Therapeutic implications of a selective alpha7 nicotinic receptor abnormality in schizophrenia

A convergence of preclinical pharmacology, and human autopsy and genetic data support the existence of reduced expression and function of the alpha7 nicotinic receptor in patients with schizophrenia. The alpha7 nicotinic receptor is a member of a family of ligand-gated ion channels. The alpha7 nicotinic receptor may play an essential role in auditory sensory gating and voluntary smooth pursuit eye movements, two psychophysiological functions that are abnormal in patients with schizophrenia and closely related unaffected biological relatives. Diminished expression or function of the alpha7 nicotinic receptor in schizophrenia has stimulated consideration of selective full or partial alpha7 nicotinic receptor agonists as possible therapeutic interventions for this disorder. Further, the availability of positive allosteric modulators of nicotinic receptors that can improve the efficiency of transduction of the acetylcholine signal and prevent the rapid desensitization of the receptor should encourage these novel treatment approaches (e.g., galantamine).     

Maternal uniparental disomy chromosome 14: case report and literature review

Uniparental disomy is a genetic cause of disease implicated in a wide variety of neurologic disorders. A recently identified condition is maternal uniparental disomy for chromosome 14 (mUPD14) syndrome. A child with hypotonia and developmental delay was found to have mUPD14 after identification of a balanced karyotypic rearrangement involving both chromosomes 14. We explore the genetic mechanisms by which uniparental disomy can cause clinical abnormalities and karyotypic findings that should raise suspicion for uniparental disomy, review the literature on the mUPD14, and discuss clinical indications on which to suspect this diagnosis. Although it is more difficult to establish a diagnosis in the absence of visible karyotypic abnormalities involving chromosome 14, a distinct phenotype exists in mUPD14 syndrome: in utero growth restriction, congenital hypotonia, gross motor delay, arrested hydrocephalus, mild to moderate mental retardation, joint hyperextensibility, short stature, and precocious puberty. Testing for mUPD14 should be considered in infants with generalized hypotonia who have a history of in utero growth restriction.     

Cutaneous implantation metastasis of cholangiocarcinoma after percutaneous transhepatic biliary drainage

Percutaneous transhepatic biliary decompression is a preoperative surgical adjunct in patients with obstructive jaundice that has been in use since 1973. It is recommended that this procedure be adopted for both palliative treatment in unresectable patients and as a preoperative means of lowering serum bilirubin in patients with potentially resectable malignancies of the pancreas or biliary tract. Metastatic tumor seeding along the transhepatic biliary catheter is an unusual complication resulting from this procedure but there have been a few cases reported in the literature. Below is a report on a 59-year-old woman in whom the percutaneous transhepatic catheter drainage of the biliary tree, performed before surgical resection of a cholangiocarcinoma, caused cutaneous tumor implantation at the catheter site 3 months later. The clinical aspect was morphea-like and histopathologic examination revealed typical features of a dermal metastasis of adenocarcinoma. Immunohistochemistry revealed cytoplasmic positivity for cytokeratin 7-19, specific for the biliary tract epithelium. A review of the literature available led us to conclude that port-site metastasis in patients with obstructive jaundice treated with percutaneous transhepatic biliary decompression was an unusual but possible complication. In fact, many catheter-tract metastatic deposits in the liver parenchyma, detected at autopsy or on operation, are mistakenly identified as hematogenous or lymphatic metastasis and are not attributed to a catheter-related process. We also report on this case because of the atypical morphea-like aspect of the skin metastasis.     

Pigment epithelium-derived factor induces the production of chemokines by rat microglia

Many studies have shown that pigment epithelium-derived factor (PEDF) has neurotrophic effects on retinal cells and hippocampal, spinal cord, and cerebellar granule cell neurons, but much less work has examined the effects of PEDF on glia. In this study, we show that PEDF changes microglial morphology within 1 h of exposure, to a more deactivated form, while having no effect on the expression of such activation markers as OX-42 and ED-1. In contrast, urea activates acid phosphatase, and PEDF blocks that activation. PEDF also activates NFkappaB, accompanied by the induction of mRNAs and proteins for the chemokines macrophage inflammatory protein-1alpha (MIP-1alpha, MIP-2, and MIP-3alpha. All the chemokines stimulate acid phosphatase activity, and high doses of MIP-2 and MIP-3alpha), alter the morphology of the microglia at 1 h after treatment. These results suggest that the use of PEDF for clinical treatments, such as for retinal neovascularization, brain injury, or ischemia, should be undertaken with caution because of the possibility of induction of inflammation caused by microglial or other immune cell migration in response to the chemokines induced by PEDF.     

Portraits or people? Distinct representations of face identity in the human visual cortex

Humans can identify individual faces under different viewpoints, even after a single encounter. We determined brain regions responsible for processing face identity across view changes after variable delays with several intervening stimuli, using event-related functional magnetic resonance imaging during a long-term repetition priming paradigm. Unfamiliar faces were presented sequentially either in a frontal or three-quarter view. Each face identity was repeated once after an unpredictable lag, with either the same or another viewpoint. Behavioral data showed significant priming in response time, irrespective of view changes. Brain imaging results revealed a reduced response in the lateral occipital and fusiform cortex with face repetition. Bilateral face-selective fusiform areas showed view-sensitive repetition effects, generalizing only from three-quarter to front-views. More medial regions in the left (but not in the right) fusiform showed repetition effects across all types of viewpoint changes. These results reveal that distinct regions within the fusiform cortex hold view-sensitive or view-invariant traces of novel faces, and that face identity is represented in a view-sensitive manner in the functionally defined face-selective areas of both hemispheres. In addition, our finding of a better generalization after exposure to a 3/4-view than to a front-view demonstrates for the first time a neural substrate in the fusiform cortex for the common recognition advantage of three-quarter faces. This pattern provides new insights into the nature of face representation in the human visual system.     

Neurophysiological indexes of speech processing deficits in children with specific language impairment

We used neurophysiological and behavioral measures to examine whether children with specific language impairment (SLI) have deficits in automatic processing of brief, phonetically similar vowels, and whether attention plays a role in such deficits. The neurophysiological measure mismatch negativity (MMN) was used as an index of discrimination in two tasks; one in which children ignored the auditory stimuli and watched a silent video and a second in which they attended to the auditory modality. Children with SLI showed good behavioral discrimination, but significantly poorer behavioral identification of the brief vowels than the children with typical language development (TLD). For the TLD children, two neurophysiological measures (MMN and a later negativity, LN) indexed discrimination of the vowels in both tasks. In contrast, only the LN was elicited in either task for the SLI group. We did not see a direct correspondence between the absence of MMN and poor behavioral performance in the children with SLI. This pattern of findings indicates that children with SLI have speech perception deficiencies, although the underlying cause may vary.     

Management of long QT syndrome

Congenital long QT syndrome (LQTS) is a genetic disorder characterized by prolongation of the QT interval on the electrocardiogram and by life-threatening cardiac arrhythmias, occurring especially during conditions of increased sympathetic activity. Existing therapies are very effective, but mortality is high among untreated, symptomatic individuals. The identification of several of the genes responsible for LQTS and the realization that they all encode cardiac ion-channels has represented a landmark finding. This advance has fostered novel genotype-phenotype studies that are providing unique insight into how close the relationship can be between molecular biology and clinical cardiology. LQTS represents a paradigm for sudden cardiac death. Indeed, the growing knowledge developed for LQTS is likely to provide the key to understanding the genetic propensity to sudden death in patients with more-common cardiovascular diseases. The data presented here illustrate how the treatment of LQTS is rapidly evolving toward a highly individually tailored approach on the basis of patient-specific genetic information.