The high affinity peripheral benzodiazepine receptor ligand DAA1106 binds specifically to microglia in a rat model of traumatic brain injury: implications for PET imaging

Traumatic brain injury (TBI) is a significant cause of mortality, morbidity, and disability. Microglial activation is commonly observed in response to neuronal injury which, when prolonged, is thought to be detrimental to neuronal survival. Activated microglia can be labeled using PK11195, a ligand that binds the peripheral benzodiazepine receptor (PBR), receptors which are increased in activated microglia and sparse in the resting brain. We compared the binding properties of two PBR ligands PK11195 and DAA1106 in rats using the controlled cortical impact (CCI) model of experimental TBI. While both ligands showed relative increases with specific binding in the cortex ipsilateral to injury compared to the contralateral side, [(3)H]DAA1106 showed higher binding affinity compared with [(3)H](R)-PK11195. Combined immunohistochemistry and autoradiography in brain tissues near the injury site showed that [(3)H]DAA1106 binding co-registered with activated microglia more than astrocytes. Further, increased [(3)H]DAA1106-specific binding positively correlated with the degree of microglial activation, and to a lesser degree with reactive astrocytosis. Finally, in vivo administration of each ligand in rats with TBI showed greater retention of [(11)C]DAA1106 compared to [(11)C](R)-PK11195 at the site of the contusion as assessed by ex vivo autoradiography. These results in a rat model of TBI indicate that [(11)C]DAA1106 binds with higher affinity to microglia when compared with PK11195, suggesting that [(11)C]DAA1106 may represent a better ligand than [(11)C](R)-PK11195 for in vivo PET imaging of activated microglia in TBI.     

Extraction techniques for the decellularization of tissue engineered articular cartilage constructs

Several prior studies have been performed to determine the feasibility of tissue decellularization to create a non-immunogenic xenogenic tissue replacement for bladder, vasculature, heart valves, knee meniscus, temporomandibular joint disc, ligament, and tendon. However, limited work has been performed with articular cartilage, and no studies have examined the decellularization of tissue engineered constructs. The objective of this study was to assess the effects of different decellularization treatments on articular cartilage constructs, engineered using a scaffoldless approach, after 4 wks of culture, using a two-phased approach. In the first phase, five different treatments were examined: 1) 1% SDS, 2) 2% SDS, 3) 2% Tributyl Phosphate, 4) 2% Triton X-100, and 5) Hypotonic followed by hypertonic solution. These treatments were applied for either 1 h or 8 h, followed by a 2 h wash in PBS. Following this wash, the constructs were assessed histologically, biochemically for cellularity, GAG, and collagen content, and biomechanically for compressive and tensile properties. In phase II, the best treatment from phase I was applied for 1, 2, 4, 6, or 8 h in order to optimize the application time. Treatment with 2% SDS for 1 h or 2 h significantly reduced the DNA content of the tissue, while maintaining the biochemical and biomechanical properties. On the other hand, 2% SDS for 6 h or 8 h resulted in complete histological decellularization, with complete elimination of cell nuclei on histological staining, although GAG content and compressive properties were significantly decreased. Overall, 2% SDS, for 1 or 2 h, appeared to be the most effective agent for cartilage decellularization, as it resulted in decellularization while maintaining the functional properties. The results of this study are exciting as they indicate the feasibility of creating engineered cartilage that may be non-immunogenic as a replacement tissue.     

Resistance of Acanthamoeba Cysts to Disinfection in Multiple Contact Lens Solutions

Acanthamoebae are free-living amoebae found in the environment, including soil, freshwater, brackish water, seawater, hot tubs, and Jacuzzis. Acanthamoeba species can cause keratitis, a painful vision-threatening infection of the cornea, and fatal granulomatous encephalitis in humans. More than 20 species of Acanthamoeba belonging to morphological groups I, II, and III distributed in 15 genotypes have been described. Among these, Acanthamoeba castellanii, A. polyphaga, and A. hatchetti are frequently identified as causing Acanthamoeba keratitis (AK). Improper contact lens care and contact with nonsterile water while wearing contact lenses are known risk factors for AK. During a recent multistate outbreak, AK was found to be associated with the use of Advanced Medical Optics Complete MoisturePlus multipurpose contact lens solution, which was hypothesized to have had insufficient anti-Acanthamoeba activity. As part of the investigation of that outbreak, we compared the efficacies of 11 different contact lens solutions against cysts of A. castellanii, A. polyphaga, and A. hatchetti (the isolates of all species were genotype T4), which were isolated in 2007 from specimens obtained during the outbreak investigation. The data, generated with A. castellanii, A. polyphaga, and A. hatchetti cysts, suggest that the two contact lens solutions containing hydrogen peroxide were the only solutions that showed any disinfection ability, with 0% and 66% growth, respectively, being detected with A. castellanii and 0% and 33% growth, respectively, being detected with A. polyphaga. There was no statistically significant difference in disinfection efficacy between the 11 solutions for A. hatchetti.Acanthamoebae, which are free-living amoebae, occur worldwide in soil and water. It has been isolated from ponds, lakes, brackish water. and seawater; filters of heating, ventilating, and air-conditioning units; medical equipment, such as gastric wash tubing, dental irrigation units, contact lenses, and contact lens solutions; as well as vegetables, cell cultures, and even human and animal tissues (7, 23, 39). It has also been isolated from toxic waste dumpsites with high levels of pesticides, herbicides, pharmaceuticals, heavy metals, and polychlorinated biphenyls (35). Acanthamoeba species have two stages in their life cycle: a vegetative or trophozoite stage that reproduces by binary fission and that feeds voraciously on the bacteria and detritus present in the environment and a nondividing, cyst stage that is resistant to environmental stress. Acanthamoeba amoebae cause different types of human disease, including central nervous system infections (granulomatous amebic encephalitis, cutaneous infections) Acanthamoeba dermatitis, and ocular infections (Acanthamoeba keratitis [AK]). Granulomatous amebic encephalitis and cutaneous infections principally occur in immunocompromised individuals, including patients with human immunodeficiency virus infection or AIDS (17, 23, 37, 43). In contrast, AK principally occurs in immunocompetent individuals.AK is a painful vision-threatening infection, which, if it is not treated promptly, may lead to ulceration of the cornea, a loss of visual acuity, and, eventually, blindness (7, 15, 16). AK is associated with trauma to the cornea and with contact lens wear as a result of poor lens care and hygiene. When introduced into the eye by a contaminated contact lens, Acanthamoeba amoebae may adhere to the corneal surface and subsequently infiltrate the stoma and cause tissue damage (10). Both Acanthamoeba cysts and trophozoites can be isolated by culture from corneal scrapings or biopsy specimens and from contact lens paraphernalia (23, 43). Confocal microscopy has been used as an aid for the diagnosis of AK (29). Molecular techniques such as real-time PCR assays have been developed for the identification of Acanthamoeba species (32, 33). Sequencing analysis of the 18S rRNA gene has been used to identify as many as 15 genotypes of Acanthamoeba, of which the T4 genotype appears to be the most common in the environment and in patients with AK (2, 23).The first documented case of AK in the United States occurred in 1973 in a south Texas rancher following trauma to his right eye (15, 40, 42). Both trophozoite and cyst stages of Acanthamoeba polyphaga were demonstrated in corneal sections. Between October 1985 and August 1986, Stehr-Green et al. (41) conducted a case-control study to investigate an outbreak of AK in the United States. The majority of case patients wore contact lenses, and illness was most commonly associated with the use of homemade saline solutions and lens care practices, such as the disinfection of the lenses less frequently than recommended and swimming while wearing contact lenses (8, 41). Contact lens use is now considered an important risk factor for AK in the United States. AK cases have continued to be diagnosed since the 1986 outbreak, but because AK is not a reportable disease in the United States, the actual number of cases occurring each year is not known.A recent study indicated a dramatic increase in the number of AK cases in the Chicago, IL, area (16). An investigation conducted by the Centers for Disease Control and Prevention (CDC) revealed that this increase in the number of AK cases was occurring nationwide, starting in 2004 and continuing through 2007 (7). A subsequent investigation identified the use of Advanced Medical Optics (AMO) Complete MoisturePlus multipurpose contact lens solution as the primary risk factor, leading to an international recall of this product by the manufacturer (7, 16). We therefore decided to examine this and other frequently used major contact lens solutions for their efficacies against Acanthamoeba species isolated from clinical samples collected during the 2007 AK outbreak investigation.     

Disruption of Esrom and Ryk identifies the roof plate boundary as an intermediate target for commissure formation

Growth cones are guided to their final destination by intermediate targets. Here, we identify intermediate targets and signaling components acting on zebrafish habenula commissural axons. Live imaging establishes that axons pause at the medial habenula before and after crossing the roof plate. esrom mutants axons fail to advance beyond the ipsilateral medial habenula. Tsc2 function is reduced in mutant axons, indicating cell autonomous defects in signaling. Consistent with signaling properties changing outside the roof plate, EphB is surface localized on axon segments within a zone demarcated by the medial habenula. wnt4a is expressed in the medial habenula and morpholino knockdown causes loss of the commissure. Electroporation of truncated Ryk causes axons to reenter the midline after reaching the contralateral habenula. These data identify Esrom as a mediator of growth cone navigation at an intermediate target and underscore the importance of midline boundaries as signaling centers for commissure formation.     

Acitretin‐Responsive Ichthyosis in Chanarin–Dorfman Syndrome with a Novel Mutation in the ABHD5/CGI‐58 Gene

Chanarin–Dorfman syndrome (CDS) is a rare nonlysosomal neutral lipid storage disorder characterized by congenital ichthyosis, lipid vacuoles in leukocytes (Jordan's anomaly), and hepatomegaly. The authors herein report an 18‐month‐old boy with ichthyosis and hepatomegaly diagnosed with CDS and confirmed to have a novel c.506–3C>G mutation in the ABHD5/CGI‐58 gene. Our case also illustrates that retinoids such as acitretin could be useful in the treatment of skin manifestations in CDS even in the presence of liver derangement.     

Carotid artery stenting: Rationale, indications, and results

Carotid stenting is a percutaneous, minimally invasive treatment for carotid stenosis. It does not carry the surgical risks of carotid endarterectomy and therefore can be applied to the elderly and to patients with comorbidities. Complications and late events appear low.     

Isolated Junctional Tachycardia in a Child After Noncardiac Surgery: An Uncommon Clinical Presentation

Isolated junctional tachycardia is rare in children but has been reported after cardiac surgery. To date, it has not been reported after noncardiac surgery. This report describes the case of a 3-year-old boy with no cardiac history who experienced transient junctional tachycardia after a right pyeloplasty. Medical therapy was not prescribed initially due to lack of symptoms. However, symptomatic junctional tachycardia recurred, prompting institution of oral beta-blocker therapy. Isolated junctional tachycardia should not be overlooked in the differential diagnosis of pediatric supraventricular tachycardia after noncardiac surgery.