Bacteriological aspects of Darier’s disease

Background There are no established data on the prevalence of bacterial colonization of lesional skin, nares and perineum in Darier’s disease (DD), or its contribution to the clinical manifestations of the disease. Objective To determine the prevalence of bacterial colonization of lesional skin and Staphylococcus aureus (S. aureus) in nares and perineum in 75 patients with DD, the association of these parameters with disease and patient characteristics, and the features of the bacterial skin infection in this group. Methods Medical interviews and physical examinations were performed. Bacteria were isolated from swabs taken from lesional skin, nares and perineum. Results S. aureus was isolated in 68%, 47% and 22% of lesional skin, nares and perineum cultures respectively. Subjects with positive S. aureus culture from lesional skin and/or nares had a statistically significant higher percentage of skin area affected and a more severe disease than patients with negative culture. Thirty of the 75 patients (40%) recalled bacterial skin infection, most often on the chest. Conclusions Patients with DD have high prevalence of S. aureus colonization in lesional skin and nares, with a correlation between disease severity and extent of the colonization. Further studies examining the consequences of S. aureus eradication in those sites may establish the need for S. aureus lesional skin and nares colonization screening and eradication as part of the treatment of DD exacerbations.     

Modulation of intein activity by its neighboring extein substrates

Inteins comprise a large family of phylogenetically widespread self-splicing protein catalysts that colonize diverse host proteins. The evolutionary and functional relationship between the intein and the split-host protein, the exteins, is largely unknown. To probe an association, we developed an in vivo and in vitro intein assay based on FRET. The FRET assay reports cleavage of the intein from its N-terminal extein. Applying this assay to randomized extein libraries, we show that the nature of the extein substrate bordering the intein can profoundly influence intein activity. Residues proximal to the intein-splicing junction in both N- and C-terminal exteins can accelerate the N-terminal cleavage rate by >4-fold or attenuate cleavage by 1,000-fold, both resulting in compromised self-splicing efficiency. The existence and the magnitude of extein effects require consideration for maximizing the utility of inteins in biotechnological applications, and they predict biases in intein integration sites in nature.     

A novel recombinant soluble splice variant of Met is a potent antagonist of the hepatocyte growth factor/scatter factor-Met pathway

PURPOSE: The Met receptor tyrosine kinase and its ligand, hepatocyte growth factor/scatter factor (HGF/SF), are involved in a wide range of biological activities, including cell proliferation, motility, invasion, and angiogenesis. The HGF/SF-Met signaling pathway is frequently activated in a variety of cancers, and uncontrolled Met activation correlates with highly invasive tumors and poor prognosis. In this study, we investigated the inhibitory effect of a novel soluble splice variant of Met on the HGF/SF-Met pathway. EXPERIMENTAL DESIGN: Using our alternative splicing modeling platform LEADS, we have identified a novel splice variant of the Met receptor, which encodes a truncated soluble form of the receptor. This variant was produced as a recombinant Fc-fused protein named Cgen-241A and was tested in various cell-based assays representing different outcomes of the HGF/SF-Met pathway. RESULTS: Cgen-241A significantly inhibited HGF/SF-induced Met phosphorylation as well as cell proliferation and survival. In addition, Cgen-241A showed a profound inhibitory effect on cell scattering, invasion, and urokinase up-regulation. The inhibitory effects of Cgen-241A were shown in multiple human and nonhuman cell types, representing different modes of Met activation. Furthermore, Cgen-241A showed direct binding to HGF/SF. CONCLUSIONS: Taken together, our results indicate that Cgen-241A is a potent antagonist of the HGF/SF-Met pathway, underlining its potential as a therapeutic agent for the treatment of a wide variety of human malignancies that are dependent on this pathway.     

Antioxidant therapy in acute central nervous system injury: current state

Free radicals are highly reactive molecules generated predominantly during cellular respiration and normal metabolism. Imbalance between cellular production of free radicals and the ability of cells to defend against them is referred to as oxidative stress (OS). OS has been implicated as a potential contributor to the pathogenesis of acute central nervous system (CNS) injury. After brain injury by ischemic or hemorrhagic stroke or trauma, the production of reactive oxygen species (ROS) may increase, sometimes drastically, leading to tissue damage via several different cellular molecular pathways. Radicals can cause damage to cardinal cellular components such as lipids, proteins, and nucleic acids (e.g., DNA), leading to subsequent cell death by modes of necrosis or apoptosis. The damage can become more widespread due to weakened cellular antioxidant defense systems. Moreover, acute brain injury increases the levels of excitotoxic amino acids (such as glutamate), which also produce ROS, thereby promoting parenchymatous destruction. Therefore, treatment with antioxidants may theoretically act to prevent propagation of tissue damage and improve both the survival and neurological outcome. Several such agents of widely varying chemical structures have been investigated as therapeutic agents for acute CNS injury. Although a few of the antioxidants showed some efficacy in animal models or in small clinical studies, these findings have not been supported in comprehensive, controlled trials in patients. Reasons for these equivocal results may include, in part, inappropriate timing of administration or suboptimal drug levels at the target site in CNS. Better understanding of the pathological mechanisms of acute CNS injury would characterize the exact primary targets for drug intervention. Improved antioxidant design should take into consideration the relevant and specific harmful free radical, blood brain barrier (BBB) permeability, dose, and time administration. Novel combinations of drugs providing protection against various types injuries will probably exploit the potential synergistic effects of antioxidants in stroke.     

Development of indole-3-propionic acid (OXIGON) for Alzheimer's disease

The accumulation of amyloid-beta and concomitant oxidative stress are major pathogenic events in Alzheimer’s disease. Indole-3-propionic acid (IPA, OXIGON™) is a potent anti-oxidant devoid of pro-oxidant activity. IPA has been demonstrated to be an inhibitor of beta-amyloid fibril formation and to be a potent neuroprotectant against a variety of oxidotoxins. This review will summarize the known properties of IPA and outline the rationale behind its selection as a potential disease-modifying therapy for Alzheimer’s disease.     

Radiofrequency ablation for hemobilia secondary to hepatocellular carcinoma

Hemobilia is a rare manifestation of hepatic malignancies. The current treatment of choice for hemobilia is transcatheter hepatic arterial embolization. However, there have been only two published reports that describe the use of hepatic arterial embolization for hemobilia caused by hepatic neoplasms. In addition, this procedure is occasionally unsuccessful in the treatment of hemobilia. A case in which hemobilia caused by hepatocellular carcinoma was successfully treated with percutaneous radiofrequency tumor ablation after several failed hepatic arterial embolizations is described in this report.     

The role of glutamatergic transmission in the pathogenesis of levodopa-induced dyskinesias. Potential therapeutic approaches

Dyskinesias are the most frequent adverse effect of chronic levodopa therapy in patients with Parkinson's disease (PD). Current pharmacological treatment for this problem is unsatisfactory. Recently, there is evidence for the role of glutamate in the basal ganglia neuronal circuitry in the generation of dyskinesias. If indeed glutamatergic overactivity beyond the dopaminergic synapses plays a role in the pathogenesis of these involuntary movements, there is hope that its suppression may be beneficial without causing loss of levodopa efficacy and parkinsonian deterioration. Indeed, NMDA receptor antagonists such as amantadine and dextrometorphan can reduce such dyskinesias. We tested the efficacy of riluzole, an inhibitor of glutamatergic transmission in the inhibition of levodopa-induced dyskinesias.     

Definitive diagnosis of fracture-separation of the distal humeral epiphysis in neonates by ultrasonography

Fracture-separation of the distal humeral epiphysis in neonates is difficult to diagnose radiologically because the cartilaginous epiphysis is radiolucent. We report a case in which fracture-separation of the distal humeral epiphysis in a neonate was diagnosed with the help of ultrasonography, which provided a clear delineation of the injury.