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C Stivers

Publications and source records attributed to C Stivers.

12 recordsLinked to original sources
PubMed2001

A search for Drosophila neural precursor genes identifies ran.

The Drosophila ran gene has been isolated in a differential cDNA screen designed to identify genes that are dynamically expressed in embryonic neuroblasts. The guanine triphosphate (GTP)-binding Ran protein, a member of the Ras superfamily, has been shown to participate in a variety of transport related processes in other organisms. Drosophila ran codes for a 216 amino acid (aa) protein that shares 78% and 86% identity with the yeast and human Ran proteins, respectively. Database searches have identified a second Drosophila ran gene, ran-like. The predicted Ran-like protein shares 59% identity with its isoform. Embryo in situ mRNA localization of ran and ran-like expression reveals that both are maternally expressed; however zygotic ran expression is restricted to central nervous system (CNS) neuroblasts undergoing late lineage formation, while ran-like expression is detected in the developing trachea and salivary gland. To investigate the significance of ran-restricted CNS expression, we have targeted its misexpression to different temporal windows of CNS development. In addition, a dominant-negative mutant form of ran was targeted to the developing CNS and to the larval eye/antenna imaginal disc to assess the role of ran-dependent functions. Embryonic CNS misexpression of the mutant, but not wild-type, ran results in larval death. Neither wild-type nor mutant ran misexpression had any detectable effect on embryonic CNS lineage specification, nuclear transport of a number of CNS-specific transcription factors or axonal guidance. However, expression of the dominant-negative mutant ran in the developing eye/antenna disc did result in a severe adult eye phenotype marked by apoptosis of photoreceptor, cone and pigment cells.

Amino Acid Sequence↗
PubMed2000

Erratum

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Journal Article↗
PubMed2000

N-methyl-D-aspartate receptor subunit NR2B is widely expressed throughout the rat diencephalon: an immunohistochemical study.

Glutamate (Glu), a major excitatory neurotransmitter within the hypothalamus and thalamus, acts upon many receptors, including the N-methyl-D-aspartate (NMDA) subtype. Abundant evidence suggests that variations in the subunit composition of NMDA receptors (NMDA-Rs) contribute to differences in Glu's immediate electrophysiological effects as well as to the patterns of signal transduction cascades it triggers to mediate long-term changes in neuronal function. We have previously shown that hypothalamic NMDA-Rs containing the NR2B subunit may be involved in the control of eating as well as in the mediation of physiological responses to osmotic stimuli. To broaden our understanding of diencephalic NMDA-R participation in other functions, we localized the NR2B subunit in the diencephalon of the adult male rat using immunoperoxidase, immunogold, and immunofluorescence techniques and an affinity-purified polyclonal antibody specific for the NR2B subunit of the NMDA-R. In addition, we used a monoclonal NR2B antibody with immunoperoxidase detection to confirm the NR2B distribution seen with the polyclonal antibody. In the hypothalamus, the highest levels of NR2B immunoreactivity (-ir) were found in the magnocellular neurosecretory system, including the paraventricular and supraoptic nuclei. A new finding was that intense NR2B-ir was present within perivascular "accessory" magnocellular groups of this system, including the nucleus circularis, anterior fornical nucleus, and scattered clusters of lateral hypothalamic cells apposed to blood vessels. Robust NR2B-ir was also present within the arcuate nucleus, the median eminence, and the tuberal nucleus, and light immunostaining was found in all other hypothalamic nuclei examined. In the thalamus, the highest NR2B-ir was observed in the medial habenula and the anterodorsal, paraventricular, rhomboid, reticular, and dorsal lateral geniculate nuclei. As in the hypothalamus, all thalamic nuclei examined displayed at least light immunostaining for this subunit. Control sections, including those incubated with the polyclonal NR2B antibody preadsorbed with its fusion protein, were virtually devoid of immunostaining. This demonstration that the NR2B subunit of the NMDA-R is widely distributed in the diencephalon, implicates it in a wide variety of functions, and provides a useful anatomical framework for establishing a comprehensive map of Glu receptor populations within this major subdivision of the brain.

Animals↗
PubMed2000

Immunolabeling reveals cellular localization of the N-methyl-D-aspartate receptor subunit NR2B in neurosecretory cells but not astrocytes of the rat magnocellular nuclei.

Previous studies suggest that activation of N-methyl-D-aspartate (NMDA) receptors facilitates phasic firing and spike clustering displayed by magnocellular neuroendocrine cells (MNCs) of the supraoptic (SON) and paraventricular nucleus of the hypothalamus (PVN). Osmotic stimulation produces similar activity patterns which, in turn, can lead to enhanced release of vasopressin and oxytocin from MNCs. Our laboratory has shown that dehydration regulates the expression of the NMDA receptor subunits, NR1 and NR2B, in the SON and PVN, suggesting their involvement in osmoregulation. In the present study, we examined the cellular localization of NR2B, one of the glutamate-binding subunits of the NMDA receptor, with an NR2B-specific antibody. Using double-label immunohistochemistry and three different detection methods with metallic, peroxidase, and fluorescence markers, it was found that both vasopressin and oxytocin-producing MNC populations synthesize NR2B. The incidence of NR2B colocalization with vasopressin-neurophysin in the SON and lateral magnocellular PVN (PVL) was 0.95 and 0.91, respectively. For oxytocin-neurophysin, the corresponding values were 0.97 and 0.95, respectively. Furthermore, the extent of colocalization in MNCs of the SON, PVL, retrochiasmatic SON, and accessory neurosecretory nuclei was similar. Astrocytes associated with the SON, and identified with antibodies targeting glial fibrillary acidic protein (GFAP) or vimentin, were not colabeled with NR2B. Our results demonstrate that NR2B protein is expressed by almost all MNCs and that it is equally prevalent in vasopressinergic and oxytocinergic populations of various magnocellular neuroendocrine nuclei supporting a role of NMDA receptors in MNC-mediated neurosecretory processes. Although NR2B may form part of functional NMDA receptors on MNCs, it is probably not present on astrocytes associated with nearby MNCs.

Animals↗
PubMed2000

Nerfin-1 and -2, novel Drosophila Zn-finger transcription factor genes expressed in the developing nervous system.

To gain insight into the regulatory networks controlling Drosophila neural-identity decisions, we have identified new neuronal precursor genes by performing an in situ hybridization screen of differentially selected embryonic head cDNAs. Here, we describe the molecular characteristics and expression profile of nerfin-1, a novel pan-neural precursor gene. This paper also documents the embryonic expression of another structurally related gene, nerfin-2. During early CNS development, nerfin-1 gene expression is activated in neuroblasts (NBs) prior to lineage formation. However, after early sublineage development, nerfin-1 expression shifts from NBs to ganglion mother cells (GMCs) but is not expressed in neurons or glia. Differing from nerfin-1, nerfin-2 is expressed only in a subset of brain neurons. Possessing a conserved putative DNA-binding domain, the predicted Nerfin-1 and -2 proteins belong to a subfamily of Zn-finger transcription factors with cognates identified in nematode, mouse and man.

Amino Acid Sequence↗
PubMed1998

Regulation of POU genes by castor and hunchback establishes layered compartments in the Drosophila CNS.

POU transcription factors participate in cell-identity decisions during nervous system development, yet little is known about the regulatory networks controlling their expression. We report all known Drosophila POU genes require castor (cas) for correct CNS expression. drifter and I-POU depend on cas for full expression, whereas pdm-1 and pdm-2 are negatively regulated. cas encodes a zinc finger protein that shares DNA-binding specificity with another pdm repressor: the gap segmentation gene regulator Hunchback (Hb). Our studies reveal that the embryonic CNS contains sequentially generated neuroblast sublineages that can be distinguished by their expression of either Hb, Pdm-1, or Cas. Hb and Cas may directly silence pdm expression in early and late developing sublineages, given that pdm-1 cis-regulatory DNA contains >=32 Hb/Cas-binding sites and its enhancer(s) are ectopically activated in cas- neuroblasts. In addition, the targeted misexpression of Cas in all neuroblast lineages reduces Pdm-1 expression without altering Hb expression. By ensuring correct POU gene expression boundaries, hb and cas maintain temporal subdivisions in the cell-identity circuitry controlling CNS development.

Animals↗
PubMed1994

Drug prevention in Zuni, New Mexico: creation of a teen center as an alternative to alcohol and drug use.

In 1991, the Center for Substance Abuse Prevention of the Department of Health and Human Services funded a project to develop alcohol prevention-oriented messages targeting teenagers of the Zuni Tribe in New Mexico. A lengthy needs assessment determined that alcohol was the most serious drug problem on the pueblo, and that Zuni teenagers often resorted to alcohol and other drug use because they had little else to do during their free time. Communication products were developed which publicized and promoted the creation of a Zuni Teen Center as a fun and safe alternative to drug use. These products, then, are serving as a catalyst for mobilizing the Zuni community around the cause of preventing alcohol use and abuse among their teens via the conversion of an old warehouse to a Zuni Teen Center. The following article describes the needs assessment, product development and distribution, and evaluation of the project's success.

Adolescent↗
PubMed1994

The relationship of gender and family environment to eating disorder risk in adolescents.

Incidence and prevalence rates of both anorexia nervosa and bulimia among adolescents have steadily increased during the past decade. The purpose of this study was to examine the relationship of gender and family environment to the risk of developing anorexia nervosa or bulimia in adolescents. The Family Environment Scale (FES; Moos & Moos, 1981) and the Setting Conditions for Anorexia Nervosa Scale (SCANS; Slade, Phil, & Dewey, 1986) were used to measure select components of family environment and risk of developing anorexia nervosa or bulimia, respectively. Data were collected from 393 students attending a private secondary boarding school located in central New Jersey. Subjects represented 35 states and 25 countries, had a mean age of 16.3 years, were predominantly Caucasian (75.6%) with a Catholic (27.5%) or Protestant (26.5%) affiliation, and reported a family income in excess of $50,000 (63.9%). Multiple regression using a unique approach revealed a significant relationship between family environment and the risk of developing anorexia nervosa or bulimia in adolescents (p < .01). The FES subscale of expressiveness was the only subscale found to have a significant relationship with the risk of developing anorexia nervosa or bulimia. Female subjects displayed a greater risk than did males (p < .01). Finally, no significant interaction was found between family environment and gender on the risk of developing anorexia nervosa or bulimia in adolescents. Simple correlation of the FES subscales was conducted by means of Pearson product moment and results indicated that lower cohesion, expressiveness, and organization were significantly associated with greater eating disorder risk (p < .01). Lower independence was significantly associated with increased eating disorder risk, but to a lesser degree (p < .05). Greater conflict (p < .01) and control (p < .05) were significantly associated with greater eating disorder risk.

Adolescent↗
PubMed1991

Why can't a woman be less like a man? Women's leadership dilemma.

Despite the emergence of new theories, our notions of organizational and political leadership are still culturally masculine. Therefore, women who lead (e.g., nurse executives and nurse managers) must deal with tensions between expectations about leaders and expectations about women. This situation suggests that nursing administration education programs can help nurses become effective leaders by including examination of what difference it makes--historically, politically, institutionally--that nursing is largely a female profession.

Education, Nursing, Graduate↗
PubMed1988

Parent-adolescent communication and its relationship to adolescent depression and suicide proneness.

Suicide is the second leading cause of death among adolescents in the United States, and the rates in this age group are increasing. A possible factor related to adolescent suicide may be inadequate or insufficient parent-adolescent communication. The purpose of this study was to investigate the communication level between selected adolescents and their parents, and to determine its relationship to the parents' perceptions of their adolescent's depression and proneness to suicide. The Parent-Adolescent Communication Inventory (PACI) was used to measure communication, and the Suicide-Depression Inventory (SDI) was used to measure depression and suicide proneness. Upon statistical analysis of the instrument scores, simple correlation coefficients expressed significant relationships between mother's and adolescent's scores, but not between father's and adolescent's scores. However, when controlling for other independent variables, neither the father's nor the mother's scores were significantly related to the adolescent's SDI score. The adolescent's PACI score was the only independent variable that produced a significant semi-partial correlation coefficient. A multiple regression procedure isolated only one of the independent variables which entered and stayed in the predictor model at the .05 level--the adolescent's PACI score (p = .001).

Adolescent↗
PubMedDate not supplied

Grassroots efforts pursue alcohol policy reform: refocusing upstream in New Mexico.

ORGANIZATION SETTING. The New Mexico Alcohol Issues Consortium (NMAIC) originated in January 1989 as a grassroots effort to focus on the reduction of driving-while-intoxicated (DWI) in New Mexico. It was the brainchild of three state health department officials and grew to include in its membership representatives from education, medicine, law enforcement, neighborhood associations, business, and local and state government. RATIONALE. New Mexico ranks at or near the top in several alcohol-related statistics, including motor vehicle fatalities, cirrhosis, and alcoholism. Furthermore, the 'alcohol environment' in New Mexico included the allowance for the purchase of alcoholic beverages at drive-up windows, lax enforcement of DWI laws, and even state legislators with DWI records. Theoretical bases upon which NMAIC goals and strategies were based include the public health model, the public health/dynamic systems, model of alcohol and other drug use, and 'refocusing upstream,' all of which give attention to the environment as a determinant of health status. IMPLEMENTATION. While the NMAIC's activities addressed a variety of alcohol-related problems in New Mexico, the bulk of the organization's efforts for four years were directed toward increasing the excise tax on alcohol, either as a statewide measure or via county-level local option referenda. Strategies which were enacted to support this legislative activity included collaboration with other programs and organizations with similar DWI-prevention goals, and staged media events to solicit public support. IMPACT. In four years, the NMAIC had established itself as a credible organization which was successful in publicly and systematically challenging existing alcohol policies in New Mexico. The NMAIC was also instrumental in empowering individuals and communities to speak and act against the alcohol problems in their own communities. Finally, during the 1993 New Mexico Legislative Session, a bill was passed which mandated a statewide excise tax increase on alcohol. For its efforts, the NMAIC has won one national level award and one state level award for its contribution to the public health of New Mexico. DISCUSSION. The NMAIC is now pursuing passage of the local option version of the excise tax increase bill, because it could generate up to three times as much revenue as the new statewide increase. Additionally, Consortium members have escalated discussions regarding nonprofit status for the NMAIC, and developing a more formal mechanism for determining leadership. Members continue their participation in trainings on community organizing, media advocacy, and alcohol policy reform.

Accidents, Traffic↗