Inheritance, Biochemical Abnormalities, and Clinical Features of Feline Mucolipidosis II: The First Animal Model of Human I-Cell Disease

Mucolipidosis II (ML II), also called I-cell disease, is a unique lysosomal storage disease caused by deficient activity of the enzyme N-acetylglucosamine-1-phosphotransferase, which leads to a failure to internalize enzymes into lysosomes. We report on a colony of domestic shorthair cats with ML II that was established from a half-sibling male of an affected cat. Ten male and 9 female kittens out of 89 kittens in 26 litters born to clinically normal parents were affected; this is consistent with an autosomal recessive mode of inheritance. The activities of three lysosomal enzymes from affected kittens, compared to normal adult control cats, were high in serum (11-73 times normal) but low in cultured fibroblasts (9-56% of normal range) that contained inclusion bodies (I-cells), reflecting the unique enzyme defect in ML II. Serum lysosomal enzyme activities of adult obligate carriers were intermediate between normal and affected values. Clinical features in affected kittens were observed from birth and included failure to thrive, behavioral dullness, facial dysmorphia, and ataxia. Radiographic lesions included metaphyseal flaring, radial bowing, joint laxity, and vertebral fusion. In contrast to human ML II, diffuse retinal degeneration leading to blindness by 4 months of age was seen in affected kittens. All clinical signs were progressive and euthanasia or death invariably occurred within the first few days to 7 months of life, often due to upper respiratory disease or cardiac failure. The clinical and radiographic features, lysosomal enzyme activities, and mode of inheritance are homologous with ML II in humans. Feline ML II is currently the only animal model in which to study the pathogenesis of and therapeutic interventions for this unique storage diseas

Bone Marrow Transplantation for Feline Mucopolysaccharidosis I

Severe mucopolysaccharidosis type I (MPS I) is a fatal neuropathic lysosomal storage disorder with significant skeletal involvement. Treatment involves bone marrow transplantation (BMT), and although effective, is suboptimal, due to treatment sequelae and residual disease. Improved approaches will need to be tested in animal models and compared to BMT. Herein we report on bone marrow transplantation to treat feline mucopolysaccharidosis I (MPS I). Five MPS I stably engrafted kittens, transplanted with unfractionated bone marrow (6.3 × 107–1.1 × 109 nucleated bone marrow cells per kilogram) were monitored for 13–37 months post-engraftment. The tissue total glycosaminoglycan (GAG) content was reduced to normal levels in liver, spleen, kidney, heart muscle, lung, and thyroid. Aorta GAG content was between normal and affected levels. Treated cats had a significant decrease in the brain GAG levels relative to untreated MPS I cats and a paradoxical decrease relative to normal cats. The α-l-iduronidase (IDUA) activity in the livers and spleens of transplanted MPS I cats approached heterozygote levels. In kidney cortex, aorta, heart muscle, and cerebrum, there were decreases in GAG without significant increases in detectable IDUA activity. Treated animals had improved mobility and decreased radiographic signs of disease. However, significant pathology remained, especially in the cervical spine. Corneal clouding appeared improved in some animals. Immunohistochemical and biochemical analysis documented decreased central nervous system ganglioside storage. This large animal MPS I study will serve as a benchmark of future therapies designed to improve on BMT

Critical bilingual leadership: liderazgo for emergent bilingual Latin@ students

The growing “Latinization” of the Unites States (U.S.) is changing the demographics of students served in schools (Irizarry, 2011). Amidst these changes of the cultural, racial, and linguistic identities of students in U.S. schools standardized approaches to school policies, structures, and practices across the country tend to privilege the experiences and opportunities of monolingual White students while marginalizing the experiences of emergent bilingual students and students of color. This case study dissertation explores Critical Bilingual Leadership (i.e. Liderazgo) as a framework to examine how the leadership of a principal and broader school community in a PK-8 public school in the Midwest foster culturally and linguistically responsive bilingual schooling for EBLS. In this school, liderazgo was operationalized across the following themes: dual language programming as the foundation for equity-oriented schooling; the experiential knowledge of the school community was viewed as a strength; relationships were fostered through cariño y confianza, and instructional bilingual leadership was shared and distributed in unique ways. Students, families, and staff members viewed dual language programming as the lens in which they challenged traditional structures of subtractive schooling (Valenzuela, 1999). Additionally, this school community valued and incorporated the linguistic and cultural identities of families and communities as strengths through hiring practices, family engagement initiatives, and through innovative opportunities to be part of the leadership structures. Additionally, relationships were fostered across the entire community through cariño y confianza, which led to open, honest, and caring relationships across all members of the community. In particular, the relationships were strengthened through the formal and informal opportunities to lead the school forward in a variety of ways, most notably through instructional bilingual leadership opportunities. While this school community was excelling in their approach to provide culturally and linguistically responsive education for EBLS, they were simultaneously working against themselves in attempting to adhere to the monolingual and standardized accountability measures of the local, state, and federal policy context. Even though the school is succeeding in a variety of measures, they are still being held accountable to the rigid measures of No Child Left Behind (NCLB), Race to the Top, and other district policies that do not reflect the linguistic and cultural strengths and needs of their community. Here, I argue that while liderazgo can foster the culturally and linguistically responsive school communities that our students and families deserve, critical bilingual leaders, schools, and the systems of educational policy at the district, state, and federal level must also seek new ways to hold schools accountable by redefining the measures for school success with EBLS

The role of cyclic AMP in oligodendrocyte differentiation

Adenosine 3′,5′-cyclic monophosphate (cAMP) accelerates the rate of oligodendrocyte differentiation in primary glial cell cultures, while inhibiting proliferation among precursors. It has been unclear whether cAMP regulates differentiation of oligodendrocytes in the absence of experimental manipulation, nor have biological ligands been identified that regulate oligodendroglia via cAMP. Finally, little is known about the expression and regulation of the enzymes that synthesize and degrade cAMP in oligodendroglia. To address these issues, we developed a novel immunohistochemical technique to visualize cAMP within single cells. As oligodendrocytes underwent endogenous differentiation in cell culture, basal cAMP levels remained uniformly low. No consistent pattern was detected between basal cAMP levels and oligodendroglial developmental stages, suggesting that differentiation is not initiated by substantial changes in basal cAMP. However, oligodendroglia did require basal cAMP signaling for normal morphological differentiation to occur: in the absence of cAMP-dependent protein kinase activity, cells expressed antigenic markers of differentiation, but did not extend elaborate processes, a hallmark of oligodendrocyte differentiation. The biological agonists calcitonin, corticotropin releasing hormone, and vasoactive intestinal peptide elicited cAMP production within oligodendroglia. Prostanoids and β-adrenergic agonists, which have previously been reported to elevate cAMP in oligodendroglia, did not increase cAMP immunofluorescence in oligodendroglia, though they stimulated non-oligodendroglial cells robustly. Cyclic AMP phosphodiesterase (PDE) activity was shown to play an important role in regulating cAMP in oligodendrocytes. Isobutylmethylxanthine, a broad-spectrum inhibitor of most PDE types, vinpocetine, a specific inhibitor of the PDE1 family, and rolipram, a specific inhibitor of the PDE4 family, inhibited PDE activity in oligodendroglia. Western blot analysis and immunofluorescence staining with subtype-specific antibodies confirmed the presence of PDE4 isoforms in oligodendroglia. cAMP regulates diverse developmental processes in oligodendroglia, and is itself precisely controlled. These studies are the first to directly demonstrate that cAMP levels are regulated in oligodendroglia by biological agonists. Additionally, they reveal a novel regulatory role for cAMP in oligodendrocyte process extension. The significant contribution PDE to the regulation of intracellular cAMP levels, which has received little study in oligodendroglia, is emphasized by our findings

The role of cyclic AMP in oligodendrocyte differentiation

Adenosine 3′,5′-cyclic monophosphate (cAMP) accelerates the rate of oligodendrocyte differentiation in primary glial cell cultures, while inhibiting proliferation among precursors. It has been unclear whether cAMP regulates differentiation of oligodendrocytes in the absence of experimental manipulation, nor have biological ligands been identified that regulate oligodendroglia via cAMP. Finally, little is known about the expression and regulation of the enzymes that synthesize and degrade cAMP in oligodendroglia. To address these issues, we developed a novel immunohistochemical technique to visualize cAMP within single cells. As oligodendrocytes underwent endogenous differentiation in cell culture, basal cAMP levels remained uniformly low. No consistent pattern was detected between basal cAMP levels and oligodendroglial developmental stages, suggesting that differentiation is not initiated by substantial changes in basal cAMP. However, oligodendroglia did require basal cAMP signaling for normal morphological differentiation to occur: in the absence of cAMP-dependent protein kinase activity, cells expressed antigenic markers of differentiation, but did not extend elaborate processes, a hallmark of oligodendrocyte differentiation. The biological agonists calcitonin, corticotropin releasing hormone, and vasoactive intestinal peptide elicited cAMP production within oligodendroglia. Prostanoids and β-adrenergic agonists, which have previously been reported to elevate cAMP in oligodendroglia, did not increase cAMP immunofluorescence in oligodendroglia, though they stimulated non-oligodendroglial cells robustly. Cyclic AMP phosphodiesterase (PDE) activity was shown to play an important role in regulating cAMP in oligodendrocytes. Isobutylmethylxanthine, a broad-spectrum inhibitor of most PDE types, vinpocetine, a specific inhibitor of the PDE1 family, and rolipram, a specific inhibitor of the PDE4 family, inhibited PDE activity in oligodendroglia. Western blot analysis and immunofluorescence staining with subtype-specific antibodies confirmed the presence of PDE4 isoforms in oligodendroglia. cAMP regulates diverse developmental processes in oligodendroglia, and is itself precisely controlled. These studies are the first to directly demonstrate that cAMP levels are regulated in oligodendroglia by biological agonists. Additionally, they reveal a novel regulatory role for cAMP in oligodendrocyte process extension. The significant contribution PDE to the regulation of intracellular cAMP levels, which has received little study in oligodendroglia, is emphasized by our findings

Challenging the Dominant Narrative: Critical Bilingual Leadership (Liderazgo) for Emergent Bilingual Latin@ Students

The growing “Latinization” of the United States is drastically changing the demographics of the students served in PK-12 public schools (Irizarry, 2011). To understand how educational leaders can best serve this changing student demographic, we use Critical Bilingual Leadership, i.e. Liderazgo, to interrogate institutional and structural racism through the use of the testimonios of members of a school community that aim to create a culturally and linguistically responsive school. We found that liderazgo was operationalized across the following themes: dual language programming as the foundation for equity; drawing on experiential knowledge as a strength; fostering relationships through transcaring; and instructional bilingual leadership.  &nbsp

Maternal Control of Development at the Midblastula Transition and beyond : Mutants from the Zebrafish II

Many maternal factors in the oocyte persist in the embryo. They are required to initiate zygotic transcription but also function beyond this stage, where they interact with zygotic gene products during embryonic development. In a four-generation screen in the zebrafish, we identified 47 maternal-effect and five paternal-effect mutants that manifest their phenotypes at the time of, or after, zygotic genome activation. We propagated a subset of 13 mutations that cause developmental arrest at the midblastula transition, defects in cell viability, embryonic morphogenesis, and establishment of the embryonic body plan. This diverse group of mutants, many not previously observed in vertebrates, demonstrates a substantial maternal contribution to the “zygotic” period of embryogenesis and a surprising degree of paternal control. These mutants provide powerful tools to dissect the maternal and paternal control of vertebrate embryogenesi

Maternal Control of Vertebrate Development before the Midblastula Transition : Mutants from the Zebrafish I

Maternal factors control development prior to the activation of the embryonic genome. In vertebrates, little is known about the molecular mechanisms by which maternal factors regulate embryonic development. To understand the processes controlled by maternal factors and identify key genes involved, we embarked on a maternal-effect mutant screen in the zebrafish. We identified 68 maternal-effect mutants. Here we describe 15 mutations in genes controlling processes prior to the midblastula transition, including egg development, blastodisc formation, embryonic polarity, initiation of cell cleavage, and cell division. These mutants exhibit phenotypes not previously observed in zygotic mutant screens. This collection of maternal-effect mutants provides the basis for a molecular genetic analysis of the maternal control of embryogenesis in vertebrate