Tufts University

About: Tufts University is a education organization based out in Medford, Massachusetts, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 32800 authors who have published 66881 publications receiving 3451152 citations. The organization is also known as: Tufts College & Universitatis Tuftensis.

Evidence for Cigarette Smoking as a Major Risk Factor for Periodontitis

Abstract: The role of smoking as a risk factor for periodontitis was assessed separately in diabetic and nondiabetic study groups. Subject listings stratified for age (19 to 40 years) and sex were obtained for subjects with insulin-dependent diabetes mellitus (IDDM) and nondiabetic subjects. For both the IDDM group (n = 132) and the nondiabetic group (n = 95), age and sex stratified samples were constructed by random selection of subjects from each subject listing. Patients were recruited by phone, examined, and their medical and dental histories obtained. Among nondiabetic subjects, the prevalence of periodontitis was markedly higher among current smokers compared with never smokers (P or = 4 mm was higher among current smokers than never smokers (P = 0.001) in the 19 to 30 (8.2% vs. 3.4%) and 31 to 40 (14.3% vs. 4.3%) age groups. The effects of smoking among IDDM subjects were similar to that observed in the nondiabetic population. There were no differences between current and never smokers in the proportion of sites positive for plaque. Attributable risk percents from prevalence data suggest that among nondiabetic subjects, a large proportion, perhaps as much as 51% of the periodontitis in the 19 to 30 year old group and 32% of the periodontitis in the 31 to 40 year old group, is associated with smoking.(ABSTRACT TRUNCATED AT 250 WORDS)

Cytotoxicity of human pI 7 interleukin-1 for pancreatic islets of Langerhans.

Abstract: Activated mononuclear cells appear to be important effector cells in autoimmune beta cell destruction leading to insulin-dependent (type 1) diabetes mellitus. Conditioned medium from activated mononuclear cells (from human blood) is cytotoxic to isolated rat and human islets of Langerhans. This cytotoxic activity was eliminated from crude cytokine preparations by adsorption with immobilized, purified antibody to interleukin-1 (IL-1). The islet-inhibitory activity and the IL-1 activity (determined by its comitogenic effect on thymocytes) were recovered by acid wash. Purified natural IL-1 and recombinant IL-1 derived from the predominant pI 7 form of human IL-1, consistently inhibited the insulin response. The pI 6 and pI 5 forms of natural IL-1 were ineffective. Natural and recombinant IL-1 exhibited similar dose responses in their islet-inhibitory effect and their thymocyte-stimulatory activity. Concentrations of IL-1 that inhibited islet activity were in the picomolar range. Hence, monocyte-derived pI 7 IL-1 may contribute to islet cell damage and therefore to the development of insulin-dependent diabetes mellitus.

The Evolution of City Size Distributions

Abstract: We review the accumulated knowledge on city size distributions and determinants of urban growth. This topic is of interest because of a number of key stylized facts, including notably Zipf's law for cities (which states that the number of cities of size greater than S is proportional to 1/S) and the importance of urban primacy. We first review the empirical evidence on the upper tail of city size distribution. We offer a novel discussion of the important econometric issues in the characterization of the distribution. We then discuss the theories that have been advanced to explain the approximate constancy of the distribution across very different economic and social systems, emphasizing both bare-bone statistical theories and more developed economic theories. We discuss the more recent work on the determinants of urban growth and, in particular, growth regressions, economic explanations of city size distributions other than Gibrat's law, consequences of major shocks (quasi natural experiments), and the dynamics of U.S. urban evolution.

Reproducibility of nerve fiber thickness, macular thickness, and optic nerve head measurements using StratusOCT.

Abstract: PURPOSE The measurement reproducibility of the third generation of commercial optical coherence tomography, OCT-3 (StratusOCT, software ver. A2, Carl Zeiss Meditec Inc., Dublin, CA) was investigated. The nerve fiber layer (NFL) thickness, macula thickness map, and optic nerve head (ONH) parameters in normal eyes were studied. METHODS Ten normal subjects were imaged six times (three before and three after dilation) per day, and the series was repeated on three different days. The order of the scans before pupil dilation was randomized in each of the 3 days of scanning. After pupil dilation, the scans were also randomized in each of the 3 days of scanning. Each series was performed separately for standard-density (128 A-scans per macular and ONH image and 256 A-scans per NFL image) and high-density (512 A-scans per image for all three scan types) scanning. RESULTS The mean macular thickness was 235 +/- 9.8 micro m. A-scan density (or image acquisition speed) had a statistically significant effect (P < 0.05) on the reproducibility of the mean macular thickness, macular volume, and a few sectors of the macular map. No significant dilation effect was found for any of the macular parameters. The best intraclass correlation coefficient (ICC; 94%) for macular scans was found for dilated high-density scanning, with an intervisit SD of 2.4 micro m and an intravisit SD of 2.2 micro m. The mean NFL thickness for standard scanning was 98 +/- 9 micro m. NFL reproducibility showed mixed results and had interactions between scan density and dilation for some parameters. For most of the NFL parameters, reproducibility was better with dilated standard-density scanning. The mean NFL thickness ICC for dilated standard scanning was 79%, with an intervisit SD of 2.5 micro m and an intravisit SD of 1.6 micro m. For the ONH analysis, the reproducibility was better for dilated standard-density scanning for almost all the parameters, except for disc area, horizontal integrated rim volume, and vertical integrated rim area, which were better before dilation. The best reproducibility was found for cup-to-disc ratio (ICC = 97%, with intervisit SD of 0.04 micro m and intravisit SD of 0.02 micro m). CONCLUSIONS StratusOCT demonstrated reproducible measurements of NFL thickness, macular thickness, and optic nerve head parameters. The best reproducibility was found for dilated standard scanning for NFL and ONH parameters and for dilated high-density scanning for macular parameters.