Elimination of Interface Energy Barriers Using Dendrimer Polyelectrolytes with Fractal Geometry

In this work we study conjugated polyelectrolyte (CPE) films based on polyamidoamine (PAMAM) dendrimers of generations G1 and G3. These fractal macromolecules are compared to branched polyethylenimine (b-PEI) polymer using methanol as the solvent. All of these materials present a high density of amino groups, which protonated by methoxide counter-anions create strong dipolar interfaces. The vacuum level shift associated to these films on n-type silicon was 0.93 eV for b-PEI, 0.72 eV for PAMAM G1 and 1.07 eV for PAMAM G3. These surface potentials were enough to overcome Fermi level pinning, which is a typical limitation of aluminium contacts on n-type silicon. A specific contact resistance as low as 20 mΩ·cm2 was achieved with PAMAM G3, in agreement with the higher surface potential of this material. Good electron transport properties were also obtained for the other materials. Proof-of-concept silicon solar cells combining vanadium oxide as a hole-selective contact with these new electron transport layers have been fabricated and compared. The solar cell with PAMAM G3 surpassed 15% conversion efficiency with an overall increase of all the photovoltaic parameters. The performance of these devices correlates with compositional and nanostructural studies of the different CPE films. Particularly, a figure-of-merit (Vσ) for CPE films that considers the number of protonated amino groups per macromolecule has been introduced. The fractal geometry of dendrimers leads to a geometric increase in the number of amino groups per generation. Thus, investigation of dendrimer macromolecules seems a very good strategy to design CPE films with enhanced charge-carrier selectivity.

Hepatitis C, diagnosis and management: a survey of practicing physicians in Hawaii

We surveyed 652 Hawaii physicians who diagnosed hepatitis C (HCV) since 1997. Less than 20% of licensed physicians have diagnosed HCV and initial estimates suggest there are 12,000 to 18,000 undiagnosed HCV cases in Hawaii. Treatment is concentrated among twelve physicians and aggressive case finding may overwhelm present resources. More primary care physicians need to participate in the detection and management of HCV.

Depression in Parkinson's disease. Pharmacological characteristics and treatment

Parkinson's disease (PD) is a common neurological illness and various degrees of depression frequently complicate its course. Risk factors for developing depression with PD include right-sided hemiparkinsonism, akinesia, increased severity of disability, anxiety and psychosis. Onset of parkinsonism at a younger age, female gender and the use of levodopa are arguable risk factors. Depression may be difficult to diagnose in patients with PD because the signs of the 2 disorders overlap. In addition, patients with atypical PD more commonly have depression than patients with classical PD presentations. Antidepressant response to antiparkinsonian treatment has been limited. Enhancement of catecholamine levels in the CNS by selegiline (deprenyl), a monoamine oxidase (MAO) type B inhibitor, has shown potential antidepressant as well as neuroprotective effects. Other MAO inhibitors have shown antidepressant efficacy in animal models but have not been well tolerated by patients with PD. A catechol-O-methyltransferase (COMT) inhibitor combined with an MAO inhibitor might synergistically maximise the levels of catecholamines in the CNS. Antidepressant medications used in patients without PD include tricyclic antidepressants (TCAs) and selective serotonin (5-hydroxytryptamine; 5-HT) reuptake inhibitors (SSRIs), but only TCAs have been carefully studied for their antidepressant effects in PD. Electroconvulsive therapy has proven efficacy as antidepressant therapy in patients with PD, and transcranial magnetic stimulation has provided temporary relief of depression under experimental conditions. Adverse effects of polypharmacy in the attempted treatment of depression in patients with PD are common in the elderly. A 'serotonin syndrome' has occurred frequently enough to preclude the coadministration of selegiline with SSRIs or TCAs, and multiple interactions between antiparkinsonian and antidepressant medications further complicate treatment strategies in patients with PD. An algorithmic approach to the pharmacological treatment of depression is described in this article.

Posterior cortical atrophy: Unique features

Abstract Posterior cortical atrophy (PCA) is a visual-cognitive syndrome caused by Creutzfeldt-Jakob disease (CJD), Alzheimer's disease (AD), or subcortical gliosis. We report a case of posterior cortical atrophy unique in (1) comprehensive documentation of clinical, radiologic, electroencephalograph, metabolic and histopathologic findings, (2) repeated clinical and laboratory assessment, and (3) establishment of unique occipital subcortical gliosis in a patient with AD. Clinical manifestations of PCA caused by AD included visual agnosia, cortical blindness, optic apraxla, delusions, hallucinations, agitation, depression, amnestic deficit, Wernicke's aphasia, acalculia, and left/right disorientation. Posterior cortical atrophy produced by AD can be demonstrated on magnetic resonance imaging, positron emission tomography, and electroencephalography; determination of the etiology requires tissue examination. Autopsy-diagnosed cases in the literature document PCA due to CJD and AD with equal frequency.

A case of spinal cord decompression sickness presenting as partial Brown-Sequard syndrome

Type II decompression sickness (DCS) usually manifests as myelopathy; however, there are no reports of Brown-Sequard syndrome in association with diving accidents. We report a 35-year-old man who developed type II DCS presenting as partial Brown-Sequard syndrome. MRI of the thoracic spine revealed two punctate foci of increased signal intensity in the right T6 spinal cord.

Neuroimaging characteristics in carbon monoxide toxicity

Neuroimaging studies for 18 patients carrying carbon monoxide toxicity as a discharge diagnosis were reviewed. The most common positive findings were low-density lesions in the globus pallidus (7/18, 39%) and deep white matter changes (5/18, 28%). Six computed tomography head scans showed no acute changes. Advanced age, method of exposure (intentional vs accidental), and severity of carboxyhemoglobin level did not predict neuroradiological or clinical outcomes. Early neuroimaging could not be used to predict clinical courses (death or coma vs discharge to either an institution or a home) in the patient population studied.

Validation of a new instrument for determining migraine prevalence: the UCSD Migraine Questionnaire

To provide a reliable instrument for use in large population surveys, we developed a short questionnaire based on existing International Headache Society diagnostic criteria and administered the questionnaire to 50 consecutive patients seeking evaluation at a university-based headache clinic. A single neurologist subsequently examined all patients. Based only on the questionnaires, reviewers scored each patient as having migraine with aura, migraine without aura, or nonmigrainous headache. High predictive validity and low interobserver variability between the examining neurologist and the independent reviewers suggest that the questionnaire may be quite useful as a survey instrument.