Psychosocial Concerns and Health-Compromising Behaviors among Overweight and Nonoverweight Adolescents

Objective: To compare weight-specific and global psychosocial concerns and health-compromising behaviors among overweight and nonoverweight youth across gender and ethnicity. Methods: A cross-sectional school-based survey of 31,122 adolescents in grades 7 to 12. Based on self-reported heights and weights, respondents were categorized as nonoverweight (body mass index (BMI) <85th percentile), moderately overweight (85th percenile <BMI <95th percentile), or severely overweight (BMI >95th percentile). Results: Global psychosocial concerns, such as emotional well-being, suicidal ideation, future job concerns, and peer concerns, did not differ greatly between nonoverweight, moderately overweight, and severely overweight adolescents. Substance abuse behaviors were equally or less prevalent among the overweight group. Overweight girls were significantly less likely to consume alcohol, whereas overweight boys were at lower risk for marijuana use. In contrast, overweight youth were more likely to perceive their health as only fair or poor and were more likely to express weight-specific concerns and engage in behaviors such as chronic dieting and binge eating than nonoverweight youth. Overweight American Indian girls perceived their physical health more positively than nonoverweight American Indian girls. Strong associations were found between overweight status and chronic dieting among African American boys and girls. Conclusions: Nutritional counseling and educational programs need to address the weight-specific concerns and behaviors of overweight adolescents. However, assumptions regarding global psychosocial concerns and health-compromising behaviors among overweight adolescents of different genders and ethnicities should be avoided. These broad issues need to be explored in more depth at both the research and intervention levels.     

Entry of immotile spermatozoa into zona-free hamster ova

We studied six men whose spermatozoa were immotile and possessed a variety of sperm tail structural abnormalities by electron microscopy. The semen of all six subjects had a normal percentage of oval forms and sperm undergoing capacitation and acrosome reaction. Despite the absence of motility, when incubated sperm from these subjects was added to a microdrop of medium containing zona pellucida-free hamster ova, sperm penetration or entry into the cytoplasm of from 1–9% of the eggs was evident with phase contrast microscopy. This latter finding suggests that, at least in this system, oocytes actively facilitate sperm incorporation. Penetration was absent when sperm of fertile men were rendered immotile, though still viable, by heat treatment.     

Effects of pH and ionic strength on the structure of collagen fibrils

The roles of pH and ionic strength on the structure and stability of collagen fibrils have been investigated by means of x-ray and neutron diffraction techniques. High-angle x-ray diffraction shows that a salt concentration of 0.5M KCl is sufficient to reduce the osmotic swelling and related disordering in the pH range 1–3. The relative intensities of the low-angle meridional x-ray and neutron diffraction Bragg reflections vary with pH. Difference Fourier syntheses between pH 7 and 1.6 data indicate, for both x-ray and neutron diffraction, a reduced scattering contribution from the telopeptides at low pH. Lyotropic relaxation is a crucial step in the appearance at low pH of a doubling of the 668-Å axial periodicity (D) of collagen fibrils. These results suggest that electrostatic interactions are essential for the structural stability of the telopeptide regions and of the 1D and 3D intermolecular staggers between collagen molecules.     

Identifying sites of simultaneous DNA replication in eukaryotes by N-methyl-N''-nitro-N-nitrosoguanidine multiple mutagenesis.

Summary N-methyl-N-nitro-N-nitrosoguanidine (NG) induces certain classes of multiple mutations in yeast at high frequency. By selecting for mutation at one locus (his4 or leu1) one frequently obtains double mutants where another mutation to temperature sensitivity has also been induced. This multiple mutagenesis exhibits a considerable specificity: for mutation at one particular locus there is a high chance that another mutation will be found in the same cell at one of a restricted number of other loci. For any given locus (e.g. his4) there is a spectrum of sites at which temperature-sensitivity mutations are coinduced. This spectrum differs for different loci, such that the spectrum of sites co-mutating with leul differs completely from that for sites co-mutating with his4. This NG-induced co-mutation is interpreted in terms of NG acting to enhance mutagenesis at sites of simultaneous DNA replication within the cell. The results so obtained indicate a very strict control over the order and timing of gene replication in Saccharomyces cerevisiae, and it is suggested that it is now possible to use NG double mutagenesis to try and locate origins of replication in yeast.     

Human adenovirus serotype 3 fiber protein. Comparison of native and recombinant proteins

We were able to isolate viral fiber and penton from Ad3-infected KB cells using for their detection antibodies obtained against recombinant Ad3 fiber. The native material was examined by electron microscopy and the characteristic fiber shape of a shaft terminated by a globular head was observed. The native fiber was compared with two recombinant fibers synthesized in Escherichia coli cells. One, the Ad3 fiber protein expressed in E. coli with a 14-amino acid NH2-terminal fusion peptide, under the control of the T7 promoter has been described previously. The second is a recombinant Ad3 fiber without the fusion peptide (recAd3fib), expressed in the same system. As with the fusion protein recAd3fib was found to be insoluble upon expression. It was solubilized in 6 M urea and the gradual removal of urea during the purification cycle led to a soluble preparation. Biochemical and biophysical studies show that, similarly to fusion fiber, recAd3fib self-assembles as trimers in prokaryotic cells. Electron microscopy shows that, whereas the fusion fiber consists of a population of heterogeneous particles, recAd3fib has the characteristic morphology and size of the Ad3 trimeric native fiber. Small angle neutron scattering gives a molecular weight consistent with a trimeric fiber and a radius of gyration consistent with the dimensions derived from electron microscopy. These results suggest that the fusion peptide at the NH2 terminus prevents correct protein folding. They also indicate that after solubilization with urea and subsequent renaturation a correctly folded eukaryotic oligomeric protein can be produced in E. coli.     

Orienting rigid and flexible biological assemblies in ferrofluids for small-angle neutron scattering studies

Small-angle scattering from macromolecules in solution is widely used to study their structures, but the information content is limited because the molecules are generally randomly oriented and hence the data are spherically averaged. The use of oriented rodlike structures for scattering, as in fiber diffraction, greatly increases the amount of structural detail that can be obtained. A new technique using a ferromagnetic fluid has been developed to align elongated structures independent of their intrinsic magnetic properties. This technique is ideal for small-angle neutron scattering because the scattering from the ferrofluid particles can be reduced significantly by matching the neutron scattering length density of the particles to a D₂O solvent (“contrast matching”). The net result is scattering primarily from the ordered biological assembly in a solution environment that can be adjusted to physiological pH and ionic strength. Scattering results from ordered tobacco mosaic virus, tobacco rattle virus, and chromain fibers are presented.     

Alpha glucosidases in white blood cells, with reference to the detection of acid alpha 1-4 glucosidase deficiency.

The iron-containing violet acid phosphatases from beef spleen and pig allantoic fluid have been purified to homogeneity. Molecular weight determinations by zonal gel filtration, SDS-gel electrophoresis, and ultracentrifugation support values close to 40,000 for both enzymes, necessitating reappraisal of literature values. Similarly, the equivalent weight for iron is close to 20,000 for both enzymes, indicating the presence of two iron atoms per molecule of enzyme. The enzymes also have very similar ultraviolet and visible spectra, with λ_max values close to 550 nm, and ?₅₅₀ values(in terms of iron) of 2.04 × 10³ and 2.00 × 10³ for the beef spleen and pig allantoic fluid enzymes respectively.     

Spatiotemporal Expression of Repulsive Guidance Molecules (RGMs) and Their Receptor Neogenin in the Mouse Brain

Neogenin has been implicated in a variety of developmental processes such as neurogenesis, neuronal differentiation, apoptosis, migration and axon guidance. Binding of repulsive guidance molecules (RGMs) to Neogenin inhibits axon outgrowth of different neuronal populations. This effect requires Neogenin to interact with co-receptors of the uncoordinated locomotion-5 (Unc5) family to activate downstream Rho signaling. Although previous studies have reported RGM, Neogenin, and/or Unc5 expression, a systematic comparison of RGM and Neogenin expression in the developing nervous system is lacking, especially at later developmental stages. Furthermore, information on RGM and Neogenin expression at the protein level is limited. To fill this void and to gain further insight into the role of RGM-Neogenin signaling during mouse neural development, we studied the expression of RGMa, RGMb, Neogenin and Unc5A-D using in situ hybridization, immunohistochemistry and RGMa section binding. Expression patterns in the primary olfactory system, cortex, hippocampus, habenula, and cerebellum were studied in more detail. Characteristic cell layer-specific expression patterns were detected for RGMa, RGMb, Neogenin and Unc5A-D. Furthermore, strong expression of RGMa, RGMb and Neogenin protein was found on several major axon tracts such as the primary olfactory projections, anterior commissure and fasciculus retroflexus. These data not only hint at a role for RGM-Neogenin signaling during the development of different neuronal systems, but also suggest that Neogenin partners with different Unc5 family members in different systems. Overall, the results presented here will serve as a framework for further dissection of the role of RGM-Neogenin signaling during neural development.