H∞ control of switched linear discrete‐time systems with polytopic uncertainties

In this paper, the problem of designing H_∞ state‐feedback controllers for switched linear discrete‐time systems with polytopic uncertainties is investigated. Two approaches on designing robust and parameter‐dependent H_∞ controllers are proposed and the existence conditions of the desired controllers are derived and formulated in terms of a set of linear matrix inequalities. By solving the corresponding convex optimization problem, the desired controllers are obtained, respectively, and different optimal H_∞ noise‐attenuation level bounds of corresponding closed‐loop systems are given as well. The designed controllers have their own advantages and disadvantages regarding the conservatism and realization complexity. An illustrative example emerging in networked control systems (NCS) and numerical simulations are presented to show the applicability and effectiveness of the obtained theoretic results. Copyright © 2006 John Wiley & Sons, Ltd.     

组织工程化肌腱研究进展

对组织工程化肌腱领域中目前研究的主要成果进行综述，着重阐述了肌腱细胞外基质替代物、肌腱细胞生物学性质及肌腱细胞与细胞外基质材料复合研究中的主要问题。认为，研制适于肌腱细胞生长、粘附和发挥功能的细胞外基质材料；建立生长、增殖可调控的肌腱细胞系；在模拟体内力学条件下，进行肌腱细胞三维培养，将是研究具有特定修复功能的组织工程化肌腱的重要问题。     

Tyrosine hydroxylase and serotonin containing cells in embryonic rat rhombencephalon: a whole-mount immunocytochemical study

Rhombencephala from rat embryos were processed as whole-mounts for immunocytochemical detection of monoaminergic cell populations, using antibodies to tyrosine hydroxylase (TH) and serotonin (5-HT). Specific advantages of the whole-mount technique over the classical serial-section method were that even isolated immunoreactive (IR) cells could be detected easily, and three-dimensional relationships could be ascertained without the need for serial reconstruction. Embryos between embryonic days (E) 12 and 16 (the day following nocturnal mating being considered as E1) were used in this study. Both TH and 5-HT immunoreactivities were already detectable at E12, even in the smallest embryos (crown-rump length: 6 mm), but there was a striking difference in the number and regional distribution of these two types of IR cells. TH was expressed in several cell groups located in the rostral rhombencephalon (the presumed anlage of the A4-7 complex) as well as in the caudal rhombencephalon (the presumed anlagen of groups A1-2 and C1-3), whereas 5-HT was expressed in very few cells located near the rostral border of the rhombencephalon (presumed anlage of the B4-9 complex). Although the three-dimensional distribution of the TH-IR cell groups underwent some modifications during the period studied, its general pattern remained relatively stable after E12. This contrasted with the sequential appearance of the 5-HT-IR cell groups and their spatial transformations during this period. Using the rhombencephalic isthmus as a landmark, we found that conspicuous 5-HT-IR fibre bundles penetrated into the mesencephalon from E13 onwards, but that the 5-HT IR cell bodies were exclusively located caudal to the borderline between the mesencephalon and the rhombencephalon (the rhombencephalic isthmus). We therefore suggest the term "rostral rhombencephalic raphe nuclei" for the rostral 5-HT cell groups instead of "mesencephalic raphe nuclei," which is a misnomer. Close spatial association between TH and 5-HT-IR elements was observed mainly in the caudal rhombencephalon, where 5-HT-IR fibres coursed through an area containing numerous TH-IR cell bodies (the presumed anlagen of groups A1-2 and C1-3).     

原发性高血压患者细胞外间质水平及其临床意义

检测血清Ⅲ型前胶原 (PCⅢ )、层粘连蛋白 (LN)和透明质酸 (HA)的水平与研究其对高血压心肌纤维化患者的临床价值。高血压左心室肥大组 35例、高血压不伴左心室肥大组 30例及对照组 4 0名 ,用超声心动图测定左心室重量指数 (LVMI) ,用酶联免疫吸附分析法 (ELISA)测定血清PCⅢ、LN和HA。高血压左心室肥大组较高血压不伴左心室肥大组和对照组的血清PCⅢ、LN和HA含量明显增高 (P <0 .0 1 )。结论是血清PCⅢ、LN和HA可以作为高血压左心室肥大患者心肌纤维化的观察指标     

细胞外基质成分及其构筑对平滑肌细胞黏着斑激酶表达的影响

目的:探讨细胞外基质纤维连接蛋白(FN)、层黏连蛋白(LN)及三维基膜Matrigel胶对平滑肌细胞黏着斑激酶(FAK)表达的影响。方法:免疫荧光组织化学技术对生长在FN、LN和Matrigel胶里的平滑肌细胞FAK的表达进行检测。结果:生长存FN、LN和Matrigel胶里的平滑肌细胞FAK的表达依次为最高、次之和最低,各组之间有统计学意义;平滑肌细胞FAK磷酸化水平和FAK的表达呈正相关,生长在FN上的平滑肌细胞FAK(py397)的表达水平最高,生长在Matrigel胶里的平滑肌表达最低。结论:细胞外基质成分及其构筑对平滑肌细胞FAK的表达具有重要调节作用。     

Fusion and Matrix Protein Gene Sequence Analysis of Paramyxoviruses of Type 1(PMV-1) Isolated from Pigeons in Slovenia

Paramyxoviruses of type 1 (PMV-l) isolated from pigeons were genetically analyzed. A part of the fusion and the matrix protein genes were amplified and sequenced, Typical amino acid sequences associated with virulence were determined at the fusion protein cleavage site in all PMV-1 isolates. All Slovene pigeon PMV-1 strains share high amino acid sequence similarity with other pigeon strains. In the phylogenetic tree, they are clustered together with pigeon PMV-1 isolates with moderate pathogenicity. Phylogenetic analysis obtained from the fusion and the matrix protein gene alignments showed the same branching order. Viruses circulating among pigeons were found to form quite unique lineage of virulent NDV strains.     

Clinical and molecular study in congenital muscular dystrophy with partial laminin alpha 2 (LAMA2) deficiency

Complete laminin alpha2 (LAMA2) deficiency causes approximately half of congenital muscular dystrophy (CMD) cases. Many loss-of-function mutations have been reported in these severe, neonatal-onset patients, but only single missense mutations have been found in milder CMD with partial laminin alpha2 deficiency. Here, we studied nine patients diagnosed with CMD who showed abnormal white-matter signal at brain MRI and partial deficiency of laminin alpha2 on immunofluorescence of muscle biopsy. We screened the entire 9.5 kb laminin alpha2 mRNA from patient muscle biopsy by direct capillary automated sequencing, single strand conformational polymorphism (SSCP), or denaturing high performance liquid chromatography (DHPLC) of overlapping RT-PCR products followed by direct sequencing of heteroduplexes. We identified laminin alpha2 sequence changes in six of nine CMD patients. Each of the gene changes identified, except one, was novel, including three missense changes and two splice-site mutations. The finding of partial laminin alpha2 deficiency by immunostaining is not specific for laminin alpha2 gene mutation carriers, with only two patients (22%) showing clear causative mutations, and an additional three patients (33%) showing possible mutations. The clinical presentation and disease progression was homogeneous in the laminin alpha2-mutation positive and negative CMD patients.     

Increased matrix metalloproteinase-9 activity in human ovarian cancer cells cultured with conditioned medium from human peritoneal tissue

Ovarian cancer cells disseminate by attachment to the peritoneal mesothelial cell surface of the abdominal cavity. We therefore investigated the influence of conditioned medium (CM) from human peritoneal tissues and mesothelial cells on the secretion of matrix metalloproteinases (MMPs) by ovarian cancer cells. The molecular weights of MMPs stimulating factors derived from human peritoneal tissues and mesothelial cells were estimated using microconcentrators with various cut-off membranes. Human peritoneal tissues were obtained from 12 surgical patients, and mesothelial cells were isolated from three peritoneal specimens. Exposure to CM from peritoneal tissue caused a concentration-dependent increase of the MMP-2 and MMP-9 bands in CM from NOM1 ovarian cancer cells, as shown by zymography. There was a significant difference in the increase of MMP-2 and MMP-9 (2.46-fold and 7.14-fold, respectively, at 0.4mg/ml protein; P < 0.005). CM from mesothelial cells also significantly increased the secretion of MMP-9 by NOM1 cells. The molecular size of possible MMP-9-stimulating factors secreted by peritoneal tissues and mesothelial cells was above M 100000. Further, CM of peritoneal tissues and mesothelial cells also induced the invasiveness of NOM1 cells. These findings suggest that mesothelial cells may secrete some factors which predominantly induce the MMP-9 production and increase invading cell numbers.