε agonist, psi ε receptor for activated c kinase (ψεRACK) can be prevented, but not reversed by intrathecal injections of antisense oligodeoxynucleotides for the cytoplasmic polyadenylation element binding protein (CPEB) mRNA, a master regulator of protein translation that coimmunoprecipitated with PKCε and is almost exclusively expressed by IB4(+)-nociceptors. Our results suggest that CPEB is downstream of PKCε in the cellular signaling cascade responsible for the induction of priming, raising the intriguing possiblity that prion-like misfolding could be a responsible mechanism for the chronification of pain.

Peripheral Administration of Translation Inhibitors Reverses Increased Hyperalgesia in a Model of Chronic Pain in the Rat

UNLABELLED Chronic pain is extremely difficult to manage, in part due to lack of progress in reversing the underlying pathophysiology. Since translation of messenger ribonucleic acids (mRNAs) in the peripheral terminal of the nociceptor plays a role in the transition from acute to chronic pain, we tested the hypothesis that transient inhibition of translation in the peripheral terminal of the nociceptor could reverse hyperalgesic priming, a model of transition from acute to chronic pain. We report that injection of translation inhibitors rapamycin and cordycepin, which inhibit translation by different mechanisms, at the peripheral terminal of the primed nociceptor produces reversal of priming in the rat that outlasted the duration of action of these drugs to prevent the development of priming. These data support the suggestion that interruption of translation in the nociceptor can reverse a preclinical model of at least 1 form of chronic pain. PERSPECTIVE This study provides evidence that ongoing protein translation in the sensory neuron terminals is involved in pain chronification, and local treatment that transiently interrupts this translation may be a useful therapy to chronic pain.

Stakeholder Engagement in HIV Cure Research: Lessons Learned from Other HIV Interventions and the Way Forward

Clinical and basic science advances have raised considerable hope for achieving an HIV cure by accelerating research. This research is dominated primarily by issues about the nature and design of current and future clinical trials. Stakeholder engagement for HIV cure remains in its early stages. Our analysis examines timing and mechanisms of historical stakeholder engagement in other HIV research areas for HIV-uninfected individuals [vaccine development and pre-exposure prophylaxis (PrEP)], and HIV-infected individuals (treatment as prevention, prevention of mother-to-child transmission, and treatment of acute HIV infection) and articulate a plan for HIV cure stakeholder engagement. The experience from HIV vaccine development shows that early engagement of stakeholders helped manage expectations, mitigating the failure of several vaccine trials, while paving the way for subsequent trials. The relatively late engagement of HIV stakeholders in PrEP research may partly explain some of the implementation challenges. The treatment-related stakeholder engagement was strong and community-led from the onset and helped translation from research to implementation. We outline five steps to initiate and sustain stakeholder engagement in HIV cure research and conclude that stakeholder engagement represents a key investment in which stakeholders mutually agree to share knowledge, benefits, and risk of failure. Effective stakeholder engagement prevents misconceptions. As HIV cure research advances from early trials involving subjects with generally favorable prognosis to studies involving greater risk and uncertainty, success may depend on early and deliberate engagement of stakeholders.

Trends, Utilization, and Immediate Perioperative Complications of Urethroplasty in the United States: Data From the National Inpatient Sample 2000-2010

OBJECTIVE To determine national urethroplasty trends based on type of surgery and patient and hospital characteristics. We hypothesized that the number of complex urethroplasty procedures performed has increased over time and may be associated with increased periprocedure complications. METHODS The National Inpatient Sample from years 2000 to 2010 was queried for patients with urethroplasty-associated International Classification of Diseases, Ninth Revision, Clinical Modification codes. We analyzed trends in urethroplasty procedures, patient demographics, comorbidities, and hospital characteristics. We evaluated the relationship between patient demographics and comorbid disease, length of hospital stay, hospital charges, and inpatient complications. RESULTS During the study period, an estimated 13,700 men (95% confidence interval, 9507-17,894) underwent urethroplasty nationally. Excision with primary anastomosis, buccal graft, and other graft or flap urethroplasty comprised 80.3%, 14.3%, and 5.4%, respectively. Buccal mucosa graft procedures increased over time (P = .03). Only 1.6% of hospitals have ≥ 20 urethroplasties performed annually. Urethroplasty type and urethroplasty volume were not associated with immediate complication rates. Hypertension, diabetes, chronic pulmonary disease, and obesity were the most common comorbidities in urethroplasty patients. Complications during urethroplasty hospitalization occurred in 6.6% of men, with surgical or wound complications being the most common (5.2%). Postoperative mortality was exceedingly rare. Older patients, African Americans, and patients with increased comorbidities were more likely to have complications. CONCLUSION An increasing number of buccal mucosa graft urethroplasties occurred over time. Urethroplasty patients have low immediate perioperative morbidity (6.6%) and mortality (0.07%). Patients who are older, African American, or have more comorbid conditions have greater risk for complications.

Mitochondrial dependence of nerve growth factor-induced mechanical hyperalgesia.

&NA; Mitochondria are present at high concentration at the site of sensory transduction in the peripheral terminals of nociceptors. Because nerve growth factor (NGF), which induces nociceptor sensitization by acting on the high‐affinity tropomyosin receptor kinase A (TrkA) receptor, also produces local recruitment of mitochondria in DRG neurons, we evaluated the role of mitochondria in NGF‐induced mechanical hyperalgesia. Inhibition of 3 major mitochondrial functions—oxidation of nutrients, adenosine triphosphate (ATP) production, and generation of reactive oxygen species—markedly attenuated NGF‐induced mechanical hyperalgesia in the rat. Disruption of microtubules, which are required for the trafficking and subcellular localization of mitochondria, also attenuated NGF‐induced hyperalgesia. Our results suggest a contribution of mitochondrial localization and function to NGF‐dependent pain syndromes. Induction of hyperalgesia by nerve growth factor (NGF) is dependent on mitochondrial oxidation of nutrients, adenosine triphosphate production, and generation of reactive oxygen species. Mitochondrial localization and function appear to contribute to NGF‐dependent pain syndromes.

Ultrasound-Guided Renal Access for Percutaneous Nephrolithotomy: A Description of Three Novel Ultrasound-Guided Needle Techniques

Ultrasound-guided renal access for percutaneous nephrolithotomy (PCNL) is a safe, effective, and low-cost procedure commonly performed worldwide, but a technique underutilized by urologists in the United States. The purpose of this article is to familiarize the practicing urologist with methods for ultrasound guidance for percutaneous renal access. We discuss two alternative techniques for gaining renal access for PCNL under ultrasound guidance. We also describe a novel technique of using the puncture needle to reposition residual stone fragments to avoid additional tract dilation. With appropriate training, ultrasound-guided renal access for PCNL can lead to reduced radiation exposure, accurate renal access, and excellent stone-free success rates and clinical outcomes.

Facilitators of HCV treatment adherence among people who inject drugs: a systematic qualitative review and implications for scale up of direct acting antivirals

BackgroundWhile the public health benefits of new HCV treatments depend on treatment adherence, particularly among people who inject drugs (PWID), several social and medical factors can jeopardize treatment adherence. The aim of this study is to examine the qualitative literature on facilitators to HCV treatment adherence among PWID.MethodsWe searched six databases to identify qualitative research studies on HCV treatment adherence facilitators among PWID. Two reviewers independently extracted and analyzed data using PRISMA guidelines and the CASP tool to evaluate study quality.ResultsFrom ten studies representing data from 525 participants, three major themes emerged across studies: logistical facilitators within health systems enhanced HCV treatment adherence, positive social interactions between PWID and staff provided positive feedback during treatment, and HCV treatment may complicate the addiction recovery process.ConclusionsAlthough PWID face several barriers to adherence, we identified treatment adherence facilitators that could be incorporated into clinical practice.

Hepatitis C Virus Treatment Access Among Human Immunodeficiency Virus and Hepatitis C Virus (HCV)-Coinfected People Who Inject Drugs in Guangzhou, China: Implications for HCV Treatment Expansion

Background. Hepatitis C virus (HCV) treatment access among human immunodeficiency virus (HIV)/HCV-coinfected people who inject drugs is poor, despite a high burden of disease in this population. Understanding barriers and facilitators to HCV treatment uptake is critical to the implementation of new direct-acting antivirals. Methods. We conducted in-depth interviews with patients, physicians, and social workers at an HIV treatment facility and methadone maintenance treatment centers in Guangzhou, China to identify barriers and facilitators to HCV treatment. We included patients who were in various stages of HCV treatment and those who were not treated. We used standard qualitative methods and organized data into themes. Results. Interview data from 29 patients, 8 physicians, and 3 social workers were analyzed. Facilitators and barriers were organized according to a modified Consolidated Framework for Implementation Research schematic. Facilitators included patient trust in physicians, hope for a cure, peer networks, and social support. Barriers included ongoing drug use, low HCV disease knowledge, fragmented reimbursement systems, HIV exceptionalism, and stigma. Conclusions. Expanding existing harm reduction programs, HIV treatment programs, and social services may facilitate scale-up of direct-acting antivirals globally. Improving integration of ancillary social and mental health services within existing HIV care systems may facilitate HCV treatment access.

Outcomes of men on active surveillance for low-risk prostate cancer at a safety-net hospital

PURPOSE To characterize demographic, disease, and cancer outcomes of men on active surveillance (AS) at a safety-net hospital and characterize those who were lost to follow-up (LTFU). METHODS From January 2004 to November 2014, 104 men with low-risk prostate cancer (PCa) were followed with AS at Zuckerberg San Francisco General Hospital (ZSFG). Criteria for AS have evolved over time; however, patients with diagnostic prostate-specific antigen (PSA) 10ng/mL or less, clinical stage T1/2, biopsy Gleason score 3 + 3 or 3 + 4, 33% or fewer positive cores, and 50% or less tumor in any single core were potentially eligible for AS. Men were longitudinally followed with a PSA or digital rectal examination or both every 3 to 6 months, and repeat prostate biopsy every 1 to 2 years. Clinical staging and grading were based on a physical examination and at least a 12-core biopsy, respectively. LTFU was defined as failure to successfully contact patients with 3 phone calls or any urology visit recorded within 18 months from a prior visit or biopsy. A secondary chart review was performed using the electronic medical record at ZSFG as well as EPIC Systems CareEverywhere which allows access to select non-ZSFG institutions to confirm that patients were truly LTFU. RESULTS Among the 104 men on AS at ZSFG, the median age at diagnosis of PCa was 61.5 years (range: 44-81). The median follow-up period was 29 months (range: 0-186 months) during which 18 (17.3%) men were LTFU and 48 (46%) remained on surveillance. Men underwent a median of 7 (1-21) serum PSA measurements and an average of 2 prostate biopsies (1-5). In total, 22 (20.6%) men had definitive treatment with the median time from diagnosis to active treatment being 26 (range: 2-87) months. Radiation therapy was more common than radical prostatectomy (12.5% vs. 7.7%). There was 1 PCa-related death and 3 noncancer deaths. Initial adherence to AS was poor; however, men committed to AS initially were ultimately more compliant over time. CONCLUSION AS for low-risk PCa is challenging among a vulnerable population receiving care in a safety-net hospital, as rates of LTFU were high. Our findings suggest the need for AS support programs to improve adherence and follow-up among vulnerable and underserved populations.