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1.
Background
Agent-based models are valuable for examining systems where large numbers of discrete individuals interact with each other, or with some environment. Diabetic Veterans seeking eye care at a Veterans Administration hospital represent one such cohort.Objective
The objective of this study was to develop an agent-based template to be used as a model for a patient with diabetic retinopathy (DR). This template may be replicated arbitrarily many times in order to generate a large cohort which is representative of a real-world population, upon which in-silico experimentation may be conducted.Methods
Agent-based template development was performed in java-based computer simulation suite AnyLogic Professional 6.6. The model was informed by medical data abstracted from 535 patient records representing a retrospective cohort of current patients of the VA St. Louis Healthcare System Eye clinic. Logistic regression was performed to determine the predictors associated with advancing stages of DR. Predicted probabilities obtained from logistic regression were used to generate the stage of DR in the simulated cohort.Results
The simulated cohort of DR patients exhibited no significant deviation from the test population of real-world patients in proportion of stage of DR, duration of diabetes mellitus (DM), or the other abstracted predictors. Simulated patients after 10 years were significantly more likely to exhibit proliferative DR (P<0.001).Conclusions
Agent-based modeling is an emerging platform, capable of simulating large cohorts of individuals based on manageable data abstraction efforts. The modeling method described may be useful in simulating many different conditions where course of disease is described in categorical stages. 相似文献2.
Chemotherapy and vaccination: a possible strategy for the control of highly virulent influenza virus. 总被引:7,自引:1,他引:6 下载免费PDF全文
The influenza A virus [A/Chicken/Pennsylvania/1370/83 (H5N2)] that caused up to 80% mortality among chickens provided a model system for testing the efficacy of chemotherapeutic agents against highly virulent influenza virus. Amantadine and rimantadine administered in drinking water were efficacious both prophylactically and therapeutically. However, under conditions simulating natural transmission of virus, amantadine- and rimantadine-resistant viruses arose and were transmitted to other birds in contact with the infected chickens, causing mortality. Simultaneous administration of inactivated H5N2 vaccine and amantadine provided protection. Thus, chemotherapy may be useful in the treatment of a highly pathogenic influenza virus outbreak in humans or other animals when used in combination with vaccine. 相似文献
3.
Pedro LC Pinheiro João CR Cardoso Ana S Gomes Juan Fuentes Deborah M Power Adelino VM Canário 《BMC evolutionary biology》2010,10(1):373
Background
Parathyroid hormone (PTH) and PTH-related peptide (PTHrP) belong to a family of endocrine factors that share a highly conserved N-terminal region (amino acids 1-34) and play key roles in calcium homeostasis, bone formation and skeletal development. Recently, PTH-like peptide (PTH-L) was identified in teleost fish raising questions about the evolution of these proteins. Although PTH and PTHrP have been intensively studied in mammals their function in other vertebrates is poorly documented. Amphibians and birds occupy unique phylogenetic positions, the former at the transition of aquatic to terrestrial life and the latter at the transition to homeothermy. Moreover, both organisms have characteristics indicative of a complex system in calcium regulation. This study investigated PTH family evolution in vertebrates with special emphasis on Xenopus and chicken. 相似文献4.
From 1981 through 1986, plasma or serum samples were obtained from 322 wild turkeys (Meleagris gallopavo) from Georgia (n = 111), Kentucky (n = 21), Louisiana (n = 22), North Carolina (n = 118), Tennessee (n = 19), Missouri (n = 24) and Iowa (n = 7). These samples were tested for antibodies to Mycoplasma gallisepticum (MG) and in most instances, M. synoviae (MS), M. meleagridis (MM), and avian influenza (AI) virus. All 322 turkeys were seronegative for MG by the rapid plate agglutination (RPA) test. All of a subsample (n = 147) also were negative (titer less than or equal to 1:40) for MG by the hemagglutination inhibition (HI) test. Five of 253 turkeys (2%) were seropositive (+4 reaction) for MS by the RPA test; however, HI tests for MS on these five turkeys were negative as were attempts to isolate MS from trachea and homogenized lung tissue. Three of 253 turkeys (1%) were seropositive (+1 to +3 reactions) for MM by the RPA test. None of 210 turkeys had antibodies to AI by the agar gel precipitation test. These data suggest that populations of native eastern wild turkeys are not important in the epizootiology of MG, MS, MM, or AI. 相似文献
5.
6.
Background
Although direct infiltration of papillary carcinoma of thyroid to larynx, trachea and esophagus is well recognized, lymphatic and vascular metastases to larynx and hypopharynx have rarely been reported. 相似文献7.
Synthesis of retinyl phosphate mannose and dolichyl phosphate mannose from endogenous and exogenous retinyl phosphate and dolichyl phosphate in microsomal fraction. Specific decrease in endogenous retinyl phosphate mannose synthesis in vitamin A deficiency. 总被引:5,自引:5,他引:0 下载免费PDF全文
Rat liver microsomal fraction synthesized Ret-P-Man (retinyl phosphate mannose) and Dol-P-Man (dolichyl phosphate mannose) from endogenous Ret-P (retinyl phosphate) and Dol-P (dolichyl phosphate). Ret-P-Man synthesis displayed an absolute requirement for a bivalent cation, and also Dol-P-Man synthesis was stimulated by bivalent metal ions. Mn2+ and Co2+ were the most active, with maximum synthesis of Ret-P-Man occurring at 5-10 mM: Mg2+ was also active, but at higher concentrations. At 5mM-Mn2+ the amount of endogenous Ret-P mannosylated in incubation mixtures containing 5 microM-GDP-mannose in 15 min at 37 degrees C was approx. 3 pmol/mg of protein. In the same assays about 7-10 pmol of endogenous Dol-P was mannosylated. Bivalentcation requirement for Ret-P-Man synthesis from exogenous Ret-P showed maximum synthesis at 2.5 mM-Mn2+ or -Co2+. In addition to Ret-P-Man and Dol-P-Man, a mannolipid co-chromatographing with undecaprenyl phosphate mannose was detected. Triton X-100 (0.5%) abolished Ret-P-Man synthesis from endogenous Ret-P and caused a 99% inhibition of Ret-P-Man synthesis from exogenous Ret-P. The presence of detergent (0.5%) also inhibited Dol-P-Man synthesis from endogenous Dol-P and altered the requirement for Mn2+. Microsomal fraction from Syrian golden hamsters was also active in Ret-P-Man and Dol-P-Man synthesis from endogenous Ret-P and Dol-P. At 5 mM-Mn2+ about 2.5 pmol of endogenous Ret-P and 3.7 pmol of endogenous Dol-P were mannosylated from GDP-mannose per mg of protein in 15 min at 37 degrees C. On the other hand, microsomal fraction from vitamin A-deficient hamsters contained 1.2 pmol of Ret-P and 14.1 pmol of Dol-P available for mannosylation. Since GDP-mannose: Ret-P and GDP-mannose: Dol-P mannosyltransferase activities were not affected, depletion of vitamin A must affect Ret-P and Dol-P pools in opposite ways. 相似文献
8.
Cyanobacterium Anacystis nidulans R2, Synechocystis sp. PCC 6803 (wild-type strain and mutants Delta2 and Delta3 lacking PSII and PSI, respectively), and Synechocystis sp. BO 9201 synthesize the pigment--protein complex CP36 (CPIV-4, CP43') under iron deficiency in the medium. Accumulation of CP36 is accompanied by structural reorganizations in the photosynthetic membranes. Integrating mean times of excitation relaxation (quenching) are 2.2 nsec (CP36), 1 nsec (PSI), and 420 psec (PSII in Fm state). The energy migration between CP36 and the photosystems can be described by a model of a one-layer ring of CP36 around core-complexes. The excitation from CP36 to PSI is transferred within <10 psec. The energy transfer from CP36 to PSII occurs during 170 psec. Cells with low content of CP36 probably contain only a latent fraction of unbound to phycobilisomes PSII which is the analog of PSIIbeta of higher plants. In PSI there are four binding sites for CP36 monomers per RC. PSII can bind up to 32 molecules of CP36 per RC. Cells with a large amount of CP36 contain monomer form of PSII core-complex which can bind eight tetramers of CP36 (8 binding sites). In conditions of iron deficiency only one monomer of a dimer PSII core-complex is destroyed and released chlorophyll is accumulated in CP36. Accumulation of CP36 in A. nidulans cells can be accompanied by membrane stacking which is similar to the stacking in chlorophyll b-containing organisms. The stacking can occur in the region of localization of PSII latent fraction bound to CP36. The membrane stacking shields PSII stromal surfaces from the aqueous phase for activation of electron transfer on the acceptor side of PSII. 相似文献
9.
P K Chiang P D Burbelo S A Brugh R K Gordon K Fukuda Y Yamada 《The Journal of biological chemistry》1992,267(7):4988-4991
3-Deazaadenosine analogs can function as inhibitors and also as alternative substrates of S-adenosylhomocysteine (AdoHcy) hydrolase. In cells treated with the analogs, AdoHcy invariably accumulates, leading to inhibition of cellular methylation. F9 teratocarcinoma cells, stably transfected with two collagen (IV) promoter-enhancer-CAT constructs and treated with 10 microM 3-deazaadenosine, 3-deaza-(+-)-aristeromycin or 3-deazaneplanocin, showed a strong induction of CAT activities without affecting differentiation. In comparison, the same 3-deaza analogs did not affect the CAT activity in F9 cells transfected with the beta-actin promoter-CAT construct. Furthermore, Northern blot analysis of endogenous mRNA from wild-type F9 cells treated with the 3-deaza nucleosides all showed an induction of the collagen alpha 1(IV) chain mRNA. Thus, the 3-deaza analogs most likely affect DNA methylation because their results are consistent with the previous observation that the integrated collagen alpha 1(IV) promoter-enhancer constructs were activated with 5-azacytidine. 相似文献
10.
Raffael AC Oliveira Ricardo VM Almeida Márcia DA Dantas Felipe N Castro Jo?o Paulo MS Lima Daniel CF Lanza 《BMC bioinformatics》2014,15(1)