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1.
A model of the statistical structure of symbol sequences that takes into account correlations between the symbols is proposed.
The formulas resulting from this model are tested by using empirical data relating to the English language; a satisfactory
agreement between the calculated and empirical values is obtained. A formula δ=αl connecting the redundancy δ of a code with the intensity α of correlations and the mean lengthl of compact groups (“words”) of the code is assumed. It is found that the correlation α between adjacent amino-acid residues
in protein molecules is less than 10−3. In order to detect this correlation by means of the χ2 test, a sample of not less than 25,000 dipeptides is required. 相似文献
2.
Takahiro Ohkubo Koh Kidena Naohiko Takimoto Akihiro Ohira 《Journal of molecular modeling》2011,17(4):739-755
We measured the water uptakes and proton conductivities of a Nafion membrane and three sulfonated polyether sulfone membranes
(SPESs) with different values of ion-exchange capacity (IEC = 0.75, 1.0 and 1.4 meq/g) in relation to relative humidity in
order to apply the findings to polymer electrolyte membrane fuel cells. The number of water molecules per sulfonic acid group
λ at each humidity level was independent of the relative humidity for all membranes, but the proton conductivities of the SPESs
were inferior to that of Nafion for the same λ value. Classical molecular dynamics simulations for the same membranes were carried out using a consistent force field at
λ = 3, 6, 9, 12 and 15. The structural properties of water molecules and hydronium ions at a molecular level were estimated
from radial distribution functions and cluster size distributions of water. We found that the radial distribution function
of S(sulfonic acid)–S(sulfonic acid) of Nafion at λ = 3 indicated a significant correlation between the S–S pair, due to water channels, while the S–S pair of the SPESs showed
a poor correlation. The cluster size distribution of water was also calculated in order to estimate the connectivity of the
water channel. It is clear that some water is present in the SPESs as small, isolated clusters, especially when the water
content is low. 相似文献
3.
Daniela Josa Angeles Peña-Gallego Jesús Rodríguez-Otero Enrique M. Cabaleiro-Lago 《Journal of molecular modeling》2011,17(6):1267-1272
A comprehensive MP2/6-311 + G(d,p) and B3LYP/6-311 + G(d,p) study of the aromatic character of phospholes, P
n
(CH)4-n
PH with n = 0-4 was conducted. For this purpose, the structures for these compounds were optimized at both theoretical levels and different
magnetic properties (magnetic susceptibility anisotropy, χanis, and the nucleus-independent chemical shifts, NICS) were evaluated. For comparison, these magnetic properties were also calculated
in the optimized structures with planarity constraints. We have also applied the ACID (anisotropy of the current-induced density)
method in this analysis. The main conclusions are the aromatic character of these compounds, the relationship between aromaticity
and planarity and the importance of other factors in this aromaticity. 相似文献
4.
Xuming Wang Yong Yang Chulang Yu Jie Zhou Ye Cheng Chengqi Yan Jianping Chen 《Molecular biotechnology》2010,46(3):211-218
Artificial microRNA (amiRNA) has become a powerful tool for gene silencing in plants. A new method for easy and rapid construction
of rice artificial miRNA vector is described. The procedure involved modification of the pCAMBIA1300-UR vector by insertion
of a ‘vector modification fragment’. This was prepared from the precursor of Os-amiR528 by eliminating the central miRNA-containing region while simultaneously creating an AfeI restriction site. The fragment was then introduced to the destination vector to produce a multipurpose ‘Highly Efficient
gene Silencing Compatible vector’ (HESC vector). AfeI was used to produce linearized HESC vectors, and a blunt end PCR product that included amiRNA sequence was cloned into this
site by a single ligation reaction to create the completed amiRNA vector. Tests showed that the method was highly efficient,
and greatly reduced the time needed for vector construction and resulted in a DNA sequence identical to that of the current
method, making it particularly suitable for use in a systems biology approach to functional genomic research. 相似文献
5.
T. V. Zheikova M. V. Golubenko S. V. Buikin O. Yu. Botkina O. A. Makeeva A. A. Lezhnev E. V. Kalyanov I. V. Tsimbalyuk V. N. Maksimov M. I. Voevoda V. M. Shipulin V. P. Puzyrev 《Molecular Biology》2012,46(3):433-437
In this study, we genotyped polymorphism in GPX1 Pro198→Leu (C→T) rs 1050450 in four groups, i.e., patients with coronary artery disease, people who lived a long time (over 90 years), people who died early (before 55 years) from cardiovascular disease, and the Russian population as a control group. We have found a significant higher T-allele frequency in men with coronary artery disease, i.e., 34.84% (χ2 = 5.228, p = 0.022; OR =1.46), and in men who died early from cardiovascular diseases, 38.16% (χ2 = 6.461, p = 0.011; OR = 1.69) compared to men in the control group, 26.8%. Moreover, a significantly higher genotype TT frequency has been shown in patients with coronary artery disease and myocardial infarction before age 50, which is 19.44% compared to the control group, which was 7.28% (χ2 = 9.55, p = 0.002). The TT frequency in individuals who lived a long time (4.39%) was the lowest and differed significantly from the group with coronary artery disease, which was 12.79% (χ2 = 8.07, p = 0.0045), and from the subgroup with coronary artery disease with myocardial infarction before age 50, which was 19.44% (χ2 = 14.49, p = 0.0001). Thus, our results indicate that the TT allele (Leu) of GPX1 Pro198→Leu (C > T) polymorphism is unfavorable for successful aging; it leads to predisposition to coronary artery disease, early myocardial infarction (before age 50), and early death (before age 55). 相似文献
6.
Kanai TH Tanioka Y Tanigawa M Matsumoto Y Ueda S Onodera T Matsumoto Y 《Immunogenetics》1999,50(5-6):295-300
The loci encoding the β chain of the pig major histocompatibility complex (MHC) class II antigens, SLA-DR and -DQ, have been
known to exhibit a remarkable degree of allelic polymorphism. Here, to understand the generation of SLA class II polymorphism, 25 SLA-DRB1 and 24 SLA-DQB genes including newly identified 12 SLA-DRB1 and 7 SLA-DQB genes obtained from miniature pigs were analyzed based on the nucleotide and deduced amino acid sequences. Most of the allelic
diversity was attributed to the variable sequences which encode a β1 domain consisting of a β-pleated sheet followed by an α helix. In the β1 domain coding region, there were four GC-rich sequences, which have been considered to involve the intra-exon sequence exchange
also in other gene evolutions. The first and second GC-rich sequences were χ-like sequences, which have been shown to be a
putative recombination signal, and were stably conserved among SLA-DRB1 and DQB genes. These χ-like sequences identified in SLA-DRB1 and SLA-DQB were found to encode the first turning point of the β-pleated sheet and the boundary between the β-pleated sheet and the
α helix. Analysis of clustered sequence variation also suggested intra-exon gene conversions in which the χ-like sequences
act as putative breakpoints. In addition to point mutations and selection mechanism, intra-exon gene conversions must be an
important mechanism in the generation of allelic polymorphism at the SLA-DRB1 and SLA-DQB.
Received: 3 December 1998 / Revised: 29 June 1999 相似文献
7.
Eberhard O. Voit 《Biometrical journal. Biometrische Zeitschrift》1992,34(7):855-878
In many statistical applications a data set needs to be evaluated but there is no solid information about which probability distribution might be most appropriate. Typical solutions to this problems are: to make assumptions that facilitate mathematical treatment; to use a family of distribution functions that contains all relevant distributions as special cases; or, to employ nonparametric methods. All three solutions have disadvantages since assumptions are usually difficult to justify, families of distributions contain too many parameters to be of practical use, and nonparametric methods make it difficult to characterize data in a succinct quantitative form. The S-distribution introduced here is a compromise between the conflicting goals of simplicity in analysis and generality in scope. It is characterized by four parameters, one of which reflects its location, the second one its spread, and the remaining two its shape; transformation to a standard form reduces the number of free parameters to two. Cumulatives and densities are computed numerically in fractions of seconds, key features like quantiles and moments are easily obtained, and results can be presented in terms of parameter values. The S-distribution rather accurately models different distribution functions, including central and noncentral distributions, and thus competes in flexibility with some distribution families. As an approximation, the S-distribution provides a graphical method for demonstrating relationships between distributions, such as the relationships between central F, χ2 and χ?2 or central and noncentral t, χ-1, and normal. 相似文献
8.
L. Banci I. Bertini K. L. Bren M. A. Cremonini H. B. Gray C. Luchinat P. Turano 《Journal of biological inorganic chemistry》1996,1(2):117-126
The availability of NOE constraints and of the relative solution structure of a paramagnetic protein permits the use of pseudocontact
shifts as further structural constraints. We have developed a strategy based on: (1) determination of the χ tensor anisotropy
parameters from the starting structure; (2) recalculation of a new structure by using NOE and pseudocontact shift constraints simultaneously; (3) redetermination of the χ tensor anisotropy parameters from the new structure,
and so on until self-consistency. The system investigated is the cyanide derivative of a variant of the oxidized Saccharomyces cerevisiae iso-1-cytochrome c containing the Met80Ala mutation. The structure has been substantially refined. It is shown that the analysis of the deviation
of the experimental pseudocontact shifts from those calculated using the starting structure may be unsound, as may the simple
structure refinement based on the pseudocontact shift constraints only.
Received: 11 July 1995 / Accepted: 30 October 1995 相似文献
9.
NOEs between the β-protons of cysteine residues across disulfide bonds in proteins provide direct information on the connectivities
and conformations of these important cross-links, which are otherwise difficult to investigate. With conventional [U-13C, 15N]-proteins, however, fast spin diffusion processes mediated by strong dipolar interactions between geminal β-protons prohibit the quantitative measurements and thus the analyses of long-range NOEs across disulfide bonds. We describe
a robust approach for alleviating such difficulties, by using proteins selectively labeled with an equimolar mixture of (2R, 3S)-[β-13C; α,β-2H2] Cys and (2R, 3R)-[β-13C; α,β-2H2] Cys, but otherwise fully deuterated. Since either one of the prochiral methylene protons, namely β2 (proS) or β3 (proR), is always replaced with a deuteron and no other protons remain in proteins prepared by this labeling scheme, all four of
the expected NOEs for the β-protons across disulfide bonds could be measured without any spin diffusion interference, even
with long mixing times. Therefore, the NOEs for the β2 and β3 pairs across each of the disulfide bonds could be observed at
high sensitivity, even though they are 25% of the theoretical maximum for each pair. With the NOE information, the disulfide
bond connectivities can be unambiguously established for proteins with multiple disulfide bonds. In addition, the conformations
around disulfide bonds, namely χ2 and χ3, can be determined based on the precise proton distances of the four β-proton pairs, by quantitative measurements of the
NOEs across the disulfide bonds. The feasibility of this method is demonstrated for bovine pancreatic trypsin inhibitor, which
has three disulfide bonds. 相似文献
10.
Kilic A Guclu AU Senses Z Bedir O Aydogan H Basustaoglu AC 《Antonie van Leeuwenhoek》2008,94(4):607-614
Methicillin-resistant Staphylococcus aureus (MRSA) cause serious community-acquired and nosocomial diseases all over the world. We determined the SCCmec types and occurrence of the PVL gene by using TaqMan real-time PCR method, and correlated these with phenotypic antibiotic
susceptibility patterns for MRSA strains collected from Gulhane Military Medical Academy Hospital (GMMAH) during 4 years study
period. To our knowledge, this is the first report from Turkey of molecular SCCmec typing analysis of MRSA stains. A total of 385 clinical MRSA isolates collected in the clinical and Microbiology Laboratory
at GMMAH between 2003 and 2006 were included in the study. Overall, SCCmec types-I, II, III, IV, V, nontypeable and PVL occurrence
were detected in 11 (2.8%), 3 (0.8%), 316 (82.1%), 20 (5.1%), 20 (5.1%), 15 (3.9%) and 5 (1.3%) isolates, respectively. A
total of 330 (85.5%) were SCCmec-I/II/III and 40 (10.3%) were SCCmec IV/V. SCCmec-I/II/III isolates were recovered more from
patients with serious infections in surgical departments especially those with intensive care units than the SCCmec-IV/V isolates (χ2 = 13.560, P < 0.001). SCCmec-I/II/III MRSA strains were predominantly recovered from blood stream (53.0%, P = 0.014), while SCCmec-IV/V strains were predominately isolated from skin and soft tissue and abscess (55.0%, P < 0.001). The PVL gene was detected in 10.0% of SCCmec-IV/V isolates in contrast to 0.3% in SCCmec-I/II/III (χ2 = 25.164, P < 0.001). SCCmec-I/II/III MRSA strains were more resistant to clindamycin (χ2 = 5.078, P = 0.024), amoxicillin-clavulanate (χ2 = 84.912, P < 0.001), erythromycin (χ2 = 4.651, P = 0.031), gentamicin (χ2 = 24.869, P < 0.001), and rifampin (χ2 = 18.878, P < 0.001) than SCCmec-IV/V MRSA strains. This data indicates that SCCmec-III MRSA strains that do not carry the PVL gene are the predominant MRSA
strains in our hospital setting in Ankara, capital of Turkey and that SCCmec-I/II/III MRSA strains may cause serious infections
in surgical departments especially those with intensive care units. 相似文献
11.
General diffusion pores and specific porin channels from outer membranes of gram-negative bacteria were reconstituted into
lipid bilayer membranes. The current noise of the channels was investigated for the different porins in the open state and
in the ligand-induced closed state using fast Fourier transformation. The open channel noise exhibited 1/f-noise for frequencies up to 200 Hz. The 1/f-noise was investigated using the Hooge formula (Hooge, Phys. Lett.
29A: 139–140 (1969)), and the Hooge parameter α was calculated for all bacterial porins used in this study. The 1/f-noise was in part caused by slow inactivation and activation of porin channels. However, when care was taken that during
the noise measurement no opening or closing of porin channels occurred, the Hooge Parameter α was a meaningful number for a given channel. A linear relationship was observed between α and the single-channel
conductance, g, of the different porins. This linear relation between single-channel conductance and the Hooge parameter α could be qualitatively explained by assuming that the passing of an ion through a bacterial porin channel is—to
a certain extent—influenced by nonlinear effects between channel wall and passing ion.
Received: 8 May 1996/Revised: 27 January 1997 相似文献
12.
Environmental heterogeneity in natural ecosystems influences several parameters at the population and community levels. In
freshwater ecosystems, habitat heterogeneity can be provided by macrophyte species with different structural shapes. Previous
studies suggest that aquatic plants with more complex architectures will support higher number, biomass, and taxon richness
of macroinvertebrates than plants with simpler shape. We investigated the influence of macrophyte structural heterogeneity
(quantified by fractal dimension) and food availability (represented by epiphytic biomass) on several parameters (number of
individuals, biomass, body size distribution, taxon richness, and diversity) of the macroinvertebrate community in a Pampean
stream. Four submerged macrophyte species (Egeria densa, Elodea ernstae, Ceratophyllum demersum, and Stuckenia striata) and associated macroinvertebrates were sampled in late spring, summer, and autumn. Plants were photographed and fractal
dimension was estimated from the images by the box-counting method. Fractal dimension was independent of plant surface area
per unit of macrophyte biomass and differed significantly among species. Mean fractal dimension varied between 1.29 and 1.62,
and increased following the sequence E. densa → S. striata → E. ernstae → C. demersum. Macrophyte species with higher fractal dimension supported a greater abundance of macroinvertebrates, especially those of
small body size (500–1,000 μm); but fractal dimension was unrelated to macroinvertebrate biomass, richness, and diversity.
However, overall animal biomass was significantly associated to the epiphytic abundance. Consequently, macrophyte heterogeneity
influences macroinvertebrate density and body size distribution, while animal biomass depends on epiphytic food resources
provided by plants. 相似文献
13.
Guo Xia Faming Pan Fangfang Liao Xiaowu Tang Rui Ge Yang Mei Heping Pan Shengqian Xu Jianhua Xu 《Molecular biology reports》2010,37(1):297-300
Ankylosing spondylitis (AS) is a rhematoid arthritis, which is a common autoimmune disease with a complex genetic etiology.
Although HLA-B27 has been identified to be associated with AS, a number of other genes may also be involved in the disease.
Fc receptor-like 3 (FCRL3) gene has been shown to be associated with rheumatoid arthritis in Japanese population. Here we
aim to explore the association FCRL3 gene and susceptibility to human leukocyte antigen (HLA)-B27-positive AS in Han Chinese
population. Among 169 AS patients, the frequencies of C and T (rs7522061) in FCRL3 gene were 38.7 and 61.3%, respectively; in 184 controls (HLA-B27-positive), the frequencies of C and T were 38.6 and 61.4%, respectively. The frequencies of alleles and genotype are not of statistically significant difference
in two groups (χ2 = 0.000, P = 0.983; χ2 = 0.099, P = 0.952, respectively),but the distribution of HLA-B27 subtypes are statistically significant difference between cases and
controls (χ2 = 8.214, P = 0.042). Our data reveal that the FCRL3 gene does not appear associated with susceptibility to HLA-B27-positive AS in Han
Chinese population. 相似文献
14.
We have characterized the conduction and blocking properties of a chloride channel from rough endoplasmic reticulum membranes
of rat hepatocytes after incorporation into a planar lipid bilayer. Our experiments revealed the existence of a channel with
a mean conductance of 164 ± 5 pS in symmetrical 200 mm KCl solutions. We determined that the channel was ten times more permeable for Cl− than for K+, calculated from the reversal potential using the Goldman-Hodgkin-Katz equation. The channel was voltage dependent, with
an open probability value ranging from 0.9 at −20 mV to 0.4 at +60 mV. In addition to its fully open state, the channel could
also enter a flickering state, which appeared to involve rapid transitions to zero current level. Our results showed a decrease
of the channel mean open time combined with an increase of the channel mean closed time at positive potentials. An analysis
of the dwell time distributions for the open and closed intervals led to the conclusion that the observed fluctuation pattern
was compatible with a kinetic scheme containing a single open state and a minimum of three closed states. The permeability
sequence for test halides determined from reversal potentials was Br− > Cl− > I−≈ F−. The voltage dependence of the open probability was modified by the presence of halides in trans with a sequence reflecting the permeability sequence, suggesting that permeant anions such as Br− and Cl− have access to an internal site capable of controlling channel gating. Adding NPPB to the cis chamber inhibited the channel activity by increasing fast flickering and generating long silent periods, whereas channel
activity was not affected by 50 μm DNDS in trans. The channel was reversibly inhibited by adding phosphate to the trans chamber. The inhibitory effect of phosphate was voltage-dependent and could be reversed by addition of Cl−. Our results suggest that channel block involves the interaction of HPO2−
4 with a site located at 70% of the membrane span.
Received: 10 January 1997/Revised: 29 May 1997 相似文献
15.
Ahmed W Malik M Saeed I Khan AA Sadeque A Kaleem U Ahmed N Ajmal M Azam M Qamar R 《Molecular biology reports》2011,38(4):2541-2548
A case–control association study on 229 Myocardial Infarction (MI) patients and 217 healthy controls was carried out to determine
the role of tissue-plasminogen activator (t-PA) (Alu-repeat insertion (I)/deletion (D)) and plasminogen activator inhibitor
(PAI-1) (4G/5G insertion/deletion) polymorphisms with MI in the Pakistani population. In MI patients the genotype distribution
of the PAI-1 gene was not found to be different when compared with the unaffected controls (P > 0.05, χ2 = 1.03). The risk allele 4G was also not associated with MI (P > 0.05, χ2 = 0.46, odds ratio (OR) = 1.1 (95% confidence interval (CI) = 0.84–1.43), P > 0.05). Similarly, the genotype frequencies of t-PA I/I, I/D and D/D were not different from the unaffected controls (P > 0.05, χ2 = 1.60), and the risk allele “I” was not found to be associated with MI (P > 0.05, χ2 = 1.35, OR = 0.86 (95% CI = 0.66–1.11), P > 0.05). However, when the data were distributed along the lines of gender a significant association of the 4G/4G PAI-1 genotype
was observed with only the female MI patients (P < 0.05, z-test = 2.21). When the combined genotypes of both the polymorphisms were analyzed, a significant association of
MI was observed with the homozygous DD/4G4G genotype (P < 0.01, z-test = 2.61), which was specifically because of the female samples (P = 0.01, z-test = 2.53). In addition smoking (P < 0.001, χ2 = 13.52, OR = 3.45 (95% CI = 1.77–6.94)), diabetes (P < 0.001, χ2 = 22.45, OR = 8.89 (95% CI = 2.96–29.95)), hypertension (OR = 7.76 (95% CI = 2.88–22.68), P < 0.001) family history (P < 0.001, χ2 = 13.72, OR = 3.7 (95% CI = 1.71–8.18)) and lower HDL levels (P < 0.05) were found to be significantly associated with the disease. In conclusion the PAI-1 gene polymorphism was found to
have a gender specific role in the female MI patients. 相似文献
16.
Aggrecan, which is a well-known proteoglycan in joint cartilage, also exists in the spinal cord and plays an important role in maintaining water content in the extracellular matrix structure. In this study, we first examined the variable number of tandem repeat (VNTR) polymorphism of the aggrecan gene in 227 HTLV-I associated myelopathy/tropical spastic paraparesis (HAM/TSP) patients, in 217 HTLV-I-infected healthy carriers (HCs), and in 85 normal controls. The VNTR allele 28 (1,630 bp) was more frequently observed in HAM/TSP patients than in HCs (χ
2=12.02, p=0.0005, odds ratio 1.79, 95% C.I. 1.29–2.50) and in controls (χ
2=13.43, p=0.0002, odds ratio 2.54, 95% C.I. 1.52–4.25), although this allele was not related to disease progression or to HTLV-I provirus load. We also found that the aggrecan concentration in cerebrospinal fluid (CSF) from rapidly progressive HAM/TSP patients was significantly higher than in slowly progressive patients (corrected p=0.0145) but not in infected non-inflammatory neurological other disease controls (OND) (corrected p=0.078). We then analyzed this aggrecan VNTR polymorphism in the different set of patients with HAM/TSP (n=58) and healthy carriers (n=70). This analysis, again, revealed that allele 28 was detected more frequently in HAM/TSP group than in HCs (χ
2=11.03, p=0.0009, odd ratio 3.04, 95% C.I. 1.55–5.97). The reproducibility of our study was regarded as a second- or third-class association by comparing combined p values and the Better Associations for Disease and GEnes (BADGE) system. Our results suggest that aggrecan polymorphism can be a novel genetic risk factor for developing HAM/TSP.Financial support: Grant in Aid for Research on Brain Science of the Ministry of Health, Labor and Welfare, Japan. 相似文献
17.
W. J. Duan T. Z. Yang Y. Dai D. L. Li X. Q. Zhang H. B. Liu N. Li C. G. Wang 《Biologia Plantarum》2012,56(4):771-774
We compared stomatal ammonia compensation point (χs) and its metabolic regulation in tobacco (Nicotiana tabacum) leaves of a quick-leaf-senescence phenotype ZY90 and a slow-leaf-senescence phenotype NC89. Compared with NC89, ZY90 had significantly higher χs values between 40 and 60 d after leaf sprouting in spite of its lower nitrogen content. During the same time, a steeper decline in glutamine synthetase activity was detected in ZY90 leaves, simultaneously with a steep increase in χs. These results suggested that the quick leaf senescence phenotype exhibited high NH3 emission potential due to efficient nitrogen recycling and remobilization, and glutamine synthetase played a key role in regulating χs in ZY90. 相似文献
18.
?brahim Doymaz 《Food biophysics》2011,6(4):461-467
The drying characteristics of pomegranate arils were investigated in temperature range of 50–70 °C. The increase in drying
air temperature resulted in a decrease in drying time. The drying rate was found to increase with temperature, thereby reducing
the total drying time. Thirteen drying models were evaluated in the kinetics research. The goodness of fit of the proposed
models was evaluated by using the determination of coefficient (R
2
), mean relative percent error (P), reduced chi-square (χ
2), and root means square error (RMSE). The Midilli et al. model showed a better fit to experimental drying data as compared to other models. Effective moisture
diffusivity (D
eff) ranged from 9.447 × 10−11 to 3.481 × 10−10 m2/s as calculated by the Fick’s second law of diffusion. The temperature dependence of the value of effective moisture diffusivity
followed an Arrhenius-type relationship. The activation energy for the moisture diffusion was determined to be 60.34 kJ/mol. 相似文献
19.
The aim of this work is to describe an epidemiological model for a capybara (Hydrochaeris hydrochaeris) population. The model
considers a tabanid (“mutuca”) population (Diptera: tabanidae), as a vector for the disease called “mal de las caderas” in Estero del Ibera, Corrientes, Argentina. The study of this problem has ecological and economical importance since the
meat and the hide of the capybara can be an exploitation resource. At first, a threshold value is determined as a function
of the model parameters, obtaining a critical carrying capacity which determines the disease propagation or eradication. Then
as the carrying capacity condition for the disease existence is satisfied, the existence of traveling wave solution is studied.
Independent speeds are considered for the susceptible capybaras, the noninfected insect, and the disease. The speed of propagation
for this model is obtained as function of model parameters followed by a discussion of strategies for controlling the spread
of the disease.
N.A. Maidana is a fellowship Fapesp and partially supported by Grant Fapesp (temático). 相似文献
20.
Detection of chromosomal aneuploidy in endometriosis by multi-color fluorescence in situ hybridization (FISH) 总被引:5,自引:0,他引:5
Jong-Chul Shin Helen L. Ross Sherman Elias Dianne D. Nguyen Dorothy Mitchell-Leef Joe Leigh Simpson F. Z. Bischoff 《Human genetics》1997,100(3-4):401-406
Endometriosis affects 10–15% of women of reproductive age and is a common cause of infertility and pelvic pain. Although
endometriosis is characterized by abnormal growth or turn-over of cells, the genetic changes involved remain unclear. We employed
a multi-color fluorescence in situ hybridization (FISH) strategy to determine the incidence of somatic chromosomal numeric
alterations in severe/late stage endometriosis. Using alpha-satellite sequence-specific DNA probes for chromosomes 7, 8, 11,
12, 16, 17, and 18, simultaneous two- and three-color FISH were performed to evaluate the frequency of monosomic, disomic,
and trisomic cells in normal control and endometriotic tissue specimens. In one of four endometriosis samples studied, a significantly
higher frequency of monosomy for chromosome 17 (14.8%, χ2
4 = 53.3, P < 0.0001) and 16 (8.8%, χ2
4 = 11.4, P < 0.05) was observed. An increased number of cells with chromosome 11 trisomy (14.8%, χ2
4 = 96.2, P < 0.0001) were detected in a second case. In a third case, a distinct colony of nuclei with chromosome 16 monosomy (14.1%,
χ2
4 = 21.39, P < 0.005) was detected. Acquired chromosome-specific aneuploidy may be involved in endometriosis, reflecting clonal expansion
of chromosomally abnormal cells. That candidate tumor suppressor genes and oncogenes have been mapped to chromosomes 11, 16,
and 17 suggests that chromosomal loss or gain plays a role in the development and/or progression of endometriosis.
Received: 27 December 1997 / Accepted: 14 April 1997 相似文献