Astrocytes have in recent years become the focus of intense experimental interest, yet markers for their definitive identification remain both scarce and imperfect. Astrocytes may be recognized as ...such by their expression of glial fibrillary acidic protein, glutamine synthetase, glutamate transporter 1 (GLT1), aquaporin-4, aldehyde dehydrogenase 1 family member L1, and other proteins. However, these proteins may all be regulated both developmentally and functionally, restricting their utility. To identify a nuclear marker pathognomonic of astrocytic phenotype, we assessed differential RNA expression by FACS-purified adult astrocytes and, on that basis, evaluated the expression of the transcription factor SOX9 in both mouse and human brain. We found that SOX9 is almost exclusively expressed by astrocytes in the adult brain except for ependymal cells and in the neurogenic regions, where SOX9 is also expressed by neural progenitor cells. Transcriptome comparisons of SOX9+ cells with GLT1+ cells showed that the two populations of cells exhibit largely overlapping gene expression. Expression of SOX9 did not decrease during aging and was instead upregulated by reactive astrocytes in a number of settings, including a murine model of amyotrophic lateral sclerosis (SOD1G93A), middle cerebral artery occlusion, and multiple mini-strokes. We quantified the relative number of astrocytes using the isotropic fractionator technique in combination with SOX9 immunolabeling. The analysis showed that SOX9+ astrocytes constitute ∼10-20% of the total cell number in most CNS regions, a smaller fraction of total cell number than previously estimated in the normal adult brain.
Astrocytes are traditionally identified immunohistochemically by antibodies that target cell-specific antigens in the cytosol or plasma membrane. We show here that SOX9 is an astrocyte-specific nuclear marker in all major areas of the CNS outside of the neurogenic regions. Based on SOX9 immunolabeling, we document that astrocytes constitute a smaller fraction of total cell number than previously estimated in the normal adult mouse brain.
The childhood leukodystrophies comprise a group of hereditary disorders characterized by the absence, malformation or destruction of myelin. These disorders share common clinical, radiological and ...pathological features, despite their diverse molecular and genetic etiologies. Oligodendrocytes and astrocytes are the major affected cell populations, and are either structurally impaired or metabolically compromised through cell-intrinsic pathology, or are the victims of mis-accumulated toxic byproducts of metabolic derangement. In either case, glial cell replacement using implanted tissue or pluripotent stem cell-derived human neural or glial progenitor cells may comprise a promising strategy for both structural remyelination and metabolic rescue. A broad variety of pediatric white matter disorders, including the primary hypomyelinating disorders, the lysosomal storage disorders, and the broader group of non-lysosomal metabolic leukodystrophies, may all be appropriate candidates for glial progenitor cell-based treatment. Nonetheless, a variety of specific challenges remain before this therapeutic strategy can be applied to children. These include timely diagnosis, before irreparable neuronal injury has ensued; understanding the natural history of the targeted disease; defining the optimal cell phenotype for each disorder; achieving safe and scalable cellular compositions; designing age-appropriate controlled clinical trials; and for autologous therapy of genetic disorders, achieving the safe genetic editing of pluripotent stem cells. Yet these challenges notwithstanding, the promise of glial progenitor cell-based treatment of the childhood myelin disorders offers hope to the many victims of this otherwise largely untreatable class of disease.
Pelizaeus-Merzbacher disease (PMD) is an X-linked disorder caused by mutations in the PLP1 gene, which encodes the proteolipid protein of myelinating oligodendroglia. PMD exhibits phenotypic ...variability that reflects its considerable genotypic heterogeneity, but all forms of the disease result in central hypomyelination associated with early neurologic dysfunction, progressive deterioration, and ultimately death. PMD has been classified into three major subtypes, according to the age of presentation: connatal PMD, classic PMD, and transitional PMD, combining features of both connatal and classic forms. Two other less severe phenotypes were subsequently described, including the spastic paraplegia syndrome and PLP1-null disease. These disorders may be associated with duplications, as well as with point, missense, and null mutations within the PLP1 gene. A number of clinically similar Pelizaeus-Merzbacher-like disorders (PMLD) are considered in the differential diagnosis of PMD, the most prominent of which is PMLD-1, caused by misexpression of the GJC2 gene encoding connexin-47. No effective therapy for PMD exists. Yet, as a relatively pure central nervous system hypomyelinating disorder, with limited involvement of the peripheral nervous system and little attendant neuronal pathology, PMD is an attractive therapeutic target for neural stem cell and glial progenitor cell transplantation, efforts at which are now underway in a number of centers internationally.
Pelizaeus-Merzbacher disease (PMD) is an X-linked disorder caused by mutation in the proteolipid protein-1 (PLP1) gene, which encodes the proteolipid protein of myelinating oligodendroglia. PMD ...exhibits phenotypic variability that reflects its considerable genotypic heterogeneity, but all forms of the disease result in central hypomyelination, associated in most cases with early neurological dysfunction, progressive deterioration, and ultimately death. PMD may present as a connatal, classic and transitional forms, or as the less severe spastic paraplegia type 2 and PLP-null phenotypes. These disorders are most often associated with duplications of the PLP1 gene, but can also be caused by coding and noncoding point mutations as well as full or partial deletion of the gene. A number of genetically-distinct but phenotypically-similar disorders of hypomyelination exist which, like PMD, lack any effective therapy. Yet as relatively pure CNS hypomyelinating disorders, with limited involvement of the PNS and relatively little attendant neuronal pathology, PMD and similar hypomyelinating disorders are attractive therapeutic targets for neural stem cell and glial progenitor cell transplantation, efforts at which are now underway in a number of research centers. Stem Cells 2017;35:311-315.
Abstract We report on tacrolimus-associated posterior reversible encephalopathy syndrome with the previously unreported finding of leptomeningeal enhancement occurring separate from the site of ...parenchymal magnetic resonance signal abnormality. Recognition of this atypical finding as a noninfectious cause of leptomeningeal enhancement may assist those caring for patients affected by posterior reversible encephalopathy syndrome.
Data regarding the pupillary responses in very premature neonates is scarce; what data exist, moreover, is not recent. The purpose of this pilot study is to collect data on direct and consensual ...pupillary light responses before 30 weeks postmenstrual age. Six neonates were studied. Mean pupillary size at rest was 3.6 ± 0.4 mm. No direct or consensual responses to light were present in any of 12 eyes. Accurate information about pupillary reflexes in very premature neonates provides relevant information about the development of the visual and neurologic systems. Available information about the development of the Edinger-Westphal nucleus, sphincter pupillary muscle, optic nerve myelinization, and autonomic nervous system is briefly reviewed.
Highlights • Astrocytes facilitate myelination. • Dysfunctional astrocytes may lead to myelin pathologies. • Astrocytes might be required for efficient remyelination in demyelinating diseases.
Abstract
HIV remains a major cause of morbidity and mortality for people living in many low-income countries. With an HIV prevalence of 12.4% among people aged over 15 years, Mozambique was ranked in ...2019 as one of eight countries with the highest HIV rates in the world. We analyzed routinely collected data from electronical medical records in HIV-infected patients aged 15 years or older and enrolled at Carmelo Hospital of Chokwe in Chokwe from 2002 to 2019. Attrition was defined as individuals who were either reported dead or lost to follow-up (LTFU) (≥ 90 days since the last clinic visit with missed medical pick-up after 3 days of failed calls). Kaplan–Meier survival curves and Cox regression analyses were used to model the incidence and predictors of time to attrition. From January 2002 to December 2019, 16,321 patients were enrolled on antiretroviral therapy (ART): 59.2% were women, and 37.9% were aged 25–34 years old. At the time of the analysis, 7279 (44.6%) were active and on ART. Overall, the 16,321 adults on ART contributed a total of 72,987 person-years of observation. The overall attrition rate was 9.46 per 100 person-years. Cox regression showed a higher risk of attrition in those following an inpatient regimen (hazard ratio HR 3.18, 95% confidence interval CI 2.89–3.50;
p
< 0.001), having CD4 counts under 50 cells/µL (HR 1.91, 95% CI 1.63–2.24,
p
< 0.001), receiving anti-TB treatment within 90 days of ART initiation (HR 6.53, 95% CI 5.72–7.45;
p
< 0.001), classified as WHO clinical stage III (HR 3.75, 95% CI 3.21–4.37;
p
< 0.001), and having Kaposi’s sarcoma (HR 1.99, 95% CI 1.65–2.39,
p
< 0.001). Kaplan–Meier analysis showed that patients with CD4 counts of less than 50 cells/µL on ART initiation had a 40% lower chance of survival at 18 years. Low CD4 cell counts, ART initiation as an inpatient, WHO clinical stage III, and anti-tuberculosis treatment within 90 days of ART initiation were strongly associated with attrition. Strengthening HIV testing and ART treatment, improving the diagnosis of tuberculosis before ART initiation, and guaranteed psychosocial support systems are the best tools to reduce patient attrition after starting ART.
Crude olive pomace oil (OPO) is a by-product of olive oil extraction. In this study, low-calorie structured triacylglycerols (TAGs) were produced by acidolysis of crude OPO with medium-chain fatty ...acids (caprylic, C8:0; capric, C10:0) or interesterification with their ethyl ester forms (C8EE, C10EE). These new TAGs present long-chain fatty acids (L) at position
-2 and medium-chain fatty acids (M) at positions
-1,3 (MLM). Crude OPO exhibited a high acidity (12.05-28.75% free fatty acids), and high contents of chlorophylls and oxidation products. Reactions were carried out continuously in a packed-bed bioreactor for 70 h, using
-1,3 regioselective commercial immobilized lipases (
lipase, Lipozyme TL IM; and
lipase, Lipozyme RM IM), in solvent-free media at 40 °C. Lipozyme RM IM presented a higher affinity for C10:0 and C10EE. Lipozyme TL IM preferred C10:0 over C8:0 but C8EE over C10EE. Both biocatalysts showed a high activity and operational stability and were not affected by OPO acidity. The New TAG yields ranged 30-60 and the specific productivity ranged 0.96-1.87 g NewTAG/h.g biocatalyst. Lipozyme RM IM cost is more than seven-fold the Lipozyme TL IM cost. Therefore, using Lipozyme TL IM and crude acidic OPO in a continuous bioreactor will contribute to process sustainability for structured lipid production by lowering the cost of the biocatalyst and avoiding oil refining.
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