Comparison of the QuantiFERON-TB Gold Plus and QuantiFERON-TB Gold In-Tube Interferon Gamma Release Assays in Patients at Risk for Tuberculosis and in Health Care Workers.

The QuantiFERON-TB Gold Plus (QFT-Plus; Qiagen, Germantown, MD) interferon gamma release assay (IGRA) received FDA clearance in 2017 and will replace the prior version of the assay, the QFT-Gold In-Tube (QFT-GIT). Here, we compared performances of the QFT-Plus assay and the QFT-GIT version in a diverse patient population, including patients undergoing evaluation for or follow-up of latent tuberculosis infection (LTBI; n = 39) or active TB infection (n = 3), and in health care workers (HCWs; n = 119) at Mayo Clinic (Rochester, MN). Compared to the QFT-GIT, the QFT-Plus assay showed 91.2% (31/34) positive, 98.4% (124/126) negative, and 96.6% (156/161) overall qualitative agreement among the 161 enrolled subjects, with a Cohen's kappa value of 0.91 (excellent interrater agreement). Among the 28 patients diagnosed with LTBI at the time of enrollment, the QFT-GIT and QFT-Plus assays agreed in 24 (85.7%) patients; in all four discordant patients, the positivity of the QFT-GIT or QFT-Plus IGRA was associated with low-level interferon gamma (IFN-γ) reactivity, ranging from 0.36 IU/ml to 0.66 IU/ml. Additionally, we document a high degree of correlation between IFN-γ levels in the QFT-GIT TB antigen tube and each of the two QFT-Plus TB antigen tubes, as well as between the QFT-Plus TB1 and TB2 tubes (Pearson's correlation coefficients [R] > 0.95). Overall, we show comparable results between the QFT-GIT and QFT-Plus assays in our study population composed of subjects presenting with a diverse spectrum of TB infections. Our findings suggest that the necessary transition to the QFT-Plus assay will be associated with a minimal difference in assay performance characteristics.

Clinical and Epidemiological Correlates of Low IFN-Gamma Responses in Mitogen Tube of QuantiFERON Assay in Tuberculosis Infection Screening During the COVID-19 Pandemic: A Population-Based Marker of COVID-19 Mortality?

Background: The clinical and epidemiological implications of abnormal immune responses in COVID-19 for latent tuberculosis infection (LTBI) screening are unclear. Methods: We reviewed QuantiFERON TB Gold Plus (QFT-Plus) results (36,709 patients) from July 2016 until October 2021 in Asturias (Spain). We also studied a cohort of ninety hospitalized patients with suspected/confirmed COVID-19 pneumonia and a group of elderly hospitalized patients with COVID-19 who underwent serial QFT-Plus and immune profiling testing. Results: The indeterminate QFT-Plus results rate went from 1.4% (July 2016 to November 2019) to 4.2% during the COVID-19 pandemic. The evolution of the number of cases with low/very low interferon-gamma (IFN-gamma) response in the mitogen tube paralleled the disease activity and number of deaths during the pandemic waves in our region (from March 2020 to October 2021). The percentages of positive QFT-plus patients did not significantly change before and during the pandemic (13.9% vs. 12.2%). Forty-nine patients from the suspected/confirmed COVID-19 pneumonia cohort (54.4%) had low/very low IFN-gamma response to mitogen, 22 of them (24.4%) had severe and critical pneumonia. None received immunosuppressants prior to testing. Abnormal radiological findings (P = 0.01) but not COVID-19 severity was associated with low mitogen response. Immune profiling showed a reduction of CD8 + T cells and a direct correlation between the number of EMRA CD8 + T-cells and IFN-gamma response to mitogen (P = 0.03). Conclusion: Low IFN-gamma responses in mitogen tube of QFT-Plus often occur in COVID-19 pneumonia, which is associated with a low number of an effector CD8 + T-cell subset and does not seem to affect LTBI screening; however, this abnormality seems to parallel the dynamics of COVID-19 at the population level and its mortality.

Non-antimicrobial airway management of non-cystic fibrosis bronchiectasis.

Bronchiectasis are often encountered in clinical practice, and are characterized by abnormal airway dilatation and distortion associated with impaired mucociliary clearance and mucous plugging, which are frequently associated with recurrent infections. Numerous etiologies can underlie the development of bronchiectasis, but the most important distinction in research and clinical practice is between bronchiectasis due to cystic fibrosis (CF) and bronchiectasis due to all other reasons (non-CF bronchiectasis). The causes of non-CF bronchiectasis are varied and often unclear. Patients disease severity and phenotypes of non-CF bronchiectasis also varied, which can influence disease trajectory, frequency of exacerbations and mortality. This article reviews the published evidence and suggests interventions to enhance airways clearance in patients with non-CF bronchiectasis, which are key components of an individualized therapeutic program in order to achieve symptomatic relief and prevention of exacerbations and functional decline.

Extracorporeal elimination of butalbital in acute aspirin-butalbital-caffeine-codeine (Fiorinal with Codeine) poisoning.

BACKGROUND: Butalbital is a small molecule (approximately 220 Da), with 26% protein binding, a 0.8 L/kg volume of distribution, and is eliminated nearly 80% unchanged in the urine. Although hemodialysis has been used to treat overdoses of other barbiturates, the extracorporeal clearance of butalbital is unknown. The objective of this case is to describe the use of extracorporeal therapy to augment elimination of butalbital after an overdose of aspirin 325 mg-butalbital 50 mg-caffeine 40 mg with codeine 30 mg (Fiorinal with Codeine). METHODS: This is a case report of a single patient. RESULTS: A 67-year-old female was admitted to the medical intensive care unit approximately 3 h after ingestion of 40 tablets of Fiorinal with Codeine. Her presentation was notable for a decline in mental status, preserved renal function and a relatively low peak salicylate concentration at 46.4 mg/dL (3.4 mmol/L). Approximately 8 h after ingestion of 2000 mg of butalbital, our patient's serum concentration was 26.9 mg/L (normal <10 mg/L). At the end of a four-hour hemodialysis session, the total body elimination of butalbital was approximately 60% which corresponded to an intradialytic clearance of 233-300 mL/min. CONCLUSIONS: The extracorporeal clearance of butalbital observed in this case demonstrates the utility of dialysis to augment drug elimination in a Fiorinal with Codeine overdose.

Transition from acute to chronic hypercapnia in patients with periodic breathing: predictions from a computer model.

Acute hypercapnia may develop during periodic breathing from an imbalance between abnormal ventilatory patterns during apnea and/or hypopnea and compensatory ventilatory response in the interevent periods. However, transition of this acute hypercapnia into chronic sustained hypercapnia during wakefulness remains unexplained. We hypothesized that respiratory-renal interactions would play a critical role in this transition. Because this transition cannot be readily addressed clinically, we modified a previously published model of whole-body CO2 kinetics by adding respiratory control and renal bicarbonate kinetics. We enforced a pattern of 8 h of periodic breathing (sleep) and 16 h of regular ventilation (wakefulness) repeated for 20 days. Interventions included varying the initial awake respiratory CO2 response and varying the rate of renal bicarbonate excretion within the physiological range. The results showed that acute hypercapnia during periodic breathing could transition into chronic sustained hypercapnia during wakefulness. Although acute hypercapnia could be attributed to periodic breathing alone, transition from acute to chronic hypercapnia required either slowing of renal bicarbonate kinetics, reduction of ventilatory CO2 responsiveness, or both. Thus the model showed that the interaction between the time constant for bicarbonate excretion and respiratory control results in both failure of bicarbonate concentration to fully normalize before the next period of sleep and persistence of hypercapnia through blunting of ventilatory drive. These respiratory-renal interactions create a cumulative effect over subsequent periods of sleep that eventually results in a self-perpetuating state of chronic hypercapnia.

Cystatin C Falsely Underestimated GFR in a Critically Ill Patient with a New Diagnosis of AIDS.

Cystatin C has been suggested to be a more accurate glomerular filtration rate (GFR) surrogate than creatinine in patients with acquired immunodeficiency syndrome (AIDS) because it is unaffected by skeletal muscle mass and dietary influences. However, little is known about the utility of this marker for monitoring medications in the critically ill. We describe the case of a 64-year-old female with opportunistic infections associated with a new diagnosis of AIDS. During her course, she experienced neurologic, cardiac, and respiratory failure; yet her renal function remained preserved as indicated by an eGFR ≥ 120 mL/min and a urine output > 1 mL/kg/hr without diuresis. The patient was treated with nephrotoxic agents; therefore cystatin C was assessed to determine if cachexia was resulting in a falsely low serum creatinine. Cystatin C measured 1.50 mg/L which corresponded to an eGFR of 36 mL/min. Given the >60 mL/min discrepancy, serial 8-hour urine samples were collected and a GFR > 120 mL/min was confirmed. It is unclear why cystatin C was falsely elevated, but we hypothesize that it relates to the proinflammatory state with AIDS, opportunistic infections, and corticosteroids. More research is needed before routine use of cystatin C in this setting can be recommended.

Glucose control in critical care.

Glycemic control among critically-ill patients has been a topic of considerable attention for the past 15 years. An initial focus on the potentially deleterious effects of hyperglycemia led to a series of investigations regarding intensive insulin therapy strategies that targeted tight glycemic control. As knowledge accumulated, the pursuit of tight glycemic control among critically-ill patients came to be seen as counterproductive, and moderate glycemic control came to dominate as the standard practice in intensive care units. In recent years, there has been increased focus on the importance of hypoglycemic episodes, glycemic variability, and premorbid diabetic status as factors that contribute to outcomes among critically-ill patients. This review provides a survey of key studies on glucose control in critical care, and aims to deliver perspective regarding glycemic management among critically-ill patients.

Experience with rituximab in the treatment of antineutrophil cytoplasmic antibody associated vasculitis.

Prior to the 1970s, severe cases of antineutrophil cytoplasmic antibody associated vasculitis (AAV) were thought to be invariably fatal. However, the use of cyclophosphamide-based treatment regimens fundamentally altered disease outcomes, transforming AAV into a manageable, chronic illness. Despite the tremendous success of cyclophosphamide in the treatment of AAV, there remained a need for alternative therapies, due to high rates of treatment failures and significant toxicities. In recent years, with the introduction of targeted biologic response modifiers into clinical practice, many have hoped that the treatment options for AAV could be expanded. Rituximab, a chimeric monoclonal antibody directed against the B-lymphocyte protein CD20, has been the most successful biologic response modifier to be used in AAV. Following the first report of its use in AAV in 2001, experience with rituximab for treatment of AAV has rapidly expanded. Rituximab, in combination with glucocorticosteroids, is now well established as a safe and effective alternative to cyclophosphamide for remission induction for severe manifestations of granulomatosis with polyangiitis and microscopic polyangiitis. In addition, initial experiences with rituximab for remission maintenance in these diseases have been favorable, as have experiences for remission induction in eosinophilic granulomatosis with polyangiitis.

Distinct molecular mechanisms for agonist peptide binding to types A and B cholecystokinin receptors demonstrated using fluorescence spectroscopy.

Fluorescence spectroscopy provides a direct method for evaluating the environment of a fluorescent ligand bound to its receptor. We utilized this methodology to determine the environment of Alexa within a cholecystokinin (CCK)-like probe (Alexa488-Gly-[(Nle(28,31))CCK-26-33]; CCK-8 probe) bound to the type A CCK receptor (Harikumar, K. G., Pinon, D. L., Wessels, W. S., Prendergast, F. G., and Miller, L. J. (2002) J. Biol. Chem. 277, 18552-18560). Here, we study this probe at the type B CCK receptor and develop another probe with its fluorophore closer to the carboxyl-terminal pharmacophore of type B receptor ligands (Alexa488-Trp-Nle-Asp-Phe-NH2; CCK-4 probe). Both probes bound to type B CCK receptors in a saturable and specific manner and represented full agonists. Similar to the type A receptor, at the type B receptor these probes exhibited shorter lifetimes and lower anisotropy when the receptor was in the active conformation than when it was shifted to its inactive, G protein-uncoupled state using guanosine 5'-[beta,gamma-imido]-triphosphate trisodium salt. Absolute values for lifetime and anisotropy were lower for the CCK-8 probe bound to the type B receptor than for this probe bound to the type A receptor, and Alexa fluorescence was more easily quenched by iodide at the type B receptor. This represents the first direct evidence that, despite having identical affinities for binding and potencies for activating type A and B receptors, CCK is docked via distinct mechanisms, with the amino terminus more exposed to the aqueous milieu when bound to the type B CCK receptor than to the type A CCK receptor. Of interest, despite this difference in binding, activation of both receptors results in analogous direction of movement of the fluorescent indicator probes.