Longitudinal Gray Matter Trajectories in Pediatric Mild Traumatic Brain Injury

BACKGROUND AND OBJECTIVES

This prospective, longitudinal cohort study examined trajectories of brain gray matter macrostructure after pediatric mild traumatic brain injury (mTBI).

METHODS

Children aged 8-16.99 years with mTBI or mild orthopedic injury (OI) were recruited from 5 pediatric emergency departments. Reliable change between preinjury and 1 month postinjury symptom ratings was used to classify mTBI with or without persistent symptoms. Children completed postacute (2-33 days) and/or chronic (3 or 6 months) postinjury T1-weighted MRI, from which macrostructural metrics were derived using automated segmentation. Linear mixed-effects models were used, with multiple comparisons correction.

RESULTS

Groups (N = 623; 407 mTBI/216 OI; 59% male; age mean = 12.03, SD = 2.38 years) did not differ in total brain, white, or gray matter volumes or regional subcortical gray matter volumes. However, time postinjury, age at injury, and biological sex-moderated differences among symptom groups in cortical thickness of the angular gyrus, basal forebrain, calcarine cortex, gyrus rectus, medial and posterior orbital gyrus, and the subcallosal area all corrected p < 0.05. Gray matter macrostructural metrics did not differ between groups postacutely. However, cortical thinning emerged chronically after mTBI relative to OI in the angular gyrus in older children (d [95% confidence interval] = -0.61 [-1.15 to -0.08]); and in the basal forebrain (-0.47 [-0.94 to -0.01]), subcallosal area (-0.55 [-1.01 to -0.08]), and the posterior orbital gyrus (-0.55 [-1.02 to -0.08]) in females. Cortical thinning was demonstrated for frontal and occipital regions 3 months postinjury in males with mTBI with persistent symptoms vs without persistent symptoms (-0.80 [-1.55 to -0.05] to -0.83 [-1.56 to -0.10]) and 6 months postinjury in females and younger children with mTBI with persistent symptoms relative to mTBI without persistent symptoms and OI (-1.42 [-2.29 to -0.45] to -0.91 [-1.81 to -0.01]).

DISCUSSION

These findings signal little diagnostic and prognostic utility of postacute gray matter macrostructure in pediatric mTBI. However, mTBI altered the typical course of cortical gray matter thinning up to 6 months postinjury, even after symptoms typically abate in most children. Collapsing across symptom status obscured the neurobiological heterogeneity of discrete clinical outcomes after pediatric mTBI. The results illustrate the need to examine neurobiology in relation to clinical outcomes and within a neurodevelopmental framework.

Altered longitudinal structural connectome in paediatric mild traumatic brain injury: an Advancing Concussion Assessment in Paediatrics study

Advanced diffusion-weighted imaging techniques have increased understanding of the neuropathology of paediatric mild traumatic brain injury (i.e. concussion). Most studies have examined discrete white-matter pathways, which may not capture the characteristically subtle, diffuse and heterogenous effects of paediatric concussion on brain microstructure. This study compared the structural connectome of children with concussion to those with mild orthopaedic injury to determine whether network metrics and their trajectories across time post-injury differentiate paediatric concussion from mild traumatic injury more generally. Data were drawn from of a large study of outcomes in paediatric concussion. Children aged 8-16.99 years were recruited from five paediatric emergency departments within 48 h of sustaining a concussion (n = 360; 56% male) or mild orthopaedic injury (n = 196; 62% male). A reliable change score was used to classify children with concussion into two groups: concussion with or without persistent symptoms. Children completed 3 T MRI at post-acute (2-33 days) and/or chronic (3 or 6 months, via random assignment) post-injury follow-ups. Diffusion-weighted images were used to calculate the diffusion tensor, conduct deterministic whole-brain fibre tractography and compute connectivity matrices in native (diffusion) space for 90 supratentorial regions. Weighted adjacency matrices were constructed using average fractional anisotropy and used to calculate global and local (regional) graph theory metrics. Linear mixed effects modelling was performed to compare groups, correcting for multiple comparisons. Groups did not differ in global network metrics. However, the clustering coefficient, betweenness centrality and efficiency of the insula, cingulate, parietal, occipital and subcortical regions differed among groups, with differences moderated by time (days) post-injury, biological sex and age at time of injury. Post-acute differences were minimal, whereas more robust alterations emerged at 3 and especially 6 months in children with concussion with persistent symptoms, albeit differently by sex and age. In the largest neuroimaging study to date, post-acute regional network metrics distinguished concussion from mild orthopaedic injury and predicted symptom recovery 1-month post-injury. Regional network parameters alterations were more robust and widespread at chronic timepoints than post-acutely after concussion. Results suggest that increased regional and local subnetwork segregation (modularity) and inefficiency occurs across time after concussion, emerging after post-concussive symptom resolve in most children. These differences persist up to 6 months after concussion, especially in children who showed persistent symptoms. While prognostic, the small to modest effect size of group differences and the moderating effects of sex likely would preclude effective clinical application in individual patients.

Comparison of CPU and GPU bayesian estimates of fibre orientations from diffusion MRI

Background

The correct estimation of fibre orientations is a crucial step for reconstructing human brain tracts. Bayesian Estimation of Diffusion Parameters Obtained using Sampling Techniques (bedpostx) is able to estimate several fibre orientations and their diffusion parameters per voxel using Markov Chain Monte Carlo (MCMC) in a whole brain diffusion MRI data, and it is capable of running on GPUs, achieving speed-up of over 100 times compared to CPUs. However, few studies have looked at whether the results from the CPU and GPU algorithms differ. In this study, we compared CPU and GPU bedpostx outputs by running multiple trials of both algorithms on the same whole brain diffusion data and compared each distribution of output using Kolmogorov-Smirnov tests.

Results

We show that distributions of fibre fraction parameters and principal diffusion direction angles from bedpostx and bedpostx_gpu display few statistically significant differences in shape and are localized sparsely throughout the whole brain. Average output differences are small in magnitude compared to underlying uncertainty.

Conclusions

Despite small amount of differences in output between CPU and GPU bedpostx algorithms, results are comparable given the difference in operation order and library usage between CPU and GPU bedpostx.

Prenatal antidepressant exposure and sex differences in neonatal corpus callosum microstructure

Prenatal exposure to selective serotonin reuptake inhibitor (SSRI) antidepressants may influence white matter (WM) development, as previous studies report widespread microstructural alterations and reduced interhemispheric connectivity in SSRI-exposed infants. In rodents, perinatal SSRIs had sex-specific disruptions in corpus callosum (CC) axon architecture and connectivity; yet it is unknown whether SSRI-related brain outcomes in humans are sex specific. In this study, the neonate CC was selected as a region-of-interest to investigate whether prenatal SSRI exposure has sex-specific effects on early WM microstructure. On postnatal day 7, diffusion tensor imaging was used to assess WM microstructure in SSRI-exposed (n = 24; 12 male) and nonexposed (n = 48; 28 male) term-born neonates. Fractional anisotropy was extracted from CC voxels and a multivariate discriminant analysis was used to identify latent patterns differing between neonates grouped by SSRI-exposure and sex. Analysis revealed localized variations in CC fractional anisotropy that significantly discriminated neonate groups and correctly predicted group membership with an 82% accuracy. Such effects were identified across three dimensions, representing sex differences in SSRI-exposed neonates (genu, splenium), SSRI-related effects independent of sex (genu-to-rostral body), and sex differences in nonexposed neonates (isthmus-splenium, posterior midbody). Our findings suggest that CC microstructure may have a sex-specific, localized, developmental sensitivity to prenatal SSRI exposure.

Hub distribution of the brain functional networks of newborns prenatally exposed to maternal depression and SSRI antidepressants

BACKGROUND

Prenatal maternal depression (PMD) and selective serotonin reuptake inhibitor (SSRI) antidepressants are associated with increased developmental risk in infants. Reports suggest that PMD is associated with hyperconnectivity of the insula and the amygdala, while SSRI exposure is associated with hyperconnectivity of the auditory network in the infant brain. However, associations between functional brain organization and PMD and/or SSRI exposure are not well understood.

METHODS

We examined the relation between PMD or SSRI exposure and neonatal brain functional organization. Infants of control (n = 17), depressed SSRI-treated (n = 20) and depressed-only (HAM-D ≥ 8) (n = 16) women, underwent resting-state functional magnetic resonance imaging at postnatal Day 6. At 6 months, temperament was assessed using Infant Behavioral Questionnaire (IBQ). We applied GTA and partial least square regression (PLSR) to the resting-state time series to assess group differences in modularity, and connector and provincial hubs.

RESULTS

Modularity was similar across all groups. The depressed-only group showed higher connector hub values in the left anterior cingulate, insula, and caudate as well as higher provincial hub values in the amygdala compared to the control group. The SSRI group showed higher provincial hub values in Heschl's gyrus relative to the depressed-only group. PLSR showed that newborns' hub values predicted 10% of the variability in infant temperament at 6 months, suggesting different developmental patterns between groups.

CONCLUSIONS

Prenatal exposures to maternal depression and SSRIs have differential impacts on neonatal functional brain organization. Hub values at 6 days predict variance in temperament between infant groups at 6 months of age.

Diagnostic Yield and Treatment Impact of Targeted Exome Sequencing in Early-Onset Epilepsy

Targeted whole-exome sequencing (WES) is a powerful diagnostic tool for a broad spectrum of heterogeneous neurological disorders. Here, we aim to examine the impact on diagnosis, treatment and cost with early use of targeted WES in early-onset epilepsy. WES was performed on 180 patients with early-onset epilepsy (≤5 years) of unknown cause. Patients were classified as Retrospective (epilepsy diagnosis >6 months) or Prospective (epilepsy diagnosis <6 months). WES was performed on an Ion Proton™ and variant reporting was restricted to the sequences of 620 known epilepsy genes. Diagnostic yield and time to diagnosis were calculated. An analysis of cost and impact on treatment was also performed. A molecular diagnoses (pathogenic/likely pathogenic variants) was achieved in 59/180 patients (33%). Clinical management changed following WES findings in 23 of 59 diagnosed patients (39%) or 13% of all patients. A possible diagnosis was identified in 21 additional patients (12%) for whom supporting evidence is pending. Time from epilepsy onset to a genetic diagnosis was faster when WES was performed early in the diagnostic process (mean: 145 days Prospective vs. 2,882 days Retrospective). Costs of prior negative tests averaged $8,344 per patient in the Retrospective group, suggesting savings of $5,110 per patient using WES. These results highlight the diagnostic yield, clinical utility and potential cost-effectiveness of using targeted WES early in the diagnostic workup of patients with unexplained early-onset epilepsy. The costs and clinical benefits are likely to continue to improve. Advances in precision medicine and further studies regarding impact on long-term clinical outcome will be important.

Brain abnormalities in children and adolescents with chronic kidney disease

BACKGROUND

Chronic kidney disease (CKD) is a risk factor for vascular disease and stroke. The spectrum of brain injury and microstructural white matter abnormalities in children with CKD is largely unknown.

METHODS

Cross sectional study at two North American pediatric hospitals. A cohort of 49 children, 29 with CKD, including renal transplant (mean age 14.4 ± 2.9 years; range 9-18), and 20 healthy controls (mean age 13.7 ± 3.1 years; range 9-18) had their conventional brain magnetic resonance images (MRIs) reviewed by one neuroradiologist to determine the prevalence of brain injury. Fractional anisotropy (FA) maps calculated from diffusion tensor imaging (DTI) were generated to compare white matter microstructure in CKD compared to controls, using tract-based spatial statistics (TBSS).

RESULTS

Focal and multifocal white matter injury was seen on brain MRI in 6 children with CKD (21%). Relative to controls, CKD subjects showed reduced white matter fractional anisotropy and increased mean diffusivity and radial diffusivity in the anterior limb of the internal capsule, suggestive of abnormal myelination.

CONCLUSION

Cerebral white matter abnormalities, including white matter injury, are under-recognized in pediatric CKD patients. Brain imaging studies through progression of CKD are needed to determine the timing of white matter injury and any potentially modifiable risk factors.

Advancing Concussion Assessment in Pediatrics (A-CAP): a prospective, concurrent cohort, longitudinal study of mild traumatic brain injury in children: protocol study

INTRODUCTION

Paediatric mild traumatic brain injury (mTBI) is a public health burden. Clinicians urgently need evidence-based guidance to manage mTBI, but gold standards for diagnosing and predicting the outcomes of mTBI are lacking. The objective of the Advancing Concussion Assessment in Pediatrics (A-CAP) study is to assess a broad pool of neurobiological and psychosocial markers to examine associations with postinjury outcomes in a large sample of children with either mTBI or orthopaedic injury (OI), with the goal of improving the diagnosis and prognostication of outcomes of paediatric mTBI.

METHODS AND ANALYSIS

A-CAP is a prospective, longitudinal cohort study of children aged 8.00-16.99 years with either mTBI or OI, recruited during acute emergency department (ED) visits at five sites from the Pediatric Emergency Research Canada network. Injury information is collected in the ED; follow-up assessments at 10 days and 3 and 6 months postinjury measure a variety of neurobiological and psychosocial markers, covariates/confounders and outcomes. Weekly postconcussive symptom ratings are obtained electronically. Recruitment began in September 2016 and will occur for approximately 24 months. Analyses will test the major hypotheses that neurobiological and psychosocial markers can: (1) differentiate mTBI from OI and (2) predict outcomes of mTBI. Models initially will focus within domains (eg, genes, imaging biomarkers, psychosocial markers), followed by multivariable modelling across domains. The planned sample size (700 mTBI, 300 OI) provides adequate statistical power and allows for internal cross-validation of some analyses.

ETHICS AND DISSEMINATION

The ethics boards at all participating institutions have approved the study and all participants and their parents will provide informed consent or assent. Dissemination will follow an integrated knowledge translation plan, with study findings presented at scientific conferences and in multiple manuscripts in peer-reviewed journals.

Epidemiology and Outcomes of Arterial Ischemic Stroke in Children: The Canadian Pediatric Ischemic Stroke Registry

BACKGROUND

Pediatric arterial ischemic stroke remains incompletely understood. Population-based epidemiological data inform clinical trial design but are scant in this condition. We aimed to determine age-specific epidemiological characteristics of arterial ischemic stroke in neonates (birth to 28 days) and older children (29 days to 18 years).

METHODS

We conducted a 16-year, prospective, national population-based study, the Canadian Pediatric Ischemic Stroke Registry, across all 16 Canadian acute care children's hospitals. We prospectively enrolled children with arterial ischemic stroke from January 1992 to December 2001 and documented disease incidence, presentations, risk factors, and treatments. Study outcomes were assessed throughout 2008, including abnormal clinical outcomes (stroke-related death or neurological deficit) and recurrent arterial ischemic stroke or transient ischemic attack.

RESULTS

Among 1129 children enrolled with arterial ischemic stroke, stroke incidence was 1.72/100,000/year, (neonates 10.2/100,000 live births). Detailed clinical and radiological information were available for 933 children (232 neonates and 701 older children, 55% male). The predominant clinical presentations were seizures in neonates (88%), focal deficits in older children (77%), and diffuse neurological signs (54%) in both. Among neonates, 44% had no discernible risk factors. In older children, arteriopathy (49% of patients with vascular imaging), cardiac disorders (28%), and prothrombotic disorders (35% of patients tested) predominated. Antithrombotic treatment increased during the study period (P < 0.001). Stroke-specific mortality was 5%. Outcomes included neurological deficits in 60% of neonates and 70% of older children. Among neonates, deficits emerged during follow-up in 39%. Overall, an initially decreased level of consciousness, a nonspecific systemic presentation, and the presence of stroke risk factors predicted abnormal outcomes. For neonates, predictors were decreased level of consciousness, nonspecific systemic presentation, and basal ganglia infarcts. For older children, predictors were initial seizures, nonspecific systemic presentation, risk factors, and lack of antithrombotic treatment. Recurrent arterial ischemic stroke or transient ischemic attack developed in 12% of older children and was predicted by arteriopathy, presentation without seizures, and lack of antithrombotic treatment. Emerging deficit was predicted by neonatal age at stroke and by cardiac disease.

CONCLUSIONS

This national data set provides a population-based disease incidence rate and demonstrates the protective effect of antithrombotic treatment in older children, and frequent long-term emerging deficits in neonates and in children with cardiac disorders. Further clinical trials are required to develop effective age-appropriate treatments for children with acute arterial ischemic stroke.

Cerebellar language mapping and cerebral language dominance in pediatric epilepsy surgery patients

Objective

Children with epilepsy often have reorganization of language networks and abnormal brain anatomy, making determination of language lateralization difficult. We characterized the proportion and distribution of language task activation in the cerebellum to determine the relationship to cerebral language lateralization.

Methods

Forty-six pediatric epilepsy surgery candidates (aged 7–19 years) completed an fMRI auditory semantic decision language task. Distribution of activated voxels and language laterality indices were computed using: (a) Broca's and Wernicke's areas and their right cerebral homologues; and (b) left and right cerebellar hemispheres. Language task activation was anatomically localized in the cerebellum.

Results

Lateralized language task activation in either cerebral hemisphere was highly correlated with lateralized language task activation in the contralateral cerebellar hemisphere (Broca vs. cerebellar: ρ = −0.54, p < 0.01). Cerebellar language activation was located within Crus I/II, areas previously implicated in non-motor functional networks.

Conclusions

Cerebellar language activation occurs in homologous regions of Crus I/II contralateral to cerebral language activation in patients with both right and left cerebral language dominance. Cerebellar language laterality could contribute to comprehensive pre-operative evaluation of language lateralization in pediatric epilepsy surgery patients. Our data suggest that patients with atypical cerebellar language activation are at risk for having atypical cerebral language organization.

•

We examine fMRI cerebellar language activation in pediatric epilepsy surgery patients.

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A semantic decision task is employed to lateralize cerebral and cerebellar language.

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Cerebral and contralateral cerebellar language activations are highly correlated.

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Cerebellar language activation is located in right or left Crus I/II.

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Cerebellar language laterality may aid pre-operative cerebral language localization.

Invasive procedures in preterm children: brain and cognitive development at school age

BACKGROUND

Very preterm infants (born 24-32 weeks' gestation) undergo numerous invasive procedures during neonatal care. Repeated skin-breaking procedures in rodents cause neuronal cell death, and in human preterm neonates higher numbers of invasive procedures from birth to term-equivalent age are associated with abnormal brain development, even after controlling for other clinical risk factors. It is unknown whether higher numbers of invasive procedures are associated with long-term alterations in brain microstructure and cognitive outcome at school age in children born very preterm.

METHODS

Fifty children born very preterm underwent MRI and cognitive testing at median age 7.6 years (interquartile range, 7.5-7.7). T1- and T2-weighted images were assessed for the severity of brain injury. Magnetic resonance diffusion tensor sequences were used to measure fractional anisotropy (FA), an index of white matter (WM) maturation, from 7 anatomically defined WM regions. Child cognition was assessed using the Wechsler Intelligence Scale for Children-IV. Multivariate modeling was used to examine relationships between invasive procedures, brain microstructure, and cognition, adjusting for clinical confounders (eg, infection, ventilation, brain injury).

RESULTS

Greater numbers of invasive procedures were associated with lower FA values of the WM at age 7 years (P = .01). The interaction between the number of procedures and FA was associated with IQ (P = .02), such that greater numbers of invasive procedures and lower FA of the superior WM were related to lower IQ.

CONCLUSIONS

Invasive procedures during neonatal care contribute to long-term abnormalities in WM microstructure and lower IQ.

Anti-basal ganglia antibodies and acute movement disorder following herpes zoster and streptococcal infections

Anti-basal ganglia antibodies (ABGA) have been associated with poststreptococcal encephalitis similar to encephalitis lethargica (EL). We report two children with parainfectious encephalitis of similar phenotype and IgG ABGA. However, the associated pathogens in the two cases differed; beta-hemolytic streptococcus and herpes zoster. ABGA may not be specific to poststreptococcal encephalitis, but rather a surrogate marker of an inflammatory mediated movement disorder, which may respond to immunotherapy.

Psychophysical Indexes of Temporal Processing Abnormalities in Children With Developmental Dyslexia

Children with dyslexia and children progressing normally in reading performed several perceptual tasks to determine (a) the psychophysical measures that best differentiate children with dyslexia from children with average reading abilities; (b) the extent of temporal processing deficits in a single, well-defined group of children with dyslexia; and (c) the co-occurrence of visual and auditory temporal processing deficits in children with dyslexia. 4 of our 12 psychophysical tasks indicated differences in temporal processing ability between children with dyslexia and children with good reading skills. These included 2 auditory tasks (dichotic pitch perception and FM tone discrimination) and 2 visual tasks (global motion perception and contrast sensitivity). The battery of 12 tasks successfully classified 80% of the children into their respective reading-level groups. Within the group of children with dyslexia who had temporal processing deficits, most were affected in either audition or vision; few children were affected in both modalities. The observed deficits suggest that impaired temporal processing in dyslexia is most evident on tasks that require the ability to synthesize local, temporally modulated inputs into a global percept and the ability to extract the resultant global percept from a noisy environment.

Dichotic pitch: a new stimulus distinguishes normal and dyslexic auditory function

Two patterns of appropriately filtered acoustic white noise can be binaurally fused by the human auditory system to extract pitch and location information that is not available to either ear alone. This phenomenon is called dichotic pitch. Here we present a new method for generating more effective and useful dichotic pitch stimuli. These novel stimuli allow the psychophysical assessment of dichotic pitch detection thresholds. We show that dichotic pitch detection is significantly impaired in individuals with developmental dyslexia, as compared to average readers. These results suggest a low-level auditory deficit associated with dyslexia and also demonstrate the potential value of our new dichotic pitch stimuli for assessment of auditory processing.

Basal ganglia infarction associated with HHV-6 infection

A 6 year old boy presented with meningoencephalitis and was found to have serological evidence of acute human herpes virus-6 (HHV-6) infection. He did not develop symptomatic seizures or the rash of exanthum subitum (roseola). His course was marked by severe spastic quadriparesis associated with radiological evidence of basal ganglia infarction. HHV-6 infection should be considered in any child with acute meningoencephalitis.

Computed tomography imaging in children with head trauma: utilization and appropriateness from a quality improvement perspective

Computed tomography (CT) imaging plays an important role in the acute evaluation and management of children with head trauma. When routine quality improvement (QI) meetings with representatives from the Children's Hospital radiology and emergency departments revealed disagreement regarding the utilization and appropriateness of CT in children presenting with head trauma, an interdepartmental QI team was formed to address this issue. Because formal criteria for obtaining CTs for head trauma were unavailable, internal institutional criteria were developed by consensus after literature review. Contrary to perceptions of some staff members, the majority (95%) of children who received CT met at least one of the established criteria over a one-year study period. There was little relationship between the presence of criteria and abnormal CT results, but decisions whether to admit patients to the hospital or to send them home were influenced by CT results. Follow-up studies suggested that patients who were discharged home with a normal CT or no CT had uniformly good outcomes.

Endotoxin-associated protein: a potent stimulus for human granulocytopoietic activity which may be accessory cell independent

Proteins coextracted with endotoxin, termed endotoxin-associated protein (EAP), have been shown to exert interleukin 1-like activities. The present studies demonstrate that EAP also exerts potent granulopoietic colony-stimulating activity (CSA) on human peripheral blood and bone marrow progenitor cells, comparable to that seen with various types of conditioned media. The CSA observed with EAP appeared to be heat (100 degrees C, 30 min) and trypsin resistant and partially pronase resistant. Similar resistance was observed with the porin proteins of the outer membrane of gram-negative bacteria, and similar CSA activity was observed with a purified porin preparation of Neisseria gonorrhoeae. The CSA of EAP could be demonstrated in human peripheral blood and bone marrow leukocytes rigorously depleted of monocytes, T lymphocytes, and B lymphocytes by treatment with specific monoclonal antibodies and complement.

Treatment of acute myeloid leukemia cells in vitro with a monoclonal antibody recognizing a myeloid differentiation antigen allows normal progenitor cells to be expressed

Monoclonal antibody L4F3 reacts with most acute myeloid leukemia (AML) cells and virtually all normal granulocyte/monocyte colony-forming cells (CFU-GM). Our objective was to determine whether lysis of AML cells with L4F3 and complement allowed expression of normal myeloid progenitors. The five glucose-6-phosphate dehydrogenase (G6PD) heterozygous patients with AML studied manifested only a single G6PD type in blast cells and in most or all granulocyte colony-forming cells, indicating that the leukemias developed clonally. The cells remaining after L4F3 treatment from two of the patients gave rise to granulocytic colonies that expressed the G6PD type not seen in the leukemic clone, indicating that they were derived from normal progenitors (CFU-GM). L4F3-treated cells from these two patients cultured over an irradiated adherent cell layer from normal long-term marrow cultures also gave rise to CFU-GM, which were shown by G6PD analysis to be predominantly nonleukemic. In the other three patients, the progenitor cells remaining after L4F3 treatment were derived mainly from the leukemic clone. The data suggest that in vitro cytolytic treatment with L4F3 of cells from certain patients with AML can enable normal, presumably highly immature progenitors to be expressed.

Human bone marrow stromal cell colonies: response to hydrocortisone and dependence on platelet-derived growth factor

Long-term bone marrow cultures are dependent on the formation in vitro of an adherent cell layer that supports hematopoiesis. We have grown bone-marrow-adherent cells, termed stromal colony-forming units, or CFU-ST, as isolated adherent colonies, and examined some of their growth requirements. Bone marrow mononuclear cells separated from aspirates by density centrifugation and cultured in medium supplemented with fetal calf serum or human plasma gave rise to adherent colonies (CFU-ST). An average of 23.4 +/- 2.1 (mean +/- SEM, n = 19) CFU-ST were produced by 10(5) bone marrow mononuclear cells. CFU-ST could not be cultured from similarly prepared peripheral blood mononuclear cells. The colonies were composed of spindle cells, flat cells, and fat-containing cells, with all three types often present in the same colony, suggesting derivation from a common progenitor. Cells were negative for nonspecific esterase and factor VIII antigen. Hydrocortisone added to the cultures at concentrations of 10(-7) M induced the formation of adipose cells in the center of one-third to one-half of the colonies but did not affect CFU-ST number. Human platelet-poor plasma and platelet-rich plasma were substituted for fetal calf serum in the medium. When all determinations for four experiments were averaged, platelet-rich plasma gave 17.8 +/- 1.2 (mean +/- SEM, n = 16) colonies, whereas platelet-poor plasma gave only 0.2 +/- 0.1 colonies (n = 15). When purified platelet-derived growth factor (PDGF) was added to platelet-poor plasma, growth of CFU-ST was enhanced, and a dose-response relationship was found between size of colonies and concentration of added PDGF. Granulocyte-macrophage colony stimulating factor added to cultures had no effect on the growth of CFU-ST.

Studies of the effects of trimethoprim and sulfamethoxazole on human granulopoiesis

Trimethoprim and sulfamethoxazole (Bactrim r) is a widely used antibiotic combination effective against a broad spectrum of microbial organisms. There are reports of neutropenia developing during even brief periods of oral therapy, particularly in individuals with either folate deficiency or increased folate requirements. We have investigated the effects of these drugs on circulating granulocyte precursors (CFU-C) from normal donors and the mechanism of inhibition on granulopoiesis using an in vitro CFU-C assay. In 12 healthy adults, the number of circulating granulocytes and granulocyte progenitors was not significantly altered by a 5-day course of therapy. However, in experiments that simulated the in vivo condition of folate deficiency (folate-free cultures were prepared with cells harvested from normal donors), trimethoprim (8 micrograms/ml) resulted in a 47% decrease in the total number of colonies; this inhibitory effect was prevented when 100 ng of folinic acid was also added to the culture. Sulfamethoxazole (40 micrograms/ml) had no discernible effect on granulopoiesis. The combination of 8 micrograms/ml of trimethoprim and 40 micrograms/ml of sulfamethoxazole resulted in a 52% decrease in the number of colonies generated and this inhibition was again prevented by folinic acid. Our results suggest that the neutropenia occasionally observed in patients treated with trimethoprim-sulfamethoxazole is due to the inhibitory effects on granulopoiesis by trimethoprim, namely its antifolate action, which is reversed by folinic acid. Based on these studies, in patients with either folate deficiency or increased folate requirements, trimethoprim-sulfamethoxazole should be used with caution.

Differential effect of hydrocortisone on eosinophil and neutrophil proliferation

Glucocorticosteroid therapy results in an increase in the number of circulating neutrophils and a decrease in the number of eosinophils. Utilizing the double layer soft agar technique, we examined the effect of physiologic to pharmacologic concentrations of hydrocortisone on the proliferation of human neutrophil progenitors and eosinophil progenitors from peripheral blood and bone marrow. When peripheral blood cultures were studied, eosinophil proliferation was inhibited in a dose-responsive fashion with 10(-8) - 10(-5) M hydrocortisone succinate, and comprised 49 +/- 4% of the colonies in control cultures and only 4 +/- 1% (P less than 0.01) at pharmacologic levels of hydrocortisone (10(-5) M). The number of neutrophil colonies, on the other hand, increased by 31% when 10(-5) M hydrocortisone was added to cultures. In order for corticosteroids to exert this effect, it was necessary to add them within 24 h of the initiation of culture. The effect of hydrocortisone on granulocyte proliferation could not be blocked by progesterone, a structurally analogous steroid. To determine whether hydrocortisone was acting directly on the progenitor cell or via an effector cell, its effect on modulating cell populations and stimulating-factor production was studied. Removal of E-rosetting cells and/or adherent cells did not affect the inhibition of eosinophil colony growth or the enhancement of neutrophil colony growth. Furthermore, addition of the potent inhibitor of T cell function, cyclosporin A, failed to affect eosinophil colony frequency, suggesting that inhibition of T cell function was an unlikely explanation for the observed hydrocortisone effect. Leukocyte conditioned media (LCM), derived from peripheral blood mononuclear cells incubated with hydrocortisone, was devoid of both neutrophil and eosinophil colony-stimulating activity, whereas a control LCM stimulated both neutrophil and eosinophil proliferation. The data suggest that the observed hydrocortisone effect on granulocyte colony formation is unlikely to be mediated by an intermediary, and that hydrocortisone acts directly on progenitor cells.

Heterogeneity of B cell involvement in acute nonlymphocytic leukemia

In order to study the pattern of B cell involvement in acute nonlymphocytic leukemia (ANLL), multiple B lymphoid cell lines were established by Epstein-Barr virus transformation of peripheral blood mononuclear cells from two patients with the disease who were heterozygous for the X chromosome-linked glucose-6-phosphate dehydrogenase (G6PD). In one patient, the progenitor cells involved by the leukemia exhibited multipotent differentiative expression, whereas in the other patient the cells showed differentiative expression restricted to the granulocytic pathway. In the patient whose abnormal clone showed multipotent expression, the ratio of B-A G6PD in B lymphoid cell lines was skewed in the direction of type B (the enzyme characteristic of the leukemia clone) and significantly different from the 1:1 ratio expected. It is, therefore, likely that the neoplastic event occurred in a stem cell common to the lymphoid series as well as to the myeloid series. In contrast, evidence for B cell involvement was not detected in the patient whose ANLL progenitor cells exhibited restricted differentiative expression. These findings underscore the heterogeneity of ANLL. Clinically and morphologically similar malignancies in these two patients originated in progenitors with different patterns of stem cell differentiative expression. This difference may reflect differences in cause and pathogenesis.

Inhibition of CFU-NM and CFU-EOS by mature granulocytes

Approximately half of the colony-forming units-culture (CFU-C) from normal peripheral blood are eosinophilic. The purpose of our study was to determine: (1) whether progenitor cells committed to eosinophil or neutrophil maturation would be differentially affected by feedback inhibition, and (2) whether mature eosinophils added to the feeder layers of the culture would inhibit the proliferation of CFU-C in a manner similar to that described for neutrophils. Concentrated eosinophils and neutrophils, obtained by separation on a metrizamide gradient, were added to feeder layers containing either 10(6) autologous whole mononuclear cells (WMNC) or 0.1 ml of leukocyte conditioned media (LCM). The average number of colonies was 123/10(6) nonadherent cells (NAC) cultured. When neutrophils or eosinophils were added to the WMNC feeder layer, the percent inhibition of growth was 40.2% +/- 1.6% (mean +/- SEM) and 42.3% +/- 5.4%, respectively, but the ratio of neutrophil to eosinophil colonies remained constant. No effect was seen when neutrophils or eosinophils were added to an LCM feeder layer. Thus, it appears that the differential control of neutrophil versus eosinophil production in vitro is not regulated through feedback inhibition by mature granulocytes. In addition, these studies suggest that eosinophils, as well as neutrophils, cause inhibition of CFU-C growth when intact cells are the source of colony-stimulating factor (CSF).

Peripheral blood myeloid progenitor cell cultures in patients with hypereosinophilic syndrome (CFU-eos in hypereosinophilic syndrome)

Myeloid progenitor cell cultures (CFU-C) were established in a double-layer agar system with peripheral blood mononuclear cells from 13 patients with the hypereosinophilic syndrome (HES). Normal controls produced 49% +/- 3.5% eosinophil colonies; results in 7 of the 13 HES patients were within the normal range, while in 5, the proportion of eosinophil colonies was greater than 3 standard deviations above the normal mean, and in 1 patient there was a low proportion of eosinophil colonies. The production of an increased proportion of eosinophil colonies correlated with more aggressive disease. Experiments in which normal progenitor cells were cultured over feeder layers of mononuclear cells demonstrated that cells of 3 of the 5 patients had an excess production of eosinophil colony-stimulating activity. When HES patients progenitor cells were cultured over normal feeder layers, 2 of the 5 patient samples continued to produce an increased proportion of eosinophil colonies, suggesting that these patients have an excess proportion of progenitor cells committed to eosinophil differentiation. Thus, the results demonstrated heterogeneity of growth characteristics for the HES patients. None, however, had the colony growth characteristic of acute or chronic myelogenous leukemia.

NIH conference. The idiopathic hypereosinophilic syndrome. Clinical, pathophysiologic, and therapeutic considerations

The idiopathic hypereosinophilic syndrome (HES) represents a heterogeneous group of disorders with the common features of prolonged eosinophilia of an undetectable cause and organ system dysfunction. Fifty patients with the idiopathic HES were studied over 11 years of the National Institutes of Health. Multiple organ systems were involved; bone marrow hypereosinophilia was common to all patients, but the most severe clinicopathologic involvement was of the heart and nervous system. Postmortem gross pathologic examination of the hearts of patients with idiopathic and nonidiopathic HES suggested that the common mechanism of cardiac disease is the eosinophilia. Endomyocardial biopsy findings showed that the endothelial cells in the endocardium and of the microvasculature were the primary targets of the tissue damage. This damage initiates thrombosis; endocardial fibrosis and restrictive endomyocardopathy may follow. In-vitro culture of circulating eosinophil colony-forming units showed some normal studies, some studies showing increased progenitor cells committed to eosinophil development, and others showing an excess production of eosinophil colony-stimulating factor. Chemotherapy to lower the eosinophil counts has resulted in marked improvement of HES prognosis, as have agressive medical and surgical approaches to cardiovascular complications.

In vitro culture of circulating CFUEOS from normal donors

Using an accurate technique for staining and scoring soft agar cultures, this study defines the incidence of circulating CFUEOS in normal donors. With whole mononuclear cells as the source of colony stimulating factor (CSF) and fetal calf serum, 49.6% +/- 3.5 of the colonies were eosinophilic; with human placental conditioned media and fetal calf serum 33.2% +/- 12.9 of the colonies were eosinophilic, with AB serum and whole mononuclear cells in the feeder layer 58.6% +/- 9.1 of the colonies were eosinophilic. The percentage of mixed neutrophil/eosinophil colonies was similar under varying culture conditions suggesting the presence of circulating progenitor cells capable of producing both lines.