Asymmetry of thalamic hypometabolism on FDG-PET/CT in neurofibromatosis type 1: Association with peripheral tumor burden.

BACKGROUND AND PURPOSE: Thalamic hypometabolism is a consistent finding in brain PET with F-18 fluorodeoxyglucose (FDG) in patients with neurofibromatosis type 1 (NF1). However, the pathophysiology of this metabolic alteration is unknown. We hypothesized that it might be secondary to disturbance of peripheral input to the thalamus by NF1-characteristic peripheral nerve sheath tumors (PNSTs). To test this hypothesis, we investigated the relationship between thalamic FDG uptake and the number, volume, and localization of PNSTs. METHODS: This retrospective study included 22 adult NF1 patients (41% women, 36.2 ± 13.0 years) referred to whole-body FDG-PET/contrast-enhanced CT for suspected malignant transformation of PNSTs and 22 sex- and age-matched controls. Brain FDG uptake was scaled voxelwise to the individual median uptake in cerebellar gray matter. Bilateral mean and left-right asymmetry of thalamic FDG uptake were determined using a left-right symmetric anatomical thalamus mask. PNSTs were manually segmented in contrast-enhanced CT. RESULTS: Thalamic FDG uptake was reduced in NF1 patients by 2.0 standard deviations (p < .0005) compared to controls. Left-right asymmetry was increased by 1.3 standard deviations (p = .013). Thalamic hypometabolism was higher in NF1 patients with ≥3 PNSTs than in patients with ≤2 PNSTs (2.6 vs. 1.6 standard deviations, p = .032). The impact of the occurrence of paraspinal/paravertebral PNSTs and of the mean PNST volume on thalamic FDG uptake did not reach statistical significance (p = .098 and p = .189). Left-right asymmetry of thalamic FDG uptake was not associated with left-right asymmetry of PNST burden (p = .658). CONCLUSIONS: This study provides first evidence of left-right asymmetry of thalamic hypometabolism in NF1 and that it might be mediated by NF1-associated peripheral tumors.

Multimodal assessment of the GABA system in patients with fragile-X syndrome and neurofibromatosis of type 1.

Fragile-X syndrome (FXS) and Neurofibromatosis of type 1 (NF-1) are two monogenic disorders sharing neurobehavioral symptoms and pathophysiological mechanisms. Namely, preclinical models of both conditions show overactivity of the mTOR signaling pathway as well as GABAergic alterations. However, despite its potential clinical relevance for these disorders, the GABAergic system has not been systematically studied in humans. In the present study, we used an extensive transcranial magnetic stimulation (TMS) assessment battery in combination with magnetic resonance spectroscopy (MRS) to provide a comprehensive picture of the main inhibitory neurotransmitter system in patients with FXS and NF1. Forty-three participants took part in the TMS session (15 FXS, 10 NF1, 18 controls) and 36 in the MRS session (11 FXS, 14 NF1, 11 controls). Results show that, in comparison to healthy control participants, individuals with FXS and NF1 display lower GABA concentration levels as measured with MRS. TMS result show that FXS patients present increased GABAB-mediated inhibition compared to controls and NF1 patients, and that GABAA-mediated intracortical inhibition was associated with increased excitability specifically in the FXS groups. In line with previous reports, correlational analyses between MRS and TMS measures did not show significant relationships between GABA-related metrics, but several TMS measures correlated with glutamate+glutamine (Glx) levels assessed with MRS. Overall, these results suggest a partial overlap in neurophysiological alterations involving the GABA system in NF1 and FXS, and support the hypothesis that MRS and TMS assess different aspects of the neurotransmitter systems.

L-carnitine supplementation for muscle weakness and fatigue in children with neurofibromatosis type 1: A Phase 2a clinical trial.

Reduced muscle tone, muscle weakness, and physical fatigue can impact considerably on quality of life for children with neurofibromatosis type 1 (NF1). Human muscle biopsies and mouse models of NF1 deficiency in muscle show intramyocellular lipid accumulation, and preclinical data have indicated that L-carnitine supplementation can ameliorate this phenotype. The aim of this study is to examine whether daily L-carnitine supplementation is safe and feasible, and will improve muscle strength and reduce fatigue in children with NF1. A 12-week Phase 2a trial was conducted using 1000 mg daily oral levocarnitine tartrate supplementation. Recruited children were between 8 and 12 years old with a clinical diagnosis of NF1, history of muscle weakness and fatigue, and naïve to L-carnitine. Primary outcomes were safety (self-reporting, biochemical testing) and compliance. Secondary outcomes included plasma acylcarnitine profiles, functional measures (muscle strength, long jump, handwriting speed, 6-minute-walk test [6MWT]), and parent-reported questionnaires (PedsQL™, CBCL/6-18). Six children completed the trial with no self-reported adverse events. Biochemical tests for kidney and liver function were normal, and the average compliance was 95%. Plasma acylcarnitine levels were low, but within a range not clinically linked to carnitine deficiency. For strength measures, there was a mean 53% increase in dorsiflexion strength (95% confidence interval [CI] 8.89-60.75; p = 0.02) and mean 66% increase in plantarflexion strength (95% CI 12.99-134.1; p = 0.03). In terms of muscle performance, there was a mean 10% increase in long jump distance (95% CI 2.97-16.03; p = 0.01) and 6MWT distance (95% CI 5.88-75.45; p = 0.03). Comparison with the 1000 Norms Project data showed a significant improvement in Z-score for all of these measures. Parent reports showed no negative impact on quality of life, and the perceived benefits led to the majority of individuals remaining on L-carnitine after the study. Twelve weeks of L-carnitine supplementation is safe and feasible in children with NF1, and a Phase 3 trial should confirm the efficacy of treatment.

Assessment of a nutritional supplement containing resveratrol, prebiotic fiber, and omega-3 fatty acids for the prevention and treatment of mild traumatic brain injury in rats.

Children and adolescents have the highest rates of traumatic brain injury (TBI), with mild TBI (mTBI) accounting for most of these injuries. Adolescents are particularly vulnerable and often suffer from post-injury symptomologies that may persist for months. We hypothesized that the combination of resveratrol (RES), prebiotic fiber (PBF), and omega-3 fatty acids (docosahexaenoic acid (DHA)) would be an effective therapeutic supplement for the mitigation of mTBI outcomes in the developing brain. Adolescent male and female Sprague-Dawley rats were randomly assigned to the supplement (3S) or control condition, which was followed by a mTBI or sham insult. A behavioral test battery designed to examine symptomologies commonly associated with mTBI was administered. Following the test battery, tissue was collected from the prefrontal cortex (PFC) and primary auditory cortex for Golgi-Cox analysis of spine density, and for changes in expression of 6 genes (Aqp4, Gfap, Igf1, Nfl, Sirt1, and Tau). 3S treatment altered the behavioral performance of sham animals indicating that dietary manipulations modify premorbid characteristics. 3S treatment prevented injury-related deficits in the longer-term behavior measures, medial prefrontal cortex (mPFC) spine density, and levels of Aqp4, Gfap, Igf1, Nfl, and Sirt1 expression in the PFC. Although not fully protective, treatment with the supplement significantly improved post-mTBI function and warrants further investigation.

Impairment of Procedural Learning and Motor Intracortical Inhibition in Neurofibromatosis Type 1 Patients.

BACKGROUND: Cognitive difficulties are the most common neurological complications in neurofibromatosis type 1 (NF1) patients. Recent animal models proposed increased GABA-mediated inhibition as one underlying mechanism directly affecting the induction of long-term potentiation (LTP) and learning. In most adult NF1 patients, apparent cognitive and attentional deficits, tumors affecting the nervous system and other confounding factors for neuroscientific studies are difficult to control for. Here we used a highly specific group of adult NF1 patients without cognitive or nervous system impairments. Such selected NF1 patients allowed us to address the following open questions: Is the learning process of acquiring a challenging motor skill impaired in NF1 patients? And is such an impairment in relation to differences in intracortical inhibition? METHODS: We used an established non-invasive, double-pulse transcranial magnetic stimulation (dp-TMS) paradigm to assess practice-related modulation of intracortical inhibition, possibly mediated by gamma-minobutyric acid (GABA)ergic-neurotransmission. This was done during an extended learning paradigm in a group of NF1 patients without any neuropsychological deficits, functioning normally in daily life and compared them to healthy age-matched controls. FINDINGS: NF1 patients experienced substantial decline in motor skill acquisition (F = 9.2, p = 0.008) over five-consecutives training days mediated through a selective reduction in the early acquisition (online) and the consolidation (offline) phase. Furthermore, there was a consistent decrease in task-related intracortical inhibition as a function of the magnitude of learning (T = 2.8, p = 0.014), especially evident after the early acquisition phase. INTERPRETATIONS: Collectively, the present results provide evidence that learning of a motor skill is impaired even in clinically intact NF1 patients based, at least partially, on a GABAergic-cortical dysfunctioning as suggested in previous animal work.

Bone mineral metabolism in patients with neurofibromatosis type 1 (von Recklingausen disease).

The neurofibromatosis type 1 (NF1) is characterized by specific cutaneous features (neurofibromas, "café-au-lait" spots of the skin) and alterations of several tissue (nervous, vascular) and bone deformities, such as scoliosis, congenital pseudoarthrosis and bone dysplasia of tibia. Moreover, several studies have shown systemic involvement of bone tissue in NF1 patients, leading to reduced bone mass. The aim of our study was to evaluate some bone mineral metabolism parameters before and after calcium and vitamin D supplementation in NF1 patients. We evaluated in 70 NF1 consecutive patients the mineral metabolism and bone mineral density compared with 40 normal subjects. We showed bone alterations in 35% of patients and the increase of bone formation markers, such as bone isoenzyme of alkaline phosphatase (41.2 ± 15.5 vs. 25.6 ± 8.7 UI; P < 0.05, respectively) and osteocalcin (18.1 ± 5.6 vs. 7.6 ± 1.9 ng/ml; P < 0.05) and reduction of circulating levels of (25OH)-vitamin D (21.8 ± 12.3 ng/ml) with an high percentage of hypovitaminosys D (>60%). Moreover, we revealed a significant reduction of bone mass density at spine (L1-L4) (0.935 ± 0.13 vs. 1.110 ± 0.17 g/cm(2); P < 0.001) and femoral neck side (0.765 ± 0.09 vs. 0.839 ± 0.12 g/cm(2); P < 0.02), with high prevalence of osteopenia (44%) and osteoporosis (18%). After 12 months of calcium (1,200 mg/die) and cholecalciferol (800 UI/die) supplementation, we found a significant increase of (25) OH-vitamin D level (21.8 ± 12.3 vs. 35 ± 13 ng/ml; P < 0.01), without changes in bone mass density. In conclusion, NF1 patients may present a mineral bone involvement, with vitamin D deficiency; calcium and vitamin D supplementation is necessary to restore these bone mineral metabolic alterations.

Proton MR spectroscopic imaging of basal ganglia and thalamus in neurofibromatosis type 1: correlation with T2 hyperintensities.

INTRODUCTION: Neurofibromatosis type 1 (NF1) is frequently associated with hyperintense lesions on T2-weighted images called "unidentified bright objects" (UBO). To better characterize the functional significance of UBO, we investigate the basal ganglia and thalamus using spectroscopic imaging in children with NF1 and compare the results to anomalies observed on T2-weighted images. METHODS: Magnetic resonance (MR) data of 25 children with NF1 were analyzed. On the basis of T2-weighted images analysis, two groups were identified: one with normal MR imaging (UBO- group; n = 10) and one with UBO (UBO+ group; n = 15). Within the UBO+ group, a subpopulation of patients (n = 5) only had lesions of the basal ganglia. We analyzed herein seven regions of interest (ROIs) for each side: caudate nucleus, capsulo-lenticular region, lateral and posterior thalamus, thalamus (lateral and posterior voxels combined), putamen, and striatum. For each ROI, a spectrum of the metabolites and their ratio was obtained. RESULTS: Patients with abnormalities on T2-weighted images had significantly lower NAA/Cr, NAA/Cho, and NAA/mI ratios in the lateral right thalamus compared with patients with normal T2. These abnormal spectroscopic findings were not observed in capsulo-lenticular regions that had UBO but in the thalamus region that was devoid of UBO. CONCLUSION: Multivoxel spectroscopic imaging using short-time echo showed spectroscopic abnormalities in the right thalamus of NF1 patients harboring UBO, which were mainly located in the basal ganglia. This finding could reflect the anatomical and functional interactions of these regions.

Schweinfurthin A selectively inhibits proliferation and Rho signaling in glioma and neurofibromatosis type 1 tumor cells in a NF1-GRD-dependent manner.

Neurofibromatosis type 1 (NF1) is the most common genetic disease affecting the nervous system. Patients typically develop many tumors over their lifetime, leading to increased morbidity and mortality. The NF1 gene, mutated in NF1, is also commonly mutated in sporadic glioblastoma multiforme (GBM). Because both NF1 and GBM are currently incurable, new therapeutic approaches are clearly needed. Natural products represent an opportunity to develop new therapies, as they have been evolutionarily selected to play targeted roles in organisms. Schweinfurthin A is a prenylated stilbene natural product that has previously shown specific inhibitory activity against brain and hematopoietic tumor lines. We show that patient-derived GBM and NF1 malignant peripheral nerve sheath tumor (MPNST) lines, as well as tumor lines derived from the Nf1-/+;Trp53-/+ (NPcis) mouse model of astrocytoma and MPNST are highly sensitive to inhibition by schweinfurthin A and its synthetic analogs. In contrast, primary mouse astrocytes are resistant to the growth inhibitory effects of schweinfurthin A, suggesting that schweinfurthin A may act specifically on tumor cells. Stable transfection of the GTPase-activating protein related domain of Nf1 into Nf1-/-;Trp53-/- astrocytoma cells confers resistance to schweinfurthin A. In addition, the profound effect of schweinfurthin A on dynamic reorganization of the actin cytoskeleton led us to discover that schweinfurthin A inhibits growth factor-stimulated Rho signaling. In summary, we have identified a class of small molecules that specifically inhibit growth of cells from both central and peripheral nervous system tumors and seem to act on NF1-deficient cells through cytoskeletal reorganization correlating to changes in Rho signaling.

Preclinical in vivo evaluation of rapamycin in human malignant peripheral nerve sheath explant xenograft.

Neurofibromatosis type 1 (NF1) patients are prone to the development of malignant tumors, the most common being Malignant Peripheral Nerve Sheath Tumor (MPNST). NF1-MPNST patients have an overall poor survival due to systemic metastasis. Currently, the management of MPNSTs includes surgery and radiation; however, conventional chemotherapy is not very effective, underscoring the need for effective biologically-targeted therapies. Recently, the NF1 gene product, neurofibromin, was shown to negatively regulate the phosphoinositide-3-kinase (PI3K)/Protein Kinase-B (Akt)/mammalian Target Of Rapamycin (mTOR) pathway, with loss of neurofibromin expression in established human MPNST cell lines associated with high levels of mTOR activity. We developed and characterized a human NF1-MPNST explant grown subcutaneously in NOD-SCID mice, to evaluate the effect of the mTOR inhibitor rapamycin. We demonstrate that rapamycin significantly inhibited human NF1-MPNST mTOR pathway activation and explant growth in vivo at doses as low as 1.0 mg/kg/day, without systemic toxicities. While rapamycin was effective at reducing NF1-MPNST proliferation and angiogenesis, with decreased CyclinD1 and VEGF respectively, there was no increase in tumor apoptosis. Rapamycin effectively decreased activation of S6 downstream of mTOR, but there was accompanied increased Akt activation. This study demonstrates the therapeutic potential and limitations of rapamycin in NF1-associated, and likely sporadic, MPNSTs.

Neurofibromin regulates somatic growth through the hypothalamic-pituitary axis.

To study the role of the neurofibromatosis-1 (NF1) gene in mammalian brain development, we recently generated mice in which Nf1 gene inactivation occurs in neuroglial progenitor cells using the brain lipid binding protein (BLBP) promoter. We found that Nf1(BLBP)CKO mice exhibit significantly reduced body weights and anterior pituitary gland sizes. We further demonstrate that the small anterior pituitary size reflects loss of neurofibromin expression in the hypothalamus, leading to reduced growth hormone releasing hormone, pituitary growth hormone (GH) and liver insulin-like growth factor-1 (IGF1) production. Since neurofibromin both negatively regulates Ras activity and positively modulates cAMP levels, we examined the signaling pathway responsible for these abnormalities. While BLBP-mediated expression of an activated Ras molecule did not recapitulate the body weight and hypothalamic/pituitary defects, treatment of Nf1(BLBP)CKO mice with rolipram to increase cAMP levels resulted in a partial restoration of the body weight phenotype. Furthermore, conditional expression of the Ras regulatory GAP domain of neurofibromin also did not rescue the body weight or Igf1 mRNA defects in Nf1(BLBP)CKO mice. Collectively, these data demonstrate a critical role for neurofibromin in hypothalamic-pituitary axis function and provide further insights into the short stature and GH deficits seen in children with NF1.

Reduced thalamic 18F-flurodeoxyglucose retention in adults with neurofibromatosis type 1.

OBJECTIVE: Neurofibromatosis type1 (NF1) is associated with cognitive and motor deficits whose pathogenesis is not well understood. 18F-Flurodeoxyglucose positron emission tomography (FDG PET) might be used to investigate putative functional correlates in the brain. METHODS: Whole-body FDG PET including the brain had been performed in 29 NF1 patients suspected for malignant peripheral nerve sheath tumours (20 females, nine males, age 31.2+/-11.8 years). Twenty-nine age-matched and sex-matched subjects without evidence of neurological/psychiatric disease in whom FDG PET had been performed for NF1-unrelated oncological indication served as controls. Individual brain FDG retention images were stereotactically normalized and scaled to a common median retention value within the brain. Scaled FDG retention was compared between the NF1 group and the control group on a voxel-by-voxel base using ANCOVA in SPM2 with the FDG uptake period as covariate. The corrected significance level alpha=0.05 was used. Voxel-based analysis was complemented by volume of interest (VOI)-based analysis using predefined standard VOIs. RESULTS: The voxel-based group comparison revealed a significant reduction of scaled FDG retention in the thalamus of the NF1 subjects within a cluster of 11.6 ml. There were no further significant effects, neither hypo-retention nor hyper-retention. Reduction of relative FDG retention in the thalamus in the NF1 subjects was confirmed by VOI analysis. The magnitude of the reduction was about 8%. CONCLUSIONS: The thalamus appears to be affected in adults with NF1. The observed magnitude of the reduction of scaled thalamic FDG retention in adults is smaller than previously reported in children. This may be consistent with a stabilization of the disease process with age.

Sichuan pepper extracts block the PAK1/cyclin D1 pathway and the growth of NF1-deficient cancer xenograft in mice.

There is increasing evidence that more than 70% of cancers including pancreatic, breast and prostate cancers as well as neurofibromatosis (NF) are highly addicted to abnormal activation of the Ser/Thr kinase PAK1 for their growth. So far FK228 is the most potent among the HDAC (histone deacetylase) inhibitors that block the activation of both PAK1 and another kinase AKT, downstream of PI-3 kinase. However, FK228 is still in clinical trials (phase 2) for a variety of cancers (but not for NF as yet), and not available for most cancer/NF patients. Thus, we have been exploring an alternative which is already in the market, and therefore immediately useful for the treatment of those desperate cancer/NF patients. Here we provide the first evidence that extracts of Chinese/ Japanese peppercorns (Zanthoxyli Fructus) from the plant Zanthoxylum piperitum called "Hua Jiao"/"Sansho", block selectively the key kinase PAK1, leading to the downregulation of cyclin D1. Unlike FK228, these extracts do not inhibit AKT activation at the concentrations that block either cancer growth or PAK1 activation. The Chinese pepper extract selectively inhibits the growth of NF1-deficient malignant peripheral nerve sheath tumor (MPNST) cells, without affecting the growth of normal fibroblasts, and suppresses the growth of NF1-deficient human breast cancer (MDA-MB-231) xenograft in mice. Our data suggest that these peppercorn extracts would be potentially useful for the treatment of PAK1-dependent NF such as MPNST, in addition to a variety of PAK1-dependent cancers including breast cancers.

Increased brain apparent diffusion coefficient in children with neurofibromatosis type 1.

PURPOSE: To describe the changes in brain water diffusibility in five anatomic locations in children with neurofibromatosis type 1 (NF 1) compared with these changes in control subjects and to describe the water diffusibility changes associated with hyperintense basal ganglia lesions in children with NF 1. MATERIALS AND METHODS: Twenty highly related pairs of children consisting of one child with NF 1 and one unaffected child were examined. Prospective comparisons of isotropic apparent diffusion coefficient (ADC) values at five anatomic locations were performed, with and without T2-hyperintense lesions included. Retrospective analysis of hyperintense globus pallidus lesions in 16 children and in the paired control subjects also was performed. RESULTS: Significant increases in ADC values were seen in all five anatomic locations in the NF 1 group. The greatest increases were seen in the globus pallidus (14%; P =.002) and brachium pontis (10.8%; P =.003). With exclusion of hyperintense lesions, significant ADC increases were measured in four locations. Significant ADC increases were seen in hyperintense globus pallidus lesions in the NF 1 group compared with ADC values in the normal-appearing contralateral globus pallidus (4.9%; P =.02) and those in the globus pallidus of the paired control subjects (16%; P =.003). CONCLUSION: Significant ADC increases were measured both in the hyperintense lesions and in the normal-appearing areas of the brain in children with NF 1.

Positron emission tomography in children with neurofibromatosis-1.

Neurofibromatosis-1 is an autosomal dominant genetic disorder commonly associated with neuropsychological complications. Focal areas of high signal intensity on magnetic resonance imaging (MRI) scans occur commonly but have shown inconsistent correlation with neuropsychological problems. Positron emission tomography (PET) scans utilizing [18F]fluoro-2-deoxy-D-glucose and MRI studies were performed on 10 children with neurofibromatosis-1 and multiple focal areas of high signal intensity to evaluate the regional cerebral metabolic rate for glucose of these lesions and other central nervous system structures. Co-registered PET and MRI studies confirmed reduced glucose metabolism of large focal areas of high signal intensity. Visual inspection and semiquantitative analysis of PET images demonstrated thalamic hypometabolism and varying degrees of cortical inhomogeneity in all cases of neurofibromatosis-1 compared to normal controls. Although a primary defect of the thalamus or cerebral cortex has not been defined, the metabolic abnormalities of this study suggest a potential relationship between these structures and the neuropsychological dysfunctions noted in neurofibromatosis-1.

Hypercalcemic hyperparathyroidism and hypophosphatemic osteomalacia complicating neurofibromatosis.

Neurofibromatosis is sometimes complicated by impaired renal tubular reabsorption of phosphate, hypophosphatemia, and osteomalacia. Hyperparathyroidism has also been reported in patients with neurofibromatosis. When hypercalcemia and elevated levels of parathyroid hormone are found in osteomalacia, however, it may be difficult to determine if the hyperparathyroidism was primary or tertiary. We describe a patient with neurofibromatosis, hypercalcemic hyperparathyroidism, hypophosphatemic osteomalacia, vitamin D deficiency, and clear-cell hyperplasia of all four parathyroid glands. Serial biomechanical, bone biopsy, and densitometric studies confirmed that treatment with ergocalciferol, calcium, and phosphate supplements significantly improved the osteomalacia but caused increased parathyroid overactivity. After subtotal parathyroidectomy, the parathyroid hormone concentration became normal and the bone mineral content increased at the spine and hip, but inappropriate phosphaturia persisted. The findings indicate that hyperparathyroidism, osteomalacia, and vitamin D deficiency adversely affect each other.

[Recklinghausen's disease with hypophosphoremia and osteomalacia. Apropos of 2 cases]. / Maladie de Recklinghausen avec hypophosphorémie et ostéomalacie. A propos de 2 observations.

The authors report two cases of osteomalacia due to phosphate diabetes in patients with Recklinghausen's disease. In one case abnormalities of vitamin D metabolism were identical with those described in cases of phosphate diabetes associated with mesenchymal tumours. The abnormalities found in the second case were different. The physiopathological mechanism of osteomalacia due to phosphate diabetes in mesenchymal diseases generally and in Recklinghausen's disease in particular is discussed.