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1.
M. Kopecká 《Folia microbiologica》1984,29(2):115-119
Light and electron microscopy was used to study the effect of papulacandin B onSaccharomyces cerevisiae in the exponential growth phase. At 1–2 μg/mL cell division in the culture continued almost in parallel with the control,
at 4 μg/mL cell proliferation was reduced and the culture contained some cells with 2–9 buds which were not separated from
the mother cell by a septum, and at higher concentrations (8, 16 and 32 μg/mL) the proliferation stopped within 2 h. Cessation
of proliferation was due to lysis of budding cells in the bud region including perforation of thinned cell wall (most often
at the bud basis and sometimes at its apex), extrusion of cytoplasm and death of cell. Lysis was also observed in cells without
visible buds. Dividing cells died without visible lysis. 相似文献
2.
Kapral M Węglarz L Parfiniewicz B Lodowska J Jaworska-Kik M 《Folia microbiologica》2010,55(6):657-661
3.
Dose-related influence of sodium selenite on apoptosis in human thyroid follicles in vitro induced by iodine, EGF, TGF-β, and H2O2 总被引:1,自引:0,他引:1
Lehmann P Rank P Hallfeldt KL Krebs B Gärtner R 《Biological trace element research》2006,112(2):119-130
Apoptosis of thyroid follicular cells is induced by high doses of iodide, epidermal growth factor (EGF), transforming growth
factor-β (TGF-β), as well as H2O2 and might be attenuated by antioxidants. Therefore, we examined the apoptotic index induced by these substances in selenium-treated
vs untreated human thyroid follicular cells. Reconstituted human thyroid follicles were incubated with sodium selenite (10
or 100 nM) for 72 h; controls received none. The follicles were then distributed to 24-well plates and incubated with potassium iodide
(5, 10, or 20 nM), EGF (5 ng/mL), TGF-β (5 ng/mL), or H2O2 (100 μM). Apoptosis was determined by a mitochondrial potential assay and the number of apoptotic cells counted by two independent,
experienced technicians and the glutathione peroxidase (GPx) activity was determined. A significant increase of apoptic cells
was obtained in control thyroid follicles treated with iodine (5, 10, or 20 μM), thyroid-stimulating hormone (TSH) 1, or 10 mU/mL in combination with 5 and 10 μM iodine, EGF (5 ng/mL) and TGF-β (5 ng/mL), or H2O2 (100 μM) (p<0.001). In contrast, in thyroid follicles preincubated with 10 or 100 nM sodium selenite, the apoptototic index was identical to the basal rate. In H2O2-treated follicles, the apoptotic index was still significantly elevated but 50% lower compared to control cells. The GPx
activity increased from 1.4±0.2 to 2.25±0.4 mU/μg DNA with 10 nM selenite and 2.6+0.4 mU/μg DNA with 100 nM selenite. Sodium selenite might increase the antioxidative potential in human thyroid follicles in vitro and therefore diminish
the apoptosis induced by TGF-β, EGF, iodide, and even H2O2 相似文献
4.
The effect of different concentrations of Na2SeO3 on human pulmonary adenocarcinoma cells and human embryonic lung diploid cells in vitro was investigated. For human pulmonary
adenocarcinoma cells, mitotic index and cell count decreased with increasing selenium concentrations. At 1 μg/mL sodium selenite,
mitotic activity and growth of human lung cancer cells were partially inhibited, and the progression of human lung cancer
cell cycle was partially arrested. When human embryonic lung diploid cells were treated with 1 μg/mL sodium selenite for five
continuous days, cell counts of the treated group were closely parallel to those of the control group. After treating human
embryonic lung diploid cells with 1–5μg/mL sodium selenite for 1–3 d, the mitotic index (MI), labeled index (LI), and average
silver grain (SG) number per 20 labeled nuclei were the same as those of the control. In mixed cultures of human embryonic
lung diploid cells and human pulmonary adenocarcinoma cells, treated with 3 and 5 μg/mL sodium selenite for 24 h, the lung
diploid cells showed a normal fusiform morphology, whereas the lung cancer cells showed heavily vacuolated cytoplasms and
distorted nuclei. 相似文献
5.
Helena Mathews R. E. Litz H. D. Wilde S. A. Merkle H. Y. Wetzstein 《In vitro cellular & developmental biology. Plant》1992,28(4):172-178
Summary Somatic proembryos of mango (Mangifera indica L. cv. Hindi) were co-cultivated withAgrobacterium tumefaciens strain A208 harboring pTiT37-Se::pMON 9749 (9749 ASE). Transformed somatic proembryos capable of growing on selection medium
containing 200 μg/ml kanamycin produced the characteristic indigo blue precipitate in the presence of 5-bromo-4-chloro-3-glucuronic
acid. These proembryos were chimeral consisting of transformed (blue) and nontransformed (yellow/white) cells. A stepwise
selection strategy was found necessary to eliminate chimeras. a) Initial screening at 200 μg/ml kanamycin to enable growth
of transformed cells, b) further screening at 400 μg/ml kanamycin to reduce chimeras, and c) recovery of pure transformed
clones of proembryos in liquid selection medium with 100 μg/ml kanamycin. The integration of the NPT II and GUS genes into
mango genome was confirmed by Southern hybridization. 相似文献
6.
The effect of the organic buffer salts MES, MOPS, and PIPES on the growth of S. thermophilus ST110, medium pH, and accumulation of the antipediococcal bacteriocin thermophilin 110 were evaluated in whey permeate media
over a period of 24 h. In nonbuffered medium, thermophilin 110 production at 37°C paralleled the growth of S. thermophilus ST110 and reached a maximum after 8–10 h. Addition of organic buffer salts decreased the drop in medium pH and resulted in
increased biomass (dry cells; μg/mL) and higher yields of thermophilin 110 (units/μg cells). The best results were obtained
by the addition of 1% (w/v) MES to the medium, which reduced the pH drop to 1.8 units after 10 h of growth (compared to 2.3
pH units in the control) and resulted in a 1.5-fold increase in cell mass (495 μg/mL) and a 7-fold increase in thermophilin
110 yield (77 units/μg dry cells) over the control. The results showed that whey permeate-based media may be suitable for
producing large amounts of thermophilin 110 needed for controlling spoilage pediococci in industrial wine and beer fermentations.
Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information
and does not imply recommendation or endorsement by the U.S. Department of Agriculture. 相似文献
7.
The sodium/iodide symporter (SLC5A5, also known as NIS) is a transmembrane glycoprotein. Physiologically, iodide transportation in the mammary gland occurs during late pregnancy
and lactation. To identify factors that may regulate this process at different iodine levels, we have studied the expression
of NIS gene and protein in cultured mammary gland explants from lactating mice by real-time quantitative PCR and In-Cell Western
methods. Mammary gland cells were grown in media with different levels of iodine for 24 h. The iodine treatment groups consist
of low iodine group I (LI-I, 0 μg/l), low iodine group II (LI-II, 5 μg/l), control group (C, 50 μg/l), high iodine group I
(HI-I, 3,000 μg/l), and high iodine group II (HI-II, 10,000 μg/l). The cells were then incubated with or without insulin-like
growth factor I (IGF-I) or transforming growth factor β1 (TGF-β1) for another 24 h. We found that iodine inhibited NIS mRNA and protein expression in a dose-dependent manner. IGF-I and TGF-β1 further decreased NIS mRNA and protein expression that iodine inhibited at different iodine levels. In summary, we have shown that iodine downregulated
NIS expression in cultured mammary gland explants from the lactating mouse. IGF-I and TGF-β1 inhibited NIS mRNA and protein expression in the mammary gland under different iodine levels. 相似文献
8.
Ling Ding Xi Li Peng Liu Shiqian Li Jiliang Lv 《Biological trace element research》2010,137(3):364-372
The biological effect of Se and Cu2+ on Escherichia coli (E. coli) growth was studied by using a 3114/3236 TAM Air Isothermal Calorimeter, ampoule method, at 37°C. From the thermogenesis
curves, the thermokinetic equations were established under different conditions. The kinetics showed that a low concentration
of Se (1–10 μg/mL) promoted the growth of E. coli, and a high concentration of Se (>10 μg/mL) inhibited the growth, but the Cu2+ was always inhibiting the growth of E. coli. Moreover, there was an antagonistic or positive synergistic effect of Se and Cu2+ on E. coli in the different culture medium when Se was 1–10 μg/ml and Cu2+ was 1–20 μg/ml. There was a negative synergistic effect of Se and Cu2+ on E. coli when Se was higher than 10 μg/ml and Cu2+ was higher than 20 μg/ml. The antagonistic or synergistic effect between Se and Cu2+ on E. coli was related to the formation of Cu–Se complexes under the different experimental conditions chosen. 相似文献
9.
Michael A. Pfaller Daniel J. Diekema Mariana Castanheira Ronald N. Jones 《Current fungal infection reports》2011,5(3):120-127
Antifungal susceptibility testing of Candida against the echinocandin antifungal agents (anidulafungin [ANF], caspofungin [CSF], micafungin [MCF]) has been standardized
by the Clinical and Laboratory Standards Institute (CLSI) Subcommittee on Antifungal Testing. The CLSI proposed a single set
of clinical breakpoints (CBPs) for all three echinocandins and all species of Candida: susceptible, minimum inhibitory concentration (MIC) ≤ 2 μg/mL; nonsusceptible, MIC > 2 μg/mL. Subsequently, these CBPs have
been shown to lack sensitivity in detecting strains of Candida with acquired resistance mechanisms associated with treatment failure. Studies using the CLSI method have defined wild-type
(WT) MIC distributions and epidemiologic cutoff values (ECVs) for each echinocandin and the common species of Candida. The ECVs serve as a sensitive means of discriminating WT strains from those with acquired resistance mechanisms. WT MIC
distributions revealed ECV ranges of 0.03 to 0.25 μg/mL for all major species except C. parapsilosis (1–4 μg/mL) and C. guilliermondii (4–16 μg/mL). These ECVs reliably differentiate WT strains of each species from non-WT strains containing fks mutations. These data, coupled with additional biochemical, clinical, pharmacokinetic, and pharmacodynamic considerations,
have resulted in new CBPs of ≤0.25 μg/mL (susceptible), 0.5 μg/mL (intermediate), and ≥1 μg/mL (resistant) for ANF, CSF, and
MCF for C. albicans, C. tropicalis, and C. krusei. For these agents and C. parapsilosis, the new CBPs are ≤2 μg/mL (susceptible), 4 μg/mL (intermediate), and ≥8 μg/mL (resistant). For C. glabrata, the CBPs for ANF and CSF are ≤0.12 μg/mL (susceptible), 0.25 μg/mL (intermediate), and ≥0.5 μg/mL (resistant), whereas those
for MCF are ≤0.06 μg/mL, 0.12 μg/mL, and ≥0.25 μg/mL, respectively. Application of both ECVs and the lower species-specific
CBPs for the echinocandins has proven useful in both resistance surveillance and clinical care and will serve as an important
step in international harmonization of in vitro susceptibility testing of this important antifungal class. 相似文献
10.
The effects of phosphorus, Zn2+, CO2, and light intensity on growth, biochemical composition, and the activity of extracellular carbonic anhydrase (CA) in Isochrysis galbana were investigated. A significant change was observed when the concentration of phosphorus in the medium was increased from
5 μmol/L to 1000 μmol/L affecting I. galbana’s cell density, biochemical composition, and the activity of extracellular CA. Phosphorous concentration of 50 μmol/L to 500
μmol/L was optimal for this microalgae. The Zn2+ concentration at 10 μmol/L was essential to maintain optimal growth of the cells, but a higher concentration of Zn2+ (≥ 1000 μmol/L) inhibited the growth of I. galbana. High CO2 concentrations (43.75 mL/L) significantly increased the cell densities compared to low CO2 concentrations (0.35 mL/L). However, the activity of extracellular CA decreased significantly with an increasing concentration
of CO2. The activity of extracellular CA at a CO2 concentration of 43.75 mL/L was approximately 1/6 of the activity when the CO2 concentration was at 0.35 mL/L CO2. Light intensity from 4.0 mW/cm2 to 5.6 mW/cm2 was beneficial for the growth, biochemical composition and the activity of extracellular CA. The lower and higher light intensity
was restrictive for growth and changed its biochemical composition and the activity of extracellular CA. These results indicate
that phosphorus, Zn2+, CO2, and light intensity are important factors that impact growth, biochemical composition and the activity of extracellular
CA in I. galbana. 相似文献
11.
Tyrosine kinase activation in LPS stimulated rat kupffer cells 总被引:2,自引:0,他引:2
Bobert L. Schultze Aniruddha Gangopadhyay Osman Cay Donald Lazure Peter Thomas 《Cell biochemistry and biophysics》1999,30(2):287-301
Kupffer cells, a majority of the body's fixed macrophages, are a major site of bacterial lipopolysaccharide (LPS) metabolism
and are mediators in the body's response to sepsis. Uptake of LPS is different in Kupffer cells than other macrophages. Signal
transduction in other macrophages in response to LPS involves phosphorylation of proteins in the 50–60 kDa range. We hypothesized
that Kupffer cells may have unique signal transduction pathways in response to LPS. Rat Kupffer cells were exposed to LPS
(1 μg/mL) for varying times ranging from 15 to 90 min. Cell lysates were Western blotted using an anti-phosphotyrosine antibody.
The blots showed an increase in the amount of tyrosine phosphorylation on two proteins of 119 kDa and 83 kDa. The effects
of varying LPS concentration (1 ng/mL-1 μg/mL) showed an increasing amount of phosphorylation with increasing LPS concentration.
To associate the importance of tyrosine phosphorylation in the response of Kupffer cells to LPS, the tyrosine kinase inhibitors,
tyrphostin, lavendustin, and genisten were used to study the effects of inhibiting phosphorylation on TNF-α production. Kupffer
cells were preincubated in the presence of the inhibitor and exposed to LPS (1 μg/mL). TNF-α was measured in the conditioned
media by ELISA. A 70% or greater decrease in TNF-α production was observed. When phagocytosis of latex beads by rat Kupffer
cells was measured in vivo using intravital video microscopy, LPS treatment significantly increased uptake. This increase
in phagocytosis was inhibited by tyrphostin. These results show what may be unique phosphorylation events in Kupffer cells
that are related to LPS induced production of TNF-α.
Presented in part at the American Association for the Study of Liver Diseases Annual Meeting, Chicago, IL (USA), November
3–7, 1995. 相似文献
12.
In order to determine the existence of synergism of the bacteriostatic action of flavonoids against G+ bacteria between a clinically interesting conventional antibiotic and a flavonoid, combinations of oxacillin (OXC) and 2,4-dihydroxychalcone
(DCH) as enhancer were assayed against methicillin-sensitive Staphylococcus aureus ATCC 29 213 and methicillin-resistant S. aureus ATCC 43 300. Using a kinetic-turbidimetric method, growth kinetics was monitored in a broth containing variable amounts of
OXC alone and combinations of variable OXC-constant DCH. The minimum inhibitory concentrations (MIC) of OXC alone and in combination
with DCH were evaluated. For the 29 213 strain, OXC MIC was 25 μg/mL, while combinations of 2–8 μg/mL OXC with 10 μg/mL of
DCH totally inhibited growth and showed synergism. The resistance of the 43 300 strain in the presence of OXC was verified;
OXC-DCH combinations decreased bacterial growth by 35 %. DCH augments the action of OXC against methicillin-susceptible S. aureus and therefore constitutes a good bacteriostatic agent for methicillin-resistant S. aureus. 相似文献
13.
A. Oren 《Archives of microbiology》1996,165(5):354-358
Many members of the Halobacteriaceae are inhibited by quinolone compounds, which inhibit type II DNA topoisomerase. Ciprofloxacin
was the most potent inhibitor, followed by ofloxacin and norfloxacin. Ciprofloxacin concentrations between 25 and 60 μg/ml
caused 50% inhibition of the growth of most Haloferax and Haloarcula species. Halobacterium species were less sensitive. At sublethal concentrations, formation of elongated and/or swollen cells was observed in many
species. The alkaliphilic Natronobacterium pharaonis was very sensitive (50% inhibition by ciprofloxacin, ofloxacin, and norfloxacin at concentrations between 4 and 15 μg/ml).
The resistance of many members of the Halobacteriaceae to high concentrations of quinolone compounds may in part be due to
the high magnesium concentrations present in the growth media. Haloferax volcanii was sensitive to 40 μg/ml ciprofloxacin when grown at suboptimal magnesium concentrations (0.1 M), but was hardly affected
by 100 μg/ml of the inhibitor when grown in the presence of 0.5–0.75 M MgCl2. It is suggested that the putative archaeal type II DNA topoisomerase has properties similar to those of the enzyme from
Bacteria, although its sensitivity to quinolone antimicrobial compounds may be lower.
Received: 6 November 1995 / Accepted: 26 February 1996 相似文献
14.
DuBok Choi Sang-Shin Park Ji-Lu Ding Wol-Suk Cha 《Biotechnology and Bioprocess Engineering》2007,12(5):516-524
We investigated the effects ofFomitopsis pinicola extract on biological activity by examining the antioxidant and antitumor activityin vitro andin vivo. When theF. pinicola extract concentration was raised from 60 to 120 μg/mL, the DPPH scavenging rate increased from 50.3 to 88.2% and the superoxide
anion radical scavenging rate increased from 45.2 to 85.3% when theF. pinicola extract concentration was raised from 500 to 700 μg/mL. After incubatingF. pinicola extract for 12 h, the linoleic acid scavenging rate increased from 35.5 to 90.5%. A similar finding was observed for butylated
hydroxytoluene. The total phenolic content of theF. pinicola extracts were approximately 10- to 16-fold higher than what was observed in theP. nebrodensis andA. camphorate extracts. The glutathione production, using decoctions prepared fromF. pinicola, was 20.0 μM/g of liver, which corresponded to approximately 4.0-fold higher than the control. The glutathione peroxidase
activity was 8.3 U/mg of protein, which was approximately 2.8-fold higher than the activity level observed in the control
rat livers. The cell viability rates of all the human cancer cells, when 100 μg/mL of ethanol extract was used for the different
types of cancer cells, decreased with increasing extract concentrations in comparison to the hot water extract. In particular,
when HeLa and Hep3B cells were incubated with 1.000 μg/mL of methanol extract, the cell viability rates were 20 and 25%, respectively,
which was approximately 3.0-fold higher than what was observed for the hot water extract.
The first two authors contributed equally to this work. 相似文献
15.
Hematopoietic progenitor colony assays were used to establish the effects of the vinca alkaloid vinorelbine (VRB) on murine
bone marrow. The in vitro growth of colony-forming units–granulocyte/macrophage (CFU-GM), burst forming units–erythroid (BFU-E) and colony-forming
units–mix (CFU-mix) was dose-dependently inhibited by VRB. The highest dose assayed (0.02 μg/ml) suppressed all of the different
progenitor cells by 100%. A comparison of the dose–response curves showed that CFU-GM, BFU-E, and CFU-mix exhibited similar
patterns of sensitivity to the cytotoxic action of VRB. Long-term bone marrow cultures have provided a valuable in vitro model for studying the role of the microenvironment of bone marrow. Cellularity of stromal layers was reduced with increasing
doses of VRB. The appearence of these layers was altered minimally with the lowest dose used; a gradual loss of cellularity
was seen in cultures exposed to 0.05 and 0.075 μg/ml; and a marked loss at the dose of 0.1 μg/ml. Our results show that VRB
has an important effect on hematopoietic progenitors at the highest dose tested, while the stromal cells were not affected
at a similar dose (0.025 μg/ml), suggesting that the stroma is more resistant to this drug.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
16.
Ali Samanci Qing Yi Jan Fagerberg Karin Strigård Gale Smith Ulla Rudén Britta Wahren Håkan Mellstedt 《Cancer immunology, immunotherapy : CII》1998,47(3):131-142
Eighteen colorectal carcinoma patients without macroscopic disease after surgery were immunized using recombinant (r) human
(h) carcinoembryonic antigen (CEA) with (n = 9) or without (n = 9) the addition of soluble granulocyte/macrophage-colony-stimulating factor (GM-CSF). The dose of rhCEA per immunization
was 100 μg (n = 6), 316 μg (n = 6) or 1000 μg (n = 6). rhCEA was given s.c. on day 1 and 80 μg/day of GM-CSF s.c. on days 1–4. The schedule was repeated six times during
a period of 9 months. All patients in the GM-CSF group developed a strong rhCEA-dose-dependent IgG antibody response while
only one-third of the non-GM-CSF patients mounted a weak antibody response. All patients (9/9) in the GM-CSF group developed
a strong rhCEA-specific proliferative T cell response as well as type I T cells (interferon γ secretion). In 45% of the patients
also a weak type II T cell response (interleukin-4 secretion) was evoked. Both MHC-class-I- and -II restricted rhCEA-specific
T cells were noted. A specific cellular response (proliferation and/or cytokine secretion) against native hCEA could be found
in 8/9 patients in the GM-CSF group, although at a significantly lower level than against rhCEA. In the non-GM-CSF group a
weak rhCEA-specific T cell response was induced. Three patients had a proliferative response, 4 patients type I T cells and
6 patients type II T cells. No signs of autoimmune reactions were noted. Local pharmacological administration of GM-CSF seemed
to be a prerequisite for the induction of a strong immunity against baculovirus-produced hCEA protein. However, the cellular
response against native CEA was of a significantly lower magnitude.
Received: 13 November 1997 / Accepted: 21 May 1998 相似文献
17.
Masami Ogasawara David A. Sirbasku 《In vitro cellular & developmental biology. Plant》1988,24(9):911-920
Summary Growth of the MCF-7, T47D, and ZR-75-1 human breast cancer cells was established in a serum-free defined medium (MOM-1) composed
of a 1∶1 (vol/vol) mixture of Ham's F12 medium and Dulbecco's modified Eagle's medium containing 15 mM HEPES (pH 7.2), 2 mM 1-glutamine, 20 μg/ml glutathione, 10 μg/ml insulin, 10 μg/ml transferrin (Tf), 10 ng/ml selenous acid, 0.3 nM triiodothyronine, 50 μg/ml ethanolamine, 20 ng/ml epidermal, growth factor, 2.0 nM 17β-estradiol, and 1.0 mg/ml bovine serum albumin (BSA). Proliferation in MOM-1 was 50 to 70% of the serum stimulated rate.
Deletion of components from MOM-1 gave a medium (Tf-BSA) containing only HEPES, 10 μg/ml Tf, and 200 μg/ml BSA, which sustained
MCF-7 and T47D cells in a slowly dividing and mitogen responsive state; ZR-75-1 cells required Tf plus 1.0 mg/ml BSA. In Tf-BSA,
insulin and insulin-like growth factor I(IGF-I) were mitogenic with ED50 values of 2 to 3 ng/ml and 30 to 150 pg/ml, respectively, with MCF-7 cells. The T47D cells were responsive to these factors
in Tf-BSA but required 10-fold higher concentrations for ED50. At saturating concentrations, insulin and IGF-I promoted 1.5 to 3.5 cell population doublings over controls in 8 d. At≤ng/ml
concentrations, epidermal growth factor, insulin-like growth factor II, and basic fibroblast growth factor were mitogenic
for human breast cancer cells in Tf-BSA. Mitogen activities in uterus and pituitary extracts were assayed readily in Tf-BSA.
This new method offers a convenient means of comparing the potencies of growth-promoting factors on human breast cancer cells
without interfering activities known to be present in serum.
This work was supported by grants CA-38024 and CA-26617, from the National Cancer Institute, Bethesda, MD, and by American
Cancer Society grant BC-255 and grant 2225 from the Council for Tobacco Research, USA, Inc. 相似文献
18.
Two groups of 16 rats each were fed the same diet with 12.9 ppm Zn. Nine days after each animal was injected with65Zn for assessing fecal zinc of endogenous origin, zinc intake and excretion were determined for a six-day period at the age
of about five (group I) and nine (II) weeks. At mean growth rates of 5.1 and 5.2 g/day, food consumption per gram of gain
was 2.01 g in group I vs 2.86 g in II. Overall, zinc retention amounted to 21 vs 25 μg Zn/g of gain. Apparent absorption averaged
92 vs 74% of Zn intake (132 vs 189 μg/day), while true absorption averaged 98 vs 92%. It was concluded that endogenous fecal
zinc excretion was limited to the indispensable loss (F
em) in group I (7 μg/day), while it exceeded this minimum loss in group II (33 μg/day). True retention, which reflected total
zinc utilization (true absorption times metabolic efficiency), was derived from apparent absorption plusF
em (11 μg/day for group II according to the greater metabolic body size of the rats). It averaged 98% of Zn intake in group
I vs 80% in group II. The mean metabolic efficiency was 100% vs 87%. The conclusion was that these marked differences between
age groups in utilizing the dietary zinc reflected the efficient homeostatic adjustments in absorption and endogenous excretion
of zinc to the respective zinc supply status. 相似文献
19.
Nagpal A Meena LS Kaur S Grover IS Wadhwa R Kaul SC 《In vitro cellular & developmental biology. Animal》2000,36(8):544-547
Summary We have investigated the effects of acetone and methanol extracts of a medicinal plant, Terminalia arjuna, on the growth of human normal fibroblasts (WI-38), osteosarcoma (U2OS), and glioblastoma (U251) cells in vitro. We found
that both extracts at 30 μg and 60 μg/ml concentrations inhibit the growth of transformed cells; the growth of normal cells
was least affected. Although the transformed cells appeared to have fragmented nucleus by Hoechst staining, no deoxyribonucleic
acid laddering effect was observed. In response to the extract treatment, the tumor suppressor protein, p53, was induced in
U2OS but not in U251 and WI-38 cells. A cyclin-dependent kinase inhibitor, p21WAF1, was induced in transformed cells only. The study suggests that the bark extract of medicinal plant, T. arjuna, has components that can induce growth arrest of transformed cells by p53-dependent and-independent pathways. 相似文献
20.
Cell-free extracts (CFEs) of chromium-resistant bacterium Bacillus sphaericus AND 303 isolated from serpentine soil of Andaman, India reduced Cr(VI) in in vitro condition, and the reductase activity was solely localized in the soluble cell-fractions (S12, S32, and S150). The enzyme was constitutive as the CFEs from cells grown in Cr(VI)-free and Cr(VI)-containing media reduced a more or less
equal amount of Cr(VI). Optimum Cr(VI) reductase activity was obtained at an enzyme (S150) concentration equivalent to 4.56 mg protein/mL, 300 μM Cr(VI) and pH 6.0 after 30 min incubation at 30°C. The enzyme was heat labile; 80% of its activity was lost when exposed
at 70°C for 15 min. Kinetics of Cr(VI) reductase activity fit well with the linearized Lineweaver-Burk plot and showed a Vmax of 1.432 μmol Cr(VI)/mg protein/min and Km of 158.12 μM Cr(VI). The presence of additional electron donors accelerated Cr(VI) reductase activity of CFE, and an increase of 28% activity
over control was recorded with 1.0 μM NADH. Heavy metal ions such as Ni(II), Cu(II), and Cd(II) were strong inhibitors of Cr(VI) reductase unlike that of 100 μM Co(II), which retained 93% activity over control. 相似文献