共查询到20条相似文献,搜索用时 15 毫秒
1.
This paper is concerned with early development of transformed epithelial cells (TECs) in the presence of fibroblasts in the
tumor micro-environment. These two types of cells interact by means of cytokines such as transforming growth factor (TGF-β) and epidermal growth factor (EGF) secreted, respectively, by the TECs and the fibroblasts. As this interaction proceeds,
TGF-β induces fibroblasts to differentiate into myofibroblasts which secrete EGF at a larger rate than fibroblasts. We monitor
the entire process in silico, in a setup which mimics experiments in a Tumor Chamber Invasion Assay, where a semi-permeable
membrane coated by extracellular matrix (ECM) is placed between two chambers, one containing TECs and another containing fibroblasts.
We develop a mathematical model, based on a system of PDEs, that includes the interaction between TECs, fibroblasts, myofibroblasts,
TGF-β, and EGF, and we show how model parameters affect tumor progression. The model is used to generate several hypotheses on
how to slow tumor growth and invasion. In an Appendix, it is proved that the mathematical model has a unique global in-time
solution. 相似文献
2.
García Arocena D de Diego Y Oostra BA Willemsen R Mirta Rodriguez M 《Human genetics》2000,106(3):366-369
Fragile X syndrome is the most common cause of hereditary mental retardation. The FMR1 gene, which is involved in fragile X syndrome, contains a polymorphic CGG repeat, which expands in affected patients. Expanding triplet repeats have been shown to be a new type of mutation, termed "dynamic mutation", responsible for more than 12 genetic diseases. These mutations occur as multiple steps rather than as a single event. The first step leads to an unstable allele that then becomes increasingly unstable generally achieving further increases in copy or occasionally contraction. In this report, we describe a fragile X boy with both a hypermethylated full mutation and a deletion of 905 bp encompassing the CGG repeat. The upstream breakpoint is 438 bp 5' to the CGG repeat and the downstream breakpoint is 420 bp 3' of the triplet repeats. The deletion includes the ATG starting codon for translation of the FMR1 gene. This was confirmed by using FMRP immunocytochemistry both on blood smears and hair roots. The deleted region is flanked by a ccgg direct repeat next to the breakpoints; this may have had a critical role in the formation of a secondary DNA structure leading to the deletion. 相似文献
3.
The association between a single nucleotide polymorphism rs13281615A > G located in the 8q24 and breast cancer risk is still controversial and ambiguous. Hence, we performed a more convincing and precise estimation of the relationship between 8q24 and breast cancer by meta-analyzing the currently available evidence from literature. PubMed, Ovid, Medline, and Web of Science databases were searched. A total of 10 publications containing 11 studies including 40,762 cases and 50,380 controls were identified. Crude odds ratio with 95 % confidence interval was used to assess the strength of association. We observed that the 8q24 rs13281615A > G polymorphism was significantly correlated with breast cancer risk when all studies were pooled into the meta analysis. In the stratified analysis by ethnicity, significantly increased risks were also found among Caucasians for all genetic models. For mixed ethnicities, significantly increased risks were found for all genetic models except for the allele contrast model. However, no significantly increased risk was found among Africans for all genetic models. Interestingly, when stratified by BRCA1 mutation carriers status, significantly decreased breast cancer risk was found for allele contrast model. But significantly increased breast cancer risk was found in the BRCA2 mutation carriers for all genetic models except for the recessive model. There was no evidence for significant association between 8q24 rs13281615A > G polymorphism and breast cancer risk in BRCA1 and BRCA2 positive cohort in all comparable models. In conclusion, this meta-analysis suggests that the 8q24 rs13281615A > G polymorphism is a low-penetrant risk factor for developing breast cancer but may not be in Africans. 相似文献
4.
Hsuan-An Su Pei-Lun Sun Wen-Wei Sung Hui-Chin Chang Jen-Hung Yang Yu-Ping Hsiao 《Mycopathologia》2017,182(7-8):715-720
We report a 66-year-old female patient with deep dermatophytosis caused by zoophilic strain of Trichophyton interdigitale, a rare granulomatous presentation of Trichophyton species infection in patients with underlying systemic diseases, and she was successfully cured by itraconazole. Since the identification of Trichophyton mentagrophytes complex had been misused for years, a brief discussion of molecular diagnosis and taxonomy of T. mentagrophytes complex is given. The pathogenesis and comparison with cases reported in the literature are also discussed. 相似文献
5.
We describe and analyze a mathematical model for schistosomiasis in which infected snails are distinguished from susceptible
through increased mortality and no reproduction. We based the model on the same derivation as Anderson and May (J. Anim. Ecol.
47:219–247, 1978), Feng and Milner (A New Mathematical Model of Schistosomiasis, Mathematical Models in Medical and Health Science, Nashville,
TN, 1997. Innov. Appl. Math., Vanderbilt Univ. Press, Nashville, pp. 117–128, 1998), and May and Anderson (J. Anim. Ecol. 47:249–267, 1978), but used logistic growth both in human and snail hosts. We introduce a parameter r, the effective coverage of medical treatment/prevention to control the infection. We determine a reproductive number for
the disease directly related to its persistence and extinction. Finally, we obtain a critical value for r that indicates the minimum treatment effort needed in order to clear out the disease from the population. 相似文献
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8.
Both uniform persistence and the existence of periodic coexistence state are established for a periodically forced Droop model
on two phytoplankton species competition in a chemostat under some appropriate conditions. Numerical simulations using biological
data are presented as well to illustrate the main result.
Research supported in part by the NSERC of Canada and the MITACS of Canada. 相似文献
9.
We consider the estimation of a nonparametric smooth function of some event time in a semiparametric mixed effects model from
repeatedly measured data when the event time is subject to right censoring. The within-subject correlation is captured by
both cross-sectional and time-dependent random effects, where the latter is modeled by a nonhomogeneous Ornstein–Uhlenbeck
stochastic process. When the censoring probability depends on other variables in the model, which often happens in practice,
the event time data are not missing completely at random. Hence, the complete case analysis by eliminating all the censored
observations may yield biased estimates of the regression parameters including the smooth function of the event time, and
is less efficient. To remedy, we derive the likelihood function for the observed data by modeling the event time distribution
given other covariates. We propose a two-stage pseudo-likelihood approach for the estimation of model parameters by first
plugging an estimator of the conditional event time distribution into the likelihood and then maximizing the resulting pseudo-likelihood
function. Empirical evaluation shows that the proposed method yields negligible biases while significantly reduces the estimation
variability. This research is motivated by the project of hormone profile estimation around age at the final menstrual period
for the cohort of women in the Michigan Bone Health and Metabolism Study. 相似文献
10.
Serological identification and molecular characterization of B (A) 02 subtype
in patients and blood donors from Eastern China
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Wen Wu Yecui Zhang Xingying Guo Peng Wu Zhibo Zhang Xiangyan Huang 《Asia-Pacific Journal of Blood Types and Genes》2017,1(1):55-59
This study was designed to identify the rare?type?ABO?blood?groups, B(A) 02, from Eastern China. Three samples with discordant serological results during routine blood type identification and four samples from one sample’ family were selected. All of them were detected by serological method. The exon 6 and 7 of the ABO genes were amplified by PCR and sequenced. They were typed as AsubB by serology and as BO by genotype. In AsubB samples, nt 700C>G mutation was detected in B gene, which was previously defined as B(A)02 alleles. In these seven samples, six showed B(A)02/O01 and one showed B(A)02/O02.B(A)02 allele was found to be more common in this study than B(A)04 which is considered to be more frequent than B(A)02. The careful identification of rare blood types is important for the safety of clinical blood transfusion. 相似文献
11.
Visceral leishmaniasis is a multisystemic zoonotic disease that can manifest with several symptoms, including neurological
disorders. Because glial cells are extensively associated with the immune response within the brain, we evaluated the morphology
of astrocytes and microglia of dogs naturally infected with Leishmania chagasi. We used immunohistochemical and lectin-histochemical techniques for morphological analyses and we also examined the glial
correlation with lymphocyte infiltration of the brain and with the presence of anti-Leishmania antibodies within the cerebrospinal fluid of the dogs. Although we did not detect a shared morphological pattern in the astrocytes
or microglia in the brain tissue, these cells were more intensely labelled in infected dogs than in the control group. The
density of microglia was increased in the ependymal/subependymal area, thus demonstrating a strong correlation with the presence
of T lymphocytes and with cerebrospinal fluid antibody titres. Thus, our results indicate a pro-inflammatory state in the
brains of dogs naturally infected with L. chagasi and strongly suggest that microglia and astrocytes are involved in the pathogenesis of the neurological disorders of visceral
leishmaniasis in dogs. 相似文献
12.
Lin F Kong ZX Zhu HL Xue SL Wu JZ Tian DG Wei JB Zhang CQ Ma ZQ 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2004,109(7):1504-1511
Scab disease caused by Fusarium spp. has been a major concern for both wheat producers and consumers. Deployment of scab-resistant varieties is the major strategy to curb this disease. To identify the scab resistance genes in wheat cv. Wangshuibai, we produced a F6:7 recombinant inbred line (RIL) population by crossing Wangshuibai with the scab-susceptible cultivar Nanda2419. The RILs were evaluated for scab resistance in the field by single floret inoculation in two replicates in 2002 and one replicate in 2003. The number of diseased spikelets (NDS) and the length of diseased rachides (LDR) were investigated to reflect the Type II resistance. Among 654 simple sequence repeat (SSR) markers surveyed, 326 were found to be polymorphic between the parents. A partial molecular map was constructed with these markers that covered over 2,210 cM of the wheat genome. Six chromosome regions showed association with both NDS and LDR in a one-way anova analysis, even though the variation explained by them varied between the two traits. Eight intervals were detected for their association with Type II resistance through interval mapping, five of which were not identified in single-point analysis. The quantitative trait loci (QTL) with large effects were the ones in the interval of Xgwm533-3–Xgwm533-1 on chromosome 3B and in the interval of Xwmc539–Xbarc024 on chromosome 6B, whose alleles favoring resistance originate from Wangshuibai. In addition, a QTL whose resistance allele originated from Nanda2419 was consistently detected in the interval of Xs1021m–Xgwm47-1 on chromosome 2B. These results suggest that Wangshuibai is the major source for Type II resistance in this population. The markers associated with these QTL would facilitate the use of scab-resistant genes of Wangshuibai in scab resistance breeding programs of wheat.F. Lin and Z.X. Kong have equally contributed to this work. 相似文献
13.
The copines are a newly identified, widely distributed class of Ca2+-dependent, phospholipid-binding proteins that may be involved in cellular signaling. The copines have a characteristic domain structure: two C2 domains in the N-terminal region and a von Willebrand A (VWA) domain in the C-terminal region. Studies suggest that copines interact with target protein(s) via their VWA domain and recruit the proteins to a membrane location through the activity of the C2 domains. Arabidopsis thaliana (L.) Heynh. plants with loss-of-function mutations in the BONZAI 1/COPINE 1 (BON1/CPN1) gene display aberrant regulation of defense responses, including development of a lesion-mimic phenotype, an accelerated hypersensitive response, and increased resistance to a bacterial and an oomycetous pathogen. The phenotype of mutants in BON1/CPN1 is both humidity- and temperature-sensitive. In this study, we generated transgenic plants expressing either the VWA or the C2 portions of BON1/CPN1 in the wild-type Columbia-0 (Col-0) genetic background. Transgenic plants expressing the BON1/CPN1 C2 domain portion appeared like wild-type plants. However, transgenic plants expressing the BON1/CPN1 VWA domain exhibited a lesion-mimic phenotype that partially phenocopied bon1/cpn1 mutant plants. Our data suggest that BON1/CPN1 VWA domain fragments may interfere with the function of the full-length endogenous BON1/CPN1 protein, possibly by competing with the full-length BON1/CPN1 protein for association with target proteins normally bound to the full-length BON1/CPN1 protein. 相似文献
14.
Logan JD 《Bulletin of mathematical biology》2008,70(1):1-20
Studies document the fact that temperature changes strongly affect interactions in many consumer-resource systems through
altered, or shifted, phenologies. The mistiming of events, such as migration or emergence times, or the contraction or expansion
of development times can upset the normal synchronization and lead to increased or decreased predation events. In this paper,
we formulate a continuous time, phenologically-structured model of predator-prey interactions that is driven by temperature
variations. It is particularly applicable to arthropod interactions because their development rates are so strongly temperature
related. The model takes the form of a system of partial differential-integral equations for the species’ population densities
in development-time variables. In special cases, the model is analytically tractable and we find a closed-form solution. By
calculating density variations under different temperature regimes, the model gives a quantitative method for assessing the
effects of global temperature change on consumer-resource interactions. 相似文献
15.
Sørensen KK Kirk HG Olsson K Labouriau R Christiansen J 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2008,117(1):1-9
New potato (Solanum tuberosum) varieties are required to contain low levels of the toxic glycoalkaloids and a potential approach to obtain this is through marker-assisted selection (MAS). Before applying MAS it is necessary to map quantitative trait loci (QTLs) for glycoalkaloid content in potato tubers and identify markers that link tightly to this trait. In this study, tubers of a dihaploid BC(1) population, originating from a cross between 90-HAF-01 (S. tuberosum(1)) and 90-HAG-15 (S. tuberosum(2) x S. sparsipilum), were evaluated for content of alpha-solanine and alpha-chaconine (total glycoalkaloid, TGA) after field trials. In addition, tubers were assayed for TGA content after exposure to light. A detailed analysis of segregation patterns indicated that a major QTL is responsible for the TGA content in tubers of this potato population. One highly significant QTL was mapped to chromosome I of the HAG and the HAF parent. Quantitative trait loci for glycoalkaloid production in foliage of different Solanum species have previously been mapped to this chromosome. In the present research, QTLs for alpha-solanine and alpha-chaconine content were mapped to the same location as for TGA content. Similar results were observed for tubers exposed to light. The simple sequence repeat marker STM5136 was closely linked to the identified QTL. 相似文献
16.
V.J.M. Baggen M.M.P. Driessen M.C. Post A.P. van Dijk J.W. Roos-Hesselink A.E. van den Bosch J.J.M. Takkenberg G.T Sieswerda 《Netherlands heart journal》2016,24(6):374-389
Background
Identification of patients at risk of deterioration is essential to guide clinical management in pulmonary arterial hypertension (PAH). This study aims to provide a comprehensive overview of well-investigated echocardiographic findings that are associated with clinical deterioration in PAH.Methods
MEDLINE and EMBASE databases were systematically searched for longitudinal studies published by April 2015 that reported associations between echocardiographic findings and mortality, transplant or clinical worsening. Meta-analysis using random effect models was performed for echocardiographic findings investigated by four or more studies. In case of statistical heterogeneity a sensitivity analysis was conducted.Results
Thirty-seven papers investigating 51 echocardiographic findings were included. Meta-analysis of univariable hazard ratios (HRs) and sensitivity analysis showed that presence of pericardial effusion (pooled HR 1.70; 95?% CI 1.44–1.99), right atrial area (pooled HR 1.71; 95?% CI 1.38–2.13) and tricuspid annular plane systolic excursion (TAPSE; pooled HR 1.72; 95?% CI 1.34–2.20) were the most well-investigated and robust predictors of mortality or transplant.Conclusions
This meta-analysis substantiates the clinical yield of specific echocardiographic findings in the prognostication of PAH patients in day-to-day practice. In particular, pericardial effusion, right atrial area and TAPSE are of prognostic value.17.
18.
Ulvik A Ueland PM Fredriksen A Meyer K Vollset SE Hoff G Schneede J 《Human genetics》2007,121(1):57-64
Two functional single nucleotide polymorphisms, 677C > T and 1298A > C have been described for the methylenetetrahydrofolate
(MTHFR) gene. Both are associated with reduced enzyme activity in vitro. For the 677T, but not the 1298C allele, significantly
lower serum folate and higher plasma total homocysteine (tHcy) have been reported. We genotyped 10,034 middle-aged (50–64 years
old) subjects and measured serum folate and tHcy. Within strata of 677 genotypes, 1,298 genotypes had significantly different
serum folate and tHcy (P ≤ 0.03 for all comparisons). Each additional 1298C allele reduced mean serum folate and increased mean tHcy, by (on average)
4.5 and 3.0%, respectively. In comparison, within strata of 1,298 genotypes, the increase from no, to one 677T-allele reduced
serum folate and increased tHcy by, 7.1 and 6.3%, respectively. Lowest serum folate and highest tHcy level was found for the
677TT/1298AA genotype. The difference in tHcy was significantly larger at low folate than at high folate when genotypes 677TT/1298AA
and 677CT/1298AA, 677CT/1298AC and 677CC/1298AC, and genotypes 677CT/1298AC and 677CT/1298AA were compared. We interpreted
these data in the context of a model of the MTHFR enzyme that describes the enzyme as a dimer that mainly exist in six different
configurations. The model reconciled the observed phenotypic effects of the 677/1,298 combination genotypes with previous
in vitro measurements, and identified enzyme configurations that are sensitive to low folate levels. In conclusion, this report
demonstrates functional inference of the MTHFR 677 C > T and 1,298 A > C polymorphisms from a large-scale epidemiological
study. 相似文献
19.
Sang-Hyun Han Kwang-Yun Shin Sung-Soo Lee Moon-Suck Ko Dong Kee Jeong Hong-Shik Oh Byoung-Chul Yang In-Cheol Cho 《Molecular biology reports》2010,37(1):467-471
Genetic polymorphisms in the glycogen debrancher enzyme (AGL) gene were assessed with regard to their association with growth and carcass traits in the F2 population crossbred Landrace and Jeju (Korea) Black pig. Three genotypes representing the insertion and/or deletion (indel)
polymorphisms of short interspersed nuclear element were detected at frequencies of 0.278 (L/L), 0.479 (L/S), and 0.243 (S/S), respectively. The AGL S allele-containing pigs evidenced significantly heavier body weights at birth, the 3rd week, 10th week, and 20th week during
developmental stages and higher average daily gains during the late period than were noted in the L/L homozygous pigs (P < 0.05), respectively. However, average daily gains during the early period were not significantly associated with genotype
distribution (P > 0.05). With regard to the carcass traits, the S allele pigs (S/-) evidenced significantly heavier carcass weights and thicker backfat than was measured in L/L homozygous pigs (P < 0.05). However, body lengths, meat color, and marbling scores were all found not to be statistically significant (P > 0.05). Consequently, the faster growth rate during the late period and backfat deposition rather than intramuscular fat
deposition cause differences in pig productivity according to genotypes of the AGL gene. These findings indicate that the AGL genotypes may prove to be useful genetic markers for the improvement of Jeju Black pig-related crossbreeding systems. 相似文献
20.
Marius Erbert Steffen Rechner Matthias Müller-Hannemann 《Algorithms for molecular biology : AMB》2017,12(1):9