Jeffrey G. Chipman

Persistent HIV-1 replication is associated with lower antiretroviral drug concentrations in lymphatic tissues

Significance We show that HIV continues to replicate in the lymphatic tissues of some individuals taking antiretroviral regimens considered fully suppressive, based on undetectable viral loads in peripheral blood, and that one mechanism for persistent replication in lymphatic tissues is the lower concentrations of the antiretroviral drugs in those tissues compared with peripheral blood. These findings are significant because they provide a rationale and framework for testing the efficacy of new agents and combinations of drugs that will fully suppress replication in lymphatic tissues. More suppressive regimens could improve immune reconstitution, as well as provide the effective regimens needed for functional cure and eradication of infection. Antiretroviral therapy can reduce HIV-1 to undetectable levels in peripheral blood, but the effectiveness of treatment in suppressing replication in lymphoid tissue reservoirs has not been determined. Here we show in lymph node samples obtained before and during 6 mo of treatment that the tissue concentrations of five of the most frequently used antiretroviral drugs are much lower than in peripheral blood. These lower concentrations correlated with continued virus replication measured by the slower decay or increases in the follicular dendritic cell network pool of virions and with detection of viral RNA in productively infected cells. The evidence of persistent replication associated with apparently suboptimal drug concentrations argues for development and evaluation of novel therapeutic strategies that will fully suppress viral replication in lymphatic tissues. These strategies could avert the long-term clinical consequences of chronic immune activation driven directly or indirectly by low-level viral replication to thereby improve immune reconstitution.

Persistent HIV-1 replication maintains the tissue reservoir during therapy

Lymphoid tissue is a key reservoir established by HIV-1 during acute infection. It is a site associated with viral production, storage of viral particles in immune complexes, and viral persistence. Although combinations of antiretroviral drugs usually suppress viral replication and reduce viral RNA to undetectable levels in blood, it is unclear whether treatment fully suppresses viral replication in lymphoid tissue reservoirs. Here we show that virus evolution and trafficking between tissue compartments continues in patients with undetectable levels of virus in their bloodstream. We present a spatial and dynamic model of persistent viral replication and spread that indicates why the development of drug resistance is not a foregone conclusion under conditions in which drug concentrations are insufficient to completely block virus replication. These data provide new insights into the evolutionary and infection dynamics of the virus population within the host, revealing that HIV-1 can continue to replicate and replenish the viral reservoir despite potent antiretroviral therapy.

Large number of rebounding/founder HIV variants emerge from multifocal infection in lymphatic tissues after treatment interruption

Significance Antiretroviral therapy (ART) effectively suppresses HIV replication; however, treatment cannot be stopped, because latently infected CD4+ T cells will rekindle infection. As one estimate of the size of the pool of latently infected cells that must be purged for cure, we asked whether recrudescent infection is the result of reactivation from one or a larger number latently infected cells. We briefly stopped ART in fully suppressed patients to see how widespread new infections were in the lymphoid tissues (LTs) and how diverse rebounding/founder viruses were in peripheral blood. Recrudescent infection was detectable in multiple different LTs, and the population was genetically diverse, consistent with reactivation from a larger number of cells. These findings underscore the challenges facing strategies to eradicate HIV infection. Antiretroviral therapy (ART) suppresses HIV replication in most individuals but cannot eradicate latently infected cells established before ART was initiated. Thus, infection rebounds when treatment is interrupted by reactivation of virus production from this reservoir. Currently, one or a few latently infected resting memory CD4 T cells are thought be the principal source of recrudescent infection, but this estimate is based on peripheral blood rather than lymphoid tissues (LTs), the principal sites of virus production and persistence before initiating ART. We, therefore, examined lymph node (LN) and gut-associated lymphoid tissue (GALT) biopsies from fully suppressed subjects, interrupted therapy, monitored plasma viral load (pVL), and repeated biopsies on 12 individuals as soon as pVL became detectable. Isolated HIV RNA-positive (vRNA+) cells were detected by in situ hybridization in LTs obtained before interruption in several patients. After interruption, multiple foci of vRNA+ cells were detected in 6 of 12 individuals as soon as pVL was measureable and in some subjects, in more than one anatomic site. Minimal estimates of the number of rebounding/founder (R/F) variants were determined by single-gene amplification and sequencing of viral RNA or DNA from peripheral blood mononuclear cells and plasma obtained at or just before viral recrudescence. Sequence analysis revealed a large number of R/F viruses representing recrudescent viremia from multiple sources. Together, these findings are consistent with the origins of recrudescent infection by reactivation from many latently infected cells at multiple sites. The inferred large pool of cells and sites to rekindle recrudescent infection highlights the challenges in eradicating HIV.

Lymphoid Tissue Damage in HIV-1 Infection Depletes Naïve T Cells and Limits T Cell Reconstitution after Antiretroviral Therapy

Highly active antiretroviral therapy (HAART) can suppress HIV-1 replication and normalize the chronic immune activation associated with infection, but restoration of naïve CD4+ T cell populations is slow and usually incomplete for reasons that have yet to be determined. We tested the hypothesis that damage to the lymphoid tissue (LT) fibroblastic reticular cell (FRC) network contributes to naïve T cell loss in HIV-1 infection by restricting access to critical factors required for T cell survival. We show that collagen deposition and progressive loss of the FRC network in LTs prior to treatment restrict both access to and a major source of the survival factor interleukin-7 (IL-7). As a consequence, apoptosis within naïve T cell populations increases significantly, resulting in progressive depletion of both naïve CD4+ and CD8+ T cell populations. We further show that the extent of loss of the FRC network and collagen deposition predict the extent of restoration of the naïve T cell population after 6 month of HAART, and that restoration of FRC networks correlates with the stage of disease at which the therapy is initiated. Because restoration of the FRC network and reconstitution of naïve T cell populations are only optimal when therapy is initiated in the early/acute stage of infection, our findings strongly suggest that HAART should be initiated as soon as possible. Moreover, our findings also point to the potential use of adjunctive anti-fibrotic therapies to avert or moderate the pathological consequences of LT fibrosis, thereby improving immune reconstitution.

Early surgery for thoracolumbar spine injuries decreases complications.

BACKGROUND The proper timing for surgical fracture repair is controversial. Early repair of long bone and cervical fractures reduces complications and is safe. Few studies exist to compare time to surgery with outcomes in thoracolumbar (TL) spine injuries. METHODS Patients with TL spine injuries were identified from the trauma registry and divided into two cohorts on the basis of Injury Severity Score (ISS). Cohorts were compared for infectious, respiratory, and total complications in patients who had early (<72 hours from injury) versus late (>72 hours from injury) surgical repair. A retrospective chart review was performed on High ISS patients (> or =15) to identify differences in resuscitation needs and neurologic, respiratory, and infectious complications. RESULTS Early surgery, Low ISS patients were younger, received fewer anterior repairs, and had shorter hospitalizations. Early patients in the High ISS cohort had significantly fewer total complications and shorter hospital and intensive care unit lengths of stay. Resuscitative requirements were similar for both surgery groups. More late surgery patients required ventilator support for noninfectious reasons. There was no difference in admission or postoperative neurologic status or the incidence of head injury. CONCLUSION Early surgery in severely injured patients with thoracolumbar spine trauma was associated with fewer complications and shorter hospital and intensive care unit lengths of stay, required less ventilator support for noninfectious reasons, and did not increase neurologic deficits.

Critical role of CD4 T cells in maintaining lymphoid tissue structure for immune cell homeostasis and reconstitution

Loss of the fibroblastic reticular cell (FRC) network in lymphoid tissues during HIV-1 infection has been shown to impair the survival of naive T cells and limit immune reconstitution after antiretroviral therapy. What causes this FRC loss is unknown. Because FRC loss correlates with loss of both naive CD4 and CD8 T-cell subsets and decreased lymphotoxin-β, a key factor for maintenance of FRC network, we hypothesized that loss of naive T cells is responsible for loss of the FRC network. To test this hypothesis, we assessed the consequences of antibody-mediated depletion of CD4 and CD8 T cells in rhesus macaques and sooty mangabeys. We found that only CD4 T-cell depletion resulted in FRC loss in both species and that this loss was caused by decreased lymphotoxin-β mainly produced by the CD4 T cells. We further found the same dependence of the FRC network on CD4 T cells in HIV-1-infected patients before and after antiretroviral therapy and in other immunodeficiency conditions, such as CD4 depletion in cancer patients induced by chemotherapy and irradiation. CD4 T cells thus play a central role in the maintenance of lymphoid tissue structure necessary for their own homeostasis and reconstitution.

Hyperbaric oxygen does not improve outcome in patients with necrotizing soft tissue infection.

BACKGROUND Patients with necrotizing soft tissue infections (NSTIs) require prompt surgical debridement, appropriate intravenous antibiotics, and intensive support. Despite aggressive treatment, their mortality and morbidity rates remain high. The benefit of hyperbaric oxygen (HBO) as an adjunctive treatment is controversial. We investigated the effect of HBO in treating NSTIs. METHODS We analyzed clinical data retrospectively for 78 patients with NSTIs: 30 patients at one center were treated with surgery, antibiotics, and supportive care; 48 patients at a different center received adjunctive HBO treatment. We compared the two groups in terms of demographic characteristics, risk factors, NSTI microbiology, and patient outcomes. To identify variables associated with higher mortality rates, we used logistic regression analysis. RESULTS Demographic characteristics and risk factors were similar in the HBO and non-HBO groups. The mean patient age was 49.5 years; 37% of the patients were female, and 49% had diabetes mellitus. Patients underwent a mean of 3.0 excisional debridements. The median hospital length of stay was 16.5 days; the median duration of antibiotic use was 15.0 days. In 36% of patients, cultures were polymicrobial; group A Streptococcus was the organism most commonly isolated (28%). We identified no statistically significant differences in outcomes between the two groups. The mortality rate for the HBO group (8.3%) was lower, although not significantly different (p = 0.48), than that observed for the non-HBO group (13.3%). The number of debridements was greater in the HBO group (3.0; p = 0.03). The hospital length of stay and duration of antibiotic use were similar for the two groups. Multivariable analysis showed that hypotension on admission and immunosuppression were significant independent risk factors for death. CONCLUSIONS Adjunctive use of HBO to treat NSTIs did not reduce the mortality rate, number of debridements, hospital length of stay, or duration of antibiotic use. Immunosupression and early hypotension were important risk factors associated with higher mortality rates in patients with NSTIs.

Professionalism and communication in the intensive care unit: reliability and validity of a simulated family conference.

Objective: An Objective Structured Clinical Exam was designed to assess physician’s ability to discuss end-of-life (EOL) and disclose iatrogenic complications (DOC) with family members of intensive care unit patients. The study explores reliability and validity based on scores from contrasting rater groups (clinicians, SPs, and examinees). Methods: Two 20-minute stations were administered to 17 surgical residents and 2 critical fellows at a university-based training program. The exam was conducted, videotaped, and scored in a standardized setting by 8 clinical raters (MD and RN) and 8 standardized families using separate rating tools (EOL and DOC). Examinees assessed themselves using the same tools. We analyzed the internal consistency, inter-rater agreement, and discriminant validity of both cases using data from each rater group. Cross-rater group comparisons were also made. Results: The internal consistency reliability correlations were above 0.90 regardless of case or rater group. Within rater groups, raters were within 1 point of agreement (5-pt and 6-pt scales) on 81% of the DOC and between 74% and 79% of the EOL items. Family raters were more favorable than clinical raters in scoring DOC, but not EOL cases. Large raw differences in performance by training level favored more experienced trainees (3rd year residents and fellows). These differences were statistically significant when based on residents own self-ratings, but not when they were based on clinical or family ratings. Discussion: The Family Conference Objective Structured Clinical Exam is a reliable exam with high content validity. It seems unique in the literature for assessing surgical trainees’ ability to discuss “bad news” with family members in intensive care.

A Novel Critical Skills Curriculum for Surgical Interns Incorporating Simulation Training Improves Readiness for Acute Inpatient Care

INTRODUCTION Surgical interns encounter complex, acute care situations often managed with limited supervision. Furthermore, medical school training does not adequately prepare students for special surgical considerations. Using simulation training, we implemented a course aimed at improving surgical intern readiness for responding to unique, life-threatening issues encountered in daily surgical care. METHODS Twenty University of Minnesota surgical interns participated in the 3-week course. The first session consisted of interactive didactics and simulation covering hypoxia, shock, and metabolic disturbances; the second session addressed cardiopulmonary emergencies, including ventricular assist device and pacemaker use. Electronic simulation scenarios comprised the third session, allowing learners to demonstrate learned/practiced skills. The outcomes were assessed objectively (pretest and posttest) and subjectively (standardized feedback evaluations). RESULTS Fifteen learners completed the pretest and posttest. The mean absolute score increase was 14% with average relative score improvement of 43%. Twenty learners completed feedback evaluations using a standard 5-point Likert scale. Respondents scored the first 2 sessions on topic importance (5 = very important), giving the first session 4.90 (+/- 0.31) and the second session 4.45 (+/- 0.89). Respondents ranked their confidence in executing practiced skills on actual patients (5 = very confident) as 4.24 (+/- 0.71). There was uniform support for the value of the electronic simulation scenarios as enhanced learning tools. CONCLUSIONS We developed a course for surgical interns incorporating didactics and simulation. Learners demonstrated objective improvement in testing and reported that the course topics were highly important. After course completion, learners provided feedback indicating a high level of confidence in executing practiced skills, suggesting improved preparation for acute surgical care.

The Feasibility of Real-Time Intraoperative Performance Assessment With SIMPL (System for Improving and Measuring Procedural Learning): Early Experience From a Multi-institutional Trial

PURPOSE Intraoperative performance assessment of residents is of growing interest to trainees, faculty, and accreditors. Current approaches to collect such assessments are limited by low participation rates and long delays between procedure and evaluation. We deployed an innovative, smartphone-based tool, SIMPL (System for Improving and Measuring Procedural Learning), to make real-time intraoperative performance assessment feasible for every case in which surgical trainees participate, and hypothesized that SIMPL could be feasibly integrated into surgical training programs. METHODS Between September 1, 2015 and February 29, 2016, 15 U.S. general surgery residency programs were enrolled in an institutional review board-approved trial. SIMPL was made available after 70% of faculty and residents completed a 1-hour training session. Descriptive and univariate statistics analyzed multiple dimensions of feasibility, including training rates, volume of assessments, response rates/times, and dictation rates. The 20 most active residents and attendings were evaluated in greater detail. RESULTS A total of 90% of eligible users (1267/1412) completed training. Further, 13/15 programs began using SIMPL. Totally, 6024 assessments were completed by 254 categorical general surgery residents (n = 3555 assessments) and 259 attendings (n = 2469 assessments), and 3762 unique operations were assessed. There was significant heterogeneity in participation within and between programs. Mean percentage (range) of users who completed ≥1, 5, and 20 assessments were 62% (21%-96%), 34% (5%-75%), and 10% (0%-32%) across all programs, and 96%, 75%, and 32% in the most active program. Overall, response rate was 70%, dictation rate was 24%, and mean response time was 12 hours. Assessments increased from 357 (September 2015) to 1146 (February 2016). The 20 most active residents each received mean 46 assessments by 10 attendings for 20 different procedures. CONCLUSIONS SIMPL can be feasibly integrated into surgical training programs to enhance the frequency and timeliness of intraoperative performance assessment. We believe SIMPL could help facilitate a national competency-based surgical training system, although local and systemic challenges still need to be addressed.