Random quasi-phase-matched second-harmonic generation in periodically poled lithium tantalate.

We observe second harmonic generation via random quasi-phase-matching in a 2.0 mum periodically poled, 1-cm-long, z-cut lithium tantalate. Away from resonance, the harmonic output profiles exhibit a characteristic pattern stemming from a stochastic domain distribution and a quadratic growth with the fundamental excitation, as well as a broadband spectral response. The results are in good agreement with a simple model and numerical simulations in the undepleted regime, assuming an anisotropic spread of the random nonlinear component.

Suggestive evidence for linkage to chromosome 13qter for autosomal dominant type 1 porencephaly.

A large three-generation family with autosomal dominant type 1 porencephaly from southern Italy was studied. A high rate of miscarriages was observed. Of the nine affected individuals, four displayed a severe phenotype, and five had slight pyramidal signs or mild cognitive abnormalities. The MRI study disclosed unilateral porencephalic cyst, or colpocephaly. A genome-wide screen resulted in suggestive evidence for linkage to chromosome 13qter with a maximum logarithm-of-the-odds score of 3.16, from multipoint analysis, with marker D13S285.

Silent celiac disease in patients with childhood localization-related epilepsies.

PURPOSE: To evaluate how many patients with a clinical picture of idiopathic childhood localization-related epilepsies may also have silent celiac disease (CD). This will help determine whether investigation for CD should be restricted to those patients with childhood partial epilepsy with occipital paroxysms (CPEO) or should be extended to all patients with childhood partial epilepsy (CPE) regardless of seizure type and electroencephalographic (EEG) paroxysms. METHODS: The study group consisted of 72 patients (31 girls and 41 boys; mean age, 12.6 +/- 4.28 years; age at onset, 6.4 +/- 3.7 years) who were observed consecutively over a 5-year period and who received an initial diagnosis of idiopathic CPE. A diagnosis of CD was confirmed by using enzyme-linked immunosorbent assay (ELISA) to assess the presence of antigliadin antibodies and the immunofluorescent undirected test to assess the presence of antiendomysium antibodies. RESULTS: Twenty-five patients had CPEO, whereas the remaining 47 had CPE with centrotemporal spikes (CPEC). None of the patients with CPEC had positive antibody tests. Of the 25 patients with CPEO, two (8%) had antiendomysium immunoglobulin (Ig) A antibodies. In both of these patients, the jejunal biopsy showed atrophy of the villi and hyperplasia of the crypts, consistent with a diagnosis of CD. Brain computed tomography (CT) was normal in one of these patients and revealed occipital corticosubcortical calcifications in the other. CONCLUSIONS: Our study indicates that CD screening should be performed routinely only in patients with CPEO.

A novel mutation in the Notch3 gene in an Italian family with cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy: genetic and magnetic resonance spectroscopic findings.

BACKGROUND: Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a hereditary syndrome caused by mutations of the Notch3 gene, usually localized to exons 3 and 4. OBJECTIVES: To report a novel pathogenetic mutation occurring in exon 6 of the Notch3 gene, a location not previously recognized in patients with CADASIL, and to report the results of magnetic resonance spectroscopy in CADASIL. METHODS: Mutation analysis of the Notch3 gene was performed in 2 patients belonging to a large kindred manifesting CADASIL, as well as in 7 clinically unaffected members of the family and 200 control chromosomes. Proton magnetic resonance spectroscopy was used to estimate metabolite resonance intensities in the 2 affected subjects. RESULTS: Sequence analysis of the Notch3 gene showed a new missense mutation CGC-->TGC in codon 332 of exon 6, resulting in the replacement of an arginine residue with a cysteine. This mutation was never observed in the 7 unaffected members of the family and the 200 control chromosomes examined. Proton magnetic resonance spectroscopy showed a diffuse decrease in cerebral N-acetylaspartate, indicating the presence of widespread axonal damage. CONCLUSIONS: Our findings emphasize the role of direct DNA sequence analysis for the diagnosis of CADASIL. Moreover, the results of proton magnetic resonance spectroscopy suggest that widespread axonal damage may be an early finding of the disease.

The parkin gene is not a major susceptibility locus for typical late-onset Parkinson's disease.

We investigated the parkin gene in 118 patients with typical Parkinson's disease (PD), i.e. in patients who had an onset of PD after the age of 45 years. The study group included 95 subjects with sporadic PD and 23 subjects from 18 families with autosomal recessive PD. No pathogenetic mutations in the parkin gene were detected either in familial or in sporadic patients. Our findings indicate that the parkin gene is not involved in the pathogenesis of classic late-onset PD.

Cerebral venous thrombosis and isolated intracranial hypertension without papilledema in CDH.

BACKGROUND: There is evidence that patients with chronic daily headache (CDH) may have isolated intracranial hypertension without papilledema (IHWOP). Recent studies have emphasized that isolated IH may be due to cerebral venous thrombosis (CVT). OBJECTIVE: To detect the occurrence of CVT in patients with CDH. METHODS: The authors investigated the occurrence of CVT in 114 consecutive patients with CDH by using MR venography (MRV). A portion of these patients underwent a lumbar puncture (LP) to measure CSF pressure. MRV and LP were also performed in 28 age-matched control subjects. RESULTS: In all the control subjects, both MRV and CSF pressure were normal. One hundred three of the 114 patients with CDH had normal MRV. Twenty-seven (Group 1) of these 103 patients underwent LP, and all of them had normal CSF pressure. Eleven (9.6%) of the 114 patients with CDH had CVT of one or both transverse sinuses. Six of these 11 patients had flowing abnormalities of one transverse sinus (Group 2), whereas the remaining five patients showed involvement of both transverse sinuses (Group 3). The CSF pressure of Group 2 was higher than that of either Group 1 or the control subjects, and one of the six patients showed isolated IHWOP. Patients of Group 3 displayed the highest CSF pressure, and four of five had isolated IHWOP. The headache profiles of patients with CDH and CVT did not differ from those of patients with CDH but normal MRV. CONCLUSIONS: CVT, as detected by MRV, occurred in 9.6% of patients who presented with CDH. Almost half of the patients with CVT had isolated IHWOP. These results suggest that MRV may be a useful tool for selecting patients with CDH who should have LP to exclude isolated IHWOP.

The parkin gene is not involved in late-onset Parkinson's disease.

Mutations in the parkin gene have been reported in patients with early onset PD. The authors investigated the parkin gene in 118 patients who had an onset of PD after age 45 years: 95 subjects were sporadic patients and 23 subjects were from 18 families with a probable autosomal recessive inheritance. No pathogenetic mutations in the parkin gene were detected either in familial or in sporadic patients. Moreover, no differences were found between patients and 100 age-matched normal controls in the allele and genotype frequencies of four exonic parkin polymorphisms.

Clinical and genetic study of a large Charcot-Marie-Tooth type 2A family from southern Italy.

The authors report a large pedigree from southern Italy with Charcot-Marie-Tooth disease type 2A (CMT2A). The clinical picture was uniform and characterized by distal muscular weakness and atrophy in the lower limbs, reduced or absent tendon reflexes mainly in the lower limbs, and mild sensory impairment in the feet. Significant linkage to the CMT2A locus on chromosome 1p35-p36 was detected. Based on informative recombination in affected individuals, the authors mapped the CMT2A gene between D1S160 and D1S170.

A new locus for autosomal dominant nocturnal frontal lobe epilepsy maps to chromosome 1.

BACKGROUND: Autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE) is caused by mutations in the alpha4 subunit of the neuronal nicotinic acetylcholine receptor (CHRNA4) gene, mapping on chromosome 20q13.2. A second ADNFLE locus was mapped on chromosome 15q24. OBJECTIVE: To report a new third ADNFLE locus on chromosome 1 in a large Italian family. METHODS: The authors performed a clinical and genetic study in a large, three-generation ADNFLE family from southern Italy, including eight affected individuals and three obligate carriers. RESULTS: The age at onset of seizures was around 9 years of age and all affected individuals manifested nocturnal partial seizures of frontal lobe origin. Interictal awake and sleep EEG recordings showed no definite epileptiform abnormalities in most patients. Ictal video-EEG showed that the attacks were partial seizures with a frontal lobe semiology. Intellectual and neurologic examinations, and brain CT or MRI results were always normal. Carbamazepine was effective in all treated patients. Exclusion mapping of the known loci linked to ADNFLE-ENFL1, and ENFL2, on chromosomes 20q13.2 and 15q24-was performed on the pedigree before starting the genome-wide linkage analysis. The whole genome scan mapping allowed the identification of a new ADNFLE locus spanning the pericentromeric region of chromosome 1. CONCLUSIONS: The authors provided evidence for a third locus associated to autosomal dominant nocturnal frontal lobe epilepsy on chromosome 1. Among the known genes mapping within this critical region, the ss2 subunit of the nicotinic receptor (CHRNB2) represents the most obvious candidate.

The long-duration response to L-dopa in the treatment of early PD.

OBJECTIVE: To investigate the long-duration response (LDR) to L-dopa resulting from different regimens of L-dopa. BACKGROUND: In clinical practice, L-dopa is usually administered without considering the LDR due to the drug. Moreover, it has not been established whether in early PD a multiple daily intake of small doses of L-dopa may induce a sustained LDR. METHODS: Twenty-four patients with early PD underwent a double-blind, crossover trial, comparing three different 15-day treatment periods with L-dopa: treatment A (250 mg every 24 hours); treatment B (250 mg every 8 hours); and treatment C (125 mg every 8 hours). After completion, 20 patients underwent a subsequent open-label randomized trial with prolonged treatments (250 mg every 24 hours or 125 mg every 8 hours) up to 3 months. LDR was measured at the end of each treatment. RESULTS: All patients achieved a sustained LDR after treatments A and B, whereas only 17% of patients reached a sustained LDR after treatment C. Overall, the LDRs resulting from treatments A and B had similar magnitude and were larger than the LDR deriving from treatment C. After 3 months of prolonged treatments, only three of 10 patients treated with 125 mg every 8 hours increased their LDR, whereas all 10 patients treated with 250 mg every 24 hours had a maximal and stable LDR. CONCLUSIONS: Sustained LDR to L-dopa is dependent on the amount of the single doses of the drug. A regimen scheduling small, divided doses during the day, as done in clinical practice, is a questionable therapy for the achievement of a sustained LDR.

Interhemispheric threshold differences in idiopathic generalized epilepsies with versive or circling seizures determined with focal magnetic transcranial stimulation.

The interhemispheric difference of the motor-cortical threshold (IDMT) was studied with focal magnetic transcranial stimulation (TCS) in ten patients with idiopathic generalized epilepsy (IGE) who also displayed versive or circling seizures (IGEvc). The data were compared with those obtained from two control groups; 13 patients with IGE without asymmetrical motor seizures, and 25 normal volunteer subjects. The IDMT, referred to as the percentage of maximum stimulator output, was assessed by focal TCS applied to the hand areas. Seven patients with IGEvc and only one patient with IGE had an interhemispheric motor threshold beyond the normal range. The IDMT in IGEvc patients was significantly higher compared to that of IGE patients and normal individuals. An interhemispheric imbalance of cortical excitability may explain lateralized ictal motor manifestations in patients with IGEvc.

Vitamin E deficiency due to chylomicron retention disease in Marinesco-Sjögren syndrome.

We report on 2 brothers (aged 19 and 12 years) with Marinesco-Sjögren syndrome who also had very low serum vitamin E concentrations with an absence of postprandial chylomicrons. The molecular study ruled out ataxia with isolated vitamin E deficiency, abetalipoproteinemia, and hypobetalipoproteinemia. The electron microscopy of the intestinal mucosa was consistent with a chylomicron retention disease. We speculate that both chylomicron retention disease and Marinesco-Sjögren syndrome are related to defects in a gene crucial for the assembly or secretion of the chylomicron particles, leading to very low serum levels of vitamin E.

Familial temporal lobe epilepsy autosomal dominant inheritance in a large pedigree from southern Italy.

To further elucidate the inheritance pattern and range of phenotypic manifestations of benign familial temporal lobe epilepsy (FTLE), we report a large family recently identified in southern Italy. There were 8 patients (4 men), ranging in age from 31 to 68 years in three generations. One affected patient was deceased at the time of the study. Genealogical study strongly supported autosomal dominant inheritance with incomplete penetrance, as three unaffected individuals transmitted the disease. Clinical anticipation could not be assessed because of the ascertainment method. Male to male transmission occurred. Identifiable antecedents for seizures were present in only two patients, who had a simple febrile convulsion and a closed head trauma, respectively. Migraine was overrepresented in this family. Onset of seizures ranged from 17 to 52 years (mean: 27 years). All patients had weekly simple partial seizures suggestive of temporal origin with vegetative or experiential phenomena. Very rare partial complex seizures occurred in 6/7 patients. One had two generalized nocturnal seizures as well. Two had previously been misdiagnosed as having gastritis or panic attacks, and one had not been diagnosed. Interictal anteromesiotemporal spiking was seen in 5/7 patients, and occurred mostly during NREM sleep. Neurological examination, brain CT or MR scans were normal. Antiepileptic medication always controlled the seizures.

The dopamine D2 receptor gene is a susceptibility locus for Parkinson's disease.

The dopamine D2 receptor (DRD2) gene has been proposed as a candidate gene underlying several psychiatric and neurologic disorders. The aim of the present study was to examine if selected polymorphisms in the DRD2 gene are associated with Parkinson's disease (PD). We determined the allelic frequencies for four polymorphisms located in the DRD2 gene in a sample of 135 patients with PD and 202 normal control subjects. No significant difference was observed in the allelic frequencies between patients with PD and control subjects with regard to the -141C Ins/Del and the Ser311/Cys311 variants. On the contrary, the A1 allele of the TaqIA polymorphism and the B1 allele of the TaqIB polymorphism were more frequent in patients with PD than in control subjects (control subjects: TaqIA A1 = 14.6%, TaqIB B1 = 10.6%; patients with PD: TaqIA A1 = 20.7%, TaqIB B1 = 17.4%). Patients carrying the A1 allele or the B allele had an increased risk of developing PD (TaqIA, odds ratio: 1.71, 95% confidence intervals: 1.08-2.73; TaqIB, odds ratio: 1.83, 95% confidence intervals: 1.12-3.02). The TaqIA and TaqIB polymorphisms were in strong linkage disequilibrium, suggesting that these two polymorphisms convey the same information about the risk of presenting with PD. Genetic variation in the DRD2 gene may influence the risk of developing PD, thus confirming that the DRD2 gene is a susceptibility locus for PD.

Apolipoprotein E polymorphisms and the risk of nonlesional temporal lobe epilepsy.

PURPOSE: To evaluate whether the inheritance of the apolipoprotein E (ApoE) epsilon4 allele is a risk factor for nonlesional temporal lobe epilepsy (TLE), and to determine whether the newly described -491 A/T ApoE polymorphism may independently affect the risk of nonlesional TLE. METHODS: The study group consisted of 63 patients (35 women and 28 men; age at onset of epilepsy, 30.6 +/- 19.6 years; mean (+/-SD). All of them had received a diagnosis of nonlesional TLE after a detailed clinical, electroencephalographic, and brain magnetic resonance investigation. The ApoE polymorphisms were determined from blood samples by standard methods. The molecular study also was performed in 220 age- and sex-matched normal individuals. RESULTS: There were no differences between TLE patients and controls in either allelic or genotypic frequencies of the ApoE and -491A/T polymorphisms. Moreover, no effect of ApoE or -491A/T polymorphisms was found on the age at onset and severity of epilepsy. CONCLUSIONS: The allelic and genotypic frequencies of ApoE polymorphisms in Italian patients with nonlesional TLE are comparable to control values, indicating that ApoE polymorphisms are not a significant genetic risk factor for the occurrence of nonlesional TLE.

APOE and risk of cognitive impairment in multiple sclerosis.

OBJECTIVES: The APOE gene polymorphism and the -491 A/T polymorphism in its regulatory region have been associated with an increased risk for developing Alzheimer's disease. We examined these polymorphisms in multiple sclerosis (MS) patients, to determine if a genetic predisposition may explain the risk for developing cognitive decline in MS. MATERIAL AND METHODS: Eighty-nine relapsing-remitting and secondary progressive MS patients underwent to a full neuropsychological battery as well as to determination of APOE and -491 A/T polymorphisms. Genetic analysis was also performed in 107 population controls. RESULTS: The APOE polymorphism was not associated with the risk of cognitive impairment in MS patients. The AA genotype of the -491 A/T polymorphism in the APOE regulatory region was more frequent in cognitively impaired than in cognitively preserved MS subjects. CONCLUSION: The AA homozygous state of the -491 A/T polymorphism of the APOE regulatory region is associated with cognitive impairment in patients with MS.

Dopamine D2 receptor gene polymorphism and the risk of levodopa-induced dyskinesias in PD.

OBJECTIVE: To investigate whether polymorphisms in the genes for dopamine receptors D1 and D2 are associated with the risk of developing peak-dose dyskinesias in PD. BACKGROUND: Peak-dose dyskinesias are the most common side effects of levodopa therapy for PD. The identified predictors may only partially account for the risk of developing peak-dose dyskinesias because a substantial proportion of patients never develop peak-dose dyskinesias. Genetic factors could play a role in determining the occurrence of peak-dose dyskinesias. METHODS: A case-control study of 136 subjects with sporadic PD and 224 population control subjects. We studied three polymorphisms involving the dopamine receptor D1 gene and one intronic short tandem repeat polymorphism of the dopamine receptor D2 gene. RESULTS: The polymorphisms of the dopamine receptor D1 gene were not associated with the risk of developing PD or peak-dose dyskinesias. The 15 allele of the polymorphism of the dopamine receptor D2 gene was more frequent in parkinsonian subjects than in control subjects. More important, the frequency of both the 13 allele and the 14 allele of the dopamine receptor D2 gene polymorphism was higher in nondyskinetic than in the dyskinetic PD subjects. The risk reduction of developing peak-dose dyskinesias for PD subjects carrying at least 1 of the 13 or 14 alleles was 72% with respect to the PD subjects who did not carry these alleles. CONCLUSIONS: Certain alleles of the short tandem repeat polymorphism of the dopamine receptor D2 gene reduce the risk of developing peak-dose dyskinesias and could contribute to varying susceptibility to develop peak-dose dyskinesias during levodopa therapy.

Pharmacodynamics of the long-duration response to levodopa in PD.

OBJECTIVE: To determine the latency, magnitude, and duration of the long-duration response (LDR) to levodopa in PD in relationship to the administration of levodopa at different interdose intervals. METHODS: In six patients with PD, two different 15-day treatment regimens were used in which the drug was administered with interdose intervals of 24 or 8 hours. RESULTS: The LDR built up within a few days with either regimen, but a faster rate of administering levodopa shortened the latency to the appearance of a sustained LDR. Once a sustained response had been reached, the magnitude of the LDR showed a stable ceiling effect that was independent of the levodopa schedule. After discontinuation of treatment, the decay of the LDR was similar for both regimens. CONCLUSIONS: The system underlying the LDR to levodopa may be completely saturated when a sustained response has been fully developed. The intervals between doses of levodopa shorter than the interval effective to reach a sustained LDR should not be used in the clinical management of patients with PD because the antiparkinsonian benefit deriving from the LDR is already maximal and briefer intervals do not provide a greater benefit.

Idiopathic generalized epilepsies with versive or circling seizures.

OBJECTIVES: To describe the electroclinical features of the idiopathic generalized epilepsies (IGEs) with versive or circling seizures. METHODS: Sixteen patients with versive or circling seizures and interictal electroclinical features of IGE were studied. Patients with insufficient clinical or imaging data, with a follow-up period less than 1 year or with partial seizures in addition to the versive or circling ones were excluded from the study. All patients underwent full interictal clinical and neurophysiological studies. The EEG patterns of 13 versive or circling seizures from 4 patients were also analyzed. RESULTS: A specific IGE syndrome was recognized in 9 out of the 16 patients (56%). More specific, 1 patient had childhood absence epilepsy (CAE), 4 had juvenile absence epilepsy (JAE), and 4 had juvenile myoclonic epilepsy (JME). No specific IGE syndrome was recognizable in the remaining 7 patients (44%). These 7 patients had a juvenile epileptic syndrome (mean age at onset of seizures was 15.7 years) characterized by versive or circling seizures followed or not by generalized tonic-clonic fits. Three main EEG patterns were identified during versive or circling seizures: 1) generalized spike-and-wave discharges at 3-4 cps; 2) generalized polyspike-and-wave discharges at 1 to 2.5 cps beginning with generalized fast activity at 12-14 cps, and 3) generalized spike-and-wave discharges at 3-4 cps intermingled with fast activity at 12-14 cps. Most patients had good response to treatment on a single drug regimen (mainly valproic acid). CONCLUSIONS: Versive or circling seizures may occur in the context of an IGE. Although many individuals share the features of different IGE syndromes including CAE, JAE and JME, a consistent number of patients, who show circling or versive seizures solely, remain without a specific syndromic diagnosis. When occurring in the context of IGE, circling or versive seizures do not worsen the prognosis.