Multiparameter analysis of stimulated human peripheral blood mononuclear cells: A comparison of mass and fluorescence cytometry.

Mass and fluorescence cytometry are quantitative single cell flow cytometry approaches that are powerful tools for characterizing diverse tissues and cellular systems. Here mass cytometry was directly compared with fluorescence cytometry by studying phenotypes of healthy human peripheral blood mononuclear cells (PBMC) in the context of superantigen stimulation. One mass cytometry panel and five fluorescence cytometry panels were used to measure 20 well-established lymphocyte markers of memory and activation. Comparable frequencies of both common and rare cell subpopulations were observed with fluorescence and mass cytometry using biaxial gating. The unsupervised high-dimensional analysis tool viSNE was then used to analyze data sets generated from both mass and fluorescence cytometry. viSNE analysis effectively characterized PBMC using eight features per cell and identified similar frequencies of activated CD4+ T cells with both technologies. These results suggest combinations of unsupervised analysis programs and extended multiparameter cytometry will be indispensable tools for detecting perturbations in protein expression in both health and disease.

Intramuscular midazolam versus intravenous lorazepam for the prehospital treatment of status epilepticus in the pediatric population.

OBJECTIVE: To examine the effectiveness of intramuscular (IM) midazolam versus intravenous (IV) lorazepam for the treatment of pediatric patients with status epilepticus (SE) in the prehospital care setting. METHODS: This multicenter clinical trial randomized patients diagnosed with SE to receive either IM midazolam or IV lorazepam administered by paramedics in the prehospital care setting. Included in this secondary analysis were only patients younger than 18 years of age. Evaluated were the associations of the treatment group (IM vs. IV) with the primary outcome, defined as seizure cessation prior to emergency department (ED) arrival, and with patient characteristics, time to important events, and adverse events. Descriptive statistics and 99% confidence intervals (CIs) were used for the analysis. RESULTS: Of 893 primary study subjects, 120 met criteria for this study (60 in each treatment group). There were no differences in important baseline characteristics or seizure etiologies between groups. The primary outcome was met in 41 (68.3%) and 43 (71.7%) of subjects in the IM and IV groups, respectively (risk difference [RD] -3.3%, 99% CI -24.9% to 18.2%). Similar results were noted for those younger than 11 years (RD -1.3%, 99% CI -25.7% to 23.1%). Time from initiating the treatment protocol was shorter for children who received IM midazolam, mainly due to the shorter time to administer the active treatment. Safety profiles were similar. SIGNIFICANCE: IM midazolam can be rapidly administered and appears to be safe and effective for the management of children with SE treated in the prehospital setting. The results must be interpreted in the context of the secondary analysis design and sample size of the study.

The impact of covariate adjustment at randomization and analysis for binary outcomes: understanding differences between superiority and noninferiority trials.

The question of when to adjust for important prognostic covariates often arises in the design of clinical trials, and there remain various opinions on whether to adjust during both randomization and analysis, at randomization alone, or at analysis alone. Furthermore, little is known about the impact of covariate adjustment in the context of noninferiority (NI) designs. The current simulation-based research explores this issue in the NI setting, as compared with the typical superiority setting, by assessing the differential impact on power, type I error, and bias in the treatment estimate as well as its standard error, in the context of logistic regression under both simple and covariate adjusted permuted block randomization algorithms. In both the superiority and NI settings, failure to adjust for covariates that influence outcome in the analysis phase, regardless of prior adjustment at randomization, results in treatment estimates that are biased toward zero, with standard errors that are deflated. However, as no treatment difference is approached under the null hypothesis in superiority and under the alternative in NI, this results in decreased power and nominal or conservative (deflated) type I error in the context of superiority but inflated power and type I error under NI. Results from the simulation study suggest that, regardless of the use of the covariate in randomization, it is appropriate to adjust for important prognostic covariates in analysis, as this yields nearly unbiased estimates of treatment as well as nominal type I error.

Endotracheal Intubation in Patients Treated for Prehospital Status Epilepticus.

INTRODUCTION: Limited data describe the frequency, timing, or indications for endotracheal intubation (ETI) in patients with status epilepticus. A better understanding of the characteristics of patients with status epilepticus requiring airway interventions could inform clinical care. We sought to characterize ETI use in patients with prehospital status epilepticus. METHODS: This study was a secondary analysis of the Rapid Anticonvulsant Medication Prior to Arrival Trial, a multi-center, randomized trial comparing intravenous lorazepam to intramuscular midazolam for prehospital status epilepticus treatment. Subjects received ETI in the prehospital, Emergency Department (ED), or inpatient setting at the discretion of caregivers. RESULTS: Of 1023 enrollments, 218 (21 %) received ETI. 204 (93.6 %) of the ETIs were performed in the hospital and 14 (6.4 %) in the prehospital setting. Intubated patients were older (52 vs 41 years, p < 0.001), and men underwent ETI more than women (26 vs 21 %, p = 0.047). Patients with ongoing seizures on ED arrival had a higher rate of ETI (32 vs 16 %, p < 0.001), as did those who received rescue anti-seizure medication (29 vs 20 %, p = 0.004). Mortality was higher for intubated patients (7 vs 0.4 %, p < 0.001). Most ETI (n = 133, 62 %) occurred early (prior to or within 30 min after ED arrival), and late ETI was associated with higher mortality (14 vs 3 %, p = 0.002) than early ETI. CONCLUSIONS: ETI is common in patients with status epilepticus, particularly among the elderly or those with refractory seizures. Any ETI and late ETI are both associated with higher mortality.

S1P, dihydro-S1P and C24:1-ceramide levels in the HDL-containing fraction of serum inversely correlate with occurrence of ischemic heart disease.

BACKGROUND: The lysosphingolipid sphingosine 1-phosphate (S1P) is carried in the blood in association with lipoproteins, predominantly high density lipoproteins (HDL). Emerging evidence suggests that many of the effects of HDL on cardiovascular function may be attributable to its S1P cargo. METHODS: Here we have evaluated how levels of S1P and related sphingolipids in an HDL-containing fraction of human serum correlate with occurrence of ischemic heart disease (IHD). To accomplish this we used liquid chromatography-mass spectrometry to measure S1P levels in the HDL-containing fraction of serum (depleted of LDL and VLDL) from 204 subjects in the Copenhagen City Heart Study (CCHS). The study group consisted of individuals having high serum HDL cholesterol (HDL-C) (females:≥ 73.5 mg/dL; males:≥ 61.9 mg/dL) and verified IHD; subjects with high HDL-C and no IHD; individuals with low HDL-C (females:≤ 38.7 mg/dL; males:≤ 34.1 mg/dL) and IHD, and subjects with low HDL-C and no IHD. RESULTS: The results show a highly significant inverse relationship between the level of S1P in the HDL-containing fraction of serum and the occurrence of IHD. Furthermore, an inverse relationship with IHD was also observed for two other sphingolipids, dihydro-S1P and C24:1-ceramide, in the HDL-containing fraction of serum. Additionally, we demonstrated that the amount of S1P on HDL correlates with the magnitude of HDL-induced endothelial cell barrier signaling. CONCLUSIONS: These findings indicate that compositional differences of sphingolipids in the HDL-containing fraction of human serum are related to the occurrence of IHD, and may contribute to the putative protective role of HDL in IHD.

Chronic HIV-1 Infection Impairs Superantigen-Induced Activation of Peripheral CD4+CXCR5+PD-1+ Cells, With Relative Preservation of Recall Antigen-Specific Responses.

Peripheral CD4+CXCR5+PD-1+ T cells are a putative circulating counterpart to germinal center T follicular helper (TFH) cells. They show both phenotypic and functional similarities to TFH cells, which provide necessary help for the differentiation of B cells to antibody-secreting plasmablasts. In this study, we evaluated the frequency, phenotypes, and responses of peripheral TFH-like (pTFH) cells to superantigen and recall antigen stimulation in 10 healthy and 34 chronically infected treatment-naive HIV-1+ individuals. There was no difference in the frequency of pTFH cells between HIV+ and HIV- individuals. Surface expression of ICOS, but not CD40L, was higher on pTFH cells at baseline in HIV+ individuals. Compared with HIV- individuals, pTFH cells from HIV+ individuals had decreased maximal expression of ICOS and CD40L in response to in vitro superantigen stimulation. This decreased response did not correlate with viral control, CD4 T-cell count, duration of infection, or the degree of neutralizing antibody breadth. Despite a decreased maximal response, pTFH responses to HIV Gag and tetanus toxoid recall antigens were preserved.

Greater activation of peripheral T follicular helper cells following high dose influenza vaccine in older adults forecasts seroconversion.

BACKGROUND: Influenza related morbidity and mortality disproportionately impacts older adults. The serologic response to vaccine is diminished in older adults; however, high dose inactivated influenza vaccine (HD IIV) has shown improved rates of seroconversion compared to standard dose (SD IIV). We hypothesize this may be due to the superior ability of high dose vaccine to activate T follicular helper (Tfh) cells and provide B cell dependent T cell help. METHODS: We measured peripheral Tfh (pTfh) activation in 50 community dwelling adults 65years or older who were randomly assigned to receive either the HD IIV or SD IIV. RESULTS: The HD vaccination elicited significantly higher levels of ICOS expression on pTfh cells, at day 7 compared to SD vaccination (p=0.02). The magnitude of the increase in ICOS+ pTfh cells from baseline to day 7 was predictive of seroconversion for both influenza A and B vaccination. CONCLUSION: Strong Tfh activation in response to influenza vaccination forecasts successful seroconversion in older adults, and HD IIV elicits greater Tfh activation than SD IIV. Future vaccine studies should focus on ways to further optimize the Tfh response.

Clinical Practice Variability in Temperature Correction of Arterial Blood Gas Measurements and Outcomes in Hypothermia-Treated Patients After Cardiac Arrest.

Mechanical ventilation in patients treated with mild therapeutic hypothermia (MTH) for the postcardiac arrest syndrome may be challenging given changes in solubility of arterial blood gases (ABGs) with cooling. Whether ABG measurements should be temperature corrected (TC) remain unknown. We sought to describe practice variability in TC at a single institution and explored the association between TC and neurological outcome. We conducted a retrospective cohort study reviewing electronic health records of all patients treated with MTH after cardiac arrest. We examined whether the percentage of TC ABGs relative to total number of ABGs drawn for each subject during hypothermia was associated with the neurological outcome at hospital discharge and 6-12-month follow-up. The cerebral performance category of 1-2 was defined as a favorable outcome in the logistic regression models. 1223 ABGs were obtained during MTH on 122 subjects over 6 years. TC was never used in 72 subjects (59%; no TC group), made available in 1-74% of ABGs in 17 subjects (14%; intermediate TC group), and made available in ≥75% of ABGs in 33 subjects (27%; mostly TC group). Groups differed in the proportion of subjects with shockable presenting rhythms (47% vs. 47% vs. 76%, p=0.02) and admitting ICU (p=0.005). Favorable 6-month outcomes were more common in the mostly TC than no TC group (48% vs. 25%; OR [95% CI]: 2.9 [1.2-7.1]), but not after adjustment (OR 1.5, 95% CI 0.33-6.9). There was substantial practice variability in the temperature correction strategy. Availability of temperature-corrected ABGs was not associated with improved neurological outcomes after adjusting for covariates.

Accounting for repeat enrollments during an emergency clinical trial: the Rapid Anticonvulsant Medications Prior to Arrival Trial (RAMPART).

OBJECTIVES: The objectives were to describe the frequency of repeat enrollment within a specific exception from informed consent trial testing benzodiazepine treatment of prehospital status epilepticus and to estimate the effect of repeat enrollments on the analysis of the primary outcome. METHODS: This was a secondary analysis of data collected as part of the Rapid Anticonvulsant Medication Prior to Arrival Trial (RAMPART), a study comparing intramuscular midazolam to intravenous lorazepam given by paramedics to patients with prehospital status epilepticus. Subjects in RAMPART achieved a successful primary outcome if they had cessation of seizures by the time of emergency department arrival. Data were collected on all subjects, but only the first enrollment for each individual was used in the primary analysis. The patterns of repeat enrollment are described, along with the demographics of these subjects. In addition, an intraclass correlation coefficient (ICC) was estimated to assess the amount of within-subject correlation and its effect on the estimated treatment effect when all enrollments are included in the analysis. RESULTS: A total of 1,023 enrollments occurred in RAMPART among 893 unique individuals (range of repeat enrollment observed = two to 14). The ICC for seizure cessation within individual was low at 0.119; when excluding subjects with benzodiazepine crossover, the ICC was 0.094. CONCLUSIONS: In clinical trials of emergency conditions with interval complete resolution, accounting for repeat enrollments is feasible. The RAMPART experience demonstrated that in this setting the within-subject correlation is low and can be accounted for at relatively low statistical cost.

Association of VH4-59 Antibody Variable Gene Usage with Recognition of an Immunodominant Epitope on the HIV-1 Gag Protein.

The human antibody response against HIV-1 infection recognizes diverse antigenic subunits of the virion, and includes a high level of antibodies to the Gag protein. We report here the isolation and characterization of a subset of Gag-specific human monoclonal antibodies (mAbs) that were prevalent in the antibody repertoire of an HIV-infected individual. Several lineages of Gag-specifc mAbs were encoded by a single antibody heavy chain variable region, VH4-59, and a representative antibody from this group designated mAb 3E4 recognized a linear epitope on the globular head of the p17 subunit of Gag. We found no evidence that mAb 3E4 exhibited any function in laboratory studies aimed at elucidating the immunologic activity, including assays for neutralization, Ab-dependent cell-mediated virus inhibition, or enhanced T cell reactivity caused by Gag-3E4 complexes. The findings suggest this immunodominant epitope in Gag protein, which is associated with VH4-59 germline gene usage, may induce a high level of B cells that encode binding but non-functional antibodies that occupy significant repertoire space following HIV infection. The studies define an additional specific molecular mechanism in the immune distraction activity of the HIV virion.

B cell responses to HIV antigen are a potent correlate of viremia in HIV-1 infection and improve with PD-1 blockade.

Infection with Human Immunodeficiency Virus Type 1 (HIV-1) induces defects of both cellular and humoral immune responses. Impaired CD4+ T cell help and B cell dysfunction may partially explain the low frequency of broadly neutralizing antibodies in HIV-infected individuals. To understand the extent of B cell dysfunction during HIV infection, we assessed the level of B cell activation at baseline and after stimulation with a variety of antigens. Increased levels of viremia were associated with higher baseline expression of the activation marker CD86 on B cells and with decreased ability of B cells to increase expression of CD86 after in vitro stimulation with inactivated HIV-1. In a series of cell isolation experiments B cell responses to antigen were enhanced in the presence of autologous CD4+ T cells. HIV infected individuals had a higher frequency of PD-1 expression on B cells compared to HIV- subjects and PD-1 blockade improved B cell responsiveness to HIV antigen, suggesting that inhibitory molecule expression during HIV-1 infection may contribute to some of the observed B cell defects. Our findings demonstrate that during chronic HIV infection, B cells are activated and lose full capacity to respond to antigen, but suppression of inhibitory pressures as well as a robust CD4+ T cell response may help preserve B cell function.

Stress- and cue-elicited craving and reactivity in marijuana-dependent individuals.

RATIONALE: Cue-elicited craving and stress responses have been identified as predictors of relapse in drug dependence, but little research exists on the contribution of these factors to marijuana use specifically. OBJECTIVES: The aims of the present study were to evaluate (1) responses to a psychological stressor, (2) responses to marijuana-related cues, and (3) if an exposure to a psychological stressor augmented craving subsequently elicited by marijuana-related cue exposure in marijuana-dependent individuals. METHODS: Subjective (craving, stress), neuroendocrine (adrenocorticotropic hormone (ACTH), cortisol), and physiologic responses to the presentation of neutral and marijuana cues were assessed after randomization to a stress (Trier Social Stress Task (TSST)) or non-stress control condition in marijuana-dependent individuals. Outcome measures were assessed at baseline, post-stressor/pre-neutral cue, post-neutral cue, and post-marijuana cue. RESULTS: Eighty-seven participants completed procedures (stress group, n = 45; non-stress group, n = 42). The stress group had a significant increase over the non-stress group in stress rating (p < 0.001), craving (p = 0.028), cortisol (p < 0.001), and ACTH (p < 0.001) after the completion of the TSST. An increased craving response for all participants was seen following the presentation of the marijuana cues (p = 0.005). Following the TSST or non-stress condition, the non-stress group had an increase in craving to marijuana cues as compared to neutral cues (p = 0.002); an increase in craving was not observed in the stress group (p = 0.404). CONCLUSIONS: Marijuana cue exposure and a social stressor increased craving in marijuana-dependent individuals. Completion of the TSST did not increase craving response to subsequent marijuana cue exposure.