A Method to Investigate Astrocyte and Microglial Morphological Changes in the Aging Brain of the Rhesus Macaque.

With a rapidly aging population, studies of neuroinflammation and degeneration associated with eugeric aging are becoming critical. Using the unique archive at the Tulane National Primate Research Center as a resource, we have developed tools to quantify morphological changes in astrocytes and microglia across the life span of monkeys. This method can be used for morphometric studies of multiple parameters simultaneously in an unbiased manner.

MRI-Arthroscopy Correlation of the Rotator Cuff: A Case-based Review.

With significant advancements over recent decades, magnetic resonance imaging (MRI) and shoulder arthroscopy are important complementary tools in guiding orthopedic surgeons to diagnosis, decision making, and treatment of rotator cuff pathology. The objective of this article is to review the basic principles and pearls of MRI-arthroscopy correlation of the rotator cuff through an overview of our approach to reading shoulder MRI followed by a case-based review of selected conditions. By understanding and comparing the subtleties of these modalities, radiologists and clinicians can better appreciate both the utility and limitations of MRI in predicting operative findings.

The flavivirus dengue induces hypertrophy of white matter astrocytes.

Flaviviruses, including Zika and dengue (DENV), pose a serious global threat to human health. Of the 50+ million humans infected with DENV annually, approximately 1-3 % progress to severe disease manifestations, dengue hemorrhagic fever (DHF) or dengue shock syndrome (DSS). Several factors are suspected to mediate the course of infection and pathogenesis of DENV infection. DHF and DSS are associated with vascular leakage and neurological sequelae. Our hypothesis was that altered astrocyte activation and morphology would alter the dynamics of the extracellular space and hence, neuronal and vascular function. We investigated the mechanisms of neuropathogenesis DENV infection in rhesus macaques. There were decreased numbers of GFAP immunopositive astrocytes per unit area, although those that remained had increased arbor length and complexity. This was combined with structural hypertrophy of white matter astrocytes in the absence of increased vascular leakage. Combined, these studies show how even low-grade infection with DENV induces measurable changes within the parenchyma of infected individuals.

Glial cell morphological and density changes through the lifespan of rhesus macaques.

How aging impacts the central nervous system (CNS) is an area of intense interest. Glial morphology is known to affect neuronal and immune function as well as metabolic and homeostatic balance. Activation of glia, both astrocytes and microglia, occurs at several stages during development and aging. The present study analyzed changes in glial morphology and density through the entire lifespan of rhesus macaques, which are physiologically and anatomically similar to humans. We observed apparent increases in gray matter astrocytic process length and process complexity as rhesus macaques matured from juveniles through adulthood. These changes were not attributed to cell enlargement because they were not accompanied by proportional changes in soma or process volume. There was a decrease in white matter microglial process length as rhesus macaques aged. Aging was shown to have a significant effect on gray matter microglial density, with a significant increase in aged macaques compared with adults. Overall, we observed significant changes in glial morphology as macaques age indicative of astrocytic activation with subsequent increase in microglial density in aged macaques.

Neuropathogenesis of Chikungunya infection: astrogliosis and innate immune activation.

Chikungunya, "that which bends up" in the Makonde dialect, is an emerging global health threat, with increasing incidence of neurological complications. Until 2013, Chikungunya infection had been largely restricted to East Africa and the Indian Ocean, with cases within the USA reported to be from foreign travel. However, in 2014, over 1 million suspected cases were reported in the Americas, and a recently infected human could serve as an unwitting reservoir for the virus resulting in an epidemic in the continental USA. Chikungunya infection is increasingly being associated with neurological sequelae. In this study, we sought to understand the role of astrocytes in the neuropathogenesis of Chikungunya infection. Even after virus has been cleared form the circulation, astrocytes were activated with regard to TLR2 expression. In addition, white matter astrocytes were hypertrophic, with increased arbor volume in gray matter astrocytes. Combined, these would alter the number and distribution of synapses that each astrocyte would be capable of forming. These results provide the first evidence that Chikungunya infection induces morphometric and innate immune activation of astrocytes in vivo. Perturbed glia-neuron signaling could be a major driving factor in the development of Chikungunya-associated neuropathology.

Naltrexone treatment reverses astrocyte atrophy and immune dysfunction in self-harming macaques.

The role of glia in the development and treatment of behavioral abnormalities is understudied. Recent reports have observed glial activation in several disorders, including depression, autism spectrum disorders and self-injurious behaviors (SIB). In the current study, we examined SIB in the physiologically and anatomically relevant nonhuman primate (NHP) model. At the Tulane National Primate Research Center (TNPRC), approximately 5% of singly housed macaques develop symptoms of SIB. We have previously demonstrated that naltrexone hydrochloride can be effective in reducing SIB. We have also demonstrated that the astrocytes of animals with SIB are distinctly atrophic and display heightened innate immune activation compared with control animals. We have added a third group of animals (five macaques identified with SIB and treated with oral naltrexone at a dose of 3.2mg/kg) to the previous cohort (six macaques with a history of SIB but not treated, and nine animals with no history of SIB) for this study. Gray and white matter astrocytes from frontal cortical tissue were examined following necropsy. Innate immune activation of astrocytes, which was increased in SIB animals, was markedly decreased in animals receiving naltrexone, as was atrophy of both grey and white matter astrocytes. This was concomitant with improved behavioral correlates. Preventing astrocyte activation in select areas of the brain to reduce injurious behavior is an innovative concept with implications for mental health studies. Differences in multiple areas of primate brain would help determine how self-injurious behavior develops. These studies suggest a stronger role for astrocytes in the cellular events associated with self-injurious behaviors.

Community practice patterns for bacterial corneal ulcer evaluation and treatment.

OBJECTIVE: To examine current practice patterns in the management of bacterial keratitis among U.S. ophthalmologists and differences in the management and opinions between cornea specialists and non-cornea specialists. METHODS: A questionnaire was distributed to randomly selected ophthalmologists in July 2011 using an online survey system. It inquired about the number of patients with corneal ulcers seen monthly, frequency of Gram staining and culturing corneal ulcers, maintenance of diagnostic supplies, opinions on when culturing is necessary for corneal ulcers, treatment preferences for different severities of bacterial corneal ulcers, and opinions regarding relative efficacy of fourth-generation fluoroquinolones and fortified broad-spectrum antibiotics. RESULTS: One thousand seven hundred one surveys were distributed, and 486 (28.6%) surveys were returned. A minority of corneal ulcers was Gram stained (23.7%±34.1%, mean±SD) or cultured (35.1%±38.0%), but cornea specialists were more likely to perform both. The most popular antibiotic for the treatment of less severe ulcers was moxifloxacin (55.4%), and the most popular treatment of more severe ulcers was fortified broad-spectrum antibiotics (62.7%). Cornea specialists were significantly more likely than non-cornea specialists to prescribe fortified antibiotics for more severe corneal ulcers (78.1% vs. 53.7%, P<0.0001). A greater number of cornea specialists stated that fourth-generation fluoroquinolones were less effective than fortified antibiotics for the treatment of more severe corneal ulcers (79.6% of cornea specialists vs. 60.9% of non-cornea specialists, P<0.001). CONCLUSIONS: Cornea specialists and non-cornea specialists manage bacterial keratitis differently, with cornea specialists more likely to perform diagnostic testing and prescribe fortified broad-spectrum antibiotics for severe bacterial keratitis. Additional prospective studies demonstrating visual outcomes after differential treatment of bacterial keratitis are needed.

Form follows function: astrocyte morphology and immune dysfunction in SIV neuroAIDS.

Cortical function is disrupted in neuroinflammatory disorders, including HIV-associated neurocognitive disorders (HAND). Astrocyte dysfunction includes retraction of foot processes from the blood-brain barrier and decreased removal of neurotransmitters from synaptic clefts. Mechanisms of astrocyte activation, including innate immune function and the fine neuroanatomy of astrocytes, however, remain to be investigated. We quantified the number of glial fibrillary acidic protein (GFAP)-labeled astrocytes per square millimeter and the proportion of astrocytes immunopositive for Toll-like receptor 2 (TLR2) to examine innate immune activation in astrocytes. We also performed detailed morphometric analyses of gray and white matter astrocytes in the frontal and parietal lobes of rhesus macaques infected with simian immunodeficiency virus (SIV), both with and without encephalitis, an established model of AIDS neuropathogenesis. Protoplasmic astrocytes (gray matter) and fibrous astrocytes (deep white matter) were imaged, and morphometric features were analyzed using Neurolucida. Gray matter and white matter astrocytes showed no change in cell body size in animals infected with SIV regardless of encephalitic status. In SIV-infected macaques, both gray and white matter astrocytes had shorter, less ramified processes, resulting in decreased cell arbor compared with controls. SIV-infected macaques with encephalitis showed decreases in arbor length in white matter astrocytes and reduced complexity in gray matter astrocytes compared to controls. These results provide the first evidence that innate immune activation of astrocytes is linked to altered cortical astrocyte morphology in SIV/HIV infection. Here, we demonstrate that astrocyte remodeling is correlated with infection. Perturbed neuron-glia signaling may be a driving factor in the development of HAND.

Innate immune activation in the pathogenesis of a murine model of globoid cell leukodystrophy.

Globoid cell leukodystrophy is a lysosomal storage disease characterized by the loss of galactocerebrosidase. Galactocerebrosidase loss leads to the accumulation of psychosine and subsequent oligodendrocyte cell death, demyelination, macrophage recruitment, and astroglial activation and proliferation. To date, no studies have elucidated the mechanism of glial cell activation and cytokine and chemokine up-regulation and release. We explored a novel explanation for the development of the pathological changes in the early stages of globoid cell leukodystrophy associated with toll-like receptor (TLR) 2 up-regulation in the hindbrain and cerebellum as a response to dying oligodendrocytes. TLR2 up-regulation on microglia/macrophages coincided with morphological changes consistent with activation at 2 and 3 weeks of age. TLR2 up-regulation on activated microglia/macrophages resulted in astrocyte activation and marked up-regulation of cytokines/chemokines. Because oligodendrocyte cell death is an important feature of globoid cell leukodystrophy, we tested the ability of TLR2 reporter cells to respond to oligodendrocyte cell death. These reporter cells responded in vitro to medium conditioned by psychosine-treated oligodendrocytes, indicating the likelihood that oligodendrocytes release a TLR2 ligand during apoptosis. TLRs are a member of the innate immune system and initiate immune and inflammatory events; therefore, the identification of TLR2 as a potential driver in the activation of central nervous system glial activity in globoid cell leukodystrophy may provide important insight into its pathogenesis.

Aerosol-induced brucellosis increases TLR-2 expression and increased complexity in the microanatomy of astroglia in rhesus macaques.

Brucella melitensis, a bacterial pathogen and agent of epizootic abortion causes multiple pathologies in humans as well as a number of agriculturally important animal species. Clinical human brucellosis manifests as a non-specific, chronic debilitating disease characterized by undulant fever, arthropathies, cardiomyopathies and neurological sequelae. These symptoms can occur acutely for a few weeks or persist for months to years. Within the brain, endothelial and glial cells can be infected leading to downstream activation events including matrix metalloprotease (MMP) and cytokine secretion and Toll-like receptor (TLR) signaling. These events are likely to lead to tissue remodeling, including morphologic changes in neuronal and glial cells, which are linked to neurological complications including depressive behavior, immune activation and memory loss. Our hypothesis was that B. melitensis infection and neurobrucellosis would lead to activation of astrocytes through upregulation of TLR2 and stimulate concurrent changes in the microanatomy. All six animals were infected via inhalation route. TLR2 expression was approximately doubled in white matter astrocytes of infected rhesus macaques. There was also a 50% increase in the number of astrocytes per unit area in subcortical white matter tracts suggesting increased innate immune activation. This coincided with dramatic increases in the length and complexity of the cell arbor of hypertrophic astrocytes in both cortical gray and white matter. Thus, aerosol-induced brucellosis results in dramatically increased innate immune activation of astrocytes in the absence of widespread neuroinflammation.

Astrocyte atrophy and immune dysfunction in self-harming macaques.

BACKGROUND: Self-injurious behavior (SIB) is a complex condition that exhibits a spectrum of abnormal neuropsychological and locomotor behaviors. Mechanisms for neuropathogenesis could include irregular immune activation, host soluble factors, and astrocyte dysfunction. METHODS: We examined the role of astrocytes as modulators of immune function in macaques with SIB. We measured changes in astrocyte morphology and function. Paraffin sections of frontal cortices from rhesus macaques identified with SIB were stained for glial fibrillary acidic protein (GFAP) and Toll-like receptor 2 (TLR2). Morphologic features of astrocytes were determined using computer-assisted camera lucida. RESULTS: There was atrophy of white matter astrocyte cell bodies, decreased arbor length in both white and gray matter astrocytes, and decreased bifurcations and tips on astrocytes in animals with SIB. This was combined with a five-fold increase in the proportion of astrocytes immunopositive for TLR2. CONCLUSIONS: These results provide direct evidence that SIB induces immune activation of astrocytes concomitant with quantifiably different morphology.

Analisis de los movimientos oculares secuenciales rapidos ("saccades") durante la lectura: comparacion entre sujetos normales y dislexicos. / Analysis of sequential saccadic eye movement during the act of reading: comparison between normal and dyslexic subjects

Los ninos dislexicos tienen las siguientes alteraciones en los movimientos oculares la lectura: 1) Incremento en la duracion del tiempo total del barrido, 2) prolongacion de los periodos de latencia intermovimientos oculares rapidos, 3) dismetria de movimientos oculares rapidos, 4) aumento del numero de estos movimientos. Estas alteraciones las encontramos ante la presencia de movimientos oculares rapidos de busqueda, de seguimiento lento y de funcion vestibular normales. Las principales conclusiones son: a)Los movimientos oculares secuenciales rapidos son anormales en los ninos dislexicos; b) normalmente, los movimientos secuenciales rapidos de los ojos se preprograman en conjunto, en tanto que los ninos dislexicos los tienen que programar separadamente; c) no sabemos si estas alteraciones indiquen alteraciones motoras o perceptuales; d) El sitio de la alteracion se localiza probablemente en el lobulo frontal, y e) el analisis visual que realizan los ninos dislexicos es por letras, y no silabicamente como en los sujetos normales