排序方式: 共有170条查询结果,搜索用时 15 毫秒
91.
Meral Birbir Baris Calli Bulent Mertoglu Rahel Elevi Bardavid Aharon Oren Mehmet Nuri Ogmen Ayse Ogan 《World journal of microbiology & biotechnology》2007,23(3):309-316
Tuz Lake is a hypersaline lake located in Central Anatolia, Turkey. The lake and its salterns, Kaldirim and Kayacik, are the
major sources of solar salt for industrial applications in Turkey, especially in the food and leather industries. Use of the
crude solar salt often results in microbial deterioration of the products. We therefore initiated a thorough characterization
of the microbial communities in Tuz Lake and its adjacent salterns, and we present here the results of investigations on diversity
of extremely halophilic Archaea. Twenty-seven colonies of aerobic red or pink Archaea (family Halobacteriaceae) were selected according to colony shape, size, consistency and pigmentation, and characterized according to their phenotypic
characteristics, polar lipid contents, and antibiotic sensitivities. Furthermore, 16S rRNA genes of the isolates were screened
by DGGE analysis and partially sequenced. Phylogenetic analysis showed that most isolates belonged to the genera Haloarcula, Halorubrum and Halobacterium. Haloarcula was found to be dominant both in Tuz Lake and in the saltern samples. Halorubrum species were isolated from Tuz Lake and from the Kaldirim saltern, and Halobacterium species were recovered from Tuz Lake and from the Kayacik saltern. All strains showed various activities of hydrolytic enzymes
(proteases, amylases, cellulases, and others), activities which are responsible for the detrimental effects of the crude salt
in food and leather products. 相似文献
92.
Ozpolat B Akar U Steiner M Zorrilla-Calancha I Tirado-Gomez M Colburn N Danilenko M Kornblau S Berestein GL 《Molecular cancer research : MCR》2007,5(1):95-108
Programmed cell death-4 (PDCD4) is a recently discovered tumor suppressor protein that inhibits protein synthesis by suppression of translation initiation. We investigated the role and the regulation of PDCD4 in the terminal differentiation of acute myeloid leukemia (AML) cells. Expression of PDCD4 was markedly up-regulated during all-trans retinoic acid (ATRA)-induced granulocytic differentiation in NB4 and HL60 AML cell lines and in primary human promyelocytic leukemia (AML-M3) and CD34(+) hematopoietic progenitor cells but not in differentiation-resistant NB4.R1 and HL60R cells. Induction of PDCD4 expression was associated with nuclear translocation of PDCD4 in NB4 cells undergoing granulocytic differentiation but not in NB4.R1 cells. Other granulocytic differentiation inducers such as DMSO and arsenic trioxide also induced PDCD4 expression in NB4 cells. In contrast, PDCD4 was not up-regulated during monocytic/macrophagic differentiation induced by 1,25-dihydroxyvitamin D3 or 12-O-tetradecanoyl-phorbol-13-acetate in NB4 cells or by ATRA in THP1 myelomonoblastic cells. Knockdown of PDCD4 by RNA interference (siRNA) inhibited ATRA-induced granulocytic differentiation and reduced expression of key proteins known to be regulated by ATRA, including p27(Kip1) and DAP5/p97, and induced c-myc and Wilms' tumor 1, but did not alter expression of c-jun, p21(Waf1/Cip1), and tissue transglutaminase (TG2). Phosphatidylinositol 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) signaling pathway was found to regulate PDCD4 expression because inhibition of PI3K by LY294002 and wortmannin or of mTOR by rapamycin induced PDCD4 protein and mRNA expression. In conclusion, our data suggest that PDCD4 expression contributes to ATRA-induced granulocytic but not monocytic/macrophagic differentiation. The PI3K/Akt/mTOR pathway constitutively represses PDCD4 expression in AML, and ATRA induces PDCD4 through inhibition of this pathway. 相似文献
93.
Akar U Ozpolat B Mehta K Fok J Kondo Y Lopez-Berestein G 《Molecular cancer research : MCR》2007,5(3):241-249
Elevated expression of tissue transglutaminase (TG2) in cancer cells has been implicated in the development of drug resistance and metastatic phenotypes. However, the role and the mechanisms that regulate TG2 expression remain elusive. Here, we provide evidence that protein kinase Cdelta (PKCdelta) regulates TG2 expression, which in turn inhibits autophagy, a type II programmed cell death, in pancreatic cancer cells that are frequently insensitive to standard chemotherapeutic agents. Rottlerin, a PKCdelta-specific inhibitor, and PKCdelta small interfering RNA (siRNA) down-regulated the expression of TG2 mRNA and protein and induced growth inhibition without inducing apoptosis in pancreatic cancer cells. Inhibition of PKCdelta by rottlerin or knockdown of TG2 protein by a TG2-specific siRNA resulted in a marked increase in autophagy shown by presence of autophagic vacuoles in the cytoplasm, formation of the acidic vesicular organelles, membrane association of microtubule-associated protein 1 light chain 3 (LC3) with autophagosomes, and a marked induction of LC3-II protein, important hallmarks of autophagy, and by electron microscopy. Furthermore, inhibition of TG2 by rottlerin or by the siRNA led to accumulation of green fluorescent protein (GFP)-LC3-II in autophagosomes in pancreatic cancer cells transfected with GFP-LC3 (GFP-ATG8) expression vector. Knockdown of Beclin-1, a specific autophagy-promoting protein and the product of Becn1 (ATG6), inhibited rottlerin-induced and TG2 siRNA-induced autophagy, indicating that Beclin-1 is required for this process. These results revealed that PKCdelta plays a critical role in the expression of TG2, which in turn regulates autophagy. In conclusion, these results suggest a novel mechanism of regulation of TG2 and TG2-mediated autophagy in pancreatic cancer cells. 相似文献
94.
Ozpolat B Akar U Zorrilla-Calancha I Vivas-Mejia P Acevedo-Alvarez M Lopez-Berestein G 《Apoptosis : an international journal on programmed cell death》2008,13(7):915-928
All-trans-retinoic acid (ATRA) and arsenic trioxide (ATO) induce differentiation and apoptosis in acute promyelocytic leukemia (APL)
cells. Here we investigated the role and regulation of death-associated protein-5 (DAP5/p97/NAT1), a novel inhibitor of translational
initiation, in APL cell differentiation and apoptosis. We found that ATRA markedly induced DAP5/p97 protein and gene expression
and nuclear translocation during terminal differentiation of APL (NB4) and HL60 cells but not differentiation-resistant cells
(NB4.R1 and HL60R), which express very low levels of DAP5/p97. At the differentiation inducing concentrations, ATO (<0.5 μM),
dimethyl sulfoxide, 1,25-dihydroxy-vitamin-D3, and phorbol-12-myristate 13-acetate also significantly induced DAP5/p97 expression
in NB4 cells. However, ATO administered at apoptotic doses (1–2 μM) induced expression of DAP5/p86, a proapoptotic derivative
of DAP5/p97. ATRA and ATO-induced expression of DAP5/p97 was associated with inhibition of the phosphatidylinositol 3-kinase
(PI3K)/Akt pathway. Furthermore, DAP5/p97 expression was upregulated by inhibition of the PI3K/Akt/mammalian target of rapamycin
(mTOR) pathway via LY294002 and via rapamycin. Finally, knockdown of DAP5/p97 expression by small interfering RNA inhibited
ATRA-induced granulocytic differentiation and ATO-induced apoptosis. Together, our data reveal new roles for DAP5/p97 in ATRA-induced
differentiation and ATO-induced apoptosis in APL and suggest a novel regulatory mechanism by which PI3K/Akt/mTOR pathway inhibition
mediates ATRA- and ATO-induced expression of DAP5/p97.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
B. Ozpolat and U. Akar contributed equally. 相似文献
95.
Reduction of postoperative adhesions by N,O-carboxymethylchitosan and spermine NONOate in rats. 总被引:2,自引:0,他引:2
Bulent Duran Dogan Ak Ali Cetin Tevfik Guvenal Meral Cetin Ayse Gonca Imir 《Experimental Animals》2003,52(4):267-272
BACKGROUND: Postsurgical adhesions can occur following virtually all types of surgery, resulting in serious clinical complications. Therefore, prevention of adhesions is an important goal of surgical practice. A rat uterine horn model was used to investigate the efficacy of N,O-carboxymethylchitosan (NOCC) and spermine NONOate (SPER/NO) alone and in combination in preventing adhesion formation. METHODS: Sixty Wistar albino rats underwent bilateral uterine horn injury with a unipolar cautery. Study groups were as follows: (i) control group, no adjuvant therapy; and those with adjuvant applied, (ii) normal saline group, 2 ml of normal saline was given; (iii) NOCC group, 2 ml of 2% NOCC gel was given; (iv) SPER/NO group, 2 ml of SPER/NO (0.5 mg/ml) was given, and (v) NOCC plus SPER/NO group, 2 ml of 2% NOCC gel including SPER/NO (0.5 mg/ml) was given. After 14 days, all animals were euthanatized, and a standard adhesion scoring system including extent and severity scores was applied by a blinded examiner. RESULTS: The extent score in NOCC plus SPER/NO group was significantly lower than those of control and normal saline groups (p < 0.05). The extent score in NOCC group was significantly lower than that of normal saline group (p < 0.05). The extent score in NOCC plus SPER/NO group was significantly lower than that of SPER/NO group (p < 0.05). The severity score was significantly lower in NOCC plus SPER/NO and NOCC groups than that of control group (p < 0.05). The severity score was significantly lower in NOCC plus SPER/NO group than that of SPER/NO group (p < 0.05). CONCLUSIONS: Postoperative administration of NOCC gel and SPER/NO alone and especially in combination to the site of peritoneal injury reduces the formation of adhesions in the rat uterine horn model. 相似文献
96.
Gorgulu Yasemin Caliyurt Okan Kose Cinar Rugul Sonmez Mehmet Bulent 《Sleep and biological rhythms》2022,20(1):73-79
Sleep and Biological Rhythms - Acute sleep deprivation upregulates hippocampal neurogenesis. Neurotrophic factors such as glial cell line-derived neurotrophic factor (GDNF), brain-derived... 相似文献
97.
Aneuploidy, or an abnormal number of chromosomes, adversely affects cell growth, but it is also linked with cancer and tumorigenesis. Now, Torres et al. (2010) help to resolve this paradox by demonstrating that aneuploid yeast cells can evolve mutations in the proteasome protein degradation pathway that alleviate imbalances in protein production and increase the cell's proliferative capacities. 相似文献
98.
Harmanpreet Kaur Rebecca Heeney Rupp Carriveau Gabriel Sosne Bulent Mutus 《Biochimica et Biophysica Acta (BBA)/General Subjects》2010
Background
Thymosin beta 4 (Tβ4) is a major actin sequestering peptide present in most mammalian cells. It also acts as an anti-inflammatory agent and promotes corneal wound healing.Methods
In the present study, we constructed a four channel cylindrical flow chambers out of polydimethylsiloxane (PDMS) on microscope coverslips. The platelet-binding proteins–fibrinogen and collagen–were immobilized onto the middle ~ 25% of the inner cylindrical surface. The flow method introduced here was employed to determine the effect of Tβ4, on the deposition of ADP-activated platelets onto fibrinogen cross-linked flow chambers.Results
The binding data from the flow chambers indicated that the both the rate constant of platelet deposition (average: 0.026 ± 0.0015 s− 1, corresponding to a half-life of 26.7 s) and the total number of deposited platelets were independent of the platelet binding protein and the activating agent. Our results show that low concentrations of Tβ4 (0.2 μM to 0.5 μM) increased both the rate constant of platelet deposition by ~ 1.5-fold (i.e. half-life decreased from 26.7 s to 17.6 s) and the total number of deposited platelets by ~ 3-fold. However at higher concentrations (> 1 μM) the Tβ4-potentiating effect was diminished to near control levels. Tβ4 did interact with fibrinogen with an estimated KD of ~ 126 ± 18 nM or 66 ± 20 nM under equilibrium or flow, respectively.Conclusion
These results suggest that Tβ4 could potentially increase the affinity of platelet receptors for their ligands thus promoting platelet deposition. Tβ4 could also bind to fibrinogen and as its concentration increased would prevent platelet–fibrinogen interactions resulting in the attenuation of platelet deposition.General significance
This work suggests that Tβ4 might have a dual role in platelet function. 相似文献99.
Culex quinquefasciatus plays a major role in the transmission of important parasites and viruses throughout the world. Because temperature is an important limiting factor on growth and longevity of all mosquito species, estimating the reaction norms provides very important basic information for understanding both plasticity and individual variations of the population. In the present study, Cx. quinquefasciatus were maintained at five different constant temperatures (15°, 20°, 23°, 27°, and 30°C) for two subsequent generations. Reproductive population parameters in blood‐fed mated females and longevities of virgin and blood‐fed mated adults reared at different temperatures were compared for the two generations. Longevity increased as temperature decreased within a range of 15° to 30°C for the unmated adults, and 15° to 27°C for the mated and blood‐fed adults. Generation times were as long as 124.07 and 106.76 days for two subsequent generations reared at 15°C, and the highest intrinsic rate of increase (rm) values were estimated at 0.22 and 0.18, respectively, from the cohorts reared at 27°C. For survival rates, reproductive rates (R0), and rm values, 30°C was found to be a critical temperature for this species. These cohorts produced the smallest amount of eggs (R0= 5.06), rm values decreasing across generations (from 0.11 to 0.06), and the survival rates from egg to adult were found to be insufficient (16.1 and 10.8%). Additionally, the rate of exponential increase with age and age specific mortalities (b) were calculated for the virgin cohorts. Age specific mortality rates increased as temperature decreased. The increase in mortality rates started to accelerate at 27°C and was more pronounced at 30°C, for both females and males. We estimated the coefficients of variation for the b values in which females have smaller coefficients than those of the males at all temperatures. 相似文献
100.
Nasal polyp (NP) is considered an inflammatory condition in nasal and paranasal sinus cavities and is frequently encountered in otolaryngology clinics. Although the pathophysiology of nasal polyps is poorly understood, it seems likely that the epithelium may play a critical role in the genesis of inflammatory nasal disease. The aim of this study was to investigate the role of free radicals and antioxidant enzymes in NP and compare these findings with concha bullosa (CB). NP and CB were obtained from 27 and 23 patients, respectively. Glutathione peroxidase (GSH-Px), catalase (CAT), xanthine oxidase (XO) total (enzymic plus non-enzymic) superoxide scavenger activity (TSSA), non-enzymic superoxide scavenger activity (NSSA), superoxide dismutase (SOD), and MDA levels in NP and CB were measured. GSH-Px activiy was significantly lower in patients with NP than in the CB group. However, CAT, XO activities and MDA levels were significantly higher in patients with NP than in the CB group, but TSSA, NSSA and SOD activities were unchanged. Increases in the levels of tissue MDA in patients with NP compared to the CB group may indicate the presence of free radical damage in patients with nasal NP. 相似文献