Spectrally-efficient all-optical OFDM by WSS and AWG.

We report on the transmission experiment of seven 12.5-GHz spaced all optical-orthogonal frequency division multiplexed (AO-OFDM) subcarriers over a 35-km fiber link, using differential quadrature phase shift keying (DQPSK) modulation and direct detection. The system does not require chromatic dispersion compensation, optical time gating at the receiver (RX) or cyclic prefix (CP), achieving the maximum spectral efficiency. We use a wavelength selective switch (WSS) at the transmitter (TX) to allow subcarrier assignment flexibility and optimal filter shaping; an arrayed waveguide grating (AWG) AO-OFDM demultiplexer is used at the RX, to reduce the system cost and complexity.

Performance analysis of communication links based on VCSEL and silicon photonics technology for high-capacity data-intensive scenario.

To face the increased demand for bandwidth, cost-effectiveness and simplicity of future Ethernet data communications, a comparison between two different solutions based on directly-modulated VCSEL sources and Silicon Photonics technologies is carried out. Also by exploiting 4-PAM modulation, the transmission of 50-Gb/s and beyond capacity per channel is analyzed by means of BER performance. Applications for optical backplane, very short reach and in case of client-optics networks and intra and inter massive data centers communications (up to 10 km) are taken into account. A comparative analysis based on the power consumption is also proposed.

A case of acute disseminated encephalomyelitis following influenza virus A-H1N1 infection.

We describe a case of acute disseminated encephalomyelitis (ADEM) occurring in a three-year old girl with influenza A (H1N1)v infection and manifesting with seizures and ataxia. The brain MRI revealed bilateral hyperintense signal changes in basal ganglia and brain stem. The patient was treated with intravenous methylprednisolone bolus followed by tapering steroids and progressively recovered without neurologic sequelae at the latest follow-up. ADEM may represent a rare postinfectious complication following novel pandemic influenza A H1N1v which should be taken into account in the differential diagnosis of associated neurologic manifestations for the specific therapeutic approach and adequate follow-up.

Robustness to mechanical perturbations of center-launching technique for transparent board-to-board and data server interconnects.

Center-launching technique appears as a promising method to allow single-mode propagation in multi-mode fibers, guaranteeing full transparency to the transmitted optical signal also for applications in board-to-board and data server interconnects. In this paper we show that this technique is robust to mechanical perturbations up to about 1 kHz, demonstrating that the vibrations do not affect the transmission performances. Different experimental configurations are tested in order to exclude multimode propagation and to confirm the only fundamental mode propagation. Finally, a theoretical discussion comments the experimental results.

Congenital muscular dystrophies with cognitive impairment. A population study.

BACKGROUND: Cognitive impairment has been reported in a significant proportion of patients with congenital muscular dystrophies (CMD), generally associated with brain changes. OBJECTIVES: The aim of this study was to establish 1) the overall prevalence of CMD and cognitive impairment in the Italian population; 2) the frequency of individual genetically defined forms; and 3) the presence of distinct phenotypes not associated with mutations in the known genes. METHODS: We included all patients with CMD and cognitive impairment followed in all the Italian tertiary neuromuscular centers. Clinical, brain MRI, and morphologic data were collected. Genetic screening of the known genes was performed according to clinical and muscle biopsy findings. RESULTS: Ninety-two of the 160 (58%) patients with CMD followed in our centers had cognitive impairment. alpha-Dystroglycan (alpha-DG) reduction on muscle biopsy was found in 73/92 (79%), with 42/73 carrying mutations in the known genes. Another 6/92 (7%) showed a laminin alpha2 deficiency on muscle biopsy and 5 of the 6 carried mutations in LAMA2. The remaining 13/92 (14%) patients had normal alpha-DG and laminin alpha2 expression on muscle. CONCLUSIONS: This is the first population study establishing the prevalence of CMD and cognitive impairment and providing a classification on the basis of clinical, MRI, and genetic findings. We also showed that cognitive impairment was not always associated with alpha-DG or laminin alpha2 reduction or with structural brain changes.

Impact of time-interleaving on directly-detected 100-Gb/s POLMUX RZ-DQPSK robustness to PDL-induced crosstalk.

The impact of PDL-induced crosstalk on 100-Gb/s POLMUX RZ-DQPSK performance is investigated both experimentally and through numerical simulations in direct detection systems. We found that RZ time-interleaving, contrary to what happens with PMD, features a strong robustness to PDL. The detrimental effect of optical narrow filtering on PDL-induced penalty is also analyzed; RZ time-interleaving still proves the best solution to deal with the PDL issue.

All-optical wavelength conversion of a 100-Gb/s polarization-multiplexed signal.

We present the results of an in-depth experimental investigation about all-optical wavelength conversion of a 100-Gb/s polarization-multiplexed (POLMUX) signal. Each polarization channel is modulated at 25 Gbaud by differential quadrature phase-shift keying (DQPSK). The conversion is realized exploiting the high nonlinear chi((2)) coefficient of a periodically poled lithium niobate waveguide, in a polarization-independent configuration. We find that slight non-idealities in the polarization independent setup of the wavelength converter can significantly impair the performance of POLMUX systems. We show that high-quality wavelength conversion can be nevertheless achieved for both the polarization channels, provided that an accurate optimization of the setup is performed. This is the first demonstration, to the best of our knowledge, of the possibility to obtain penalty-free all-optical wavelength conversion in a 100-Gb/s POLMUX transmission system using direct-detection.

Congenital muscular dystrophies with defective glycosylation of dystroglycan: a population study.

BACKGROUND: Congenital muscular dystrophies (CMD) with reduced glycosylation of alpha-dystroglycan (alpha-DG) are a heterogeneous group of conditions associated with mutations in six genes encoding proven or putative glycosyltransferases. OBJECTIVES: The aim of the study was to establish the prevalence of mutations in the six genes in the Italian population and the spectrum of clinical and brain MRI findings. METHODS: As part of a multicentric study involving all the tertiary neuromuscular centers in Italy, FKRP, POMT1, POMT2, POMGnT1, fukutin, and LARGE were screened in 81 patients with CMD and alpha-DG reduction on muscle biopsy (n = 76) or with a phenotype suggestive of alpha-dystroglycanopathy but in whom a muscle biopsy was not available for alpha-DG immunostaining (n = 5). RESULTS: Homozygous and compound heterozygous mutations were detected in a total of 43/81 patients (53%), and included seven novel variants. Mutations in POMT1 were the most prevalent in our cohort (21%), followed by POMT2 (11%), POMGnT1 (10%), and FKRP (9%). One patient carried two heterozygous mutations in fukutin and one case harbored a new homozygous variant in LARGE. No clear-cut genotype-phenotype correlation could be observed with each gene, resulting in a wide spectrum of clinical phenotypes. The more severe phenotypes, however, appeared to be consistently associated with mutations predicted to result in a severe disruption of the respective genes. CONCLUSIONS: Our data broaden the clinical spectrum associated with mutations in glycosyltransferases and provide data on their prevalence in the Italian population.

From computerized tomography data processing to rapid manufacturing of custom-made prostheses for cranioplasty. Case report.

Cranioplasty is a surgical repair of a structural or morphological deformity of the skull, involving the resection, remolding and displacement of the bones of the head. As it pertains to abnormal head shape, cranioplasty is an operative procedure aimed to fill a gap in the cranial theca or to replace bone removed either as a result of trauma or infection, by means of a biocompatible artificial bony substitute. In the present paper authors report a case of custom-made cranioplasty for the reconstruction of a large bilateral skull defect, based on advanced computerized tomography data processing and rapid prototyping (stereolithography) techniques.

The Hammersmith functional score correlates with the SMN2 copy number: a multicentric study.

Previous studies showed that SMN2 copy number correlates inversely with the disease severity. Our aim was to evaluate SMN2 copy numbers and the Hammersmith functional motor scale in 87 patients with SMA II in order to establish whether, within SMAII, the number of copies correlates with the severity of functional impairment. Our results showed a relative variability of functional scores, but a significant correlation between the number of SMN2 genes and the level of function.

Randomized, double-blind, placebo-controlled trial of phenylbutyrate in spinal muscular atrophy.

OBJECTIVE: To assess the efficacy of phenylbutyrate (PB) in patients with spinal muscular atrophy in a randomized, double-blind, placebo-controlled trial involving 10 Italian centers. METHODS: One hundred seven children were assigned to receive PB (500 mg/kg/day) or matching placebo on an intermittent regimen (7 days on/7 days off) for 13 weeks. The Hammersmith functional motor scale (primary outcome measure), myometry, and forced vital capacity were assessed at baseline and at weeks 5 and 13. RESULTS: Between January and September 2004, 107 patients aged 30 to 154 months were enrolled. PB was well tolerated, with only one child withdrawing because of adverse events. Mean improvement in functional score was 0.60 in the PB arm and 0.73 in placebo arm (p = 0.70). Changes in the secondary endpoints were also similar in the two study arms. CONCLUSIONS: Phenylbutyrate was not effective at the regimen, schedule, and duration used in this study.

Reliability of the Hammersmith functional motor scale for spinal muscular atrophy in a multicentric study.

The aim of this study was to validate the Hammersmith functional motor scale for children with spinal muscular atrophy in a large cohort of 90 non-ambulant children with spinal muscular atrophy type 2 or 3. All had a baseline assessment (T0) and were reassessed either at 3 months (T1) (n = 66) or at 6 months (T2) (n = 24). Inter-observer reliability, tested on 13 children among 3 examiners, was > 95%. Of the 66 children examined after 3 months 4 had adverse effects in between assessments and were excluded from the analysis. Forty-two (68%) of the remaining 62 reassessed had no variation in scores between T0 and T1 and 13 (21%) were within +/- 1 point. 9 (37.5%) of the 24 children reassessed after 6 months had no variation in scores between T0 and T2 and another 9 (37.5%) had variations within +/- 1 point. Our study confirms previous observations of the reliability of the scale and helps to establish a baseline for assessing changes of functional ability over 3 and 6 month intervals. This information can be valuable in view of therapeutic trials.

Bilateral motor cortex output with intended unimanual contraction in congenital mirror movements.

In congenital mirror movements (MM), it is unclear whether the "mirror" motor cortex (M1) produces output during intended unimanual movements. In two patients with MM, the cortical silent period (CSP) was abnormally short after focal transcranial magnetic stimulation (TMS) of either M1, but simultaneous bilateral TMS led to significant CSP lengthening. Thus, it is likely that the shortened CSP after unilateral TMS is caused by output from the nonstimulated M1, suggesting that both M1 produce output with intended unimanual movements in patients with MM.

[Convulsions during treatment of acute lymphoblastic leukemia in children]. / Crisi convulsive durante il trattamento per leucemia linfoblastica acuta nel bambino.

BACKGROUND: The prevalence of seizures in children with acute lymphoblastic leukemia (ALL) varies between 3 and 13% depending on the various studies, whereas it is 1% in the general population aged under 15 years etiopathogenesis and outcome of seizures in children during treatment for ALL. METHODS: A retrospective study was carried out in 204 children with a consecutive diagnosis of ALL, 89 females and 115 males, aged between 5 months and 17 years and 11 months, diagnosed between 15-4-1988 and 15-4-1998, and treated at the Division of Pediatric Oncology and Pediatric Hematology of Turin University using three successive generations of AIEOP protocols 88 (48 cases), 91 (86 cases) and 95 (70 cases). Observation of the patients in the study ended on 30-9-1998. The criteria for eligibility were those stated in the respective protocols. Seizures were classified using the international classification; the diagnosis was made if a doctor, a nurse or a reliable relative witnessed the event with confirmation by the consultant neurologist. RESULTS: Twelve out of 204 (5.8%) patients in this series presented seizures: 2 out of 48 cases using protocol 88 (4.1%), 6 out of 86 cases using protocol 91 (6.9%) and 4 out of 70 cases using protocol 95 (5.7%). None of the patients had critical episodes or other significant neurological pathologies prior to the onset of ALL, nor had they been affected by leukemic meningosis or undergone cranial radiotherapy. When evaluating the possible etiology, the authors noted that, except for one case of febrile convulsion, the seizures in the remaining patients could be attributed to the toxicity of chemotherapy. With regard to the evolution of seizures, only one patient died, whereas the others showed no neurologic sequelae. CONCLUSIONS: The frequency of seizures in children receiving treatment for ALL in the series analysed here is in line with that reported in the literature. Neurotoxicity caused by chemotherapy appears to be the main etiopathogenetic factor.

Neurophysiologic exploration: a reliable tool in HIV-1 encephalopathy diagnosis in children.

BACKGROUND: HIV-1 related encephalopathy has a bad prognostic meaning in the course of AIDS disease, but the early association of different drugs can modify its course. For this reason it is very important to recognize CNS involvement as soon as possible. As shown in the literature, at least in adult studies, EEG and Evoked Potentials (EP) are good tools in evaluating CNS alterations. In children data are rare. METHODS: A ten-year prospective study of 44 infected children out of 142 born from HIV-1 positive mothers has been done. The children have been submitted to EEG recording every six months in the first 18 months of life and then every year, to multimodal EP every six months. A total of 357 EEG, 47 P-VEP, 62 F-VEP and 98 BAEP have been performed. RESULTS: EEG: we found no pathologic results in patients belonging to category A; results were pathologic in 17.7% in category B, in 47.7% in C and in 77% of encephalopathic patients. It seems that EEG alterations are parallel to disease progression, with a relative risk of developing encephalopathy (R.R. = 1.15) and of death (R.R. = 2.33) for patients belonging to category C. We obtained a statistically significant lengthening in BAEP interpeak latency of left ear in all groups. For patients in category C the risk of developing encephalopathy is statistically significant (p = 0.045; R.R. = 6.75) and risk of death is high (R.R. = 4). CONCLUSIONS: Neurophysiologic exams are a reliable tool for the diagnosis of encephalopathy, in addition to clinical evidence.

Optical implementation of asynchronous-transfer-mode header-error control.

The asynchronous transfer mode (ATM) is a promising technique for broadband switching that is capable of supporting high-bit-rate multimedia services. Progress in all-optical parallel processing shows that photonics may be used in the future in full-functionality ATM switching nodes. All-optical switching fabrics and buffers have already been demonstrated. Fewer studies have been dedicated to ATM header-processing functions. As an example of photonic header processing, the implementation of a header-error control (HEC) subsystem by means of an optical circuit is investigated. Although traditional electronic decoders perform HEC in a serial mode, the architecture chosen for the optical HEC subsystem is based on parallelism, and an appropriate parallel-decoding algorithm was used in designing it.

Evolution of HIV-1 encephalopathy in children.

BACKGROUND: This study has been conducted on a series of HIV-1 infected children, with the aim of illustrating the features of encephalopathy onset, its evolution and its influence on life expectancy. The most useful exams for diagnosis are also outlined. METHODS: The perspective study lasted from January 1989 to June 1997. Forty six symptomatic patients, out of 142 seropositive children, were followed up in the Department of Paediatric and Adolescence Sciences of the University of Turin. The patients, now between 1 yr 2 mth and 13 yr 9 mth old, were born from HIV-1 seropositive mothers; seroreverters have been excluded. Scheduled neuropsychiatric consultations were used, consisting of a neurologic exam and an interview with parents, cognitive evaluations, EEGs, Evoked Potentials and CT scans. The results have been evaluated with log-rank test for the analysis of the survival curves. RESULTS: We found a significantly higher mortality rate in encephalopathic versus non encephalopathic patients; encephalopathic patients, in whom neurologic signs began in the first year of life, have a worse prognosis than the other patients, in whom encephalopathy appeared later. We did not find a statistical correlation between clinical course and immunological deficit. The clinical features of encephalopathy are mainly characterized by pyramidal signs and cognitive deterioration. Clinical sign evolution is linked to the age of encephalopathy onset: plateau pattern encephalopathy, characterized by an early onset, severe motor signs and cognitive delay from the very beginning, shows a greater severity and a shorter survival than progressive encephalopathy, characterized by a slowly progressive evolution of pyramidal signs, to which a cognitive deterioration may be added. CONCLUSIONS: Neuropsychological exams can be helpful in the diagnosis and follow-up of encephalopathy.

Lower extremity counterpart of the Poland syndrome.

Below-the-knee right leg hypoplasia and ipsilateral toe brachysyndactyly were observed in a 4-year-old female with an otherwise normal phenotype. Electromyographic and nerve conduction studies were normal. The Doppler evaluation was consistent with a 50% reduction in the blood supply from the femoral artery, suggesting vascular disruption as the pathogenic mechanism. Our observations support the hypothesis that a lower extremity counterpart of the Poland syndrome does exist and that the extent of limb involvement is dependent on the level of vascular disruption.

Diagnostic value of multimodal evoked potentials in HIV-1 infected children.

Evoked potentials (EP) help guide the diagnosis of central nervous system involvement in demyelinating pathologies regarding both children and adults, and in human immunodeficiency virus-1 (HIV-1) correlated pathologies only in regard to adult patients. EP have been shown to be useful in highlighting early signs of the disease. We therefore studied EP in HIV-1 infected children with the aim of verifying the association of results with disease progression, clinical signs and electroencephalogram, and individualizing the most reliable test. Thirty-six patients (20 male and 16 female subjects, age range: 10 months to 12 years) belonging to a group of 45 symptomatic subjects seen at the Pediatric Department were included into the study from November 1991 to December 1994. Ten presented with neurological signs as of disease onset, eight others developed encephalopathy during the follow-up. One hundred seventeen EP, i.e., 27 pattern visual, 64 flash visual and 26 brain stem auditory EP, were recorded. Univariate statistical analysis using the Wilcoxon-Mann-Whitney U test and Student's t test was done. As a whole, we found 22.5% of abnormal EP in subjects without neurological signs and 28.3% in subjects with neurological signs. Results that were obtained suggested a close relationship between both the pattern of visual and brain stem auditory EP exams and disease progression.

Concomitant deficiency of beta- and gamma-sarcoglycans in 20 alpha-sarcoglycan (adhalin)-deficient patients: immunohistochemical analysis and clinical aspects.

We have investigated the expression, using immunohistochemistry, of beta- and gamma-sarcoglycans in the muscles of 20 patients in whom previous screening had revealed a deficiency of alpha-sarcoglycan. alpha-, beta- and gamma-sarcoglycans were absent in 7 patients and variably reduced in 8 patients, in 2 of whom beta-sarcoglycan was more reduced than the alpha- and gamma-proteins. In 5 other patients with variably reduced alpha- and beta-sarcoglycans, gamma-sarcoglycan was completely absent. In all patients the distribution of hyposthenia at disease onset was similar, and predominantly involved pelvic girdle muscles; however, the age at onset and rate of disease progression were highly variable. In severely compromised patients, the onset of disease was before 10 years of age and gamma-sarcoglycan or all three sarcoglycans were absent from muscles. Immunohistochemical analysis of sarcoglycans should be part of routine screening for muscle dystrophies to identify patients with sarcoglycanopathy. Gene analysis is necessary to identify the primary defect; however, sarcoglycan immunohistochemistry may be useful for indicating which gene to investigate. Further biochemical characterization of the interactions between these proteins is required to fully elucidate their roles in causing severe, moderate or mild muscular dystrophy.