Children are not little adults: just ask their hematopoietic stem cells

Pediatric Medical Countermeasures: Antidotes and Cytokines for Radiological and Nuclear Incidents and Terrorism

The war in Ukraine raises concerns for potential hazards of radiological and nuclear incidents. Children are particularly vulnerable in these incidents and may need pharmaceutical countermeasures, including antidotes and cytokines. Searches found no published study comparing pediatric indications and dosing among standard references detailing pediatric medications for these incidents. This study addresses this gap by collecting, tabulating, and disseminating this information to healthcare professionals caring for children. Expert consensus chose the following references to compare their pediatric indications and dosing of medical countermeasures for radiation exposure and internal contamination with radioactive materials: Advanced Hazmat Life Support (AHLS) for Radiological Incidents and Terrorism, DailyMed, Internal Contamination Clinical Reference, Medical Aspects of Radiation Incidents, and Medical Management of Radiological Casualties, as well as Micromedex, POISINDEX, and Radiation Emergency Medical Management (REMM). This is the first study comparing pediatric indications and dosing for medical countermeasures among commonly used references for radiological and nuclear incidents.

Radiation Injuries: Acute Radiation Syndrome in Children

The conflict in Ukraine has raised the specter of radiological and nuclear incidents, including fighting at the Zaporizhzhia nuclear plant, the largest nuclear powerplant in Europe; concerns that a radiological dispersion device ("dirty bomb") may be used; and threats to deploy tactical nuclear weapons. Children are more susceptible than adults to immediate and delayed radiation health effects. This article reviews the diagnosis and treatment of acute radiation syndrome. Although definitive treatment of radiation injuries should involve consultation with specialists, nonspecialists should learn to recognize the distinctive signs of radiation injury and make an initial assessment of severity of exposure. [Pediatr Ann. 2023;52(6):e231-e237.].

Far from Health: The Bone Marrow Microenvironment in AML, A Leukemia Supportive Shelter

Acute myeloid leukemia (AML) is the second most common leukemia among children. Although significant progress in AML therapy has been achieved, treatment failure is still associated with poor prognosis, emphasizing the need for novel, innovative therapeutic approaches. To address this major obstacle, extensive knowledge about leukemogenesis and the complex interplay between leukemic cells and their microenvironment is required. The tremendous role of this bone marrow microenvironment in providing a supportive and protective shelter for leukemic cells, leading to disease development, progression, and relapse, has been emphasized by recent research. It has been revealed that the interplay between leukemic cells and surrounding cellular as well as non-cellular components is critical in the process of leukemogenesis. In this review, we provide a comprehensive overview of recently gained knowledge about the importance of the microenvironment in AML whilst focusing on promising future therapeutic targets. In this context, we describe ongoing clinical trials and future challenges for the development of targeted therapies for AML.

Examining variation in skeletal tuberculosis in a late pre-contact population from the eastern mountains of Peru

OBJECTIVE AND MATERIALS

This research evaluates the presence and chronology of tuberculosis (TB) in the northeastern highlands of Peru (CE 800-1535) through the analysis of osseous lesions from Pre-Contact Kuelap, Chachapoyas.

METHODS

We examined macroscopic lesion morphology and distribution from the skeletal series (MNI = 207).

RESULTS

We determined that skeletal evidence was highly consistent with advanced multifocal and spinal tuberculosis in 13 individuals. Destructive lesions of the lower thoracic and/or lumbar vertebra bodies and sacroiliac joints are evident in most cases, but we also observed lesions within the manubriosternal, hip, and knee joints. Both adult males (n = 7) and females (n = 6) present skeletal lesions from young adult to older adults, but there is only one late adolescent. Only three individuals demonstrate similar lesion distributions.

CONCLUSIONS

Variation in lesion distribution in this population-based study shows the importance of identifying extra-vertebral tuberculosis and suggests that the disease may have manifested differently than at other coastal sites. These cases confirm the presence of tuberculosis both before and after Inca occupation across this central Andean highlands region.

SIGNIFICANCE

This evidence for the likely endemic presence of TB in the New World prior to European Contact furthers our understanding of the distribution of this infectious disease across the region as well as elucidating lesion distribution.

LIMITATIONS

The diagnosis of tuberculosis is based on skeletal lesions and it should be confirmed by molecular analysis.

FUTURE RESEARCH

Additional examination of vertebral bodies (including juvenile remains) for evidence of earlier manifestations of infection.

RBMY, a novel inhibitor of glycogen synthase kinase 3β, increases tumor stemness and predicts poor prognosis of hepatocellular carcinoma

Male predominance of hepatocellular carcinoma (HCC) occurs particularly among young children aged 6-9 years, indicative of a possible role of the Y chromosome-encoded oncogene in addition to an androgenic effect. The discovery of oncogenic activation of RBMY (RNA-binding motif on Y chromosome), which is absent in normal hepatocytes but present in male HCC tissues, sheds light on this issue. Herein, we report on a critical hepatocarcinogenic role of RBMY and its ontogenic origin. During liver development, the Ser/Thr phosphorylated RBMY is expressed in the cytoplasm of human and rodent fetal livers. It is then silenced in mature hepatocytes and restricted to scarce expression in the bile ductular cells. Upon hepatocarcinogenesis, a noteworthy increase of cytoplasmic and nuclear RBMY is observed in HCC tissues; however, only the former is expressed dominantly in hepatic cancer stem cells and correlates significantly to a poor prognosis and decreased survival rate in HCC patients. Cytoplasmic expression of RBMY, which is mediated by binding to nuclear exporter chromosome region maintenance 1 and further enriched upon Wnt-3a stimulation, confers upon tumor cells the traits of cancer stem cell by augmenting self-renewal, chemoresistance, cell-cycle progression, proliferation, and xenograft tumor growth. This is achieved mechanistically through increasing Ser9 phosphorylation-inactivation of glycogen synthase kinase 3β by RBMY, thereby impeding the glycogen synthase kinase 3β-dependent degradation of β-catenin and eventually inducing the nuclear entry of β-catenin for the transcription of downstream oncogenes.

CONCLUSION

RBMY is a novel oncofetal protein that plays a key role in attenuating glycogen synthase kinase 3β activity, leading to aberrant activation of Wnt/β-catenin signaling, which facilitates malignant hepatic stemness; because of its absence from normal human tissues except the testis, RBMY represents a feasible therapeutic target for the selective eradication of HCC cells in male patients.

Human fetal liver: an in vitro model of erythropoiesis

We previously described the large-scale production of RBCs from hematopoietic stem cells (HSCs) of diverse sources. Our present efforts are focused to produce RBCs thanks to an unlimited source of stem cells. Human embryonic stem (ES) cells or induced pluripotent stem cell (iPS) are the natural candidates. Even if the proof of RBCs production from these sources has been done, their amplification ability is to date not sufficient for a transfusion application. In this work, our protocol of RBC production was applied to HSC isolated from fetal liver (FL) as an intermediate source between embryonic and adult stem cells. We studied the erythroid potential of FL-derived CD34(+) cells. In this in vitro model, maturation that is enucleation reaches a lower level compared to adult sources as observed for embryonic or iP, but, interestingly, they (i) displayed a dramatic in vitro expansion (100-fold more when compared to CB CD34(+)) and (ii) 100% cloning efficiency in hematopoietic progenitor assays after 3 days of erythroid induction, as compared to 10-15% cloning efficiency for adult CD34(+) cells. This work supports the idea that FL remains a model of study and is not a candidate for ex vivo RBCS production for blood transfusion as a direct source of stem cells but could be helpful to understand and enhance proliferation abilities for primitive cells such as ES cells or iPS.

Inflammatory cytokine profiles during exercise in obese, diabetic, and healthy children

OBJECTIVE

Modulation of inflammatory status is considered a key component of the overall health effects of exercise. This may be especially relevant in children with obesity (Ob) or type 1 diabetes (T1DM), in which an imbalance between pro- and anti-inflammatory mediators could accelerate onset and progression of cardiovascular complications. To date, exercise-induced alterations in immuno-modulatory mediators in Ob and T1DM children remain largely unknown.

METHODS

In this study, we monitored the kinetic profiles of 8 pro-and anti-inflammatory cytokines (TNF-a, IL-6, IL-2, IL-8, IL-5, IL-13, IL-10, IL-4) during a standardized exercise challenge (ten 2-min cycling bouts at 80% VO2max, separated by 1-min intervals) in 23 Ob (12 females, 11 males), 23 T1DM (10 females and 13 males) patients and 20 healthy (CL, 10 females and 10 males) children. Blood glucose of T1DM patients was kept in the 4.4-6.1 mM range for at least 90 minute prior to and during exercise. Blood samples were drawn at rest and after every other exercise bout.

RESULTS

In Ob, TNF-a and IL-2 were significantly greater (p<0.0167) as compared to T1DM and CL, both at baseline and throughout exercise. All other variables, while not significant, were quantitatively elevated in Ob vs. CL. In T1DM, IL-4 and IL-8 levels were similar to Ob, IL-2 and TNF-a similar to CL, and IL-6, IL-5, IL-13, IL-4 levels were intermediate between the Ob and CL groups.

CONCLUSIONS

During exercise, therefore, both Ob and T1DM children displayed exaggerated pro-inflammatory responses, although with clearly different magnitude and involved mediators. Our data support the necessity to identify specific exercise formats through which each at-risk pediatric population can draw maximal beneficial health effects.

Altered inflammatory, oxidative, and metabolic responses to exercise in pediatric obesity and type 1 diabetes

Obesity (Ob) and type 1 diabetes (T1DM) are associated with increased inflammation and oxidative stress, which are major pathogenetic pathways toward higher cardiovascular risks. Although long-term exercise protects against systemic inflammation and oxidation, acute exercise actually exerts pro-inflammatory and oxidative effects, prompting the necessity for better defining these molecular processes in at-risk patients; in particular, very little is known regarding obese and T1DM children. We therefore examined key inflammatory and oxidative stress variables during exercise in 138 peripubertal children (47 Ob, 12.7 ± 0.4 yr, 22 F, BMI% 97.6 ± 0.2; 49 T1DM, 13.9 ± 0.2 yr, 20 F, body mass index% [BMI] 63.0 ± 3.6; 42 healthy, CL, 13.5 ± 0.5 yr, 24 F, BMI% 57.0 ± 3.6), who performed 10 bouts of 2-min cycling ~80% VO(2max) , separated by 1-min rest intervals. Blood samples were drawn at baseline and peak exercise. Ob displayed elevated baseline interleukin-6 (IL-6, 2.1 ± 0.2 pg/mL, p < 0.005) vs. CL (1.5 ± 0.3), whereas T1DM displayed the greatest maximum exercise-induced change in IL-6 (1.2 ± 0.3) than in both Ob (0.7 ± 0.1, p < 0.001) and CL (0.6 ± 0.1, p < 0.0167). Myeloperoxidase (MPO) was elevated in T1DM (143 ± 30 ng/mL, p < 0.0167) vs. CL (89 ± 10) and Ob (76 ± 6), whereas increases in exercise only occurred in Ob and CL. Disparate baseline and exercise responses were also observed for 8-hydroxy-2'-deoxyguanosine, glutathione, and F(2) -isoprostane. This data show distinct patterns of dysregulation in baseline and adaptive immunologic and oxidative responses to exercise in Ob and T1DM. A full understanding of these alterations is required so that developing exercise regimens aimed at maximizing health benefits for specific dysmetabolic states can be achieved based on complete scientific characterization rather than empirical implementation.

Increased oxidative stress and altered substrate metabolism in obese children

OBJECTIVE

Pediatric obesity, a major risk factor for cardiovascular diseases and diabetes, has steadily increased in the last decades. Although excessive inflammation and oxidation are possible biochemical links between obesity and cardiovascular events in adults, little information is available in children. Furthermore, effects of gender and fitness on the interaction between dyslipidemia and oxidative/inflammatory stress in children are mostly unknown.

METHODS

Therefore, we measured systemic markers of oxidation (F(2)-isoprostanes [F(2)-IsoP] and antioxidants) and inflammation (interleukin-6 [IL-6] and leukocyte counts) and metabolic variables in 113 peripubertal children (55 obese [Ob] age and gender-adjusted BMI% ≥ 95(th), 25 Females [F]; 15 overweight [OW] BMI% 85(th)-95(th), 8 F; 43 normoweight [NW] 25 F).

RESULTS

When compared with NW, Ob displayed elevated F(2)-IsoP (99 ± 7 vs. 75 ± 4 pg/mL, p<0.005), IL-6 (2.2 ± 0.2 vs. 1.5 ± 0.3 pg/mL, p<0.005), elevated total leukocytes and neutrophils, altered levels of total cholesterol , low- and high-density-lipoprotein cholesterol, triglycerides, free fatty acids, glucose, and insulin (all p<0.005). This pattern was present in both genders and over a broad range of fitness in Ob.

CONCLUSIONS

Our data indicate that alterations in metabolic control and a concomitant increase in inflammation and oxidative stress occur early in life in obese children, likely exposing both genders to a similar degree of increased risk of future cardiovascular diseases.

Microwaves from Mobile Phones Inhibit 53BP1 Focus Formation in Human Stem Cells More Strongly Than in Differentiated Cells: Possible Mechanistic Link to Cancer Risk

BACKGROUND

It is widely accepted that DNA double-strand breaks (DSBs) and their misrepair in stem cells are critical events in the multistage origination of various leukemias and tumors, including gliomas.

OBJECTIVES

We studied whether microwaves from mobile telephones of the Global System for Mobile Communication (GSM) and the Universal Global Telecommunications System (UMTS) induce DSBs or affect DSB repair in stem cells.

METHODS

We analyzed tumor suppressor TP53 binding protein 1 (53BP1) foci that are typically formed at the sites of DSB location (referred to as DNA repair foci) by laser confocal microscopy.

RESULTS

Microwaves from mobile phones inhibited formation of 53BP1 foci in human primary fibroblasts and mesenchymal stem cells. These data parallel our previous findings for human lymphocytes. Importantly, the same GSM carrier frequency (915 MHz) and UMTS frequency band (1947.4 MHz) were effective for all cell types. Exposure at 905 MHz did not inhibit 53BP1 foci in differentiated cells, either fibroblasts or lymphocytes, whereas some effects were seen in stem cells at 905 MHz. Contrary to fibroblasts, stem cells did not adapt to chronic exposure during 2 weeks.

CONCLUSIONS

The strongest microwave effects were always observed in stem cells. This result may suggest both significant misbalance in DSB repair and severe stress response. Our findings that stem cells are most sensitive to microwave exposure and react to more frequencies than do differentiated cells may be important for cancer risk assessment and indicate that stem cells are the most relevant cellular model for validating safe mobile communication signals.

The elderly as a sensitive population in environmental exposures: making the case

The US population is aging. CDC has estimated that 20% of all Americans will be 65 or older by the year 2030. As a part of the aging process, the body gradually deteriorates and physiologic and metabolic limitations arise. Changes that occur in organ anatomy and function present challenges for dealing with environmental stressors of all kinds, ranging from temperature regulation to drug metabolism and excretion. The elderly are not just older adults, but rather are individuals with unique challenges and different medical needs than younger adults. The ability of the body to respond to physiological challenge presented by environmental chemicals is dependent upon the health of the organ systems that eliminate those substances from the body. Any compromise in the function of those organ systems may result in a decrease in the body's ability to protect itself from the adverse effects of xenobiotics. To investigate this issue, we performed an organ system-by-organ system review of the effects of human aging and the implications for such aging on susceptibility to drugs and xenobiotics. Birnbaum (1991) reported almost 20 years ago that it was clear that the pharmacokinetic behavior of environmental chemicals is, in many cases, altered during aging. Yet, to date, there is a paucity of data regarding recorded effects of environmental chemicals on elderly individuals. As a result, we have to rely on what is known about the effects of aging and the existing data regarding the metabolism, excretion, and adverse effects of prescription medications in that population to determine whether the elderly might be at greater risk when exposed to environmental substances. With increasing life expectancy, more and more people will confront the problems associated with advancing years. Moreover, although proper diet and exercise may lessen the immediate severity of some aspects of aging, the process will continue to gradually degrade the ability to cope with a variety of injuries and diseases. Thus, the adverse effects of long-term, low-level exposure to environmental substances will have a longer time to be manifested in a physiologically weakened elderly population. When such exposures are coupled with concurrent exposure to prescription medications, the effects could be devastating. Public health officials must be knowledgeable about the sensitivity of the growing elderly population, and ensure that the use of health guidance values (HGVs) for environmental contaminants and other substances give consideration to this physiologically compromised segment of the population.

The central role of the chemokine receptor, CXCR4, in haemopoietic stem cell transplantation: will CXCR4 antagonists contribute to the treatment of blood disorders?

Recent clinical trials have used CXCR4 antagonists for the rapid mobilization of CD34(+) haemopoietic stem/progenitor cells (HSC/HPC) from the bone marrow to the blood in patients refractory to granulocyte-colony-stimulating factor (G-CSF). These antagonists not only mobilize non-cycling cells with a higher proportion of repopulating cells, but also enhance CD34(+) cell mobilization when used in combination with G-CSF. Here, we review the importance of CXCR4 and its ligand CXCL12 in haemopoiesis, and the potential roles of CXCR4 antagonists in the clinical HSC transplant setting.