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91.
Increasing emphasis has been recently put on large-scale network processing of brain functions. To explore these networks, many approaches have been proposed in functional magnetic resonance imaging (fMRI). Their objective is to answer the following two questions: (1) what brain regions are involved in the functional process under investigation? and (2) how do these regions interact? We review some of the key concepts and corresponding methods to cope with both issues. 相似文献
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C Gallet J P Rosa A Habib M Lebret S Lévy-Tolédano J Maclouf 《The Journal of biological chemistry》1999,274(33):23610-23616
Thromboxane A(2) (TxA(2)) is a potent vasoconstrictor and platelet agonist. Pharmacological studies have defined two classes of thromboxane receptors (TPs) in human platelets; sites that bind the agonist 1S-(1,2(5Z),3-(1E,3S),4)-7- 3-(3-hydroxy-4-(4'-iodophenoxy)-1-butenyl)-7-oxabicyclo-2.2. 1-heptan-2-yl-5-heptenoic acid (I-BOP) with high affinity support platelet shape change, whereas low affinity sites that bind irreversibly the antagonist GR 32191 transduce platelet aggregation. As the mechanisms of signal transduction involved in platelet aggregation begin to be elucidated, few results concern those involved in platelet shape change, which is independent of the engagement of GPIIb/IIIa. To elucidate the respective role of the two classes of pharmacological binding sites of TPs in shape change, platelets were incubated with I-BOP at low concentrations or stimulated by I-BOP at high concentrations after pretreatment with GR 32191 or activated with low concentrations of 8-epi-prostaglandin F(2)alpha. Under these three conditions, there is a rapid stimulation of protein tyrosine phosphorylation of the 80/85-kDa doublet identified as the cytoskeletal protein cortactin. Tyrosine phosphorylation of cortactin is kinetically correlated with the occurrence of shape change. These biochemical and morphological events are both inhibited by SQ 29548, a TP antagonist, indicating the specificity of the signal. Since tyrosine kinase Syk was activated early during platelet activation, we examined the possibility that cortactin is a potential substrate of Syk in TxA(2)-induced platelet shape change. p72 Syk phosphorylation and kinase activity took place during the period when platelets were changing shape upon low concentrations of I-BOP stimulation. Furthermore, cortactin was associated with Syk, and this association increases along with the level of phosphorylation. These data suggest a novel pathway for a G protein-coupled TxA(2) high affinity receptor to the protein-tyrosine kinase Syk, which is associated with cortactin in the very early steps of platelet activation. 相似文献
95.
Sublethal effects of hexaflumuron on development and reproduction of the diamondback moth,Plutella xylostella (Lepidoptera: Yponomeutidae) 总被引:1,自引:0,他引:1
Mohammad Mahmoudvand Habib Abbasipour Aziz Sheikhi Garjan Ali Reza Bandani 《Insect Science》2011,18(6):689-696
Abstract Effects of hexaflumuron at 10% lethal concentration (LC10) and LC25 on development and reproduction parameters of the diamondback moth, Plutella xylostella (Linnaeus, 1753) (Lep.: Yponomeutidae) were investigated. Estimated LC50, LC10 and LC25 values of leaf dip bioassay of hexaflumuron on the third instar larvae of the P. xylostella were 1.48, 0.59 and 0.91 mg/L, respectively. Hexaflumuron decreased pupal weight in the parent generation at sublethal concentrations but in the offspring generation, this effect was not observed. Sublethal concentrations increased egg, first and second larval instar and pupa developmental time and shortened life span of adults, but did not change the third and fourth larval instars and pre‐pupa developmental period. Also fecundity of females reduced significantly but hatchability of treatments and control were similar. Survival rate of pre‐adult stages declined significantly at LC25 concentration. Reproduction parameters such as reproductive rate (R0) and intrinsic rate of increase in sublethal concentrations were significantly lower compared with control, but gross reproduction rate (GRR) at the LC10 concentration was increased and it could be hormoligosis. Also hexaflumuron significantly increased doubling time (Dt). We conclude that the sublethal effects of hexaflumuron might exhibit significant effects on the population dynamics of P. xylostella. 相似文献
96.
Heena Imtiaz Malik Abdul Rouf Mir Minhal Abidi Safia Habib Fahim Halim Khan 《Journal of biomolecular structure & dynamics》2020,38(7):1984-1994
AbstractAutoimmune responses against post-translationally modified antigens are a hallmark of several autoimmune diseases. In this work, we have studied the changes in alpha-2-macroglobulin (α2M) upon modification by peroxynitrite. Furthermore, we have evaluated the immunogenicity of modified α2M in experimental rabbits and rheumatoid arthritis (RA) patients. Peroxynitrite-modified α2M showed disturbed microenvironment and altered aromatic residues under UV and fluorescence studies. Aggregation, reduction in β-sheet content, production of nitrotyrosine and shift in amide I and II bands were observed in the modified α2M by polyacrylamide gel electrophoresis besides CD and FTIR spectroscopic analysis. The exposure of hydrophobic clusters and changes in contact positions were observed in ANS and ThT binding assays. Immunological studies using ELISA showed peroxynitrite-modified α2M as highly immunogenic producing high titre of specific antibodies in immunized rabbits. Cross-reactivity studies revealed the polyspecificity of the elicited antibodies. Direct binding ELISA and competitive inhibition studies confirmed the presence of circulating antibodies in the sera of RA patients having high specificity towards the peroxynitrite-modified α2M as compared to the native α2M. Sera from healthy (normal) human subjects showed lower binding with the native and modified protein. This study confirms that peroxynitrite induces structural modifications in α2M and makes it immunogenic. The presence of neo-antigenic determinants on modified α2M with enhanced binding for circulating autoantibodies in RA patients could offer new possibilities for diagnosis and etiopathology of the disease. Communicated by Ramaswamy H. Sarma 相似文献
97.
Sally H. Cross Victoria H. Clark Martin W. Simmen Wendy A. Bickmore Habib Maroon Cordelia F. Langford Nigel P. Carter Adrian P. Bird 《Mammalian genome》2000,11(5):373-383
CpG islands are found at the 5′ end of approximately 60% of human genes and so are important genomic landmarks. They are
concentrated in early-replicating, highly acetylated gene-rich regions. With respect to CpG island content, human Chrs 18
and 22 are very different from each other: Chr 18 appears to be CpG island poor, whereas Chr 22 appears to be CpG island rich.
We have constructed and validated CpG island libraries from flow-sorted Chrs 18 and 22 and used these to estimate the difference
in number of CpG islands found on these two chromosomes. These libraries contain normalized collections of sequences from
the 5′ end of genes. Clones from the libraries were sequenced and compared with the sequence databases; one third matched
ESTs, thus anchoring these ESTs at the 5′ end of their gene. However, it was striking that many clones either had no match
or matched only existing CpG island clones. This suggests that a significant proportion of 5′ gene sequences are absent from
databases, presumably either because they are difficult to clone or the gene is poorly expressed and/or has a restricted expression
pattern. This point should be taken into consideration if the currently available libraries are those used for the elucidation
of complete, as opposed to partial, gene sequences. The Chr 18 and 22 CpG island libraries are a sequence resource for the
isolation of such 5′ gene sequences from specific human chromosomes.
Received: 15 November 1999 / Accepted: 31 January 2000 相似文献
98.
Nazia Riaz Romana Idress Sadia Habib Iqbal Azam El-Nasir MA Lalani 《Translational oncology》2018,11(4):920-929
BACKGROUND: Androgen receptor (AR) has emerged as a significant prognostic marker in early breast cancer (BCa). Association of AR with cancer stem cell (CSC) markers in BCa is unknown. Aim of the present study was to evaluate the immunohistochemical expression of AR, CD44, CD24 and ALDH1 in a cohort of Pakistani patients diagnosed with invasive BCa and to correlate the expression with 5- year disease free survival. PATIENTS AND METHODS: We evaluated immunohistochemical expression AR, CD44, CD24 and ALDH1 in formalin fixed paraffin embedded archival blocks of 166 cases of primary invasive BCa (stage I-III) and correlated the expression with clinicopathological variables and outcome using univariable and multivariable analysis. Survival data was computed by Kaplan Meier curves. RESULTS: Expression of AR was observed in 62.7% tumors whereas CD44, CD24 and ALDH1 were expressed in 61.4%, 44% and 30.1% tumors, respectively. AR expression was significantly associated with T1-T2 tumors, lower grade, estrogen and progesterone receptor expression (P < .05) and remained an independent prognostic indicator in multivariable analysis (adjusted HR 0.33, 95% CI 0.13–0.81; P = .016). Significant association was observed between concordant expression of AR and CD24 (P = .001) with a favorable impact on survival (P = .007) whereas expression of CSC phenotypes (CD44+, CD44+/CD24? and ALDH1+) did not correlate with adverse outcome (P > .05). However, AR expression retained the association with better prognosis even in patients whose tumors exhibited a CSC phenotype. CONCLUSIONS: Expression of AR and CD24 in stage I-III invasive BCa correlates with favorable clinicopathological features and delineates a subgroup of patients with better disease-free survival. 相似文献
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100.
Insects are unable to synthesize sterols and require exogenous sterol sources for their normal development and reproduction. A few exceptions are insects associated with symbiotic yeasts or fungi. We analyzed sterols by GC-MS in two anobiid beetles (Lasioderma serricorne and Stegobium paniceum), their intracellular yeast-like symbiotes (YLS), and their diets in order to clarify the sterols synthesized by YLS and the metabolic pathways of the sterols in the beetles. Several C(27), C2(8), and C(29) saturated and unsaturated sterols were identified; the predominant sterols were cholesterol and 7-dehydrocholesterol in the anobiid beetles and ergosterol in the YLS. Most sterols detected in YLS were those known in the late pathway of the ergosterol biosynthesis in yeasts and most of the sterols in the beetles appear to be intermediate metabolites from YLS sterols to 7-dehydrocholesterol. The anobiid beetles appear to use ergosterol and 5-dihydroergosterol as sources for 7-dehydrocholesterol. 相似文献