Mesenteric Vascular Injury in Trauma: An NTDB Study.

BACKGROUND: Although abdominal trauma remains a major cause of morbidity and mortality, there has not been a large-scale multicenter study regarding outcomes in patients who incur mesenteric vascular injuries. The goal of this retrospective analysis was to investigate the factors associated with outcomes in patients with trauma diagnosed with mesenteric vascular injuries. METHODS: A retrospective database analysis was performed on patients who sustained a mesenteric vascular injury (MVI, ICD-9 902.20-902.29) identified by the 2012 National Trauma Data Bank. Data were analyzed to identify differences in hospital length of stay, emergency room (ER) and final hospital disposition, and mortality based on patient age, gender, race, Injury Severity Score (ISS), and injury type (blunt or penetrating). RESULTS: Of the 1,133 total patients included, blunt trauma accounted for 740 (65%) of the injuries, whereas penetrating trauma accounted for 364 of the injuries (32%). Patients with penetrating injuries were 1.43 times more likely to die from their injuries than those suffering from blunt trauma (95% CI 1.04-1.98, P < 0.05). Patients with a higher ISS (>16) were 5.39 times more likely to die from their injuries than those with a lower ISS (95% CI 1.89-15.4, P = 0.002); if ISS was >25, the patient was 15.1 times more likely to die (95% CI 5.5-41.7, P < 0.001). Men were more likely to suffer from penetrating injuries than women (37% vs. 13%, P < 0.001), and African Americans were nearly 4 times more likely to present with penetrating injuries (69% vs 17%, P < 0.001). Age was also associated with mortality as patients >65 years and between 21 and 44 years were more likely to die from their injuries than patients in other age categories. Of the 740 patients with blunt MVIs, 326 (44%) were taken directly from the ER to the operating room (OR) and 306 (41%) to the intensive care unit (ICU), whereas with penetrating MVIs, 311 (85%) were taken to the OR from the emergency department and 18 (5%) to the intensive care unit. Of the 740 blunt MVIs, 115 died (16%), compared with 76 (21%) of the penetrating MVIs (P < 0.001). Injuries to the hepatic and superior mesenteric arteries were associated with higher mortality, with OR 2.03 and 3.03, respectively (P < 0.001). CONCLUSIONS: The presence of mesenteric arterial injury warrants rapid identification and management as these injuries are associated with significant morbidity and mortality, with penetrating mechanism, injury to large mesenteric vessels, and increased ISS associated with increased mortality.

The Impact of Anticoagulation on Trauma Outcomes : An National Trauma Data Bank Study.

BACKGROUND: Increased prevalence of patients on anticoagulants and the advent of new therapies raise concern over how these patients fare if they sustain a traumatic injury. We investigated the role of prehospitalization anticoagulation therapy in trauma-related mortality and postacute disposition. METHODS: A retrospective analysis was performed on patients who sustained traumatic injury identified in the 2017 National Trauma Data Bank (NTDB). Patients with and without anticoagulation therapy were analyzed to identify differences in demographics, injury type, Injury Severity Score (ISS), and trauma outcomes including hospital length of stay, ER, final hospital disposition, and mortality. Logistic regression was used to correlate anticoagulation to mortality and facility discharge. RESULTS: Of the 1 000 596 patients included, 73 602 (7%) patients were on anticoagulants at the time of their trauma. Increased age was the strongest predictor for anticoagulation therapy (odds ratio 5.54, 95% CI 5.44-5.63), but being female and white were also independent predictors of anticoagulation (P < .001). Patients on anticoagulants had a significantly longer length of stay (5.11 days; 95% CI 5.06-5.15) than those who were not (4.37 days, 95% CI 4.36-4.39), were 2.20 times more likely to die (95% CI 2.12-2.28, P < .001), and were 2.77 times more likely to be discharged to a facility (95% CI 2.73-2.81, P < .001). Anticoagulation remained a significant predictor of worse trauma outcomes even when accounting for age and ISS in multivariate analysis. DISCUSSION: Anticoagulation preceding trauma-related admission is associated with higher mortality and an increased likelihood of the need for a posthospital care facility.

Appendiceal Carcinoid Tumors: Is There a Survival Advantage to Colectomy over Appendectomy?

BACKGROUND: Guidelines recommend colectomy for appendiceal carcinoid tumors larger than 2 cm, but physicians debate whether colectomy would be beneficial in treating smaller tumors. We sought to determine when colectomy confers a survival advantage over appendectomy. METHODS: Appendiceal carcinoid patients in the US Surveillance, Epidemiology, and End Results (SEER) database (1988-2011) were stratified by age group, gender, TNM stage, tumor grade, and race. Kaplan-Meier and logistic regression analyses relating grade, stage, and receipt of colectomy to overall and cancer-specific survival were performed. RESULTS: Of 817 patients who underwent surgical extirpation of an appendiceal carcinoid, 338 (41%) had appendectomy alone and 479 (59%) had additional colectomy. Surprisingly, patients who underwent colectomy had worse cancer-specific survival (HR 1.98, 95% CI 1.32-2.98, p = 0.001) than those who underwent appendectomy, and colectomy did not confer a survival advantage over appendectomy in any subset analysis including low-grade or high-grade tumors, smaller or larger than 2 cm, or node-positive, non-metastatic tumors. Even when accounting for stage and grade, colectomy was not associated with significantly better survival rates. Furthermore, as colectomy frequency has increased over the last decade, the 5-year survival rate has trended down. The main predictors of cancer-specific mortality in carcinoid patients were high-grade (grades 3-4) and high-stage (node positive or metastatic) tumors. CONCLUSIONS: Survival in patients with carcinoid tumor of the appendix is primarily determined by tumor grade and stage. Our study found no survival advantage to colectomy over appendectomy in a large cohort of patients with the disease. Further investigation is necessary prior to recommending change of practice for patients with appendiceal carcinoid tumors.

Farm Injuries: Animal Most Common, Machinery Most Lethal: An NTDB Study.

To characterize both emergency room (ER) and hospital discharge dispositions of patients presenting with farm-related injuries. The 2012 National Trauma Data Bank was queried in August 2017 for injuries occurring on a farm. Patients were stratified by gender, age group, race, Injury Severity Score (ISS), and injury type. We performed logistic regression analysis to correlate parameters with likelihood of discharge home or death. P values < 0.05 were considered significant. Five thousand six hundred thirty-one patients were identified, the majority of whom were male (72%) and white (85%). The most common mechanisms of injury included animal-related (29%), followed by falls, vehicles, and other causes. The highest ISSs were seen in vehicular injuries (11% ISS of 25+) and the greatest fatality rate was seen in machinery injuries (4%). Four thousand seven hundred fifty-three (84%) patients were admitted to the hospital, and 4056 (72%) were discharged home from the ER or after hospitalization. One hundred thirty patients (2%) died of their farm-related injury. Most patients presenting to the ER with farm-related injuries survive, are admitted to the hospital, and are ultimately discharged home. Few patients die of their injuries. Animal injury is most common and machinery injury most lethal of farm trauma patients presenting to the ER.

Abdominal and Pelvic Vascular Injury: A National Trauma Data Bank Study.

The aim of this study was to characterize the outcomes of traumatic abdominal and pelvic vascular injuries. Using the 2012 National Trauma Data Bank, we identified 5858 patients with major abdominal and/or pelvic vascular injury. Patients were stratified by age group, gender, race, Injury Severity Score (ISS), and mechanism of injury. We evaluated the percentage of patients with blunt and penetrating trauma by demographic and correlated the mechanism of injury to the ISS score, emergency room disposition, and hospital disposition. We performed a logistic regression analysis to calculate predictors of death. In the final cohort, 1458 patients (25%) with abdominal/pelvic vascular injury died of trauma. In total, 3368 patients (57%) had a blunt mechanism of injury, whereas 2353 (40%) were victims of a penetrating trauma. Patients with penetrating injuries were 1.72 times more likely to die from their injuries than those with blunt traumas. Patients with higher ISS scores (>16) were more likely to die from their injuries than patients with lower ISS scores. Men were more likely to experience a penetrating vascular injury than women (48% vs 17%). Similarly, 77 per cent of black patients had a penetrating mechanism of injury compared with 20 per cent of white patients. There were 1910 patients with penetrating injuries (81%) that went immediately from the emergency room to the OR, compared with 1287 patients with blunt injuries (38%). Of the patients with blunt injuries, 695 (21%) died, whereas 727 (31%) patients with penetrating injuries died. Abdominal and pelvic traumatic vascular injuries carry a high mortality rate. Penetrating mechanism of injury, ISS score, and race are independent predictors of mortality.

Survival trends in patients with tracheal carcinoma from 1973 to 2011.

PURPOSE: The prognosis for primary tracheal cancer is dismal. We investigated whether there has been improvement in survival in tracheal cancer patients and how treatment modality affected overall and cancer-specific survival. MATERIALS AND METHODS: Using the Surveillance, Epidemiology, and End Results database, 1144 patients with tracheal cancer were identified between 1973 and 2011. Patients were stratified by age group, gender, race, tumor histology, and treatment modality. Radical surgery and survival rates based upon these stratifications were determined. Longitudinal analyses of survival and the percentage of patients undergoing surgery and radiation were conducted. RESULTS: In the final cohort, 327 tracheal cancer patients (34%) underwent radical surgery. Patients of younger age, female gender, and who presented with non-squamous cell tumors were statistically more likely to undergo surgery. Over time, utilization of radiation has declined while use of radical surgery has increased. Concomitantly, 5-year survival has increased from approximately 25% in 1973 to 30% by 2006. Those who did not have surgery were 2.50 times more likely to die of tracheal cancer (95% Confidence Interval 2.00-3.11, p<0.001) than those who did have surgery. Additionally, patients who underwent radical surgery alone (without adjuvant radiation therapy) were 50% or 19% less likely to die of tracheal cancer than those who underwent no treatment or combination therapy, respectively (both p<0.001). CONCLUSIONS: Survival in patients with tracheal cancer is improving over time. The utilization of radical surgery is increasing and confers the highest survival advantage to patients who are candidates.

Socioeconomic and gender disparities in anal cancer diagnosis and treatment.

BACKGROUND AND OBJECTIVES: We investigated whether receipt of radiation in patients with anal carcinoma is related to income level and other demographic factors. METHODS: The SEER database (1988-2011) was queried and linked to the Area Health Resources File (AHRF). We used logistic regression and Kaplan-Meier analyses to correlate receipt of radiation and overall and cancer-specific survival with tumor stage, age, gender, and income. RESULTS: Of 28,028 patients with anal cancer, 14,783 (53%) received radiation. Patients in the lowest quartile for median household income were significantly more likely to present at higher stages, were 1.87 times more likely to receive radiation (95% CI 1.74-2.00, p < 0.001), and 1.27 times more likely to die of anal cancer (95% CI 1.18-1.33, p < 0.001) than those in the highest income quartile. Within most stages, however, the wealthiest patients were more likely to receive radiation therapy than the poorest patients. Additionally, we found that women presented at higher stages (p < 0.001), were 2.67 times more likely to receive radiation (95% CI 2.55-2.81, p < 0.001), and were 1.25 times more likely to die of anal cancer than men (95% CI 1.17-1.32, p < 0.001). CONCLUSIONS: Women and poorer patients present with more advanced stages of anal cancer, more commonly receive radiation, and are more likely to die of anal cancer than men and wealthier patients, respectively.

Effect of median household income on surgical approach and survival in renal cell carcinoma.

PURPOSE: We sought to determine whether median household income (MHI) independently predicts surgical approach (partial vs. radical nephrectomy) and survival in patients with renal cell carcinoma. METHODS: The U.S. Surveillance Epidemiology and End Results Database (1988-2011) was queried to examine kidney cancer cases and linked to the Area Health Resources File. We correlated surgical approach and survival, both overall and cancer-specific, with tumor stage, age, race, sex, and income data. RESULTS: Of 152,589 patients diagnosed with renal cell carcinoma, 24,221 (16%) patients underwent partial nephrectomy, 102,771 (67%) patients underwent radical nephrectomy, and 25,597 (17%) patients had no surgery. There was no significant difference in stage of presentation between the wealthiest and poorest MHI quartiles, with approximately 35% of patients in each quartile presenting with T1aN0M0 disease and 17% of patients presenting with metastatic disease. Despite this, 18% of patients in the wealthiest quartile underwent partial nephrectomy compared to 14% of patients in the poorest quartile. Although the percentage of patients undergoing partial nephrectomy rose over the timeframe studied in both the wealthiest and poorest quartiles, the rate of rise was highest in the wealthier group. Those in the poorest quartile were 0.10 times more likely to die of all causes (95% CI: 1.09-1.11, P<0.001) and 0.09 times more likely to die of kidney cancer (95% CI: 1.05-1.10, P<0.001) than those in the wealthiest quartile over the timeframe studied. CONCLUSIONS: Despite presenting with similar stage, patients with lower MHI less commonly undergo partial nephrectomy and are more likely to die of kidney cancer than those in the highest MHIs.

Trends in lymph node excision and impact of positive lymph node ratio in patients with colectomy for primary colon adenocarcinoma: Population based study 1988 to 2011.

BACKGROUND: Studies suggest increased lymph node excision in patients with colon cancer portends improved survival. Guidelines recommend excising 12 or more lymph nodes during colectomy. There is an inverse correlation between the positive lymph node ratio and survival in patients of these patients. OBJECTIVE: We sought to determine whether colon cancer patients have adequate lymph node excision and whether positive lymph node ratio can be used as a guiding factor for their treatment plan. DESIGN: Retrospective, Observational. SETTINGS: United States, 1988-2011. PATIENTS: Utilizing the Surveillance, Epidemiology, and End Results registry, we identified 318,323 patients who underwent colectomy for colonic adenocarcinoma. Patients were stratified by age, tumor stage, tumor grade, race, ratio of positive nodes, and year of diagnosis. MAIN OUTCOME MEASURES: We determined the percentage of patients undergoing lymph node excision and mean number of nodes excised by year of diagnosis. In patients with adequate lymph node excision, positive lymph node ratio versus overall and cancer-specific survival was evaluated. RESULTS: 302,620 patients (95%) had at least 1 lymph node excised and 164,583 patients (52%) had 12 or more lymph nodes excised. This correlates to an increase from approximately 30% in 1988 to 80% by 2011. The mean number of nodes excised doubled from 9 to 18 in the entire cohort over the timeframe studied. On multivariate analysis, the 4 year cluster of diagnosis was the largest predictor of receipt of adequate lymph node excision with a 1.68 times higher odds per 4-year increase from 1988 (95% CI 1.67-1.69, p < 0.001). Higher positive lymph node ratio correlated with significantly worse overall and cancer-specific survival in those who had 12 or more lymph nodes excised. At a positive lymph node ratio of 0.16, there is a 15.7% increased rate of cancer specific mortality. CONCLUSIONS: Despite improvement in the performance of lymph node excision in patients undergoing colectomy for colon adenocarcinoma since 1988, only 80% of patients had adequate lymph node excision in 2011. Increasing positive lymph node ratio predicts significantly worse cancer-specific survival and a ratio of 0.16 may be considered an indication for a more aggressive therapeutic plan. CATEGORY: Colorectal/Anal Neoplasia.

Caring to Care: Applying Noddings' Philosophy to Medical Education.

The authors argue that Nel Noddings' philosophy, "an ethic of caring," may illuminate how students learn to be caring physicians from their experience of being in a caring, reciprocal relationship with teaching faculty. In her philosophy, Noddings acknowledges two important contextual continuities: duration and space, which the authors speculate exist within longitudinal integrated clerkships. In this Perspective, the authors highlight core features of Noddings' philosophy and explore its applicability to medical education. They apply Noddings' philosophy to a subset of data from a previously published longitudinal case study to explore its "goodness of fit" with the experience of eight students in the 2012 cohort of the Columbia-Bassett longitudinal integrated clerkship. In line with Noddings' philosophy, the authors' supplementary analysis suggests that students (1) recognized caring when they talked about "being known" by teaching faculty who "cared for" and "trusted" them; (2) responded to caring by demonstrating enthusiasm, action, and responsibility toward patients; and (3) acknowledged that duration and space facilitated caring relations with teaching faculty. The authors discuss how Noddings' philosophy provides a useful conceptual framework to apply to medical education design and to future research on caring-oriented clinical training, such as longitudinal integrated clerkships.

Opening School-Based Health Centers in a Rural Setting: Effects on Emergency Department Use.

BACKGROUND: Previous studies of urban school-based health centers (SBHCs) have shown that SBHCs decrease emergency department (ED) utilization. This study seeks to evaluate the effect of SBHCs on ED utilization in a rural setting. METHODS: This retrospective, controlled, quasi-experimental study used an ED patient data set from the Bassett Healthcare Network in rural New York to compare ED visits between school-aged children from 12 SBHC schools before and after the SBHC opening. Time series analysis was used to determine trends in SBHC schools and 2 control schools without SBHCs over the 18-year study period. RESULTS: ED visit incidence densities for all 12 school districts combined showed a significant increase in ED visits post-SBHC (Rate ratio (RR) = 1.15; p < .0001). This increase may, in part, be explained by the upward trend of ED visits in the region, as seen in the small, but significant, positive slope (RR = 0.0033, p < .0001) for control schools. There was variation in the change in incidence density post-SBHC among school districts, with increases in 78% of schools. CONCLUSIONS: The opening of SBHCs in rural settings results in a slight, but significant, increase in ED use, which is contrary to previous cross-sectional studies in urban settings.

HIV-1 integrates into resting CD4+ T cells even at low inoculums as demonstrated with an improved assay for HIV-1 integration.

Human Immunodeficiency Virus Type 1 (HIV-1) establishes a latent reservoir early in infection that is resistant to the host immune response and treatment with highly active antiretroviral therapy (HAART). The best understood of these reservoirs forms in resting CD4(+) T cells. While it remains unclear how reservoirs form, a popular model holds that the virus can only integrate in activated CD4(+) T cells. Contrary to this model, our previous results suggest that HIV-1 can integrate directly into the genomes of resting CD4(+) T cells. However, a limitation of our previous studies was that they were conducted at high viral inoculum and these conditions may lead to cellular activation or saturation of restriction factors. In the present study, we tested if our previous findings were an artifact of high inoculum. To do this, we enhanced the sensitivity of our integration assay by incorporating a repetitive sampling technique that allowed us to capture rare integration events that occur near an Alu repeat. The new technique represents a significant advance as it enabled us to measure integration accurately down to 1 provirus/well in 15,000 genomes--a 40-fold enhancement over our prior assay. Using this assay, we demonstrate that HIV can integrate into resting CD4(+) T cells in vitro even at low viral inoculum. These findings suggest there is no threshold number of virions required for HIV to integrate into resting CD4(+) T cells.

A novel assay allows genotyping of the latent reservoir for human immunodeficiency virus type 1 in the resting CD4+ T cells of viremic patients.

A latent reservoir for human immunodeficiency virus type 1 (HIV-1) consisting of integrated provirus in resting memory CD4+ T cells prevents viral eradication in patients on highly active antiretroviral therapy (HAART). It is difficult to analyze the nature and dynamics of this reservoir in untreated patients and in patients failing therapy, because it is obscured by an excess of unintegrated viral DNA that constitutes the majority of viral species in resting CD4+ T cells from viremic patients. Therefore, we developed a novel culture assay that stimulates virus production from latent, integrated HIV-1 in resting CD4+ T cells in the presence of antiretroviral drugs that prevent the replication of unintegrated virus. Following activation, resting CD4+ T cells with integrated HIV-1 DNA produced virus particles for several days, with peak production at day 5. Using this assay, HIV-1 pol sequences from the resting CD4+ T cells of viremic patients were found to be genetically distinct from contemporaneous plasma virus. Despite the predominance of a relatively homogeneous population of drug-resistant viruses in the plasma of patients failing HAART, resting CD4+ T cells harbored a diverse array of wild-type and archival drug-resistant viruses that were less fit than plasma virus in the context of current therapy. These results provide the first direct evidence that resting CD4+ T cells serve as a stable reservoir for HIV-1 even in the setting of high levels of viremia. The ability to analyze archival species in viremic patients may have clinical utility in detecting drug-resistant variants not present in the plasma.

Intermittent HIV-1 viremia (Blips) and drug resistance in patients receiving HAART.

CONTEXT: Many patients infected with human immunodeficiency virus type 1 (HIV-1) and receiving highly active antiretroviral therapy experience intermittent episodes of detectable viremia ("blips"), which may raise concerns about drug resistance, lead to costly repeat measurements of viral RNA, and sometimes trigger alterations in therapy. OBJECTIVE: To test the hypothesis that blips represent random biological and statistical variation around mean steady-state HIV-1 RNA levels slightly below 50 copies/mL rather than biologically significant elevations in viremia. DESIGN, SETTING, AND PATIENTS: Between June 19, 2003, and February 9, 2004, patients receiving therapy underwent intensive sampling (every 2-3 days) over 3 to 4 months to define the frequency, magnitude, and duration of blips and their association with drug levels and other clinical variables. Blips were defined as HIV-1 RNA measurements greater than or equal to 50 copies/mL preceded and followed by measurements less than 50 copies/mL without a change in treatment. To determine whether blips result from or lead to drug resistance, an ultrasensitive genotyping assay was used to detect drug resistance mutations before, during, and after blips. Patients were 10 HIV-1-infected asymptomatic adults recruited by clinicians and followed up in the Moore Clinic at the Johns Hopkins Hospital. Patients had suppression of viremia to below 50 copies/mL while receiving a stable antiretroviral regimen for 6 months or longer. MAIN OUTCOME MEASURES: At each time point, plasma HIV-1 RNA levels were measured in 2 independent laboratories and drug resistance mutations were analyzed by clonal sequencing. RESULTS: With the intensive sampling, blips were detected in 9 of 10 patients. Statistical analysis was consistent with random assay variation around a mean viral load below 50 copies/mL. Blips were not concordant on independent testing and had a short duration (median, <3 days) and low magnitude (median, 79 copies/mL). Blip frequency was not associated with demographic, clinical, or treatment variables. Blips did not occur in relation to illness, vaccination, or directly measured antiretroviral drug concentrations. Blips were marginally associated (P = .08) with reported episodes of nonadherence. Most importantly, in approximately 1000 independent clones sequenced for both protease and reverse transcriptase, no new resistance mutations were seen before, during, or shortly after blips. CONCLUSION: Most blips in this population appear to represent random biological and statistical variation around mean HIV-1 levels below 50 copies/mL rather than clinically significant elevations in viremia.

Resting CD4+ T cells from human immunodeficiency virus type 1 (HIV-1)-infected individuals carry integrated HIV-1 genomes within actively transcribed host genes.

Resting CD4+ T-cell populations from human immunodeficiency virus type 1 (HIV-1)-infected individuals include cells with integrated HIV-1 DNA. In individuals showing suppression of viremia during highly active antiretroviral therapy (HAART), resting CD4+ T-cell populations do not produce virus without cellular activation. To determine whether the nonproductive nature of the infection in resting CD4+ T cells is due to retroviral integration into chromosomal regions that are repressive for transcription, we used inverse PCR to characterize the HIV-1 integration sites in vivo in resting CD4+ T cells from patients on HAART. Of 74 integration sites from 16 patients, 93% resided within transcription units, usually within introns. Integration was random with respect to transcriptional orientation relative to the host gene and with respect to position within the host gene. Of integration sites within well-characterized genes, 91% (51 of 56) were in genes that were actively expressed in resting CD4+ T cells, as directly demonstrated by reverse transcriptase PCR (RT-PCR). These results predict that HIV-1 sequences may be included in the primary transcripts of host genes as part of rapidly degraded introns. RT-PCR experiments confirmed the presence of HIV-1 sequences within transcripts initiating upstream of the HIV-1 transcription start site. Taken together, these results demonstrate that HIV-1 genomes reside within actively transcribed host genes in resting CD4+ T cells in vivo.

Novel single-cell-level phenotypic assay for residual drug susceptibility and reduced replication capacity of drug-resistant human immunodeficiency virus type 1.

Human immunodeficiency virus type 1 (HIV-1)-infected individuals who develop drug-resistant virus during antiretroviral therapy may derive benefit from continued treatment for two reasons. First, drug-resistant viruses can retain partial susceptibility to the drug combination. Second, therapy selects for drug-resistant viruses that may have reduced replication capacities relative to archived, drug-sensitive viruses. We developed a novel single-cell-level phenotypic assay that allows these two effects to be distinguished and compared quantitatively. Patient-derived gag-pol sequences were cloned into an HIV-1 reporter virus that expresses an endoplasmic reticulum-retained Env-green fluorescent protein fusion. Flow cytometric analysis of single-round infections allowed a quantitative analysis of viral replication over a 4-log dynamic range. The assay faithfully reproduced known in vivo drug interactions occurring at the level of target cells. Simultaneous analysis of single-round infections by wild-type and resistant viruses in the presence and absence of the relevant drug combination divided the benefit of continued nonsuppressive treatment into two additive components, residual virus susceptibility to the drug combination and selection for drug-resistant variants with diminished replication capacities. In some patients with drug resistance, the dominant circulating viruses retained significant susceptibility to the combination. However, in other cases, the dominant drug-resistant viruses showed no residual susceptibility to the combination but had a reduced replication capacity relative to the wild-type virus. In this case, simplification of the regimen might still allow adequate suppression of the wild-type virus. In a third pattern, the resistant viruses had no residual susceptibility to the relevant drug regimen but nevertheless had a replication capacity equivalent to that of wild-type virus. In such cases, there is no benefit to continued treatment. Thus, the ability to simultaneously analyze residual susceptibility and reduced replication capacity of drug-resistant viruses may provide a basis for rational therapeutic decisions in the setting of treatment failure.

Continued production of drug-sensitive human immunodeficiency virus type 1 in children on combination antiretroviral therapy who have undetectable viral loads.

Highly active antiretroviral therapy (HAART) can suppress plasma human immunodeficiency virus type 1 (HIV-1) levels to below the detection limit of ultrasensitive clinical assays. However, HIV-1 persists in cellular reservoirs, and in adults, persistent low-level viremia is detected with more sensitive assays. The nature of this viremia is poorly understood, and it is unclear whether viremia persists in children on HAART, particularly those who start therapy shortly after birth. We therefore developed a reverse transcriptase PCR (RT-PCR) assay that allows genotyping of HIV-1 protease even when viremia is present at levels as low as 5 copies of HIV-1 RNA/ml. We demonstrated that viremia persists in children with plasma virus levels below the limit of detection of clinical assays. Viremia was detected even in children who began HAART in early infancy and maintained such strong suppression of viremia that HIV-1-specific antibody responses were absent or minimal. The low-level plasma virus lacked protease inhibitor resistance mutations despite the frequent use of nelfinavir, which has a low mutational barrier to resistance. Protease sequences resembled those of viruses in the latent reservoir in resting CD4(+) T cells. Thus, in most children on HAART with clinically undetectable viremia, there is continued virus production without evolution of resistance in the protease gene.

Barrier-to-autointegration factor BAF binds p55 Gag and matrix and is a host component of human immunodeficiency virus type 1 virions.

Barrier-to-autointegration factor (BAF) is a conserved human chromatin protein exploited by retroviruses. Previous investigators showed that BAF binds double-stranded DNA nonspecifically and is a host component of preintegration complexes (PICs) isolated from cells infected with human immunodeficiency virus type 1 (HIV-1) or Moloney murine leukemia virus. BAF protects PIC structure and stimulates the integration of salt-stripped PICs into target DNA in vitro. PICs are thought to acquire BAF from the cytoplasm during infection. However, we identified two human tissues (of 16 tested) in which BAF mRNA was not detected: thymus and peripheral blood leukocytes, which are enriched in CD4(+) T lymphocytes and macrophage precursors, respectively. BAF protein was detected in activated but not resting CD4(+) T lymphocytes; thus, if BAF were essential for PIC function, we hypothesized that virions might "bring their own BAF." Supporting this model, BAF copurified with HIV-1 virions that were digested with subtilisin to remove microvesicle contaminants, and BAF was present in approximately zero to three copies per virion. In three independent assays, BAF bound directly to both p55 Gag (the structural precursor of HIV-1 virions) and its cleaved product, matrix. Using lysates from cells overexpressing Gag, endogenous BAF and Gag were coimmunoprecipitated by antibodies against Gag. Purified recombinant BAF had low micromolar affinities (1.1 to 1.4 micro M) for recombinant Gag and matrix. We conclude that BAF is present at low levels in incoming virions, in addition to being acquired from the cytoplasm of newly infected cells. We further conclude that BAF might contribute to the assembly or activity of HIV-1 PICs through direct binding to matrix, as well as DNA.