Concentration of voxelotor in sickle cell disease can be estimated using electrophoresis and high-performance liquid chromatography.

OBJECTIVES: Voxelotor can increase hemoglobin levels in patients living with sickle cell disease (SCD). A clinician who is monitoring voxelotor response may want to know whole-blood voxelotor concentration, but this cannot be measured in most clinical settings. However, voxelotor has been demonstrated to cause "peak splitting" in common methods of hemoglobin measurement such as capillary zone electrophoresis (CZE) and high-performance liquid chromatography (HPLC). We hypothesized that we could use the size of the peak split to estimate the whole-blood concentration. METHODS: Blood from people with SCD was dosed with known concentrations of voxelotor, and multiparameter regression was used to derive the relationship of voxelotor concentration to the degree of peak splitting observed. To validate these equations, 21 patients started on voxelotor at 1500 mg/d had blood samples drawn at days 0, 14, 30, and 60. Samples were sent out for gold standard voxelotor concentration testing. The derived equations were then used to calculate voxelotor concentration. RESULTS: Calculated concentrations correlated strongly with measured concentrations for both CZE (R2 = 0.83, P < .001) and HPLC (R2 = 0.76, P < .001). Voxelotor concentration also had a significant effect on increases in hemoglobin (R2 = 0.40, P < .001). CONCLUSIONS: Thus, peak splitting CZE and HPLC can be used to estimate voxelotor concentration.

Excess deaths among adults with sickle cell disease in 2020 compared to prior years.

In 2020, there was a 20% increase in excess deaths in the USA due to COVID infections but also to changes in the healthcare system due to the pandemic. We hypothesized that people living with sickle cell disease (SCD) may be vulnerable to these changes as SCD can lead to rapid decompensation. We examined all deaths of people with SCD at our center in 2020. Cause of death was determined, clinical variables, and healthcare utilization, and the presence of COVID infection, sepsis, and acute organ failure during the death event was obtained from the electronic medical record. Deaths in 2020 were compared to deaths in 2017-2019. In 2020, deaths increase 244% (22 vs 9), but acute or previous COVID infections were identified in only 36% of 2020 deaths. People who died in 2020 were more likely to have developed acute organ failure during the death event (70.6% vs 21.1%, p = 0.003) compared to prior years. They were also more likely to have a history of stroke and more frequent hematology clinic visits. Deaths in 2020 doubled compared to prior years and COVID infection could not account for all of this excess mortality. People who died in 2020 may have had more severe disease as suggested by having more clinic visits and higher rates of stroke and were more likely to develop organ failure during the death event. This demonstrates that people with SCD may be especially vulnerable to delays in care. Larger multicenter studies should be conducted to examine this further.

Thoracic Pedicle Screw Placement Utilizing Hands-On Training Session on Three-Dimensional Models.

The utilization of three-dimensional (3D) models has been an important element of medical education. We demonstrate a three-dimensionally-printed (3DP) thoracic spine model for use in the teaching of freehand pedicle screw placement. Neurosurgical residents with varying years of experience practiced screw placement on these models. Residents were timed, and models were evaluated for medial and lateral breaches. Overall, this technical report describes the utility of 3D spine models in the training of thoracic pedicle screw placement. The tactile feedback from the 3D models was designed to represent both cortical and cancellous bones.

External Ventricular Drain (EVD) Placement Using a Hands-On Training Session on a Simple Three-Dimensional (3D) Model.

Neurosurgery is a demanding field with small margins of error within the operative field. Small errors can yield devastating consequences. Simulation has been proposed as a methodology for improving surgical skills within the neurosurgical realm. This study was conducted to investigate a novel realistic design for a clinical simulation based, low-cost alternative of external ventricular drain (EVD) placement, an essential basic neurosurgical procedure that is necessary for clinicians to master. A low-cost three-dimensional (3D) printed head using thermoplastic polylactic acid was designed with the tactile feedback of outer table, cancellous bone, and inner tables for drilling with replaceable frontal bones pieces for multi-use purposes. An agar gel filled with water was designed to simulate tactile passage through the cortex and into the ventricles. Neurosurgical and emergency resident physicians participated in a didactic session and then attempted placement of an EVD using the model to gauge the simulated model for accuracy and realism. Positioning, procedural time, and realism was evaluated. Improvements in procedural time and positioning were identified for both neurosurgical and emergency medicine (EM) residents. Catheter placement was within ideal position for all participants by the third attempt. All residents stated they felt more comfortable with placement with subsequent attempts. Neurosurgical residents subjectively noted similarities in tactile feedback during drilling compared to in-vivo. A low-cost realistic 3D printed model simulating basic neurosurgical procedures demonstrated improved procedural times and precision with neurosurgical and EM residents. Further, similarities between in-vivo tactile feedback and the low-cost simulation technology was noted. This low cost-model may be used as an adjunct for teaching to promote early procedural competency in neurosurgical techniques to promote learning without predisposition to patient morbidity.

Hydroxyurea and fetal hemoglobin effect on leg ulcers in patients with sickle cell disease.

The presence of leg ulcers in individuals with sickle cell disease often represents an early sign of vasculopathy and future end organ damage. Pathophysiological mechanisms of formation and evolution of leg ulcers are poorly understood; nevertheless, HbF has been associated with lower incidence of leg ulcers, while hydroxyurea has been correlated with high risk of leg ulcers. As a result, there is hesitation regarding hydroxyurea use in patients with SCD and leg ulcers. In this study, we aim to define (1) a target of HbF that offers protection against leg ulcer development and (2) the impact of hydroxyurea therapy on leg ulcer prevalence. Our study demonstrated that in order to reduce leg ulcer incidence by one-third, a HbF > 25% is needed, a threshold not commonly reached and maintained in the adult SCD population. Importantly, leg ulcer incidence appears to be independent of HU use (p = 0.50). Our interpretation of this data is that the use of HU in a patient with SCD and leg ulcers should be guided by a careful assessment of risks and benefits of this therapeutic modality.

Colocating Wound Care for Patients with Sickle Cell Ulcers in a Hematology Clinic.

OBJECTIVE: Leg ulcers affect 15% of people with sickle cell disease. However, wound centers typically treat few people with this condition, which makes it difficult to concentrate clinical expertise or support the scientific study of this orphan disease. This article describes an initiative to increase engagement in care through a partnership between wound healing and hematology leadership that led to colocating wound services within a sickle cell clinic. METHODS: Via a retrospective chart review, the authors collected records of all adult patients with sickle cell disease who received wound care in the last decade, including 7 years of wound center data and 3 years of data from the colocated services. Patient and visit characteristics were analyzed using descriptive analytics. RESULTS: The general wound center had previously treated 35 patients with sickle cell ulcers over 7 years. In contrast, colocated services engaged 56 patients within 3 years, including 20 who transferred care and 36 new patients. The majority of patients at the colocated site were women, unlike at the wound center (58% vs 47%, P = .07). Results indicated that 36% of patients healed initial wounds, and 45% had new wound occurrences. CONCLUSIONS: Colocation successfully increases the number of patients with sickle cell ulcers who will engage in wound care at a single site, laying the foundation for clinical studies to improve the evidence base for this difficult-to-treat condition.

Spontaneous Rupture of Empyema Necessitans in the Emergency Department.

An empyema necessitans is a rare complication of a collection of purulent material in the pleural space that spreads outside of the pleural cavity and involves the soft tissues of the chest wall. Due to compression forces created by the size of the collection of empyema in the chest cavity, patients are usually symptomatic and present with severe dyspnea. Chest X-ray or ultrasound of the chest cavity are the ideal screening tools to visualize the empyema and followed by computerized tomography scan of the chest to confirm the presence and extent of the pathology. In rare occasions, the empyema can rupture spontaneously, which may lead to critical situation requiring emergent intervention. We report the case of a 72-year-old male who presented to the emergency department with severe dyspnea and was diagnosed with empyema necesitans. During the initial management of the case, the empyema necessitans ruptured spontaneously and required emergent interventions to stabilize the patient.

Clinical predictors of poor outcomes in patients with sickle cell disease and COVID-19 infection.

We aimed to identify predictors of outcomes and survival in patients living in 4 major metropolitan areas who had sickle cell disease (SCD) and COVID-19 to inform best approaches to prevention and care. Data were collected at baseline and during the clinical course in SCD patients diagnosed with COVID-19 in four COVID-19 epicenters. Patients were followed up posthospital discharge for up to 3 months. Of sixty-six SCD patients with COVID-19, fifty patients (75%) required hospitalization, and seven died (10.6%). Patients with preexisting kidney disease (chronic kidney disease) were more likely to be hospitalized. The most common presenting symptom was vaso-occlusive pain. Acute chest syndrome occurred in 30 (60%) of the 50 hospitalized patients and in all who died. Older age and histories of pulmonary hypertension, congestive heart failure, chronic kidney disease, and stroke were more prevalent in patients who died, as were higher creatinine, lactate dehydrogenase, and D-dimer levels. Anticoagulation use while inpatient was twice less common in patients who died. All deaths occurred in individuals not taking hydroxyurea or any other SCD-modifying therapy. Patients with SCD and COVID-19 exhibited a broad range of disease severity. We cannot definitively state that the overall mortality is higher in patients with SCD, although our case fatality rate was ∼10% compared with ∼3% in the general population, despite a median age of 34 years. Individuals with SCD aged >50 years, with preexisting cardiopulmonary, renal disease, and/or stroke not receiving hydroxyurea, who present with high serum creatinine, lactate dehydrogenase, and D-dimer levels, are at higher risk of death, irrespective of genotype or sex.

HbF Levels in Sickle Cell Disease Are Associated with Proportion of Circulating Hematopoietic Stem and Progenitor Cells and CC-Chemokines.

The concentration of circulating hematopoietic stem and progenitor cells has not been studied longitudinally. Here, we report that the proportions of Lin-CD34+38- hematopoietic multipotent cells (HMCs) and of Lin-CD34+CD38+ hematopoietic progenitors cells (HPCs) are highly variable between individuals but stable over long periods of time, in both healthy individuals and sickle cell disease (SCD) patients. This suggests that these proportions are regulated by genetic polymorphisms or by epigenetic mechanisms. We also report that in SCD patients treated with hydroxyurea, the proportions of circulating HMCs and HPCs show a strong positive and negative correlation with fetal hemoglobin (HbF) levels, respectively. Titration of 65 cytokines revealed that the plasma concentration of chemokines CCL2, CCL11, CCL17, CCL24, CCL27, and PDGF-BB were highly correlated with the proportion of HMCs and HPCs and that a subset of these cytokines were also correlated with HbF levels. A linear model based on four of these chemokines could explain 80% of the variability in the proportion of circulating HMCs between individuals. The proportion of circulating HMCs and HPCs and the concentration of these chemokines might therefore become useful biomarkers for HbF response to HU in SCD patients. Such markers might become increasingly clinically relevant, as alternative treatment modalities for SCD are becoming available.

Characterization of Hematopoiesis in Sickle Cell Disease by Prospective Isolation of Stem and Progenitor Cells.

The consequences of sickle cell disease (SCD) include ongoing hematopoietic stress, hemolysis, vascular damage, and effect of chronic therapies, such as blood transfusions and hydroxyurea, on hematopoietic stem and progenitor cell (HSPC) have been poorly characterized. We have quantified the frequencies of nine HSPC populations by flow cytometry in the peripheral blood of pediatric and adult patients, stratified by treatment and control cohorts. We observed broad differences between SCD patients and healthy controls. SCD is associated with 10 to 20-fold increase in CD34dim cells, a two to five-fold increase in CD34bright cells, a depletion in Megakaryocyte-Erythroid Progenitors, and an increase in hematopoietic stem cells, when compared to controls. SCD is also associated with abnormal expression of CD235a as well as high levels CD49f antigen expression. These findings were present to varying degrees in all patients with SCD, including those on chronic therapy and those who were therapy naive. HU treatment appeared to normalize many of these parameters. Chronic stress erythropoiesis and inflammation incited by SCD and HU therapy have long been suspected of causing premature aging of the hematopoietic system, and potentially increasing the risk of hematological malignancies. An important finding of this study was that the observed concentration of CD34bright cells and of all the HSPCs decreased logarithmically with time of treatment with HU. This correlation was independent of age and specific to HU treatment. Although the number of circulating HSPCs is influenced by many parameters, our findings suggest that HU treatment may decrease premature aging and hematologic malignancy risk compared to the other therapeutic modalities in SCD.

Emergency Department Utilization for Patients Living With Sickle Cell Disease: Psychosocial Predictors of Health Care Behaviors.

STUDY OBJECTIVE: Individuals living with sickle cell disease (SCD) often require urgent care; however, some patients hesitate to present to the emergency department (ED), which may increase the risk of serious clinical complications. Our study aims to examine psychosocial, clinical, and demographic factors associated with delaying ED care. METHODS: This was a cross-sectional study of 267 adults with SCD from the national INSIGHTS Study. The binary outcome variable asked whether, in the past 12 months, participants had delayed going to an ED when they thought they needed care. Logistic regression was performed with clinical, demographic, and psychosocial measures. RESULTS: Approximately 67% of the participants reported delaying ED care. Individuals who delayed care were more likely to have reported higher stigma experiences (odds ratio [OR]=1.09; 95% confidence interval [CI] 1.03 to 1.16), more frequent pain episodes (OR=1.15; 95% CI 1.01 to 1.32), lower health care satisfaction (OR= 0.74; 95% CI 0.59 to 0.94), and more frequent ED visits (OR=6.07; 95% CI 1.18 to 31.19). Disease severity and demographics, including sex, age, and health insurance status, were not significantly associated with delay in care. CONCLUSION: Psychosocial factors, including disease stigma and previous negative health care experiences, are associated with delay of ED care in this SCD cohort. There is a need to further investigate the influence of psychosocial factors on the health care-seeking behaviors of SCD patients, as well as the downstream consequences of these behaviors on morbidity and mortality. The resulting knowledge can contribute to efforts to improve health care experiences and patient-provider relationships in the SCD community.

Bioaccumulation of total mercury in the earthworm Eisenia andrei.

Earthworms are a major part of the total biomass of soil fauna and play a vital role in soil maintenance. They process large amounts of plant and soil material and can accumulate many pollutants that may be present in the soil. Earthworms have been explored as bioaccumulators for many heavy metal species such as Pb, Cu and Zn but limited information is available for mercury uptake and bioaccumulation in earthworms and very few report on the factors that influence the kinetics of Hg uptake by earthworms. It is known however that the uptake of Hg is strongly influenced by the presence of organic matter, hence the influence of ligands are a major factor contributing to the kinetics of mercury uptake in biosystems. In this work we have focused on the uptake of mercury by earthworms (Eisenia andrei) in the presence of humic acid (HA) under varying physical conditions of pH and temperature, done to assess the role of humic acid in the bioaccumulation of mercury by earthworms from soils. The study was conducted over a 5-day uptake period and all earthworm samples were analysed by direct mercury analysis. Mercury distribution profiles as a function of time, bioaccumulation factors (BAFs), first order rate constants and body burden constants for mercury uptake under selected conditions of temperature, pH as well as via the dermal and gut route were evaluated in one comprehensive approach. The results showed that the uptake of Hg was influenced by pH, temperature and the presence of HA. Uptake of Hg(2+) was improved at low pH and temperature when the earthworms in soil were in contact with a saturating aqueous phase. The total amount of Hg(2+) uptake decreased from 75 to 48 % as a function of pH. For earthworms in dry soil, the uptake was strongly influenced by the presence of the ligand. Calculated BAF values ranged from 0.1 to 0.8. Mercury uptake typically followed first order kinetics with rate constants determined as 0.2 to 1 h(-1).

A novel device to preserve intestinal tissue ex-vivo by cold peristaltic perfusion.

In the past two decades, much advancement has been made in the area of organ procurement and preservation for the transplant of kidneys, livers, and lungs. However, small intestine preservation remains unchanged. We propose a new preservation system for intestinal grafts that has the potential to increase the viability of the organ during transport. When experimented with porcine intestine, our device resulted in superior tissue quality than tissue in standard of care.

Nontraumatic, spontaneous dislocation of polyethylene tibial insert 1 year after TKA.

The authors report a case of nontraumatic, spontaneous dislocation of a polyethylene insert detected 1 year after total knee arthroplasty. The patient demonstrated initial improvement and returned to work 4 months postoperatively. At 6 months postoperatively, the patient developed pain and a clunking sensation with motion; however, he denied any traumatic precipitating events. An arthroscopic procedure revealed arthrofibrotic formations but no signs of locking mechanism failure. At 12 months postoperatively, the patient developed sudden instability, and radiographs demonstrated an anteriorly dislodged insert. Revision surgery was performed, and the insert was removed. The insert showed some signs of fatigue due to the locking mechanism. We postulated that repetitive flexion produced an anterior superior force leading to failure of the locking mechanism.

Solid phase extraction in combination with comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry for the detailed investigation of volatiles in South African red wines.

Comprehensive two-dimensional gas chromatography in combination with time-of-flight mass spectrometry (GC×GC-TOFMS) has been applied for the analysis of volatile compounds in three young South African red wines. In spite of the significant benefits offered by GC×GC-TOFMS for the separation and identification of volatiles in such a complex matrix, previous results utilizing headspace solid phase micro extraction (HS-SPME) demonstrated certain limitations. These were primarily associated with the choice of sample preparation technique, which failed to extract some influential semi-volatile wine constituents. Therefore, in the current report, we utilized solid phase extraction (SPE) in combination with GC×GC-TOFMS for the detailed investigation of particularly low-level semi-volatiles in South African wine. 214 compounds previously reported in grapes and related beverages were tentatively identified based on mass spectral data and retention indices, while 62 additional compounds were positively identified using authentic standards. The method proved particularly beneficial for the analysis of terpenes, lactones and volatile phenols, and allowed us to report the presence of numerous volatile compounds for the first time in Pinotage wines.

Acrolein in wine: importance of 3-hydroxypropionaldehyde and derivatives in production and detection.

Certain lactic acid bacteria strains belonging to the genus Lactobacillus have been implicated in the accumulation of 3-hydroxypropionaldehyde (3-HPA) during anaerobic glycerol fermentation. In aqueous solution 3-HPA undergoes reversible dimerization and hydration, resulting in an equilibrium state between different derivatives. Wine quality may be compromised by the presence of 3-HPA due to the potential for spontaneous conversion into acrolein under winemaking conditions. Acrolein is highly toxic and has been implicated in the development of bitterness in wine. Interconversion between 3-HPA derivatives and acrolein is a complex and highly dynamic process driven by hydration and dehydration reactions. Acrolein is furthermore highly reactive and its steady-state concentration in complex systems very low. As a result, analytical detection and quantification in solution is problematic. This paper reviews the biochemical and environmental conditions leading to accumulation of its precursor, 3-HPA. Recent advances in analytical detection are summarized, and the roles played by natural chemical derivatives are highlighted.

Photoelectrochemical determination of inorganic mercury in aqueous solutions.

An analytical method using an optical probe in a photoelectrochemical cell for the sensitive and selective determination of aqueous Hg(2+) is presented. A previously synthesized Hg(2+) selective chemosensor, proven to be Hg(2+) sensitive up to 2 microg L(-1), has been immobilized onto indium tin oxide (ITO) electrodes in a composite form with polyaniline. The coated ITO electrode was placed in a photoelectrochemical cell under closed circuit conditions in which the optical recognition of the chemosensor was converted to a measurable signal. A composite of the fluorescent chemosensor, Rhodamine 6G derivative (RS), and polyaniline (PANI) was immobilized on ITO glass plates and subjected to photovoltage measurements in the absence and presence of Hg(2+). The optical responses of the coated electrode were used to determine the sensitivity and selectivity of the immobilized sensor to Hg(2+) in the presence of background ions. The optical response of the PANI-dye coated electrode increased linearly with increasing Hg(2+) concentration in the range 10-150 microg L(-1), with a detection limit of 6 microg L(-1).

Analysis of volatiles in Pinotage wines by stir bar sorptive extraction and chemometric profiling.

A fast, simple, cost-effective, and reliable method based on stir bar sorptive extraction (SBSE) in the headspace mode was used for the analysis of 39 volatile components in Pinotage wines. The method was sensitive, with LODs ranging from 50.0 pg/L to 281 ng/L and LOQs between 180 pg/L and 938 ng/L. Precision was between 6 and 20%. The intermediate precision was within the acceptable range. Moreover, good calibration curves with R(2) > 0.99 for all compounds were achieved. The method was successfully applied for the analysis of 87 young Pinotage wines of vintages 2005 and 2006 collected from various South African regions. To characterize the results based on vintage and origin, the obtained concentrations of the compounds were subjected to chemometric analysis. Exploratory factor analysis (FA), principal component analysis (PCA), and analysis of variance (one-way ANOVA) were consecutively done. The chemometrics approach revealed a reasonable correlation among the volatile components of these wines, as well as with respect to their year of production.

The use of GC x GC with time-of-flight mass spectrometry to investigate dienes and Diels-Alder polymerisation products in high-temperature Fischer-Tropsch-based fuels.

Comprehensive GC in the reversed polarity mode i.e. a polar main column and an apolar secondary column have been used to differentiate cyclic olefins, dienes and cyclic dienes in high temperature Fischer-Tropsch (FT)-based fuels. The elucidation of the blobs in the contour plot was based on spectral data obtained by TOF-MS. The effectiveness of selective catalytic hydrogenation in transforming dienes into olefins could be studied. Dienes are prone to polymerisation by Diels-Alder reactions and dimers and trimers were detected in the 2-D plot by operating the MS in the ion extraction mode. Polymerisation is thought to be partially responsible for gum formation in high temperature FT-derived products.