State Responses of Several Classes of Linear Systems Based on Fundamental Matrices.

State responses for several classes of linear systems are investigated in this article. The involved systems include state-delayed linear systems, and high-order linear systems. At first, the single-fundamental-matrix-based approach is extended to these systems, and their state responses are expressed by their fundamental matrices (FMs). In addition, the multiple-FMs-based approach is presented for these systems. Based on a group of FMs, the state responses for the considered time-invariant systems are derived. For the considered time-variant systems, their state responses are explicitly expressed by their transition matrices. As an application of the fundamental-matrix-based approach, a stabilizing control law is designed for a class of high-order fully actuated continuous-time linear systems with a single input-delay.

On Bicon-Numbers With Their Basic Properties and Applications in Quantum Systems.

Motivated by the fact that there exists the operation of conjugation in quantum systems, the concept of bicon-numbers is proposed in this article. The bicon-numbers are defined by introducing two symbolic parameters into the set of complex numbers. The basic functions of these two symbolic parameters are specified by an axiom which abstracts the operation of complex conjugation. Basic properties are developed for the operations of addition and multiplication in the bicon-number set. In addition, several different forms are given for bicon-numbers, and the corresponding operation rules are established. By exploring the relations of the vensors in the bicon-number set, the structure of the bicon-number set is depicted, and real matrix representations of bicon-numbers are also presented. Besides, bicomplex matrix representations for bicon-numbers are also investigated in view that the operation of multiplication for bicomplex numbers possesses commutativity property. In addition, the matrices with bicon-numbers as entries are investigated, and state responses of some quantum systems are given within the framework of bicon-numbers.

A Parametric Predictor for Disturbance Attenuation of Discrete-Time Linear Systems With Input Delays.

In this article, a parametric predictor is constructed to predict the future state of a discrete-time linear system with a known constant input delay and external disturbances by introducing a tuning parameter. Then, a predictor-based feedback controller is given to attenuate the unknown disturbance signal. The ultimate bound of the state of the resulted closed-loop system is obtained when the state feedback control law based on this novel predictor is utilized. Based on the expression of the ultimate bounds, the capacity to attenuate the unknown disturbance is analyzed for the parametric predictor within a certain range of parameters. An easily calculated interval is provided for the range of the tuning parameter such that the proposed predictor achieves a better disturbance attenuation capacity. Moreover, for the unknown constant disturbance, the estimation error between the proposed predictor with an arbitrary parameter and the future state can be eliminated. Finally, two numerical examples are utilized to illustrate the effectiveness of the proposed parametric predictor for bounded time-varying disturbances.

Autophagic regulation of cell growth by altered expression of Beclin 1 in triple-negative breast cancer.

Beclin 1 is a promoter gene for autophagy as well as a key factor for regulating tumor cell growth and death. Allelic deletion of Beclin 1 has been observed in certain triple-negative breat cancer (TNBC) cells, and it might be associated with increased proliferation and invasion in TNBC cells. In this study we investigated the relationship between Beclin 1 expression and prognosis for TNBC patients, as well as the influence on cell growth by Beclin 1 overexpression in different cultural conditions. Beclin 1 expression in TNBC tissues was measured by immunohistochemical staining and correlated with clinicopathologic parameters for TNBC patients. The plasmid of pDS-RED-C1-Beclin 1 was transfected to BT-549 and MDA-MB-231 cells and autophagy, proliferation, apoptosis, cell cycle and Epithelial-mesenchymal transition (EMT) process were measured. Results indicated that high level of Beclin 1 expression was correlated with more lymph nodes and distant metastasis but unrelated to survival rates in 5 years for TNBC patients. In vitro, overexpression of Beclin 1 improved cellular autophagy in both BT-549 and MDA-MB-231 cells, inhibited cell proliferation at normal cultural condition and increased cell survival in starvation, hypoxia or with doxorubicin stimulation. Besides, Beclin 1 overexpression decreased cell apoptosis, induced cells to be in G0/G1 phase and promoted EMT process through Wnt/ß-catenin pathway in starvation. Thus, Beclin 1 overexpression plays a double role in BT-549 and MDA-MB-231 cell growth by elevating the capability of autophagy. These findings might be useful for searching a proper method for clinical therapy of TNBC from the aspect of autophagy in future.

Biocompatible composite nanoparticles with large longitudinal relaxivity for targeted imaging and early diagnosis of cancer.

Early diagnosis of cancer greatly increases the chances of successful treatment by radical resection. The sensitivity of magnetic resonance imaging (MRI) techniques for detecting early stage tumors can be increased with the assistance of a positive MRI contrast agent. However, the traditional positive MRI contrast agents, such as Gd-chelates and Gd-based inorganic nanoparticles, are often limited by their cytotoxicity and low specificity. Here, we propose a new design of MRI contrast agent based on gadolinium oxide nanocrystals (GON) for targeted imaging and cancer early diagnosis with good biocompatibility. The GON were prepared using a polyol method and then encapsulated into albumin nanoparticles (AN), which were cross-linked with glutaraldehyde and found to exhibit bright and stable autofluorescence without conjugation to any fluorescent agent. After that, a target molecule, folic acid (FA), was conjugated onto the surface of the GON-loaded AN (GON-AN) to construct a GON-AN-FA composite. The as-prepared nanoparticles are biocompatible and stable in serum. The results of MRI relaxation studies show that the longitudinal relaxivities (r1) of GON-AN (11.6 mM-1 s-1) and GON-AN-FA (10.8 mM-1 s-1) are much larger than those of traditional positive MRI contrast agents, such as Magnevist (3.8 mM-1 s-1). The results of cell viability assays indicate that GON-AN and GON-AN-FA are almost non-cytotoxic. Furthermore, the specificities of GON-AN and GON-AN-FA were evaluated with two kinds of cancer cells which overexpress folate receptor alpha (FRα). The results reinforce that the autofluorescent GON-AN-FA is able to target cancer cells via recognition of the ligand FA and the receptor FRα. Therefore, our autofluorescent GON-AN-FA possessing a large longitudinal relaxivity and good biocompatibility represents a significant advance for the targeted imaging and early diagnosis of cancer.

[Study on the epidemiological significance related to community-structural difference of the rat plague host and vectors in Western Yunnan, China].

OBJECTIVE: To study the epidemiological significance of community-structural difference regarding both small mammal and flea communities on Rattus flavipectus in Dehong and Baoshan areas, Yunnan province, during 1982 to 1996. METHODS: Methodologies as cluster analysis, communities dominated constitution and species diversity were used for data analysis. RESULTS: 75 490 small mammals of 27 species could be divided into three types: I. Ruili habitat-communities dominated by R. flavipectus (54.41%) and Suncus murinus (33.37%); II. Longchuan and Yingjiang habitat-communities dominated by R. flavipectus (62.99%), S. murinus (23.25%) and Mus musculus (10.06%); III. Baoshan habitat-community dominated by R. flavipectus (48.07%), S. murinus (19.56%) and Crocidura attenuats (14.37%). The captured 61 122 fleas of 11 species on R. flavipectus could be divided into three types: i. Ruili habitat-communities dominated by Xenopsylla cheopis (83.51%) and Lentistivslius ferinus (13.86%); ii. Longchuan and Yingjiang habitats X. cheopis (74.42%) and L. segnis (22.94%); iii. Baoshan habitat-communities dominated by L. segnis (70.62%) and X. cheopis (22.70%). There had been 1471 strains of Y. pestis isolated from the hosts of 7 species and vectors of 5 species in Dehong areas for the ten year period. 36 strains of Y. pestis were isolated from host of one species and vectors of 2 species in Baoshan area for ten years. The constitution ratio of R. flavipectus and X. cheopis was higher in Dehong area with average as 58.70% and 78.97% respectively. However, the diversities of species among host and vector communities were low, with average as 1.010 and 0.625. On the contrary, the constitution ratios of R. flavipectus and X. cheopis were lower in Baoshan area, with an average as 48.07% and 22.70% respectively but the diversities of species among host and vector community were higher with the averages as 1.471 and 0.829 respectively. The main dominative flea species from 'group ii' to 'group iii' in the flea community had changed from X. cheopis to L. segnis. CONCLUSION: The species diversity index of host and vector community was higher in Baoshan area, while the constitution ratio of main host and vector community was lower. This findings seemed to be the important factor of the decrease of plague prevalence in Baoshan area.

Generalized PID observer design for descriptor linear systems.

A type of generalized proportional-integral-derivative observers is proposed for descriptor linear systems. Based on a general parametric solution to a type of generalized Sylvester matrix equations, a parametric design approach for such observers is established. The proposed approach provides parameterizations for all the observer gain matrices, gives the parametric expression for the corresponding left eigenvector matrix of the observer system matrix, realizes the elimination of impulsive behaviors, and guarantees the regularity of the observer system. The design method can offer all the degrees of design freedom, which can be utilized to achieve various desired system specifications and performances. In addition, a numerical example is employed to show the design procedure and illustrate the effect of the presented approach.

[Targeted killing of colorectal tumor cells by lentiviral constructs containing CD/TK suicide genes and KDR promoter].

OBJECTIVE: To investigate the selective killing of colorectal tumor cells by lentivirus-mediated double suicide gene under the regulation of KDR promoter. METHODS: 293T packaging cells were transfected with the plasmid FGW-KDRP-CD/TK to obtain the infectious viruses. KDR-expressing LoVo cells and LS174T cells that did not produce KDR were transfected with the recombinant virus, and the transfection efficiency was evaluated by the fluorecence microscope. RT-PCR was employed to examine the expression of CDglyTK. After treatment of the cells with 5-FC and GCV, the killing effects on the two cell lines were evaluated. RESULTS: The recombinant construct showed similar infection rate of the two cell lines. RT-PCR demonstrated that CDglyTK gene was expressed only in LoVo cells infected with FGW-KDRP-CD/TK but not in LS147T cells, and the sensitivity of the two cell lines to the prodrugs was significantly different (P<0.001). The killing effect of the double suicide gene was much stronger than that of single suicide gene administered (P<0.001). CONCLUSION: The double suicide gene driven by KDR promoter has specific killing effect on the KDR-expressing colorectal tumor cells.

Design of PI observers for continuous-time descriptor linear systems.

A parametric design approach for proportional-integral (PI) observers for continuous-time descriptor linear systems is proposed based on a complete general parametric solution to the generalized Sylvester matrix equation. The proposed approach provides complete parameterizations for all the observer gain matrices, gives the parametric expression for the corresponding finite left eigenvector matrix of the observer system matrix, realizes elimination of impulsive responses, and guarantees the regularity of the observer system. The design method offers all the degrees of design freedom, which can be utilized to achieve various desired system specifications and performances and, thus, has great potentials in applications. A numerical example is employed to show the design procedure and illustrate the effect of the proposed approach. Simulation results show a satisfactory tracking performance for descriptor linear systems.

[Expression of COX-2 protein in colorectal carcinoma and the clinical implication].

OBJECTIVE: To investigate the relationship between COX-2 expression and the clinicopathological factors in colorectal carcinoma and assess the prognostic value of COX-2 detection. METHODS: Tissue microarray and immunohistochemistry by SABC method was employed for detecting COX-2 expression in 126 patients with advanced colorectal cancer, and the relationship of COX-2 expression with the clinicopathological features and prognosis of the patients was retrospectively analyzed. RESULTS: The patients were divided into two groups of low and high COX-2 groups according to the grade and extent of COX-2 expression. High COX-2 expression was detected in 32 (25.4%) cases, and low expression in 94 (74.6%) cases. No significant correlation was noted between COX-2 expression and the patients' age, sex, tumor size, tumor location, histological type, lymphatic-node metastasis and Dukes' classification, but high COX-2 expression was strongly correlated with tumor recurrence and especially with blood-borne metastasis (P<0.05). The survival rate without tumor recurrence for high- and low-COX-2 groups was assessed by the Kaplan-Meier method and compared by log-rank test, which revealed significant difference between the two groups (P=0.0067). Multivariate analysis for all patients suggested that among the 8 prognostic factors (age, sex, tumor size, tumor location, histological type, lymphatic-node metastasis, Dukes' stage, and COX-2 expression), Dukes' stage and COX-2 expression was the independent significant factor related to disease-free survival. CONCLUSION: The expression of COX-2 is strongly correlated with recurrence of colorectal cancer, especially with blood-borne metastasis. COX-2 is an independent factor for prognostic evaluation of the patients, and tissue microarray allows rapid, convenient, economic and accurate COX-2 detection for large-scale application.

[Expression of survivin and its clinical significance in colorectal carcinoma].

OBJECTIVE: To investigate the relationship between the expression of survivin and the clincopathological factors of colorectal carcinoma and evaluate the significance of survivin in prognostic assessment of the patients. METHODS: Using tissue microarray and immunohistochemical method (SABC), we examined survivin expression in 126 patients with advanced colorectal cancer and retrospectively analyzed the relationship between survivin and both the clinicopathological features and prognosis of the malignancy. RESULT: Of the 126 patients, 26 (21%) were found to have a high survivin expression and 100 (79%) had a low expression, without relation to the patients' age, gender, tumor size, tumor location, histological type, lymph node metastasis and Dukes' classification. High survivin expression was strongly correlated with tumor recurrence and especially with hematogenous metastasis (P<0.05). Kaplan-Meier method and log-rank test indicated significantly different disease-free survival rates between high- and low-survivin groups (P<0.05), and Dukes' stage and survivin expression of the tumor were identified in multivariate analysis as the independent significant factors related to disease-free survival. CONCLUSIONS: Survivin expression in colorectal cancer has strong positive correlation with tumor recurrence as the independent risk factor related to prognosis. Tissue microarray enables rapid, convenient, economic and accurate large-scale examination of clinical specimens.

[Effects of the lipid-lowering drugs on endothelial hyperplasia in inferior vena cava grafts in dogs].

OBJECTIVE: To investigate the effects of the lipid-lowering drugs in alleviating endothelial hyperplasia in the inferior vena cava (IVC) grafts in dogs. METHODS: The Dacron grafts seeded with autologous venous fragments were implanted into the IVC of 20 dogs, including 12 dogs receiving oral lipid-lowering drugs serving as the treatment group and the other 8 without medication as the control group. The levels of total cholesterol (TC), low-density lipoprotein cholesterol (LDL-ch) and high-density lipoprotein cholesterol (HDL-ch) in the serum were measured regularly, and all the grafts harvested to measure the thickness of the endothelium. RESULTS: The total patency rate of the IVC were higher in the treatment group (75%) than in the control group (37.5%), and new endothelial lining was formed two weeks after the operation. Compared with the control group, the endothelial thickness of the grafts at the proximal (P<0.01), middle (P<0.05) and distal segments (P<0.05) of the IVC were all smaller in the treatment group, which also had lower serum LDL-ch and TC levels (both P<0.05) but with comparable HDL-ch levels (P>0.05). CONCLUSION: Administration of lipid-lowering drugs may reduce the level of serum LDL-ch and TC and the endothelial thickness of the grafts to improve the patency rate of the vessels.