Influences of context on early writing development

Research on children's early writing development in the past has focused primarily on product and process. In reviewing the more recent research on early writing development, however, a new focus of context emerges. Occurrences of literacy are now being observed in the home, the school, and the community. With this new emphasis, comes the task of defining context. A definition of context reflects theoretical perspectives, areas of research interests, and types of methodologies employed in conducting research. Therefore, the purpose of this article is to address the following aspects of context: #op1#cp multidiscipline perspectives and definitions of context, #op2#cp contextual shifts observed between the home and the school, #op3#cp contextual factors present when learning how to write, and #op4#cp pedagogical implications for curriculum development.     

Characterization of a highly polymorphic marker adjacent to the SLC4A1 gene and of kidney immunostaining in a family with distal renal tubular acidosis.

BACKGROUND: Mutations in the human SLC4A1 (AE1/band 3) gene are associated with hereditary spherocytic anaemia and with distal renal tubular acidosis (dRTA). The molecular diagnosis of AE1 mutations has been complicated by the absence of highly polymorphic genetic markers, and the pathogenic mechanisms of some dRTA-associated AE1 mutations remain unclear. Here, we characterized a polymorphic dinucleotide repeat close to the human AE1 gene and performed an immunocytochemical study of kidney tissue from a patient with inherited dRTA with a defined AE1 mutation. METHODS: One CA repeat region was identified in a phage P1-derived artificial chromosome (PAC) clone containing most of the human AE1 gene and the upstream flanking region. We determined its heterozygosity value in multiple populations by PCR analysis. Genotyping of one family with dominant dRTA identified the AE1 R589H mutation, and family member genotypes were compared with the CA repeat length. AE1 and vH(+)-ATPase polypeptides in kidney tissue from an AE1 R589H patient were examined by immunocytochemistry for the first time. RESULTS: This CA repeat, previously reported as D17S1183, is approximately 90 kb upstream of the AE1 gene and displayed considerable length polymorphism, with small racial differences, and a heterozygosity value of 0.56. The allele-specific length of this repeat confirmed co-segregation of the AE1 R589H mutation with the disease phenotype in a family with dominant dRTA. Immunostaining of the kidney cortex from one affected member with superimposed chronic pyelonephritis revealed vH(+)-ATPase-positive intercalated cells in which AE1 was undetectable, and proximal tubular epithelial cells with apparently enhanced apical vH(+)-ATPase staining. CONCLUSIONS: The highly polymorphic dinucleotide repeat adjacent to the human AE1 gene may be useful for future studies of disease association and haplotype analysis. Intercalated cells persist in the end-stage kidney of a patient with familial autosomal dominant dRTA associated with the AE1 R589H mutation. The absence of detectable AE1 polypeptide in those intercalated cells supports the genetic prediction that the AE1 R589H mutation indeed causes dominant dRTA.     

Heightened risk of breast cancer following pregnancy: could lasting systemic immune alterations contribute?

The protective effect of having a first full-term pregnancy (FFTP) at a younger age on women's lifetime risk of breast cancer is well known. Less appreciated is the increased risk seen in the years immediately following pregnancy. This adverse effect is more pronounced and more prolonged in women with later age at FFTP. The mechanisms responsible for this increased risk are still poorly understood. In the present paper, we put forward the hypothesis that the marked peripheral immune changes induced by pregnancy may account for these effects. We highlight immune changes that characterize the unique immune state of pregnancy (a combination of cellular immunosuppression and enhanced inflammatory response), note the resemblance of these changes to cancer escape mechanisms, and discuss why such immune changes may be critical for the development of breast cancer following pregnancy. We further support this idea by initial findings from our own laboratory that the age at FFTP is negatively related to natural killer cell cytotoxicity many years later and propose possible models for the kinetics of the immune changes during and following pregnancy. The effect of age at FFTP on the immune function is currently understudied. Its potential relevance to the development of breast cancer stresses the need for further research.     

Modulation of carcinogenicity in 1,2,3,4-tetrahydro-7,12- dimethylbenz[a]anthracene (THDMBA) by fluorine substitution: crystal structures of the 5- and 6-fluoro regioisomers.

1,2,3,4-Tetrahydro-7,12-dimethylbenz[a]anthracene (THDMBA) is an animal carcinogen which lacks an aromatic bay-region and shows promise as a model to investigate non-classical mechanisms of carcinogenesis. The fluorine-substituted derivatives at positions 5 and 6 on the B-ring exhibit a striking range of oncogenic potential wherein the 6F-THDMBA is twice as potent as the parent carcinogen, but the 5F-THDMBA is virtually inactive. To study structure-reactivity relationships for these fluorine regioisomers, we have determined the three-dimensional structures of the compounds by single-crystal X-ray diffraction. These crystal structures are the first such to be reported for any monofluoro anthracene (or pyrene) derivative. The partially-reduced A-ring exists in both enantiomeric half-chair conformers in the crystalline state, and the compounds have quasi-planar anthracene ring systems which exhibit a right-handed twist in the 'beta'-conformer, with the expected opposite twist in the other. A complete analysis of bond lengths, bond angles and torsion angles is presented. Preliminary electrostatic potentials have been derived from the X-ray data sets, and the results indicate significant differences in potential between 5F- and 6F-THDMBA at positions near the partially reduced bay region. Such results are likely to be of importance in the understanding of metabolic activation to reactive intermediates capable of bonding covalently to DNA.     

HIV-Related Concerns and Educational Needs of Public Health Nurses in a Rural State

Abstract An anonymous questionnaire was completed by 369 nurses in public health departments in a rural Southeastern state to examine the relationship between nurses' prior HIV training and their HIV-related knowledge, attitudes, concerns, and perceived training needs. The survey was conducted in three predominantly urban counties with the highest number of AIDS cases and in 38 rural counties with two or fewer reported AIDS cases. Knowledge answers were generally 70%-90% correct and attitudes more favorable than unfavorable. Attitude was more frequently associated with HIV training level than was knowledge. Concerns about working with persons with high-risk behaviors were expressed by more than half the nurses and were more prevalent in rural areas. Nurses with more training had more concerns about client care and fewer fears about HIV work. Almost all (85%) were concerned about lack of community resources. Most nurses wanted more training of the client-sensitive type provided by the state. With the increasing incidence of HIV/AIDS in rural areas, planning continuing education for staff not only on new developments and current therapies (desired by 98%) but on managing feelings about clients with high-risk behaviors seems especially important not only for the staff, but for their significant others and communities.     

Mutagenicity of benzo(a)pyrenyl-1-sulfate in the Ames test.

Comparison of the mutagenicity of nine isomeric benzo(a)pyrenyl [B(a)P] phenols conjugated with either sulfate or glucuronide was carried out using strain Salmonella typhimurium TA98. Of the nine conjugates tested, only B(a)P-1-sulfate was mutagenic. Accordingly, the mutagenicity of B(a)P-1-sulfate was compared with that of B(a)P and 1-hydroxybenzo(a)pyrene [B(a)P-1-OH] in the presence and absence of rat lung S9 and Aroclor-induced liver S9 with and without an NADPH-generating system. B(a)P-1-sulfate was slightly mutagenic, whereas B(a)P and the 1-hydroxy derivative were nonmutagenic when S9 fractions and NADPH were omitted. Addition of induced liver S9 with NADPH caused mutagenicity with B(a) -1-OH greater than B(a)P greater than B(a)P-1-sulfate. B(a)P-1-sulfate was the only mutagenic species when lung S9 was added. This mutagenicity did not require NADPH. Sodium sulfite, an inhibitor of arylsulfatase, decreased the mutagenicity of B(a)P-1-sulfate. These data suggest that a unique mutagenic species is generated from B(a)P-1-sulfate via arylsulfatase in rat lung.     

Inactivation of platelet-activating factor by a putative acetylhydrolase from the gastrointestinal nematode parasite Nippostrongylus brasiliensis.

The adult stage of Nippostrongylus brasiliensis, a strongyloid parasite of the gastrointestinal tract of rats, released a product during in vitro culture which functionally inhibited platelet-activating factor (PAF), measured by its ability to mediate platelet aggregation. The extent of inhibition was proportional to the concentration of excretory/secretory (ES) products and the duration of preincubation with PAF prior to the assay of biological activity. The inhibitory activity was heat labile and was specific for PAF, as incubation of ES products with thrombin showed no diminution of platelet aggregation. Experiments using radiolabelled preparations of PAF demonstrated that the acetyl group esterified at the sn-2 position of the glycerol backbone was liberated on incubation with ES products, indicative of an acetylhydrolase activity. This activity was susceptible to inhibition by DFP, partial inhibition by eserine, but was resistant to PMSF and TPCK at concentrations which inhibit serine proteases.