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This study examined the associations between internalizing and externalizing symptoms during early adolescence and the subsequent development of Major Depressive Disorder. The role that temperament plays in predisposing individuals to these particular pathways was also examined. Temperament at approximately age 12 was used to produce a risk-enriched subsample of 243 (124 female) participants. Data was collected in four waves over 6-7 years roughly corresponding to ages 13, 15, 17 and 19. Participants were excluded from the study, prior to the first wave, based on current or prior depressive, substance-use, or eating disorders. Logistic regression analyses revealed that internalizing symptoms and social-externalizing problems were significant risk pathways to the development of depression. Moreover, mediation analyses revealed that high temperamental negative emotionality, high affiliation, low effortful control, and low surgency were significant vulnerability factors for depression via the internalizing symptom pathway, whereas low effortful control was the only significant predictor for depression via the social-externalizing problem pathway. As such, high levels of effortful control acted as a protective factor for the development of depression across both symptom pathways, suggesting that is may be an important target for prevention strategies.

Numerous barriers to clinic-based HIV testing exist (e.g., stigmatization) for African American youth. These barriers may be addressed by new technology, specifically HIV self-implemented testing (SIT). We conducted a series of formative phase 3 translation studies (49 face-to-face interviews, 9 focus groups, 1 advisory panel review) among low-income African American youth (15-19 years) and providers of adolescent services in two US cities to identify potential translation difficulties of the OraQuick SIT. Based on content analysis, we found that providers and African American youth viewed SITs positively compared to clinic-based testing. Data suggest that SITs may reduce social stigma and privacy concerns and increase convenience and normalization of HIV testing. Challenges with SIT implementation include difficulties accessing confirmatory testing, coping with adverse outcomes, and instructional materials that may be inappropriate for low socioeconomic status (SES) persons. Study results underscore the need for translation studies to identify specific comprehension and implementation problems African American youth may have with oral SITs.

Effective biological application of nanocrystalline semiconductor quantum dots continues to be hampered by the lack of easily implemented and widely applicable labeling chemistries. Here, we introduce two new orthogonal nanocrystal bioconjugation chemistries that overcome many of the labeling issues associated with currently utilized approaches. These chemistries specifically target either (1) the ubiquitous amines found on proteins or (2) thiols present in either antibody hinge regions or recombinantly introduced into other proteins to facilitate site-specific labeling. The amine chemistry incorporates aniline-catalyzed hydrazone bond formation, while the sulfhydryl chemistry utilizes nanocrystals displaying surface activated maleimide groups. Both reactive chemistries are rapidly implemented, yielding purified nanocrystal-protein bioconjugates in as little as 3 h. Following initial characterization of the nanocrystal materials, the wide applicability and strong multiplexing potential of these chemistries are demonstrated in an array of applications including immunoassays, immunolabeling in both cellular and tissue samples, in vivo cellular uptake, and flow cytometry. Side-by-side comparison of the immunolabeled cells suggested a functional equivalence between results generated with the amine and thiol-labeled antibody-nanocrystal bioconjugates in that format. Three-color labeling was achieved in the cellular uptake format, with no significant toxicity observed while simultaneous five-color labeling of different epitopes was demonstrated for the immunolabeled tissue sample. Novel labeling applications are also facilitated by these chemistries, as highlighted by the ability to directly label cellular membranes in adherent cell cultures with the thiol-reactive chemistry.

We examined the potential for increasing the reach of HIV testing to African American youths through the dissemination of oral-HIV testing. From 2012 through 2013 we examined the perceptions of alternatives to pharmacy dissemination of SITs in African American youths (5 focus groups) and service providers (4 focus groups), and conducted an ethnographic study of pharmacies (n = 10). Participants perceived significant advantages to delivering SITs through community health and services for adolescents (e.g., increased confidentiality, reduced stigma) over pharmacy dissemination. Given proper attention to fit, SIT dissemination could be facilitated through distribution by health and social service sites, and by improving elements of pharmacy dissemination.

Loss of arginase I (AI) results in a metabolic disorder characterized by growth retardation, increased mental impairment and spasticity, and potentially fatal hyperammonemia. This syndrome plus a growing body of evidence supports a role for arginase and arginine metabolites in normal neuronal development and function. Here we report our initial observations of the effects of AI loss on proliferation and differentiation of neural stem cells (NSCs) isolated from the germinal zones of embryonic and newborn AI knockout (KO) mice compared with heterozygous (HET) and wild-type (WT) control animals. By using both short and long-term proliferation assays (3 and 10 days, respectively), we found a 1.5–2-fold increase in the number of KO cells compared with WT. FACS analysis showed an increase in KO cells in the synthesis phase of the cell cycle vs. WT cells. After NSC differentiation, AI-deficient cells expressed β-tubulin, SMI81 (SNAP25), glial fibrillary acidic protein, and CNPase, which are markers consistent with neurons, astrocytes, and oligodendrocytes. Many KO cells exhibited a more mature morphology and expressed mature neuronal markers that were decreased or not present in HET or WT cells. Limited, comparative expression array and quantitative RT-PCR analysis identified differences in the levels of several mRNAs encoding structural, signaling, and arginine metabolism proteins between KO and WT cells. The consequence of these changes may contribute to the differential phenotypes of KO vs. WT cells. It appears that AI may play an important and unanticipated role in growth and development of NSCs. © 2006 Wiley-Liss, Inc.

During development of the CNS, neurons and glia are generated in a sequential manner. The mechanism underlying the later onset of gliogenesis is poorly understood, although the cytokine-induced Jak-STAT pathway has been postulated to regulate astrogliogenesis. Here, we report that the overall activity of Jak-STAT signaling is dynamically regulated in mouse cortical germinal zone during development. As such, activated STAT1/3 and STAT-mediated transcription are negligible at early, neurogenic stages, when neurogenic factors are highly expressed. At later, gliogenic periods, decreased expression of neurogenic factors causes robust elevation of STAT activity. Our data demonstrate a positive autoregulatory loop whereby STAT1/3 directly induces the expression of various components of the Jak-STAT pathway to strengthen STAT signaling and trigger astrogliogenesis. Forced activation of Jak-STAT signaling leads to precocious astrogliogenesis, and inhibition of this pathway blocks astrocyte differentiation. These observations suggest that autoregulation of the Jak-STAT pathway controls the onset of astrogliogenesis.

Neural stem cells (NSCs) were isolated from embryonic day 16 Sprague-Dawley rats and cultured in a novel serum-free stem cell medium that selected for the growth of NSCs and against the growth of GFAP(+) cells (astrocytes). NSCs maintained in culture for extended periods of time retained immunoreactivity for both nestin and PSA-NCAM, two markers characteristic of the stem cell phenotype. Moreover, using an oligodendrocyte (OL) specification medium, NSCs differentiated into OL as evidenced by their morphology and expression of multiple oligodendrocyte/myelin-specific markers. In addition, NSCs are capable of acquiring a neuronal phenotype as evidenced by expressing neuronal markers, such as neurofilament (NF) and NeuN when cultured in a defined medium for neurons indicating that these cells are also a good source of neuroblasts, which could be used to replace neuronal populations in the brain. We also showed successful propagation and differentiation of NSCs into OL after cryostorage, allowing for the later use of stored NSCs. The long-term goal of culturing NSCs and committed oligodendrocyte progenitors (OLP) is to obtain homogeneous populations for transplantation with the goal of remyelinating the myelin-deficient CNS. Our preliminary experiments carried out on normal and myelin deficient rats demonstrate that these cells survive and migrate extensively in both types of hosts. NSCs grafted as such, as well as cells derived from NSCs exposed to selective specification before grafting, are able to differentiate within the host brain. As expected, NSCs are capable of giving rise to astrocytes in a medium favoring this phenotype.

We analyzed the role of 4 genes, TCL-1, MTCP-1, TML-1 and ATM, in the early pathogenesis of T cell leukemia, with particular interest in the characteristics of long-standing non-leukemic clonal proliferations in ataxia-telangiectasia (A-T) patients. Five patients were studied: 4 patients had A-T (2 of whom had non-leukemic clonal proliferations [ATCP]), 1 had B cell lymphoma and 1 had T-ALL; a fifth patient with T-PLL did not have A-T. We measured the levels of expression for TCL-1, MTCP-1 and TML-1. TCL-1, not expressed in unstimulated mature T cells, was upregulated in the peripheral blood leukocytes (PBL) of the 2 A-T patients with ATCP. It was also expressed in the malignant cells of the A-T patient with B cell lymphoma and the T-PLL cells of the patient without A-T. In the same cells, MTCP-1 type A was expressed equally in all 5 patients, as well as in the controls; MTCP-1 type B transcripts were not observed. TML-1, also not expressed in unstimulated T cells, was expressed in the PBL of one A-T patient with ATCP and in the leukemic cells of the non-A-T T-PLL patient. These expression patterns were compared to cellular immunophenotypes. The non-leukemic clonal T cell populations had the characteristics of immature T cells. We conclude that TCL-1 and TML-1 play a role in cell proliferation and survival but are not pivotal genes in the progression to malignancy, even when the ATM gene is mutated. Additional genetic alterations must occur to initiate tumorigenesis. © 2001 Wiley-Liss, Inc.

Many issues in A-T research remain unresolved. However, certain common denominators are becoming clear that were not obvious just a few years ago, i.e., the relationship between double-strand break rejoining, radiosensitivity, and immunodeficiency. The downstream pathways that are activated by ATM phosphorylating p53, c-abl, chk2, Brca1, nibrin, RPA, and other proteins that contribute to cell-cycles checkpoints and DNA repair complexes, are helping to understand the cancer susceptibility of A-T patients, and perhaps of A-T heterozygotes. The identification and categorization of mutations in the ATM, NBS and Mre11 genes now allow more definitive diagnoses. Developmental studies are rapidly identifying early sites of pathogenesis that can perhaps be targeted for neural stem cell implantation therapy. If over-whelmed oxidative stress responses underlie the neurological degeneration of A-T patients, maintaining adequate therapeutic levels of free-radical scavengers, such as Vitamin E, alpha-lipoic acid, aspirin, and Coenzyme Q10, may be of some therapeutic benefit.

Cell loss within the central nervous system due to disease, trauma, or aging results in severe disability. Recent research indicates that proliferating populations of neural precursors are a promising source of cells for neural grafting and CNS repair. In our study, neural stem cells (NSCs) isolated from embryonic day (ED) 16 Sprague–Dawley rats were cultured in a novel serum-free stem cell medium that allowed their propagation for extended periods of time, retaining immunoreactivity for both nestin and PSA-NCAM, two markers characteristic of the stem cell phenotype. Alternatively, oligospheres were obtained from NSCs neurospheres by using a combination of an oligodendrocyte (OL) specification medium and the NSC medium. When neurospheres or oligospheres were plated as single spheres on poly-d-lysine and fed with OL specification medium their progenies gave rise to only OL progenitors that matured into MBP+ cells. Preliminary data from transplantation studies showed that when either neurospheres or oligospheres were grafted into the md rat brain cells survived and migrated extensively. Some of the neurosphere derived cells differentiated into NeuN+ cells. In contrast, oligosphere grafted into the md brain gave rise to transferrin, but not to GFAP or NeuN expressing cells. These results indicate that oligosphere derived cells only gave rise to OL progenitors, but not to neurons or astrocytes. Acknowledgements: NICHD #06576 and AT Foundation.

The ability of an AEF (axolemma-enriched fraction) to influence the proliferation, survival and differentiation of OPC (oligodendrocyte progenitor cells) was evaluated. Following addition of AEF to cultured OPC, the AEF associated with the outer surface of OPC so that subsequent metabolic events were likely mediated by direct AEF-OPC contact. Addition of AEF to the cultured OPC resulted in a dose- and time-dependent increase in proliferation that was partially dependent on Akt (protein kinase B) and MAPK (mitogen-activated protein kinase) activation. The major mitogen in an AEF-SE (soluble 2.0 M NaCl extract of the AEF) was identified as aFGF (acidic fibroblast growth factor) and accounted for 50% of the mitogenicity. The remaining 50% of the mitogenicity had properties consistent with bFGF (basic fibroblast growth factor) but was not unequivocally identified. Under conditions that limit the survival of OPC in culture, AEF treatment prolonged the survival of the OPC. Antigenic and morphological examination of the AEF-treated OPC indicated that the AEF treatment helped the OPC survive in a more immature state. The potential downstream metabolic pathways potentially activated in OPC by AEF and the consequences of these activated pathways are discussed. The results of these studies are consistent with the view that direct contact of axons with OPC stimulates their proliferation and survival while preventing their differentiation.

Much progress has been made in the early diagnosis of ataxia-telangiectasia since the gene was cloned in 1995. A clinical diagnosis can now be confirmed by radiosensitivity testing (colony survival assay), immunoblotting, and mutation detection. The diagnostic value of serum alpha-fetoprotein levels and radiosensitivity has been reevaluated using patients with diagnoses based on the presence of mutations in the ATM gene and the absence of ATM protein in nuclear extracts. Little progress has been made in treating the progressive ataxia.

Objectives: To utilize radiosensitivity testing to improve early diagnosis of patients with ataxia-telangiectasia (A-T). Study design: We established normal ranges for the colony survival assay (CSA) by testing cells from 104 patients with typical A-T, 29 phenotypic normal patients, and 19 A-T heterozygotes. We also analyzed 61 samples from patients suspected of having A-T and 25 patients with related disorders to compare the CSA with other criteria in the diagnosis of A-T. Results: When cells were irradiated with 1.0 Gy, the mean survival fraction (μSF ± 1 SD) for patients with A-T was 13.1% ± 7.2% compared with 50.1% ± 13.5% for healthy control patients. These data served to define a diagnostic range for the CSA (ie, 36%), and a nondiagnostic intermediate range of 21% to 36%. The mutations of patients with A-T with intermediate radiosensitivity tended to cluster around the functional domains of the ATM gene. Conclusions: The CSA is a useful adjunctive test for confirming an early clinical diagnosis of A-T. However, CSA is also abnormal in other chromosomal instability and immunodeficiency disorders. (J Pediatr 2002;140:724-31)

We analyzed the role of 4 genes, TCL-1, MTCP-1, TML-1 and ATM, in the early pathogenesis of T cell leukemia, with particular interest in the characteristics of long-standing non-leukemic clonal proliferations in ataxia-telangiectasia (A-T) patients. Five patients were studied: 4 patients had A-T (2 of whom had non-leukemic clonal proliferations [ATCP]), 1 had B cell lymphoma and 1 had T-ALL; a fifth patient with T-PLL did not have A-T. We measured the levels of expression for TCL-1, MTCP-1 and TML-1. TCL-1, not expressed in unstimulated mature T cells, was upregulated in the peripheral blood leukocytes (PBL) of the 2 A-T patients with ATCP. It was also expressed in the malignant cells of the A-T patient with B cell lymphoma and the T-PLL cells of the patient without A-T. In the same cells, MTCP-1 type A was expressed equally in all 5 patients, as well as in the controls; MTCP-1 type B transcripts were not observed. TML-1, also not expressed in unstimulated T cells, was expressed in the PBL of one A-T patient with ATCP and in the leukemic cells of the non-A-T T-PLL patient. These expression patterns were compared to cellular immunophenotypes. The non-leukemic clonal T cell populations had the characteristics of immature T cells. We conclude that TCL-1 and TML-1 play a role in cell proliferation and survival but are not pivotal genes in the progression to malignancy, even when the ATM gene is mutated. Additional genetic alterations must occur to initiate tumorigenesis.

Previous studies on a limited number of ataxia-telangiectasia (A-T) patients with detectable levels of intracellular ATM protein have suggested a genotype/phenotype correlation. We sought to elucidate this possible correlation by comparing ATM protein levels with mutation types, radiosensitivity, and clinical phenotype. In this study, Western blot analysis was used to measure ATM protein in lysates of lymphoblastoid cell lines (LCLs) from 123 unrelated A-T patients, 10 A-T heterozygotes, and 10 patients with phenotypes similar to A-T. Our Western blot protocol can detect the presence of ATM protein in as little as 1 microg of total protein; at least 25 microg of protein was tested for each individual. ATM protein was absent in 105 of the 123 patients (85%); most of these patients had truncating mutations. The remaining subset of 18 patients (15%) had reduced levels of normal-sized ATM protein; missense mutations were more common in this subset. We used a colony survival assay to characterize the phenotypic response of the LCLs to radiation exposure; patients with or without detectable ATM protein were typically radiosensitive. Nine of 10 A-T heterozygotes also had reduced expression of ATM, indicating that both alleles contribute to ATM protein production. These data suggest that although ATM-specific mRNA is abundant in A-T cells, the abnormal ATM protein is unstable and is quickly targeted for degradation. We found little correlation between level of ATM protein and the type of underlying mutation, the clinical phenotype, or the radiophenotype.

SummaryMutations resulting in defective splicing constitute a significant proportion (30/62 [48%]) of a new series of mutations in the ATM gene in patients with ataxia-telangiectasia (AT) that were detected by the protein-truncation assay followed by sequence analysis of genomic DNA. Fewer than half of the splicing mutations involved the canonical AG splice-acceptor site or GT splice-donor site. A higher percentage of mutations occurred at less stringently conserved sites, including silent mutations of the last nucleotide of exons, mutations in nucleotides other than the conserved AG and GT in the consensus splice sites, and creation of splice-acceptor or splice-donor sites in either introns or exons. These splicing mutations led to a variety of consequences, including exon skipping and, to a lesser degree, intron retention, activation of cryptic splice sites, or creation of new splice sites. In addition, 5 of 12 nonsense mutations and 1 missense mutation were associated with deletion in the cDNA of the exons in which the mutations occurred. No ATM protein was detected by western blotting in any AT cell line in which splicing mutations were identified. Several cases of exon skipping in both normal controls and patients for whom no underlying defect could be found in genomic DNA were also observed, suggesting caution in the interpretation of exon deletions observed in ATM cDNA when there is no accompanying identification of genomic mutations.