Thermodynamic signatures of quantum criticality in cuprate superconductors.

The three central phenomena of cuprate (copper oxide) superconductors are linked by a common doping level p*-at which the enigmatic pseudogap phase ends and the resistivity exhibits an anomalous linear dependence on temperature, and around which the superconducting phase forms a dome-shaped area in the phase diagram1. However, the fundamental nature of p* remains unclear, in particular regarding whether it marks a true quantum phase transition. Here we measure the specific heat C of the cuprates Eu-LSCO and Nd-LSCO at low temperature in magnetic fields large enough to suppress superconductivity, over a wide doping range2 that includes p*. As a function of doping, we find that Cel/T is strongly peaked at p* (where Cel is the electronic contribution to C) and exhibits a log(1/T) dependence as temperature T tends to zero. These are the classic thermodynamic signatures of a quantum critical point3-5, as observed in heavy-fermion6 and iron-based7 superconductors at the point where their antiferromagnetic phase comes to an end. We conclude that the pseudogap phase of cuprates ends at a quantum critical point, the associated fluctuations of which are probably involved in d-wave pairing and the anomalous scattering of charge carriers.

Genetic linkage studies in familial frontal epilepsy: exclusion of the human chromosome regions homologous to the El-1 mouse locus.

Familial frontal epilepsy has been recently described in six pedigrees. All families reported show autosomal dominant inheritance with incomplete penetrance. Affected individuals develop predominantly nocturnal seizures with frontal lobe semiology. In 1959, a genetic mouse model for partial epilepsy, the El mouse, was reported. In the El mouse, a major seizure susceptibility gene, El-1, segregates in an autosomal dominant fashion and has been localized to a region distal to the centromere of mouse ch 9. Comparative genetic maps between man and mouse have been used to predict the location of several human disease genes. The El-1 locus in the mouse is homologous to human chromosomes 3p23-p21.2, 3p11.2-q11.2, 3q21-q25.3, 6p12-q12 and 15q24. Polymorphic microsatellite markers covering these candidate regions were used for genotyping individuals in the three larger families ascertained, one of which is French-Canadian and two are Australian. Significant negative two-point and multipoint lod scores were obtained separately for each family, thus excluding linkage with the candidate regions on chromosomes 3, 6 and 15.

[Obstructive parietal hemodissection of the intracranial vessels, a particular form of dissecting aneurysm]. / Hémodissection pariétale oblitérante des vaisseaux intracrâniens, une forme particulière d'anévrysme disséquant.

A six year old girl complained of sudden severe headache, became hemiplegic and unconscious. A right carotid arteriogram revealed an obstruction of the right anterior cerebral artery and many sulvian branches. Death occurred four days later. At autopsy, a recent softening of nearly all the right middle cerebral arterial territory was found. Thrombus filled the sylvian artery and its main branches. Histologic examination of the vessel walls showed a dissecting infiltration of blood between the internal elastic lamina and the media. This particular form of dissecting aneurysm, occurring in young subjects, in the absence of atherosclerosis, high blood pressure and idiopathic medial necrosis, represents a distinct medial necrosis, represents a distinct nosologic entity that has been called "Obstructive parietal hemodissection of intracranial vessels." The pathogenesis of the disease is unknown: trauma has been mentioned, also congenital defects in the elastic lamina or other morphologic abnormalities of that lamina.

Death, dying, and the brain.

These cases have been cited and these issues presented to make the point that principles are often out of phase with perceptions. The argument is not that principles should cede to perceptions. This would imply resignation to the unlikelihood of moral development. Neither do we claim that perceptions should simply and generally capitulate to principles. This could mean an intolerable dictatorship of one philosophy over experience. Clinical ethics is the challenge to integrate principles and perceptions continuously and critically in resolving value conflicts about the best care of individual patients.

Intranasal meningoencephalocele with recurrent meningitis.

Two patients presented with repeated bouts of meningitis. RISA cisternography established the diagnosis in both cases. An intranasal meningoencephalocele was the cause of these infections. Frontal craniotomy and section of the peduncular connection of the meningoencephalocele and sealing of the bony defect was successfully performed in both cases. Postoperative investigations showed complete cure.

Lateral ventricle plexus papilloma and communicating hydrocephalus.

A choroid plexus papilloma was found in the right lateral ventricle of a five-month-old boy. Though it was associated with an important communicating hydrocephalus, it was seen at operation to be freely mobile and did not directly obstruct the flow of the cerebrospinal fluid. Computerized axial tomography was the most helpful para-clinical investigation for diagnostic purposes, and for follow-up study. Tumor removal alone was sufficient to cure the hydrocephalus, and no shunt was necessary. We feel that this case demonstrates that hyperproduction of CSF is sufficient alone to cause communicating hydrocephalus in patients with choroid plexus papilloma of the lateral ventricle.

New drugs for epilepsy: a review.

Four relatively new drugs used as symptomatic treatment against epileptic seizures-carbamazepine (Tegretol), valproic acid (Depakene), clonazepam (Rivotril) and nitrazepam (Mogadon)-are reviewed from the standpoint of pharmacokinetic parameters, clinical indication, toxicity and practical use.

[Skull lacunae in myelomeningocele]. / Les lacunes crâniennes dans les myéloméningocèles.

Lacunar skull was found in 60% of 80 patients with myelomeningocele. Most patients with lacunae were neonates. Lacunar skull is significantly correlated with hydrocephalus, stenosis of aqueduct of Sylvius, and Arnold-Chiari malformation. All infants with myelomeningocele should have roentgenograms of the skull at birth. Lacunar skull is associated with a poor mental prognosis.

[Recessive autosomal spastic ataxia]. / L'ataxie spastique autosomique récessive.

The authors report the case of a 12 year-old child who presented with a syndrome, isolated in Quebec, including spasticity, ataxia, distal muscle wasting, pes cavus, retinal striation, and the frequent presence of a prolapse of the mitral valve. This autosomal recessive disease is similar to Friedreich disease.

Mapping of a gene determining familial partial epilepsy with variable foci to chromosome 22q11-q12.

We identified two large French-Canadian families segregating a familial partial epilepsy syndrome with variable foci (FPEVF) characterized by mostly nocturnal seizures arising from frontal, temporal, and occasionally occipital epileptic foci. There is no evidence for structural brain damage or permanent neurological dysfunction. The syndrome is inherited as an autosomal dominant trait with incomplete penetrance. We mapped the disease locus to a 3. 8-cM interval on chromosome 22q11-q12, between markers D22S1144 and D22S685. Using the most conservative diagnostic scheme, the maximum cumulative LOD score was 6.53 at recombination fraction (straight theta) 0 with D22S689. The LOD score in the larger family was 5.34 at straight theta=0 with the same marker. The two families share an identical linked haplotype for >/=10 cM, including the candidate interval, indicating a recent founder effect. A severe phenotype in one of the probands may be caused by homozygosity for the causative mutation, as suggested by extensive homozygosity for the linked haplotype and a bilineal family history of epilepsy. An Australian family with a similar phenotype was not found to link to chromosome 22, indicating genetic heterogeneity of FPEVF.