United States Department of the Army

About: United States Department of the Army is a government organization based out in Arlington, Virginia, United States. It is known for research contribution in the topics: Poison control & Population. The organization has 32668 authors who have published 42453 publications receiving 947075 citations. The organization is also known as: DA & U.S. Department of the Army.

The Effect of Nicotine on the Attachment of Human Fibroblasts to Glass and Human Root Surfaces in Vitro

Abstract: This study examined the effect of nicotine on fibroblast attachment to glass and nondiseased human root surfaces. Human foreskin fibroblasts (HFF) were trypsinized, suspended in RPMI 1640 medium, and incubated with autoclaved human root sections and nicotine concentrations of zero (control), 25, 50, 100, 200, or 400 ng/ml. The root sections were examined for fibroblast attachment at 24, 48, and 72 hours by light microscopy and scanning electron microscopy (SEM). Additional trypsinized HFF were incubated on glass surfaces with the same concentrations of nicotine and examined at one week by light microscopy. HFF attached and grew on glass and root surfaces at all concentrations of nicotine. Controls on glass surfaces exhibited a normal monolayer of long spindle-shaped fibroblasts with a parallel alignment and minimal overlapping. Nicotine-treated HFF exhibited a haphazard arrangement with cell overlapping and vacuolization of the cytoplasm. Under SEM, the controls had smooth surfaces and appeared firmly attached to the root surface via (1) microvilli and filopodia on the cell boundaries and (2) short, branched, thin-to-medium width cytoplasmic processes with microvilli and filopodia on their boundaries. Few microvilli were noted on the control cell surfaces. HFF exposed to nicotine had microvilli and filopodia on the cell surfaces and long thin and long broad cytoplasmic processes with many microvilli and filopodia that projected away from the root surface. These findings suggest that the nature of fibroblast attachment to glass and root surfaces is altered by nicotine. A similar disturbance in fibroblast attachment may occur in humans who use nicotine-containing products, making them more susceptible to destruction of the periodontium and less responsive to new attachment after periodontal therapy.

Different strains of Mycobacterium tuberculosis cause various spectrums of disease in the rabbit model of tuberculosis.

Abstract: The rabbit model of tuberculosis has been used historically to differentiate between Mycobacterium tuberculosis and Mycobacterium bovis based on their relative virulence in this animal host. M. tuberculosis infection in market rabbits is cleared over time, whereas infection with M. bovis results in chronic, progressive, cavitary disease leading to death. Because of the innate resistance of commercial rabbits to M. tuberculosis, 320 to 1,890 log-phase, actively growing inhaled bacilli were required to form one grossly visible pulmonary tubercle at 5 weeks. The range of inhaled doses required to make one tubercle allows us to determine the relative pathogenicities of different strains. Fewer inhaled organisms of the M. tuberculosis Erdman strain were required than of M. tuberculosis H37Rv to produce a visible lesion at 5 weeks. Furthermore, with the Erdman strain, only 7 of 15 rabbits had healed lesions at 16 to 18 weeks; among the other animals, two had chronic, progressive cavitary disease, a phenotype usually seen only with M. bovis infection. Genotypic investigation of the Erdman strain with an H37Rv-based microarray identified gene differences in the RD6 region. Southern blot and PCR structural genetic analysis showed significant differences between M. tuberculosis strains in this region. Correlation of the relative pathogenicity, including disease severity, in the rabbit model with the strain genotype may help identify stage-specific M. tuberculosis genes important in human disease.

Breast cancer screening behaviors and attitudes in three racial/ethnic groups.

Abstract: Data from a multiethnic sample of women participating in the American Cancer Society 1987 Texas Breast Screening Project was used to compare attitudes and behaviors related to breast cancer screening for whites, blacks, and Hispanics. In general, similar patterns of association were observed across racial/ethnic groups between a number of demographic and risk factors and prior mammography and recent clinical breast examination (CBE), although the magnitude of the associations varied somewhat across groups. Reasons for not having had prior mammography also were similar across groups, with lack of physician referral and cost cited as the two most important reasons. However, Hispanics were less likely than blacks or whites to report prior breast cancer screening, including mammography, CBE, and breast self-examination (BSE). This study demonstrated that women of different racial/ethnic backgrounds can be successfully recruited to participate in a patient-initiated, community-based program. However, this programmatic approach requires augmentation with other intervention strategies designed to reach low-income women because women with more years of education and higher family income were overrepresented in all three groups.

Measurement of the Finish of Diamond-Turned Metal Surfaces By Differential Light Scattering

Abstract: This paper discusses the measurement of the finish of diamond-turned surfaces by differential light scattering. Experimental scattering data are analyzed by electromagnetic theory to give the two-dimensional power spectral density of the surface roughness. These spectral densities are direct functional measures of the surface quality, and may be characterized in terms of topographic finish parameters. These parameters can then be used to specify surface finish, to predict scattering under a variety of conditions, and to aid in studies of other functional properties of these surfaces. Scattering spectra are separated in-to three groups corresponding to three classes of surface roughness: periodic tool marks and one- and two-dimensional random roughness. Periodic tool marks give rise to discrete diffraction lines in the scattering spectrum and are characterized by their surface periods and their Fourier amplitudes. Random one- and two-dimensional roughness give rise to one- and two-dimensional continua underlying the diffraction lines and are characterized by band-limited values of the rms surface heights and slopes, and transverse length parameters. Using HeNe light, vertical roughnesses are measured from a fraction of an Angstrom to several hundred Angstroms, for transverse spatial wavelengths from a fraction of a micron to several hundred microns. We re-view experimental techniques for making these measurements with emphasis on the scatterometer developed in our laboratory, which uses a fixed source-detector geometry and a rotating sam-ple. Results are illustrated by a number of scattering spectra taken with this instrument.