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101.
Several lines of evidence show that neurohumoral systems, especially those involving catecholamines, play a crucial role in cardiac diseases. Changes in the beta-adrenergic receptor (beta-AR) system such as receptor down-regulation, uncoupling from G-proteins, receptor internalization and receptor degradation may account for some of the abnormalities of contractile function in this disease. Increases in the level of inhibitory G-protein subunits also appears to be involved in attenuating the beta-AR signal. Finally beta-AR signalling is strongly regulated by members of the G-protein-coupled receptor kinase family (GRKs), the best known of which is beta-adrenergic receptor kinase 1 (beta-ARK1). beta-ARK1 mRNA, protein level and enzymatic activity is increased in heart disease, further contributing to an attenuation in beta-AR signalling. The combination of these negative alterations are presumably related to the contractile dysfunction seen in human heart disease. The combination of biochemical, physiological and molecular biological studies bearing on the normal function and regulation of these various molecules should provide strategies for elucidating the pharmacological basis of the regulation of myocardial contractility in the normal and failing heart. 相似文献
102.
Chakraborty D Banerjee S Sen A Banerjee KK Das P Roy S 《Journal of immunology (Baltimore, Md. : 1950)》2005,175(5):3214-3224
Leishmania donovani-infected splenic macrophages and P388D1 (P388D1(I)) failed to activate T cells in response to low dose of exogenous peptide. The membrane fluidity of P388D1(I) was greater than that of the normal counterpart P388D1(N), but could be reduced either by exposing the cell below phase transition point or by loading cholesterol into membrane (L-P388D1(I)), and this was associated with enhanced Ag-presenting ability of P388D1(I). Presentation of endogenous leishmanial Ag, kinetoplastid membrane protein-11, was also defective, but could be corrected by loading cholesterol into membrane. Because membrane rafts are important for Ag presentation at a low peptide dose, raft architecture of P388D1(I) was studied using raft (CD48 and cholera toxin-B) and non-raft (CD71) markers in terms of their colocalization with I-A(d). Binding of anti-CD48 mAb and cholera toxin B subunit decreased significantly in P388D1(I), and consequently, colocalization with I-A(d) was not seen, but this could be restored in L-P388D1(I). Conversely, colocalization between I-A(d) and CD71 remained unaffected regardless of the presence or the absence of intracellular parasites. P388D1(N) and L-P388D1(I), but not P388D1(I), formed peptide-dependent synapse with T cells quite efficiently and this was found to be corroborated with both intracellular Ca2+ mobilization in T cells and IL-2 production. This indicated that intracellular parasites disrupt the membrane rafts, possibly by increasing the membrane fluidity, which could be corrected by making the membrane rigid. This may be a strategy that intracellular L. donovani adopts to evade host immune system. 相似文献
103.
The peptide deformylase in bacteria is involved in removal of N-formyl group from newly synthesized proteins. The gene encoding this enzyme from Mycobacterium tuberculosis was cloned and expressed in Escherichia coli. The enzyme activity of the recombinant protein (mPDF) was insensitive to modulation by common monovalent/divalent cations. Kinetic analysis, using N-formylmethionine-alanine as the substrate, yielded K(cat)/K(m) of approximately 1220 M(-1)s(-1). Actinonin, a naturally occurring antibiotic, and 1,10-ortho-phenanthroline strongly inhibited the enzyme activity. The mPDF was very stable at 30 degrees C with a half-life of approximately 4h and exhibited resistance to oxidizing agents, like H(2)O(2). Thus, the mPDF achieved distinction in its behavior among any reported iron-containing peptide deformylases. Furthermore, amino acid sequence analysis of mPDF revealed the presence of an unusually long carboxy-terminal end (residues 182-197), which is atypical for any gram-positive bacteria. Our results, through deletion analysis, for the first time established the role of this region in mPDF enzyme activity. 相似文献
104.
Chakraborti S Mandal A Das S Chakraborti T 《Molecular and cellular biochemistry》2005,280(1-2):107-117
Treatment of bovine pulmonary artery smooth muscle with the O2•− generating system hypoxanthine plus xanthine oxidase stimulated MMP-2 activity and PKC activity; and inhibited Na+ dependent Ca2+ uptake in the microsomes. Pretreatment of the smooth muscle with SOD (the O2•− scavenger) and TIMP-2 (MMP-2 inhibitor) prevented the increase in MMP-2 activity and PKC activity, and reversed the inhibition
of Na+ dependent Ca2+ uptake in the microsomes. Pretreatment with calphostin C (a general PKC inhibitor) and rottlerin (a PKCδ inhibitor) prevented
the increase in PKC activity and reversed O2•− caused inhibition of Na+ dependent Ca2+ uptake without causing any change in MMP-2 activity in the microsomes of the smooth muscle. Treatment of the smooth muscle
with the O2•− generating system revealed, respectively, 36 kDa RACK-1 and 78 kDa PKCδ immunoreactive protein profile along with an additional
38 kDa immunoreactive fragment in the microsomes. The 38 kDa band appeared to be the proteolytic fragment of the 78 kDa PKCδ
since pretreatment with TIMP-2 abolished the increase in the 38 kDa immunoreactive fragment. Co-immunoprecipitation of PKCδ
and RACK-1 demonstrated O2•− dependent increase in PKCδ-RACK-1 interaction in the microsomes. Immunoblot assay elicited an immunoreactive band of 41 kDa
Giα in the microsomes. Treatment of the smooth muscle tissue with the O2•− generating system causes phosphorylation of Giα in the microsomes and pretreatment with TIMP-2 and rottlerin prevented the phosphorylation. Pretreatment of the smooth muscle
tissue with pertussis toxin reversed O2•− caused inhibition of Na+ dependent Ca2+ uptake without affecting the protease activity and PKC activity in the microsomes. We suggest the existence of a pertussis
toxin sensitive G protein mediated mechanism for inhibition of Na+ dependent Ca2+ uptake in microsomes of bovine pulmonary artery smooth muscle under O2•− triggered condition, which is regulated by PKCδ dependent phosphorylation and sensitive to TIMP-2 for its inhibition. (Mol
Cell Biochem xxx: 107–117, 2005) 相似文献
105.
D Chakraborti 《BMJ (Clinical research ed.)》1985,291(6506):1426-1427
106.
A total of 110 patients of symptomatic otomycosis was investigated, prospectively. Aural swabs were collected on 1st, 7th and 14th day and examined by direct microscopy and culture for fungi. Of these, 80 patients found to be having pure fungal infection, were taken up for mycological and therapeutic study. Fungi belonging to genus Aspergillus were isolated in 76 (95.0%) patients of which Aspergillus niger was the commonest isolate in 46 (57.5%), followed by A. flavus in 27 (33.7%), A. fumigatus in 3 (3.7%), Candida species in 3 (3.7%) and Mucor in 1 (1.2%). The patients were of all age groups but majority were between 21 and 30 years and the male-female ratio was equal. Of the total of 40 male patients, twenty-one were Sikhs using turban. Before developing the symptoms, forty five patients used oil, mixture of oil and garlic juice, antibiotics, steroids, antiseptics or wax solvent as ear drops. Only two patients were diabetic! No patient had fungal infection elsewhere in the body. The patients were called for regular follow-up for three weeks. In forty cases mercurochrome was applied as the antifungal agent after cleaning the external auditory canal, in twenty-three clotrimazole and in rest of the seventeen patients miconazole was used. On 7th day, only 11 (13.7%) patients grew different fungi in culture. They became symptom-free on 14th day and no fungal material could be seen on otoscopy, direct microscopy or culture. Mercurochrome was found to be most effective in these patients. 相似文献
107.
Activities and a few properties of alkaline phosphatase and 5’-nucleotidase were compared in the developing human placenta.
Both the enzymes were mostly membrane-bound and displayed similar developmental patterns with the highest activities at 24/26
weeks of the placenta. L-Phenylalanine, L-tryptophan and L-leucine were inhibitors of alkaline phosphatase, whereas they had
no effect on the 5’-nucleotidase. Alkaline phosphatase from a late stage of gestation appeared to be almost heat-stable. An
appreciable part of 5’-nucleotidase was also resistant to heat inactivation and this fraction varied with gestational age
of the tissue. For both the enzymes, Vmax changed without alteringK
m values with periods of gestation. Ca2+, Mg2+ and Mn2+ ions stimulated the alkaline phosphatase activity and Hg2+, Zn2+, Cu2+, Ni2+ were inhibitory. 5’-Nucleotidase was not activated by any of these cations. EDTA and Concanavalin A inhibited both the enzymes,
although the extent of inhibition was different and also varied with gestation. 相似文献
108.
109.
110.
Biotechnological approaches for field applications of chitooligosaccharides (COS) to induce innate immunity in plants 总被引:1,自引:0,他引:1
Subha Narayan Das Jogi Madhuprakash P. V. S. R. N. Sarma Pallinti Purushotham Katta Suma Kaur Manjeet 《Critical reviews in biotechnology》2015,35(1):29-43
Plants have evolved mechanisms to recognize a wide range of pathogen-derived molecules and to express induced resistance against pathogen attack. Exploitation of induced resistance, by application of novel bioactive elicitors, is an attractive alternative for crop protection. Chitooligosaccharide (COS) elicitors, released during plant fungal interactions, induce plant defenses upon recognition. Detailed analyses of structure/function relationships of bioactive chitosans as well as recent progress towards understanding the mechanism of COS sensing in plants through the identification and characterization of their cognate receptors have generated fresh impetus for approaches that would induce innate immunity in plants. These progresses combined with the application of chitin/chitosan/COS in disease management are reviewed here. In considering the field application of COS, however, efficient and large-scale production of desired COS is a challenging task. The available methods, including chemical or enzymatic hydrolysis and chemical or biotechnological synthesis to produce COS, are also reviewed. 相似文献