Labeling of cells with ferumoxides-protamine sulfate complexes does not inhibit function or differentiation capacity of hematopoietic or mesenchymal stem cells

Two FDA-approved agents, ferumoxides (Feridex), a suspension of superparamagnetic iron oxide (SPIO) nanoparticles and protamine sulfate, a drug used to reverse heparin anticoagulation, can be complexed and used to label cells magnetically ex vivo. Labeling stem cells with ferumoxides-protamine sulfate (FePro) complexes allows for non-invasive monitoring by MRI. However, in order for stem cell trials or therapies to be effective, this labeling technique must not inhibit the ability of cells to differentiate. In this study, we examined the effect of FePro labeling on stem cell differentiation. Viability, phenotypic expression and differential capacity of FePro labeled CD34 + hematopoietic stem cells (HSC) and mesenchymal stem cells (MSC) were compared with unlabeled control cells. Colony-forming unit (CFU) assays showed that the capacity to differentiate was equivalent for labeled and unlabeled HSC. Furthermore, labeling did not alter expression of surface phenotypic markers (CD34, CD31, CXCR4, CD20, CD3 and CD14) on HSC, as measured by flow cytometry. SDF-1-induced HSC migration and HSC differentiation to dendritic cells were also unaffected by FePro labeling. Both FePro-labeled and unlabeled MSC were cultured in chondrogenesis-inducing conditions. Alcian blue staining for proteoglycans revealed similar chondrogenic differentiation for both FePro-labeled and unlabeled cells. Furthermore, collagen X proteins, indicators of cartilage formation, were detected at similar levels in both labeled and unlabeled cell pellets. Prussian blue staining confirmed that cells in labeled pellets contained iron oxide, whereas cells in unlabeled pellets did not. It is concluded that FePro labeling does not alter the function or differentiation capacity of HSC and MSC. These data increase confidence that MRI studies of FePro-labeled HSC or MSC will provide an accurate representation of in vivo trafficking of unlabeled cells.     

Isolation of Chlamydia psittaci from avian sources using growth in cell culture

A method is described for the isolation of Chlamydia psittaci using cell culture treated with 5-iodo-2-deoxyuridine, and subsequent identification by direct fluorescent antibody staining. The method was applied to 110 sets of tissues from a variety of avian specimens submitted for diagnosis. Chlamydiae were isolated and identified in 24 specimens: 13 from parrots, 7 from turkeys and 4 from pigeons.     

Evaluating Differences in Whole Blood,Serum, and Urine Screening Tests for Zika Virus,Puerto Rico,USA, 2016

We evaluated nucleic acid amplification testing (NAAT) for Zika virus on whole-blood specimens compared with NAAT on serum and urine specimens among asymptomatic pregnant women during the 2015–2016 Puerto Rico Zika outbreak. Using NAAT, more infections were detected in serum and urine than in whole blood specimens.     

The Accuracy of Incident Vertebral Fracture Detection in Children Using Targeted Case-Finding Approaches

Vertebral fractures are clinically important sequelae of a wide array of pediatric diseases. In this study, we examined the accuracy of case-finding strategies for detecting incident vertebral fractures (IVF) over 2 years in glucocorticoid-treated children (n = 343) with leukemia, rheumatic disorders, or nephrotic syndrome. Two clinical situations were addressed: the prevalent vertebral fracture (PVF) scenario (when baseline PVF status was known), which assessed the utility of PVF and low lumbar spine bone mineral density (LS BMD; Z-score <−1.4), and the non-PVF scenario (when PVF status was unknown), which evaluated low LS BMD and back pain. LS BMD was measured by dual-energy X-ray absorptiometry, vertebral fractures were quantified on spine radiographs using the modified Genant semiquantitative method, and back pain was assessed by patient report. Forty-four patients (12.8%) had IVF. In the PVF scenario, both low LS BMD and PVF were significant predictors of IVF. Using PVF to determine which patients should have radiographs, 11% would undergo radiography (95% confidence interval [CI] 8–15) with 46% of IVF (95% CI 30–61) detected. Sensitivity would be higher with a strategy of PVF or low LS BMD at baseline (73%; 95% CI 57–85) but would require radiographs in 37% of children (95% CI 32–42). In the non-PVF scenario, the strategy of low LS BMD and back pain produced the highest specificity of any non-PVF model at 87% (95% CI 83–91), the greatest overall accuracy at 82% (95% CI 78–86), and the lowest radiography rate at 17% (95% CI 14–22). Low LS BMD or back pain in the non-PVF scenario produced the highest sensitivity at 82% (95% CI 67–92), but required radiographs in 65% (95% CI 60–70). These results provide guidance for targeting spine radiography in children at risk for IVF. © 2021 American Society for Bone and Mineral Research (ASBMR).     

Acute rheumatic fever: Findings of a hospital-based study and an overview of reported outbreaks

To review the characteristics of reported outbreaks of acute rheumatic fever in the United States, and to determine if there is an increase in the incidence of acute rheumatic fever in the population served by the Hospital for Sick Children, Toronto, Ontario, the authors conducted a literature search and a retrospective review of inpatients and outpatients, satisfying the revised Jones criteria for the diagnosis of acute rheumatic fever, from 1972 to 1988. Patients satisfying the revised Jones criteria for the time period 1972-88 were included in the study. There have been eight articles reporting an increase in acute rheumatic fever in the United States. In three, the majority of children were white and from middle class suburban/rural communities in different geographic locations. Mucoid strains of group A streptococci were implicated but not confirmed as being associated with the outbreaks in three. The results of the chart review at the Hospital for Sick Children revealed that 83 cases satisfied the revised Jones criteria. The number of cases per 100,000 children (aged 18 years or less) per year, decreased progressively over the study period. Polyarthritis was the most frequently seen major criterion occurring in 73% of patients (61 of 83). The most frequently affected ethnic groups were Italians 23%, Afro-Canadians 19% and Orientals 8%. The reported outbreaks in the United States are multifocal and predominantly confined to white middle class children residing in suburban/rural communities. There was no evidence of an increase in the number of cases of acute rheumatic fever seen in the population served by the Hospital for Sick Children; there was a progressive decline in number of cases over the study period. The results facilitate the characterization of acute rheumatic fever within North America into three different patterns of occurrence.     

An examination of the effects of isoenergetic intragastric infusions of pure macronutrients on cold pain perception in healthy human volunteers

Our previous study demonstrated that meals, particularly when rich in fat, significantly reduced the pain induced by the cold pressor stimulus in healthy human subjects. To determine the mechanisms involved, the aim of this study was to bypass the taste and cognitive component of food and to investigate the scope of these analgesic effects with direct intragastric infusion of pure macronutrients in a group of 16 healthy human volunteers (eight male and eight female) on the response to cold-induced pain. All subjects underwent the cold pressor test (CPT) on three occasions in a counterbalanced order: before and after intragastric intubation and infusion of isoenergetic fat (10% intralipid), carbohydrate (CHO-maltodextrin), and a control infusion of isotonic saline. All solutions were of equal volume and administered at room temperature. The CPT was carried out four times on each test day, once before intubation, and 0.5, 1.5, and 2.5 h after intragastric infusion. Radial pulse and blood pressure measurements and visual analogue scales of mood/emotional state were carried out before and after each CPT. There were no significant differences in pain scores between the three test conditions, suggesting that by bypassing the cognitive and taste component of eating, the trigger for any postingestive analgesic effects of food are lost.