Evaluation of oxidative stress effects on different macromolecules in adult growth hormone deficiency.

Adult growth hormone deficiency (GHD) is being increasingly recognized to cause premature mortality exacerbated by oxidative stress. A case-control observational study has been performed with the primary objective of evaluating new parameters of oxidative stress and macromolecular damage in adult GHD subjects: serum nitrotryptophan; Total Antioxidant Capacity expressed as LAG time; urinary hexanoil-lysine; urinary dityrosine and urinary 8-OH-deoxyguanosine. GHD was diagnosed using Growth Hormone-Releasing Hormone 50µg iv+arginine 0,5 g/Kg test, with a peak GH response <9 µg /L when BMI was <30 kg/m2 or <4 µg/L when BMI was >30 kg/m2. Patients affected by adult GHD were divided into three groups, total GHD (n = 26), partial GHD (n = 25), and controls (n = 29). Total Antioxidant Capacity, metabolic and hormonal parameters have been determined in separate plasma samples; nitrotryptophan in serum samples; hexanoil-lysine, dityrosine, 8-OH-deoxyguanosine in urine samples. Assessment of hexanoil-lysine exhibited a trend to increase in comparing total GHD vs partial and controls, although not significant. Values of 8-OH-deoxyguanosine did not significantly differ among the three groups. Significant lower levels of dityrosine in partial GHD vs total and controls were found. No significant difference in nitrotriptophan serum levels was found, while significantly greater values of Total Antioxidant Capacity were showed in total and partial GHD vs controls. Thus, our result confirm that oxidative stress is increased both in partial and total adult GHD. The lack of compensation by antioxidants in total GHD may be connected to the complications associated to this rare disorder.

AQP1 Overexpression in the CSF of Obstructive Hydrocephalus and Inversion of Its Polarity in the Choroid Plexus of a Chiari Malformation Type II Case.

The choroid plexus (ChP) is involved in the production of cerebrospinal fluid (CSF) and is intimately related to CSF physiopathology. Aquaporin-1 (AQP1) is the water channel directly implicated in CSF production and a potential therapeutic target in the management of CSF circulation disorders. Pathologies that present ventriculomegaly are associated with defective CSF turnover and AQPs are involved in both the production and reabsorption of CSF. This work examines the levels of AQP1 and its dynamics in ventriculomegaly conditions such as congenital hydrocephalus (communicating and obstructive) or type II lissencephaly versus control. We specifically address the expression of AQP1 in the CSF of 16 term-pregnancy infants where it was found to be significantly increased in obstructive cases when compared with communicating hydrocephalus or control patients. We also defined histologically the expression of AQP1 in the ChP from 6 nonsurvival preterm-pregnancy infants ranging ages between 20 and 25 gestational weeks in which AQP1 was mainly expressed at the apical pole of the ChP epithelium (ChPE) in control and lissencephalic patients. AQP1 expression from the Chiari malformation case showed an inverted polarity being expressed in the basal pole of the ChPE colocalizing with the glucose transporter 1 where this transporter is naturally located.

Chiari I "malformations"--an acquired disorder?

Caudal herniation of the hindbrain, indistinguishable from the Chiari I deformity, may occur after the establishment of spinal subarachnoid shunts and become symptomatic years after the procedure. Examples are presented and others are cited from the literature. It is proposed that the force responsible for the displacement is the difference in pressure between the cranial and spinal compartments. On the basis of these observations and other considerations as well, a similar process, disproportionate absorption of cerebrospinal fluid from the spinal region, might account for the spontaneous form of the Chiari I deformity.

Nerve Growth Factor (NGF) up-regulation in the cerebrospinal fluid of newborns with myelomeningocele.

BACKGROUND: Neurotrophic factors, such as Nerve Growth Factor (NGF), play a key role in the stimulation of sprouting, synaptic plasticity, and reorganization after spinal cord damage. AIM: The aim of this study was to investigate the expression of nerve growth factor (NGF) in the cerebrospinal fluid (CSF) of newborns with myelomeningocele (MMC) and to determine its correlation with this spinal malformation. PATIENTS AND METHODS: To measure the expression of NGF, we collected CSF samples of 14 newborns with MMC taken immediately before the neurosurgical correction of the spinal malformation and of 14 matched controls. Endogenous NGF levels were quantified using a two-site immuno-enzymatic assay. The statistical analysis was performed using the Mann-Whitney two-tailed two-sample test. RESULTS: In the CSF of patients with MMC, NGF levels showed a significant increase compared to the mean levels of the control group (63.05 ± 7.3 vs 18.32 ± 4.5 pg/mL; (p < 0.001). No correlation was found between NGF expression and different types of MMC malformation, such as the level of spinal lesion and the association with Chiari II syndrome. CONCLUSIONS: Our study shows an over-expression of NGF in the CSF of newborns with MMC. The observed pattern of NGF up-regulation in this subset of patients may stimulate axonal sprouting and synaptic reorganization of the damaged neural cells at the site of spinal cord injury, thereby representing an important biochemical marker of spinal cord damage in MMC patients.

Hydrodynamic and longitudinal impedance analysis of cerebrospinal fluid dynamics at the craniovertebral junction in type I Chiari malformation.

Elevated or reduced velocity of cerebrospinal fluid (CSF) at the craniovertebral junction (CVJ) has been associated with type I Chiari malformation (CMI). Thus, quantification of hydrodynamic parameters that describe the CSF dynamics could help assess disease severity and surgical outcome. In this study, we describe the methodology to quantify CSF hydrodynamic parameters near the CVJ and upper cervical spine utilizing subject-specific computational fluid dynamics (CFD) simulations based on in vivo MRI measurements of flow and geometry. Hydrodynamic parameters were computed for a healthy subject and two CMI patients both pre- and post-decompression surgery to determine the differences between cases. For the first time, we present the methods to quantify longitudinal impedance (LI) to CSF motion, a subject-specific hydrodynamic parameter that may have value to help quantify the CSF flow blockage severity in CMI. In addition, the following hydrodynamic parameters were quantified for each case: maximum velocity in systole and diastole, Reynolds and Womersley number, and peak pressure drop during the CSF cardiac flow cycle. The following geometric parameters were quantified: cross-sectional area and hydraulic diameter of the spinal subarachnoid space (SAS). The mean values of the geometric parameters increased post-surgically for the CMI models, but remained smaller than the healthy volunteer. All hydrodynamic parameters, except pressure drop, decreased post-surgically for the CMI patients, but remained greater than in the healthy case. Peak pressure drop alterations were mixed. To our knowledge this study represents the first subject-specific CFD simulation of CMI decompression surgery and quantification of LI in the CSF space. Further study in a larger patient and control group is needed to determine if the presented geometric and/or hydrodynamic parameters are helpful for surgical planning.

Chiari malformation type I: a case-control association study of 58 developmental genes.

Chiari malformation type I (CMI) is a disorder characterized by hindbrain overcrowding into an underdeveloped posterior cranial fossa (PCF), often causing progressive neurological symptoms. The etiology of CMI remains unclear and is most likely multifactorial. A putative genetic contribution to CMI is suggested by familial aggregation and twin studies. Experimental models and human morphometric studies have suggested an underlying paraxial mesoderm insufficiency. We performed a case-control association study of 303 tag single nucleotide polymorphisms (SNP) across 58 candidate genes involved in early paraxial mesoderm development in a sample of 415 CMI patients and 524 sex-matched controls. A subgroup of patients diagnosed with classical, small-PCF CMI by means of MRI-based PCF morphometry (n = 186), underwent additional analysis. The genes selected are involved in signalling gradients occurring during segmental patterning of the occipital somites (FGF8, Wnt, and retinoic acid pathways and from bone morphogenetic proteins or BMP, Notch, Cdx and Hox pathways) or in placental angiogenesis, sclerotome development or CMI-associated syndromes. Single-marker analysis identified nominal associations with 18 SNPs in 14 genes (CDX1, FLT1, RARG, NKD2, MSGN1, RBPJ1, FGFR1, RDH10, NOG, RARA, LFNG, KDR, ALDH1A2, BMPR1A) considering the whole CMI sample. None of these overcame corrections for multiple comparisons, in contrast with four SNPs in CDX1, FLT1 and ALDH1A2 in the classical CMI group. Multiple marker analysis identified a risk haplotype for classical CMI in ALDH1A2 and CDX1. Furthermore, we analyzed the possible contributions of the most significantly associated SNPs to different PCF morphometric traits. These findings suggest that common variants in genes involved in somitogenesis and fetal vascular development may confer susceptibility to CMI.

Children with growth hormone deficiency and Chiari I malformation: a morphometric analysis of the posterior cranial fossa.

OBJECTIVE: The posterior fossa (PF) has been found to be small in various forms of Chiari malformation. Explanations involving a connection between growth hormone deficiency (GHD) and Chiari I malformation (CIM) have been proposed. However, to date, no quantitative analysis of the PF of patients with CIM and GHD has been performed. Our study was performed to determine the geometry of the PF in children with GHD and CIM. METHODS: Morphometric analysis of the PF was performed in 10 children with GHD and CIM (group 1), 20 children with GHD and no CIM (group 2) and 50 controls. RESULTS: PF volumes for group 1 ranged from 128 to 259 +/- 33 ml, and for group 2, they ranged from 115 to 186.2 +/- 25.4 ml. Lengths of the foramen magnum for groups 1 and 2 had means of 36 and 38 mm, respectively. The mean basiocciput length and tentorial angle for groups 1 and 2 were 20 and 19 mm and 89 and 87.5 degrees, respectively. CONCLUSIONS: We have determined that children with GHD with or without CIM have no significant difference in their PF volume compared to controls. However, our data demonstrate significant underdevelopment of portions of the bony PF in both patients with GHD alone and in patients with GHD and CIM. Tentorial angles were elevated in noncontrol groups. We propose that this association is not due to an increased rate of 'midline' defects seen in GHD but rather a structurally distorted PF that is not capacious enough to house the entire developing rhombencephalon. These data will hopefully aid in the further understanding of the pathophysiology of CIM.

Regional ependymal upregulation of vimentin in Chiari II malformation, aqueductal stenosis, and hydromyelia.

Vimentin, glial fibrillary acidic protein (GFAP) and S-100beta protein were studied by immunocytochemistry in the ependyma of patients with Chiari II malformations, congenital aqueductal stenosis, and hydromyelia. Paraffin sections of brains and spinal cords of 16 patients were examined, 14 with Chiari II malformations, most with aqueductal stenosis and/or hydromyelia as associated features, and 2 patients with congenital aqueductal stenosis without Chiari malformation. Patients ranged in age from 20-wk gestation to 48 years. The results demonstrated: 1) in the fetus and young infant with Chiari II malformations, congenital aqueductal stenosis, and hydromyelia, vimentin is focally upregulated in the ependyma only in areas of dysgenesis and not in the ependyma throughout the ventricular system; 2) GFAP and S-100beta protein are not coexpressed, indicating that the selective upregulation of vimentin is not simple maturational delay; 3) vimentin upregulation also is seen in the ependymal remnants of the congenital atretic cerebral aqueduct, not associated with Chiari malformation; 4) in the older child and adult with Chiari II malformation, vimentin overexpression in the ependyma becomes more generalized in the lateral ventricles as well, hence evolves into a nonspecific upregulation. The interpretation from these findings leads to speculation that it is unlikely that ependymal vimentin is directly involved in the pathogenesis of Chiari II malformation, but may reflect a secondary upregulation due to defective expression of another gene. This gene may be one of rhombomeric segmentation that also plays a role in defective programming of the paraxial mesoderm for the basioccipital and supraoccipital bones resulting in a small posterior fossa. This interpretation supports the hypothesis of a molecular genetic defect, rather than a mechanical cause, as the etiology of the Chiari II malformation.