"Virtual patch clamp analysis" for predicting the functional significance of pathogenic variants in sodium channels.

OBJECTIVE: Opening of voltage-gated sodium channels is crucial for neuronal depolarization. Proper channel opening and influx of Na+ through the ion pore, is dependent upon binding of Na+ ion to a specific amino-acid motif (DEKA) within the pore. In this study we used molecular dynamic simulations, an advanced bioinformatic tool, to research the dysfunction caused by pathogenic variants in SCN1a, SCN2a and SCN8a genes. METHOD: Molecular dynamic simulations were performed in six patients: three patients with Dravet syndrome (p.Gly177Ala,p.Ser259Arg and p.Met1267Ile, SCN1a), two patients with early onset drug resistant epilepsy(p.Ala263Val, SCN2a and p.Ile251Arg, SCN8a), and a patient with autism (p.Thr155Ala, SCN2a). After predicting the 3D-structure of mutated proteins by homology modeling, time dependent molecular dynamic simulations were performed, using the Schrödinger algorithm. The opening of the sodium channel, including the detachment of the sodium ion to the DEKA motif and pore diameter were assessed. Results were compared to the existent patch clamp analysis in four patients, and consistency with clinical phenotype was noted. RESULTS: The Na+ ion remained attached to DEKA filter longer when compared to wild type in the p.Gly177Ala, p.Ser259Arg,SCN1a, and p.Thr155Ala, SCN2a variants, consistent with loss-of-function. In contrast, it detached quicker from DEKA than wild type in the p.Ala263Val,SCN2a variant, consistent with gain-of-function. In the p.Met1267Ile,SCN1a variant, detachment from DEKA was quicker, but pore diameter decreased, suggesting partial loss-of-function. In the p.Leu251Arg,SCN8a variant, the pore remained opened longer when compared to wild type, consistent with a gain-of-function. The molecular dynamic simulation results were consistent with the existing patch-clamp analysis studies, as well as the clinical phenotype. SIGNIFICANCE: Molecular dynamic simulation can be useful in predicting pathogenicity of variants and the disease phenotype, and selecting targeted treatment based on channel dysfunction. Further development of these bioinformatic tools may lead to "virtual patch-clamp analysis".

Asymptomatic idiopathic intracranial hypertension in children.

OBJECTIVE: To define characteristics of pediatric asymptomatic idiopathic intracranial hypertension (IIH). PATIENTS AND METHODS: We retrospectively reviewed our Neuro-Ophthalmology database (2000-2006) for all cases of symptomatic and asymptomatic pediatric IIH. RESULTS: Out of 45 IIH cases, 14 (31.1%) were asymptomatic (incidental examination). When compared with children with symptomatic IIH, asymptomatic cases were younger [5.6 (1.8-15) vs 11.0 (5-17) years, P = 0.007], had lower percentage of obesity (14.3% vs 48.4%, P = 0.046), and had male predominance (71.4% vs 38.7%, P = 0.06). Asymptomatic cases required shorter duration of acetazolamide treatment [3 (0-8), vs 6 (0-20) months, P = 0.021], and resulted in complete resolution of swollen discs. CONCLUSIONS: We speculate that asymptomatic IIH may be more common in young children and could represent a milder form or a presymptomatic phase before evolving into classic symptomatic IIH. Further studies to assess the clinical significance of asymptomatic IIH are warranted.

Electromagnetic navigation improves minimally invasive robot-assisted lung brachytherapy.

OBJECTIVE: Recent advances in minimally invasive thoracic surgery have renewed an interest in the role of interstitial brachytherapy for lung cancer. Our previous work has demonstrated that a minimally invasive robot-assisted (MIRA) lung brachytherapy system produced results that were equal to or better than those obtained with standard video-assisted thoracic surgery (VATS) and comparable to results with open surgery. The purpose of this project was to evaluate the performance of an integrated system for MIRA lung brachytherapy that incorporated modified electromagnetic navigation and ultrasound image guidance with robotic assistance. METHODS: The experimental test-bed consisted of a VATS box, ZEUS and AESOP surgical robotic arms, a seed injector, an ultrasound machine, video monitors, a computer, and an endoscope. Our previous custom-designed electromagnetic navigational software and the robotic controller were modified and incorporated into the MIRA III system to become the next-generation MIRA IV. Inactive brachytherapy seeds were injected as close as possible to a small metal ball target embedded in an opaque agar cube. The completion time, the number of attempts, and the accuracy of seed deployment were compared for manual placement, standard VATS, MIRA III, and the new MIRA IV system. RESULTS: The MIRA IV system significantly reduced the median procedure time by 61% (104 s to 41 s), tissue trauma by 75% (4 attempts to 1 attempt), and mean seed placement error by 64% (2.5 mm to 0.9 mm) when compared to a standard VATS. MIRA IV also reduced the mean procedure time by 48% (85 s to 44 s) and the seed placement error by 68% (2.8 mm to 0.9 mm) compared to the MIRA III system. CONCLUSIONS: A modified integrated system for performing minimally invasive robot-assisted lung brachytherapy was developed that incorporated electromagnetic navigation and an improved robotic controller. The MIRA IV system performed significantly better than standard VATS and better than MIRA III.

Blood pressure values in children with intrauterine growth retardation.

BACKGROUND: Low birth weight has been shown to be strongly related to hypertension in adult life. OBJECTIVES: To determine whether blood pressure is higher in children with intrauterine growth retardation than in control subjects. METHODS: Blood pressure was measured in 58 children aged 4-6 years with IUGR and in 58 age-matched controls. The control children, whose birth weight was appropriate for gestational age, were also matched for gestational age. RESULTS: The children with IUGR had significantly higher mean values of systolic (P < 0.05) and diastolic blood pressures (P < 0.05) and mean arterial pressure (P < 0.05). Significant differences in blood pressure values were found between preterm IUGR (n = 21) and preterm controls (P < 0.05). CONCLUSIONS: These data indicate that children with IUGR may be at higher risk of hypertension already in childhood.

The effect of intrauterine growth restriction on the development and health of children.

The neurodevelopmental and cognitive outcome of long-term Intrauterine Growth Restriction (IUGR) has been followed up from pregnancy to school age at the Tel Aviv Child Development Centre.

Methylenetetrahydrofolate reductase deficiency: importance of early diagnosis.

Methylenetetrahydrofolate reductase deficiency is the most common inborn error of folate metabolism and should be suspected when homocystinuria is combined with hypomethioninemia. The main clinical findings are neurologic signs such as severe developmental delay, marked hypotonia, seizures, microcephaly, apnea, and coma. Most patients present in early life. The infantile form is severe, with rapid deterioration leading to death usually within 1 year. Treatment with betaine has been shown to be efficient in lowering homocysteine concentrations and returning methionine to normal, but the clinical response is variable. We report two brothers with methylenetetrahydrofolate reductase deficiency: the first was undiagnosed and died at 8 months of age from neurologic deterioration and apnea, while his brother, who was treated with betaine from the age of 4 months, is now 3 years old and has developmental delay.

Experimental intrauterine growth retardation alters renal development.

Vascular placental insufficiency is considered a common pathogenic factor in human intrauterine growth retardation (IUGR), resulting in small-for-gestational-age, asymmetric newborns. IUGR neonates experience higher morbidity and mortality rates, as well as a possible contribution towards late sequelae, such as hypertension, and cardiovascular disease in adulthood. To simulate vascular placental insufficiency, an experimental rabbit IUGR model was used. Intrauterine growth retardation was achieved by ligation of 25-30% uteroplacental vessels of half of the fetuses during the last third of gestation. Ischemic fetuses were significantly small, asymmetric, and had a disproportionately small body with a relatively large head. The kidneys from all groups were analyzed for relative estimated glomeruli number (REGN) using an unbiased blind design. The glomeruli number was significantly reduced in the asymmetric IUGR rabbit fetuses, probably due to decreased renal vascular supply. Our results support the concept that the reduced number of glomeruli may contribute to impaired renal function, thus predisposing to neonatal renal dysfunction and late sequelae, such as adult hypertension. This study emphasizes the clinical importance of early IUGR diagnosis and prevention.

Six-year follow-up of children with intrauterine growth retardation: long-term, prospective study.

This prospective study was designed to characterize the neurodevelopmental and cognitive difficulties specific to children with intrauterine growth retardation and to detect early clinical predictors of these difficulties. Eighty-one children with intrauterine growth retardation were monitored up to 6 to 7 years of age using biometric parameters, perinatal risk questionnaires, and detailed neurodevelopmental and cognitive assessments. Forty-one children served as age-matched, appropriate for gestational age controls. A significant difference in growth parameters (P < .001), neurodevelopmental score (P < .05), and IQ (P < .05) was found between the children with intrauterine growth retardation and controls. A specific profile of difficulties in coordination, lateralization, spatial and graphomotor skills, and abundance of associated movements is typical of the children with intrauterine growth retardation and hints at possible later learning disabilities. The clinical parameters best predicting neurodevelopmental outcome were the neonatal risk score (P < .05) and the weight and height at 6 years of age (P < .05). The children with intrauterine growth retardation with neonatal complications had lower neurodevelopmental scores than the controls but no difference in IQ. Intrauterine growth retardation children diagnosed prenatally had the same neurodevelopmental and IQ scores as those diagnosed at birth, probably due to the careful perinatal and obstetric care provided. Children with intrauterine growth retardation demonstrate a specific profile of neurodevelopmental disabilities at preschool age. Early diagnosis and intervention could probably reduce these difficulties to a minimum.

Complete sequence of a novel protein containing a femtomolar-activity-dependent neuroprotective peptide.

The vulnerability of neurons and the irreversibility of loss make discoveries of neuroprotective compounds fundamentally important. Here, the complete coding sequence of a novel protein (828 amino acids, pI 5.99), derived from mouse neuroglial cells, is revealed. The sequence contained (1) a neuroprotective peptide, NAPVSIPQ, sharing structural and immunological homologies with the previously reported, activity-dependent neurotrophic factor; (2) a glutaredoxin active site; and (3) a zinc binding domain. Gene expression was enriched in the mouse hippocampus and cerebellum and augmented in the presence of the neuropeptide vasoactive intestinal peptide, in cerebral cortical astrocytes. In mixed neuron-astrocyte cultures, NAPVSIPQ provided neuroprotection at subfemtomolar concentrations against toxicity associated with tetrodotoxin (electrical blockade), the beta-amyloid peptide (the Alzheimer's disease neurotoxin), N-methyl-D-aspartate (excitotoxicity), and the human immunodeficiency virus envelope protein. Daily NAPVSIPQ injections to newborn apolipoprotein E-deficient mice accelerated the acquisition of developmental reflexes and prevented short-term memory deficits. Comparative studies suggested that NAPVSIPQ was more efficacious than other neuroprotective peptides in the apolipoprotein E-deficiency model. A potential basis for rational drug design against neurodegeneration is suggested with NAPVSIPQ as a lead compound. The relative enrichment of the novel mRNA transcripts in the brain and the increases found in the presence of vasoactive intestinal peptide, an established neuroprotective substance, imply a role for the cloned protein in neuronal function.

High-dose intravenous immunoglobulin in transient neonatal myasthenia gravis.

A preterm newborn had transient neonatal myasthenia gravis and was mechanically ventilated for 9 days. In addition to the usual supportive care, she was treated with neostigmine and underwent two exchange transfusions. High-dose intravenous immunoglobulin therapy (2 gm/kg) was used for the first time in transient neonatal myasthenia gravis to the best of our knowledge. The clinical and laboratory responses are presented.

Localized fibromyalgia in a child.

A 14-year-old male was investigated because of a limp and a localized sharp pain in the right lumber paravertebral region radiating to the lower abdomen and the medial aspect of the thigh, which started following forced physical activity. With the diagnosis of fibromyalgia the patient received two perifacetal injections of local anaesthetics with steroids followed by transcutaneous electrical nerve stimulation (TENS). Following the injections, pain intensity dropped dramatically, disability was reduced and muscle swelling resolved. The possible association of symptoms to sport activity raises the question of sport-induced fibromyalgia, and the excellent response to treatment may suggest a facet joint irritation as possible aetiology.

Localized Wegener's granulomatosis relapsing as diffuse massive intra-alveolar hemorrhage.

In a 75-year-old patient presenting with a solitary pulmonary mass, a localized form of Wegener's granulomatosis was diagnosed after lobectomy. In the absence of extrapulmonary manifestations and after a benign postoperative course, the patients was discharged without medical treatment. Three months later, diffuse alveolar hemorrhage developed abruptly, necessitating mechanical ventilation, and was followed by cardiac complications and a fatal outcome. This case and another previously reported strongly suggest the need for medical treatment in patients with a localized form of pulmonary Wegener's granulomatosis, even when complete remission after surgical resection of the lung lesion seems to have been achieved.

Dilated cardiomyopathy associated with Chlamydia trachomatis infection.

A 26-year-old man was admitted to hospital with acute myocarditis complicated by congestive heart failure, and atrial and ventricular arrhythmias. Detailed investigations to determine the aetiological factors involved yielded negative results, except for serological evidence of infection with Chlamydia trachomatis. During the follow-up period, dilated cardiomyopathy developed. To the best of our knowledge a similar case has not been reported previously.