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I. A. Vladimirova I. B. Filippov E. M. Kulieva Yu. B. Dyskina V. Ya. Ganitkevich 《Neurophysiology》2007,39(1):20-28
Our studies of the role of phospholipase C in inhibitory synaptic action upon visceral smooth muscles demonstrated that, under
conditions of carbachol (CCh)-induced pre-activation of cholinoreceptors, ATP-or noradrenaline (NA)-evoked relaxation of these
muscles is mediated by the phospholipase C-independent pathway, while the phospholipase C-dependent pathway does not manifest
itself as a mechanism that determines the inhibitory effect of the above transmitters. Under conditions of pre-activation
of muscarinic cholinoreceptors, ATP-and NA-induced relaxation is continued due to activation of inositol trisphosphate (InsP3)-sensitive receptors despite the fact that the pathway of inhibition is phospholipase C-independent. This is confirmed by
complete depression of the inhibitory effects of ATP and NA against the background of CCh-induced contraction after pre-incubation
of the studied preparations together with 100 μM 2-APB, a blocker of InsP3 receptors. Selective blockings of either M2 or M3 cholinoreceptors are accompanied by a complete loss of the ability of the above blocker of InsP3 receptors (2-APB) to suppress ATP-and NA-induced contraction of smooth muscles in the state of CCh-induced contraction. It
can be hypothesized that, under conditions of selective pre-activation of M2 or M3 cholinoreceptors, the mechanisms of intracellular signalling mediating the inhibition events are modified. The InsP3-dependent pathway that determines both adrenergic and purinergic inhibition of smooth muscles is switched off, and the inhibitory
action of neurotransmitters is realized under such conditions through the InsP3-independent pathway. Therefore, in our study we first found differences between cellular mechanisms underlying ATP-and NA-induced
inhibition of smooth muscles under conditions of selective activation of either M2 or M3 cholinoreceptors and the mechanisms underlying the relaxing action of inhibitory neurotransmitters under conditions of combined
synergistic activation of cholinoreceptors of both the above-mentioned subtypes.
Neirofiziologiya/Neurophysiology, Vol. 39, No. 1, pp. 22–31, January–February, 2007. 相似文献
295.
Cell wall lytic enzymes are valuable tools for the biotechnologist, with many applications in medicine, the food industry,
and agriculture, and for recovering of intracellular products from yeast or bacteria. The diversity of potential applications
has conducted to the development of lytic enzyme systems with specific characteristics, suitable for satisfying the requirements
of each particular application. Since the first time the lytic enzyme of excellence, lysozyme, was discovered, many investigations
have contributed to the understanding of the action mechanisms and other basic aspects of these interesting enzymes. Today,
recombinant production and protein engineering have improved and expanded the area of potential applications. In this review,
some of the recent advances in specific enzyme systems for bacteria and yeast cells rupture and other applications are examined.
Emphasis is focused in biotechnological aspects of these enzymes. 相似文献
296.
Of 23 strains of halotolerant (up to 12% w/v NaCl) photosynthetic bacteria isolated from various sources, one isolate, SH5,
accumulated intracellular 5-aminolevulinic acid (ALA) at 0.45 μg/g dry cell wt (DCW) growing aerobically in the dark. The
strain was identified as Rhodobacter sphaeroides using 16S rDNA sequencing. Biosynthesis of ALA was enhanced to 14 μg/g DCW using modified glutamate/glucose (50 mM) medium
with the addition of 10 mM levulinic acid after 24 h cultivation. Addition of 30 μM Fe2+ to this medium increased the yield to 226 μg/g DCW. 相似文献
297.
Angiogenesis, i.e., new blood vessel formation, is required in normal and pathological states. A dysfunction in the microvascular
endothelium occurs in diabetes, leading to decreased blood flow and limb amputation. In cancer, angiogenesis is increased
to allow for growth, invasion, and metastasis of tumor cells. Better understanding of the molecular events that cause or are
associated with either of these diseases is needed to develop therapies. The tumor and angiogenic cells micro-environment
is acidic and not permissive for growth. We have shown that to survive this environment, highly metastatic and angiogenic
cells employ vacuolar H+-ATPase at their plasma membranes (pmV-ATPases) to maintain an alkaline pHcyt. However, in lowly metastatic and in microvascular endothelial cells from diabetic model, the density of pmV-ATPase and the
cell invasiveness are decreased. Therefore, the overexpression of the pmV-ATPase is important for cell invasion, and essential
for tumor progression, angiogenesis and metastasis. Both, cancer and diabetes are heterogenous diseases that involve many
different proteins and signaling pathways. Changes in pHcyt have been associated with the regulation of a myriad of proteins, signaling molecules and pathways affecting many if not
all cellular functions. Since changes in pHcyt are pleiotropic, we hypothesize that alteration in a single protein, pmV-ATPase, that can regulate pHcyt may explain the dysfunction of many proteins and cellular pathways in diabetes and cancer. Our long term goal is to determine
the molecular mechanisms by which pmV-ATPase expression regulates tumor angiogenesis and metastasis. Such knowledge would
be useful to identify targets for cancer therapy. 相似文献
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Selvam R Ganesan K Narayana Raju KV Gangadharan AC Manohar BM Puvanakrishnan R 《Life sciences》2007,80(26):2403-2410
Rheumatoid arthritis (RA) is a chronic inflammatory disorder affecting 1% of the population worldwide. Pulsed electromagnetic field (PEMF) has a number of well-documented physiological effects on cells and tissues including antiinflammatory effect. This study aims to explore the antiinflammatory effect of PEMF and its possible mechanism of action in amelioration of adjuvant induced arthritis (AIA). Arthritis was induced by a single intradermal injection of heat killed Mycobacterium tuberculosis at a concentration of 500 μg in 0.1 ml of paraffin oil into the right hind paw of rats. The arthritic animals showed a biphasic response regarding changes in the paw edema volume. During the chronic phase of the disease, arthritic animals showed an elevated level of lipid peroxides and depletion of antioxidant enzymes with significant radiological and histological changes. Besides, plasma membrane Ca2+ ATPase (PMCA) activity was inhibited while intracellular Ca2+ level as well as prostaglandin E2 levels was noticed to be elevated in blood lymphocytes of arthritic rats. Exposure of arthritic rats to PEMF at 5 Hz × 4 μT × 90 min, produced significant antiexudative effect resulting in the restoration of the altered parameters. The antiinflammatory effect could be partially mediated through the stabilizing action of PEMF on membranes as reflected by the restoration of PMCA and intracellular Ca2+ levels in blood lymphocytes subsequently inhibiting PGE2 biosynthesis. The results of this study indicated that PEMF could be developed as a potential therapy for RA in human beings. 相似文献
300.
Reactive oxygen species produced by NADPH oxidase are involved in pollen tube growth 总被引:14,自引:2,他引:12
Tip-localized reactive oxygen species (ROS) were detected in growing pollen tubes by chloromethyl dichlorodihydrofluorescein diacetate oxidation, while tip-localized extracellular superoxide production was detected by nitroblue tetrazolium (NBT) reduction. To investigate the origin of the ROS we cloned a fragment of pollen specific tobacco NADPH oxidase (NOX) closely related to a pollen specific NOX from Arabidopsis. Transfection of tobacco pollen tubes with NOX-specific antisense oligodeoxynucleotides (ODNs) resulted in decreased amount of NtNOX mRNA, lower NOX activity and pollen tube growth inhibition. The ROS scavengers and the NOX inhibitor diphenylene iodonium chloride (DPI) inhibited growth and ROS formation in tobacco pollen tube cultures. Exogenous hydrogen peroxide (H2O2) rescued the growth inhibition caused by NOX antisense ODNs. Exogenous CaCl2 increased NBT reduction at the pollen tube tip, suggesting that Ca2+ increases the activity of pollen NOX in vivo. The results show that tip-localized ROS produced by a NOX enzyme is needed to sustain the normal rate of pollen tube growth and that this is likely to be a general mechanism in the control of tip growth of polarized plant cells. 相似文献