Point mutations in Arf1 reveal cooperative effects of the N-terminal extension and myristate for GTPase-activating protein catalytic activity.

The ADP-ribosylation factors (Arfs) constitute a family of small GTPases within the Ras superfamily, with a distinguishing structural feature of a hypervariable N-terminal extension of the G domain modified with myristate. Arf proteins, including Arf1, have roles in membrane trafficking and cytoskeletal dynamics. While screening for Arf1:small molecule co-crystals, we serendipitously solved the crystal structure of the non-myristoylated engineered mutation [L8K]Arf1 in complex with a GDP analogue. Like wild-type (WT) non-myristoylated Arf1•GDP, we observed that [L8K]Arf1 exhibited an N-terminal helix that occludes the hydrophobic cavity that is occupied by the myristoyl group in the GDP-bound state of the native protein. However, the helices were offset from one another due to the L8K mutation, with a significant change in position of the hinge region connecting the N-terminus to the G domain. Hypothesizing that the observed effects on behavior of the N-terminus affects interaction with regulatory proteins, we mutated two hydrophobic residues to examine the role of the N-terminal extension for interaction with guanine nucleotide exchange factors (GEFs) and GTPase Activating Proteins (GAPs. Different than previous studies, all mutations were examined in the context of myristoylated Arf. Mutations had little or no effect on spontaneous or GEF-catalyzed guanine nucleotide exchange but did affect interaction with GAPs. [F13A]myrArf1 was less than 1/2500, 1/1500, and 1/200 efficient as substrate for the GAPs ASAP1, ARAP1 and AGAP1; however, [L8A/F13A]myrArf1 was similar to WT myrArf1. Using molecular dynamics simulations, the effect of the mutations on forming alpha helices adjacent to a membrane surface was examined, yet no differences were detected. The results indicate that lipid modifications of GTPases and consequent anchoring to a membrane influences protein function beyond simple membrane localization. Hypothetical mechanisms are discussed.

Impact of Intraoperative Hypothermia on Incidence of Infection in Implant-Based Breast Reconstruction.

BACKGROUND: Infection following implant-based breast reconstruction can lead to devastating complications. Risk factors for infection include smoking, diabetes, and obesity. Intraoperative hypothermia may represent another modifiable risk factor. This study analyzed the effect of hypothermia in postmastectomy immediate implant-based reconstruction on postoperative surgical-site infection (SSI). METHODS: This was a retrospective review of 122 patients with intraoperative hypothermia, defined as less than 35.5°C, and 106 normothermic patients who underwent postmastectomy implant-based reconstruction between 2015 and 2021. Demographics, comorbidities, smoking status, hypothermia (and its duration), and length of surgery were collected. The primary outcome was SSI. Secondary outcomes included reoperation and delayed wound healing. RESULTS: A total of 185 patients (81%) underwent staged reconstruction with tissue expander placement and 43 patients (18.9%) had a direct-to-implant procedure. Over half (53%) of the patients experienced intraoperative hypothermia. In the hypothermic group, a higher proportion of patients had SSIs (34.4% versus 17% of normothermic patients; P < 0.05) and wound healing complications (27.9% versus 16%; P < 0.05). Intraoperative hypothermia predicted SSI (OR, 2.567; 95% CI, 1.367 to 4.818; P < 0.05) and delayed wound healing (OR, 2.023; 95% CI, 1.053 to 3.884; P < 0.05). Longer duration of hypothermia significantly correlated with SSI, with an average 103 minutes versus 77 minutes ( P < 0.05). CONCLUSIONS: This study demonstrates that intraoperative hypothermia is a significant risk factor for postoperative infection in postmastectomy implant-based breast reconstruction. Maintaining strict normothermia during implant-based breast reconstruction procedures may improve patient outcomes by reducing the risk of postoperative infection and delayed wound healing. CLINICAL QUESTION/LEVEL OF EVIDENCE: Risk, II.

Impact of Intraoperative Hypothermia on Autologous Breast Reconstruction.

OBJECTIVE: Studies have identified perioperative hypothermia as a risk factor for impaired wound healing, increased hospital length of stay, and surgical site infection. This study examines the effect of intraoperative hypothermia on postoperative outcomes in autologous microvascular free flap breast reconstruction. METHODS: This was a retrospective review of 55 patients who experienced intraoperative hypothermia, defined as less than 35.0°C core body temperature and 99 normothermic patients who underwent autologous-based microvascular free flap breast reconstruction from 2013 to 2021. Demographics, comorbidities, smoking status, intraoperative warming devices, type of autologous reconstruction, hypothermia (and its duration), and length of surgery were collected. The outcomes assessed were infection rate, reoperation within 90 days, skin necrosis, wound healing complications, hematoma, seroma, and readmission within 90 days. RESULTS: In the study population of 154 consecutive patients, 8.4% had type 1 or type 2 diabetes and 3.2% were current smokers. A total of 90.3% of patients (139) underwent deep inferior epigastric perforator flap reconstruction, 7.1% (11) superficial inferior epigastric artery flap reconstruction, and 4 (2.6%) another free flap type. A total of 35.7% of the patients (55) experienced intraoperative hypothermia defined as less than 35.0°C. In the hypothermic group, a higher proportion of patients had wound healing complications (52.7% vs 29.3%, P < 0.05), hematoma (16.4% vs 5.1%, P < 0.05), and readmission for postoperative complications (34.5% vs 14.1%, P < 0.05). There was also a trend toward higher incidence of seroma (7.3% vs 5.1%), surgical site infection (12.7% vs 9.1%), skin necrosis (12.7% vs 9.1%), and unplanned reoperation within 90 days (10.9% vs 7.1%). Further analysis via Firth logistic regression demonstrated intraoperative hypothermia predicted postoperative hematoma (odds ratio [OR], 3.68; 95% confidence interval [CI], 1.17-11.60; P < 0.05), readmission within 90 days (OR, 3.20; 95% CI, 1.45-7.08; P < 0.05), and wound healing complications (OR, 2.69; 95% CI, 1.36-5.33; P < 0.05). CONCLUSIONS: This study demonstrates that intraoperative hypothermia is a significant risk factor for postoperative wound healing complications, hematoma, and readmission within 90 days in autologous breast reconstruction. Because of a finite amount of donor sites, it is important to find ways to minimize the risk of postoperative complications. Our results support that maintaining strict normothermia during autologous breast reconstruction can significantly improve patient outcomes and reduce morbidity.

Framing and Policymaker Evaluations of the Opioid Crisis.

Several extremely influential theories, including the multiple streams approach and punctuated equilibrium theory, predict that dramatic policy change occurs when problems are reframed. However, there is little direct evidence of how framing messages influence policymaker attitudes, perceptions, and behaviors. In an online survey of local policymakers in Illinois, we find that different media frames of the opiate epidemic influence policymaker attitudes and attributions of responsibility. We conclude with some implications for framing theory and its role in theories of policymaking.

One Size Does Not Fit All; Patient Preference for Breast Reconstruction.

Background: A myriad of patient education modalities for breast reconstruction exist, although the optimal tools for patient education remain undetermined. The aim of this study is to determine patient preferences for breast reconstruction education modalities based on demographic variables. Methods: A prospective observational study at a tertiary care university health system was conducted between November 2020 and May 2021. A questionnaire was administered to breast reconstruction patients to collect information on demographics, research sources used before the initial appointment, and preferred education modalities. Differences based on age were analyzed using an independent samples t test, whereas a Fisher exact test was used to analyze differences based on ethnicity and education level. Statistical significance was defined as P < .05. Results: The most preferred patient education tools overall were books/written materials and videos. Younger patients were significantly more likely than older patients to have referenced additional physician sources (P = .0174) and to seek out information on the institution's website (P = .0465). Those with a college degree were significantly more likely to have performed research prior to the initial appointment (P = .0206). White patients were significantly more likely than nonwhite patients to talk to friends/family as a research source (P = .0150). Conclusions: Regardless of age, education, or ethnicity, most patients prefer books/written materials and video presentations for education on breast reconstruction. Providers should strive to include written and video options to meet the needs of this diverse patient population.

The Impact of Preoperative Breast Volume on Development of Mastectomy Skin Flap Necrosis in Immediate Breast Reconstruction.

BACKGROUND: Mastectomy skin flap necrosis (MSFN) can significantly impact outcome after immediate breast reconstruction. Several techniques exist to predict MSFN, but these may require additional testing and information, and they are often not available before surgery. We aim to identify whether breast volume, as calculated from preoperative mammography, can be used as a preoperative predictor of MSFN. METHODS: A retrospective chart review from 2010 to 2020 resulted in 378 patients who underwent immediate implant-based breast reconstruction. Complete imaging data were available for 278 patients and 441 reconstructed breasts. Demographic, perioperative, and outcomes data were collected. Measurements from preoperative diagnostic mammograms were used to calculate breast volume. Univariate and multivariate analyses were used to evaluate the association of variables available preoperatively, including breast volume from mammogram and MSFN. Secondary analyses were performed for need for reoperation and loss of reconstruction. RESULTS: On univariate analysis of MSFN development, demographic variables found to be significantly associated with MSFN included body mass index (P = 0.04), diabetes (P = 0.03), and breast volume calculated from routine mammography (P ≤ 0.0001). Average preoperative breast volume via mammography without and with MSFN was 970.6 mL (95% confidence interval [CI], 908.9-1032.3) and 1298.3 mL (95% CI, 1140.0-1456.5) (P < 0.0001), respectively. Statistically significant intraoperative variables for MSFN development included prolonged operative time (P = 0.005), greater initial tissue expander fill volumes (P ≤ 0.001), and prepectoral implant location (P = 0.02). Higher initial tissue expander fill volumes in implant-based reconstructions were associated with increased rates of MSFN, 264.1 mL (95% CI, 247.2-281.0) without MSFN and 349.9 mL (95% CI, 302.0-397.8) in the group with MSFN, respectively (P < 0.001). On multivariate analysis, preoperative imaging volume (P = 0.02) was found to be significant, whereas body mass index and diabetes lost significance (P = 0.40) in association with MSFN. CONCLUSIONS: The results of this study establish an association between larger breast volume on preoperative imaging and development of MSFN. This may be useful as a tool for more appropriate patient selection and guidance in the setting of immediate breast reconstruction.

It's not all White: Implicit Racial Bias in Imagery Used in Plastic Surgery Resident Education.

OBJECTIVE: Plastic surgery education relies heavily on images featuring patient skin tone; while images can be useful representations, it is highly susceptible to implicit bias, a known contributor to healthcare disparities. Using skin tone as a proxy, this study evaluates patient representation in images used in the American Society of Plastic Surgery Resident Education Curriculum. DESIGN: Color photographs, graphics, and videos featured in the American Society of Plastic Surgery "Course Materials" for each module were categorized using the Fitzpatrick scale (I-II, III-IV, or V-VI) by six reviewers. Proportional data and average number ± standard deviation of photos and graphics for each category were reported. Significant difference between Fitzpatrick I to II and V to VI was investigated via a one-way analysis of variance with a Tukey's post-test to adjust for multiple comparisons. RESULTS: An average of 1861 photographs and 237 graphics were assessed with 82% (1518 ± 25.11) of photos and 97% (231 ± 24.45) of graphics categorized as Fitzpatrick I to II. A one-way analysis of variance with a Tukey's post-test demonstrates a statistical difference between images and graphics categorized as Fitzpatrick I to II and Fitzpatrick V to VI (p < 0.001). CONCLUSIONS: Our data reveals an opportunity to improve racial representation in resident education. When 76% of patients in the United States are white and 13% are Black, our findings demonstrate both an unequal and unrepresentative distribution of photos and graphics of non-white patients. Residency is a formative time in a surgeon's career and therefore, exposure to accurate representation of a diverse patient population is of the utmost importance.

Utilizing a Comprehensive Wound Care Team to Lower Hospital-Acquired Pressure Injuries in an Academic Public Hospital: A Retrospective Cohort Study.

PURPOSE: Hospital-acquired pressure injuries (HAPIs) have significant impacts on patient morbidity and mortality, with approximately 2.5 million patients treated for pressure-related injuries annually.1 This study aimed to describe the influence of a comprehensive wound care team on HAPIs over an 8-year period. DESIGN: Retrospective cohort study. SUBJECTS AND SETTING: All inpatients at an academic public hospital system with HAPIs during the study period from May 2012 to February 2020. METHODS: Data on wound stage, location, infection, medical device location if applicable, and risk factors were recorded from medical records. A 1-way analysis of variance was performed to assess for significance of mean number of cases, National Pressure Injury Advisory Panel (NPIAP) stage on initial presentation, and mean number of medical device-related wounds by year. RESULTS: A total of 957 cases were included. The median stage of pressure injury on assessment was 2, with the mean NPIAP stage declining from 2012 to 2020 (P = .003). Thirty-three percent of pressure injuries were attributed to medical devices, most commonly endotracheal tubing. The most common site of pressure injury was the sacrum (33.6%). CONCLUSION: Creation of a comprehensive wound care team within our academic public hospital system demonstrated a significant decline in device-related and pressure injury cases over the past 8 years. The wound care team focused on frequent assessment, education, and evidence-based treatment to lower these HAPI events.

Breast Implants: A Historical Review With Implications for Diagnosis and Modern Surgical Planning.

ABSTRACT: Modern breast surgery was first introduced in the United States in 1962 with the use of silicone gel-filled breast implants. Over the past 6 decades, development of breast implants has been challenged by a variety of influencers including aesthetic appeal in shape, texture, and material; challenges in managing outcomes such as contracture, disease, and rupture; and public perception of risks associated with implants. In 1992, silicone breast prostheses were banned by the US Food and Drug Administration with exception for use in breast reconstruction, congenital deformities, or to replace existing implants.The ban led to heightened concerns about implants and possible disease manifestations. Knowledge of the historical evolution of breast prostheses is useful for understanding the associated risks and outcomes unique to each breast implant era. This article aimed to explore characteristics of breast implants by generation, with implications for diagnosis and assistance to modern surgical planning for novice plastic surgeons.

Analysis of Pediatric Dog Bite Injuries at a Level 1 Trauma Center Over 10 Years.

BACKGROUND: Dog bite injuries cause significant preventable patient morbidity and health care expenditure in children. This study aimed to characterize the patient and healthcare burden related to pediatric dog bite injuries at a level 1 trauma center. METHODS: This is a retrospective review of 356 pediatric patients who presented to Virginia Commonwealth University Pediatric Emergency Department between July 2007 and August 2017 after sustaining dog bite injuries. Demographic information, injury details, management, outcomes, and financial information were analyzed. RESULTS: Most pediatric dog bite injuries afflicted male children (55.6%), ages 6 to 12 years (45.7%), by a household dog (36.2%). The most common offending breed was a pit bull or pit bull mix (53.0%). Infants and grade schoolers were more likely to sustain bites to the head/face (P = 0.001). Usual management consisted of primary repair (75.9%), whereas approximately 25% of the patients required advanced reconstructive techniques. Most patients healed uneventfully, but prolonged antibiotics, additional wound care, or procedures were necessary in 8.4% of the patients. Hospital charges per patient averaged US $8830.70 and tended to be higher in the younger age groups. Insurance status was statistically associated with use of conscious sedation, surgical consult placement, and surgical repair. CONCLUSIONS: Although most pediatric dog bite injuries in this study healed uneventfully from primary management in the emergency department, 25% required additional interventions. Furthermore, patient care for these injuries was associated with significant but potentially avoidable personal and financial burden to families. Our data reflect a need for safety education on animal care, behavior, and interaction.

A 15-Year Review of Iatrogenic Burn Injuries in an Academic Public Hospital.

Hospital-acquired burn injuries can result in increased length of hospitalization, costs of stay, and potential for additional procedures. The aim of this study is to describe iatrogenic burn injuries over a 15-year period at an academic public hospital system. Data was collected from January 2004 to June 2019. Data included time of injury, hospital location, mechanism, level of harm caused, and anatomic location of the injury. Demographic information included patient age, gender, body mass index, payer status, primary admission diagnosis and length of stay. 122 patients were identified through an internal hospital database that tracked reported injuries. Incidence was highest between 2005-2012 (12.3 ± 4.1 per year) as compared to 2013-2019 (2.9 ± 2.1 per year). A majority (77%) resulted in harm caused to the patient. Most (41%) of the injuries occurred on the general medical floors, followed by the operating room (33.6%). The most common etiology was scald (23%), followed by electrocautery (14.8%). Five of the injuries resulted in burn consults, although none of these patients required surgery. Iatrogenic burns appear to be decreasing. While a majority were reported to have caused patient harm, none were serious enough to warrant surgery. Most injuries occurred on the medical floors with a scald mechanism. This review presents an opportunity to emphasize in-hospital burn prevention, as well as an opportunity for the burn team to affect change in concert with hospital administration.

Assessing Readability of Patient Education Materials on Breast Reconstruction by Major US Academic Hospitals as Compared With Nonacademic Sites.

PURPOSE: Women undergoing postmastectomy breast reconstruction face many complex choices. A myriad of online patient education materials exist to assist in decision making. Understanding of these materials, termed health literacy, affects surgical decision making and outcomes. The National Institutes of Health recommends writing patient education materials at a sixth- to seventh-grade reading level. The primary goal of this study was to assess readability of online breast reconstruction materials. METHODS AND MATERIALS: Resources were collected from every academic hospital with a plastic surgery residency program, 97 in total. These data were compared with the top nonacademic Web sites ranked by search engine results, 14 in total. Materials were analyzed using 3 validated readability assessment scales: Coleman-Liau Index, SMOG (Simplified Measure of Gobbledygook) Readability Formula, and Flesch-Kincaid Grade Level. Average readability was analyzed, and results were compared using a 1-way analysis of variance to assess for significance between the different tools and a 2-sided t test to assess for significance between academic and nonacademic readability results. RESULTS: The mean readability scores across the academic programs were a Coleman-Liau Index of 13.38 (standard Deviation [SD] 2.81, 13th to 14th grade), Flesch-Kincaid Grade Level of 13.04 (SD = 3.9, 13th grade), and SMOG Readability of 13.64 (SD = 2.99, 13th to 14th grade). For the 14 nonacademic sites, results showed a Coleman-Liau Index of 11.93 (SD = 1.14, 12th grade), Flesch-Kincaid of 11.82 (SD = 2.33, 11th to 12th grade), and SMOG Readability of 10.91 (SD = 1.79, 11th grade). One-way analysis of variance demonstrated no significant differences in mean readability scores across the 3 readability tools used (academic F = 2.7804, P = 0.06; nonacademic F = 1.14, P = 0.33). Two-tailed t test results demonstrated that there was statistical significance between readability of the academic in comparison with nonacademic search engine results (t = 2.04, P = 0.04). CONCLUSIONS: Average readability across all Web sites were much higher than the recommended reading level, at a 13th to 14th grade reading level for academic institutions, and an 11th to 12th grade for nonacademic Web sites. Plastic surgeons may contribute to improving patient understanding and perioperative outcomes through revising patient education materials.

Relationship of Absolute and Relative Lower-Body Strength to Predictors of Athletic Performance in Collegiate Women Soccer Players.

The purpose of this study was to investigate the relationships between absolute and relative lower-body strength on predictors of athletic performance among Division II collegiate women's soccer players. Archived pre-season testing data for seventeen (n = 17) female National Collegiate Athletics Association (NCAA) Division II soccer players were analyzed, including: vertical jump, 3RM back squat, 505-agility, modified T-test, 10 m and 30 m sprint, and 20 m multistage fitness test (20 m MSFT). Relative strength was calculated based on the estimated 1RM back squat divided by the athlete's body mass. Significant correlations were discovered between absolute lower-body strength and 505-agility (Right: r = -0.51, p < 0.05; Left: r = -0.59, p < 0.05), modified T-test (r = -0.55, p < 0.05), 10 m and 30 m (r = -0.59, p < 0.05; r = -0.54, p < 0.05), and sprint performance. Relative lower-body strength showed significant correlations with vertical jump (r = 0.54, p < 0.05), 505-agility (Right: r = -0.58, p < 0.05; Left: r = -0.67, p < 0.01), modified T-test (r = -0.75, p < 0.01), 10 m and 30 m (r = -0.59 p < 0.05; r = -0.67, p < 0.01), and the 20 m MSFT (r = 0.58, p < 0.05). These results indicate that strength and conditioning coaches should emphasize the development of absolute and relative lower-body strength with their players to improve power, agility, and speed performance.

Patent foramen ovale and neurologic events in patients undergoing liver transplantation.

BACKGROUND: Patent foramen ovale (PFO) is present in approximately 20% of individuals. During liver transplantation (LT), intra-operative transesophageal echocardiography can observe transient intra-cardiac shunting of atheromatous debris via a PFO. Closure of PFOs prior to LT has thus been suggested as a potential treatment to reduce peri-operative cerebral vascular accident (CVA). The objective of this study was to assess if the presence of PFO is associated with CVA in patients undergoing LT. METHODS: Three hundred fifty-eight patients undergoing LT at a single academic institution were included. All patients underwent standardized cardiac evaluation including a detailed cardiovascular history and physical examination, electrocardiogram and transthoracic echocardiogram. Five patients were excluded because of poor transthoracic echocardiographic image quality, and three patients were excluded because of PFO closure prior to LT, yielding a study population of 350 patients. Medical records were reviewed to determine demographics, echocardiographic findings and outcome following LT. Major adverse cardiovascular events, myocardial infarction, CVA and death were collected. RESULTS: Mean age was 53.4 ±â€¯10.2 years; 61% male and 5% of patients had a prior history of CVA. Alcohol and hepatitis C were the most common etiologies for liver disease. Forty-six patients (13.1%) were diagnosed with PFO prior to LT. In-hospital CVA occurred in 6 patients (1.7%). The prevalence of a CVA was not significantly higher in patients with PFO compared to patients without PFO, 2.2% vs 1.6%, p = 0.57. In-hospital mortality was similar in patients with PFO compared to patients without PFO, 4.4% and 5.3%, p = 1.0. CONCLUSIONS: The presence of a PFO in patients undergoing LT is not associated with postoperative CVA. Prophylactic closure of PFOs, in the absence of other indications, does not appear to be warranted in patients undergoing LT.

Human brain metastatic stroma attracts breast cancer cells via chemokines CXCL16 and CXCL12.

The tumor microenvironment is composed of heterogeneous populations of cells, including cancer, immune, and stromal cells. Progression of tumor growth and initiation of metastasis is critically dependent on the reciprocal interactions between cancer cells and stroma. Through RNA-Seq and protein analyses, we found that cancer-associated fibroblasts derived from human breast cancer brain metastasis express significantly higher levels of chemokines CXCL12 and CXCL16 than fibroblasts from primary breast tumors or normal breast. To further understand the interplay between cancer cells and cancer-associated fibroblasts from each site, we developed three-dimensional organoids composed of patient-derived primary or brain metastasis cancer cells with matching cancer-associated fibroblasts. Three-dimensional CAF aggregates generated from brain metastasis promote migration of cancer cells more effectively than cancer-associated fibroblast aggregates derived from primary tumor or normal breast stromal cells. Treatment with a CXCR4 antagonist and/or CXCL16 neutralizing antibody, alone or in combination, significantly inhibited migration of cancer cells to brain metastatic cancer-associated fibroblast aggregates. These results demonstrate that human brain metastasis cancer-associated fibroblasts potently attract breast cancer cells via chemokines CXCL12 and CXCL16, and blocking CXCR6-CXCL16/CXCR4-CXCL12 receptor-ligand interactions may be an effective therapy for preventing breast cancer brain metastasis.

Accumulation of non-outer segment proteins in the outer segment underlies photoreceptor degeneration in Bardet-Biedl syndrome.

Compartmentalization and polarized protein trafficking are essential for many cellular functions. The photoreceptor outer segment (OS) is a sensory compartment specialized for phototransduction, and it shares many features with primary cilia. As expected, mutations disrupting protein trafficking to cilia often disrupt protein trafficking to the OS and cause photoreceptor degeneration. Bardet-Biedl syndrome (BBS) is one of the ciliopathies associated with defective ciliary trafficking and photoreceptor degeneration. However, precise roles of BBS proteins in photoreceptor cells and the underlying mechanisms of photoreceptor degeneration in BBS are not well understood. Here, we show that accumulation of non-OS proteins in the OS underlies photoreceptor degeneration in BBS. Using a newly developed BBS mouse model [Leucine zipper transcription factor-like 1 (Lztfl1)/Bbs17 mutant], isolated OSs, and quantitative proteomics, we determined 138 proteins that are enriched more than threefold in BBS mutant OS. In contrast, only eight proteins showed a more than threefold reduction. We found striking accumulation of Stx3 and Stxbp1/Munc18-1 and loss of polarized localization of Prom1 within the Lztfl1 and Bbs1 mutant OS. Ultrastructural analysis revealed that large vesicles are formed in the BBS OS, disrupting the lamellar structure of the OS. Our findings suggest that accumulation (and consequent sequestration) of non-OS proteins in the OS is likely the primary cause of photoreceptor degeneration in BBS. Our data also suggest that a major function of BBS proteins in photoreceptors is to transport proteins from the OS to the cell body or to prevent entry of non-OS proteins into the OS.

Antigen-specific inhibition of high-avidity T cell target lysis by low-avidity T cells via trogocytosis.

Current vaccine conditions predominantly elicit low-avidity cytotoxic T lymphocytes (CTLs), which are non-tumor-cytolytic but indistinguishable by tetramer staining or enzyme-linked immunospot from high-avidity CTLs. Using CTL clones of high or low avidity for melanoma antigens, we show that low-avidity CTLs can inhibit tumor lysis by high-avidity CTLs in an antigen-specific manner. This phenomenon operates in vivo: high-avidity CTLs control tumor growth in animals but not in combination with low-avidity CTLs specific for the same antigen. The mechanism involves stripping of specific peptide-major histocompatibility complexes (pMHCs) via trogocytosis by low-avidity melanoma-specific CTLs without degranulation, leading to insufficient levels of specific pMHC on target cell surface to trigger lysis by high-avidity CTLs. As such, peptide repertoire on the cell surface is dynamic and continually shaped by interactions with T cells. These results describe immune regulation by low-avidity T cells and have implications for vaccine design.

Antiretroviral drugs induce oxidative stress and neuronal damage in the central nervous system.

HIV-associated neurocognitive disorder (HAND), characterized by a wide spectrum of behavioral, cognitive, and motor dysfunctions, continues to affect approximately 50 % of HIV(+) patients despite the success of combination antiretroviral drug therapy (cART) in the periphery. Of note, potential toxicity of antiretroviral drugs in the central nervous system (CNS) remains remarkably underexplored and may contribute to the persistence of HAND in the cART era. Previous studies have shown antiretrovirals (ARVs) to be neurotoxic in the peripheral nervous system in vivo and in peripheral neurons in vitro. Alterations in lipid and protein metabolism, mitochondrial damage, and oxidative stress all play a role in peripheral ARV neurotoxicity. We hypothesized that ARVs also induce cellular stresses in the CNS, ultimately leading to neuronal damage and contributing to the changing clinical and pathological picture seen in HIV-positive patients in the cART era. In this report, we show that ARVs are neurotoxic in the CNS in both pigtail macaques and rats in vivo. Furthermore, in vitro, ARVs lead to accumulation of reactive oxygen species (ROS), and ultimately induction of neuronal damage and death. Whereas ARVs alone caused some activation of the endogenous antioxidant response in vitro, augmentation of this response by a fumaric acid ester, monomethyl fumarate (MMF), blocked ARV-induced ROS generation, and neuronal damage/death. These findings implicate oxidative stress as a contributor to the underlying mechanisms of ARV-induced neurotoxicity and will provide an access point for adjunctive therapies to complement ARV therapy and reduce neurotoxicity in this patient population.

Gene expression profiling of flaxseed in mouse lung tissues-modulation of toxicologically relevant genes.

BACKGROUND: Flaxseed (FS), a nutritional supplement consisting mainly of omega-3 fatty acids and lignan phenolics has potent anti-inflammatory, anti-fibrotic and antioxidant properties. The usefulness of flaxseed as an alternative and complimentary treatment option has been known since ancient times. We have shown that dietary FS supplementation ameliorates oxidative stress and inflammation in experimental models of acute and chronic lung injury in mice resulting from diverse toxicants. The development of lung tissue damage in response to direct or indirect oxidant stress is a complex process, associated with changes in expression levels of a number of genes. We therefore postulated that flaxseed might modulate gene expression of vital signaling pathways, thus interfering with the development of tissue injury. METHODS: We evaluated gene expression in lungs of flaxseed-fed (10%FS) mice under unchallenged, control conditions. We reasoned that array technology would provide a powerful tool for studying the mechanisms behind this response and aid the evaluation of dietary flaxseed intervention with a focus on toxicologically relevant molecular gene targets. Gene expression levels in lung tissues were analyzed using a large-scale array whereby 28,800 genes were evaluated. RESULTS: 3,713 genes (12.8%) were significantly (p < 0.05) differentially expressed, of which 2,088 had a >1.5-fold change. Genes affected by FS include those in protective pathways such as Phase I and Phase II. CONCLUSIONS: The array studies have provided information on how FS modulates gene expression in lung and how they might be related to protective mechanisms. In addition, our study has confirmed that flaxseed is a nutritional supplement with potentially useful therapeutic applications in complementary and alternative (CAM) medicine especially in relation to treatment of lung disease.