scholarly journals Growth of Mycobacterium tuberculosis in a Defined Medium Is Very Restricted by Acid pH and Mg2+ Levels

2000 ◽  
Vol 68 (8) ◽  
pp. 4518-4522 ◽  
Author(s):  
Debra L. Piddington ◽  
Ali Kashkouli ◽  
Nancy A. Buchmeier
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Divalent Cations ◽  
Defined Medium ◽  
Acidic Ph ◽  
Mycobacterial Species ◽  
Acidic Media ◽  
Restricted Environment ◽  
Extreme Sensitivity ◽  
Acidic Conditions ◽  
Influence Of Ph

ABSTRACT Mycobacterium tuberculosis grows within the phagocytic vacuoles of macrophages, where it encounters a moderately acidic and possibly nutrient-restricted environment. Other mycobacterial species encounter acidic conditions in soil and aquatic environments. We have evaluated the influence of pH and divalent cation levels on the growth of M. tuberculosis and seven other mycobacterial species. In a defined medium, the growth of M. tuberculosis was very restricted by acidic pH. Higher levels of Mg2+ were required for growth of M. tuberculosis in mildly acidic media (pH 6.0 to 6.5) compared to pH 7.0 medium. The divalent cations Ca2+, Zn2+, or Mn2+ could not replace Mg2+ during growth at pH 6.25, but Ca2+could at least partially substitute for Mg2+ during growth at pH 7.0. Among eight species of mycobacteria tested, there was a diversity of growth rates in media with acidic pH and low Mg2+ levels. M. tuberculosis was the most restricted in growth at pH 6.0, and all of this growth required elevated levels of Mg2+. M. kansasii andM. smegmatis also grew very poorly in acidic media with limiting Mg2+. M. fortuitum, M. marinum, M. scrofulaceum, M. avium, andM. chelonae grew at pH 6.0 in an unrestricted manner. These results demonstrate that M. tuberculosis is unique among the mycobacteria in its extreme sensitivity to acid and indicate thatM. tuberculosis must acquire sufficient Mg2+ in order to grow in a mildly acidic environment such as within the phagosome of macrophages.

Adsorption of zearalenone by Aspergillus japonicus conidia: new trends for biological decontamination in animal feed

2009 ◽  
Vol 2 (4) ◽  
pp. 391-397 ◽  
Author(s):  
G. Jard ◽  
T. Liboz ◽  
F. Mathieu ◽  
A. Guyonvarc'h ◽  
A. Lebrihi
Keyword(s):  
Heat Treatment ◽  
Animal Feed ◽  
Animal Health ◽  
Acidic Ph ◽  
Fusarium Spp ◽  
Aspergillus Japonicus ◽  
Heat Treated ◽  
Acidic Conditions ◽  
Influence Of Ph

Zearalenone (ZEA) is an oestrogenic mycotoxin produced by Fusarium spp. on a wide variety of grains. The presence of ZEA impairs farm animal health. In this study, the ability to remove ZEA by conidia of Aspergilli was evaluated in vitro. This mycotoxin was successfully eliminated in vitro by living and heat-treated conidia just after conidial inoculation, especially by Aspergillus japonicus Mu541 (IMI389204) conidia. Consequently, components involved in adsorption are not affected by heat-treatment. The influence of pH on ZEA removal was also determined. Results have shown that ZEA removal was 53% at pH 2 while 2% removal was observed at pH 11. Then, the adsorption capacity was evaluated in vitro in porcine gastrointestinal tract conditions. We observed that there was better adsorption in acidic stomach conditions. Finally, the phenomenon has been modelled using Hill's equation. This model was very suitable and confirmed better adsorption at acidic pH. Aspergilli section Nigri conidia were able to adsorb ZEA instantaneously especially in acidic conditions as in the stomach. The use of heat-treated conidia could be a very interesting means of decreasing ZEA levels in animal feed. It must now be assessed directly on naturally contaminated feed and on animals.

Changes of the phagosomal elemental concentrations by Mycobacterium tuberculosis Mramp

Microbiology ◽  
2005 ◽  
Vol 151 (1) ◽  
pp. 323-332 ◽  
Author(s):  
Dirk Wagner ◽  
Jörg Maser ◽  
Ivana Moric ◽  
Neio Boechat ◽  
Stefan Vogt ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Efflux Pump ◽  
Divalent Cations ◽  
Peritoneal Macrophages ◽  
Bacterial Survival ◽  
Knockout Mutant ◽  
Elemental Concentrations ◽  
Restricted Environment ◽  
Mouse Peritoneal Macrophages ◽  
Strain H37rv

Pathogenic mycobacteria survive within phagosomes which are thought to represent a nutrient-restricted environment. Divalent cation transporters of the Nramp family in phagosomes and mycobacteria (Mramp) may compete for metals that are crucial for bacterial survival. The elemental concentrations in phagosomes of macrophages infected with wild-type Mycobacterium tuberculosis (M. tuberculosis strain H37Rv) and a M. tuberculosis Mramp knockout mutant (Mramp-KO), derived from a clinical isolate isogenic to the strain MT103, were compared. Time points of 1 and 24 h after infection of mouse peritoneal macrophages (bcg S) were compared in both cases. Increased concentrations of P, Ni and Zn and reduced Cl concentration in Mramp-KO after 1 h of infection were observed, compared to M. tuberculosis vacuoles. After 24 h of infection, significant differences in the P, Cl and Zn concentrations were still present. The Mramp-KO phagosome showed a significant increase of P, Ca, Mn, Fe and Zn concentrations between 1 and 24 h after infection, while the concentrations of K and Ni decreased. In the M. tuberculosis vacuole, the Fe concentration showed a similar increase, while the Cl concentration decreased. The fact that the concentration of several divalent cations increased in the Mramp-KO strain suggests that Mramp may have no impact on the import of these divalent cations into the mycobacterium, but may function as a cation efflux pump. The concordant increase of Fe concentrations within M. tuberculosis, as well as within the Mramp-KO vacuoles, implies that Mramp, in contrast to siderophores, might not be important for the attraction of Fe and its retention in phagosomes of unstimulated macrophages.

scholarly journals Synthesis and In Vitro Assessment of pH-Sensitive Human Serum Albumin Conjugates of Pirarubicin

2020 ◽  
Vol 14 (1) ◽  
pp. 22
Author(s):  
Kenji Tsukigawa ◽  
Shuhei Imoto ◽  
Keishi Yamasaki ◽  
Koji Nishi ◽  
Toshihiko Tsutsumi ◽  
...  
Keyword(s):  
Human Serum Albumin ◽  
Serum Albumin ◽  
Human Serum ◽  
Coupling Reaction ◽  
Synthetic Polymer ◽  
Ph Sensitive ◽  
Acidic Ph ◽  
Polymer Conjugate ◽  
Acidic Conditions

In a previous study, we reported on the development of a synthetic polymer conjugate of pirarubicin (THP) that was formed via an acid-labile hydrazone bond between the polymer and the THP. However, the synthetic polymer itself was non-biodegradable, which could lead to unexpected adverse effects. Human serum albumin (HSA), which has a high biocompatibility and good biodegradability, is also a potent carrier for delivering antitumor drugs. The objective of this study was to develop pH-sensitive HSA conjugates of THP (HSA-THP), and investigate the release of THP and the cytotoxicity under acidic conditions in vitro for further clinical development. HSA-THP was synthesized by conjugating maleimide hydrazone derivatives of THP with poly-thiolated HSA using 2-iminothiolane, via a thiol-maleimide coupling reaction. We synthesized two types of HSA-THP that contained different amounts of THP (HSA-THP2 and HSA-THP4). Free THP was released from both of the HSA conjugates more rapidly at an acidic pH, and the rates of release for HSA-THP2 and HSA-THP4 were similar. Moreover, both HSA-THPs exhibited a higher cytotoxicity at acidic pH than at neutral pH, which is consistent with the effective liberation of free THP under acidic conditions. These findings suggest that these types of HSA-THPs are promising candidates for further development.

General properties and comparison of the corrosion inhibition efficiencies of the triazole derivatives for mild steel

2018 ◽  
Vol 36 (6) ◽  
pp. 507-545 ◽  
Author(s):  
Muhammad Faisal ◽  
Aamer Saeed ◽  
Danish Shahzad ◽  
Nadir Abbas ◽  
Fayaz Ali Larik ◽  
...  
Keyword(s):  
Cost Effectiveness ◽  
Mild Steel ◽  
Corrosion Inhibitors ◽  
Mechanisms Of Action ◽  
Effect Of Temperature ◽  
General Effect ◽  
Acidic Media ◽  
Triazole Derivatives ◽  
Concentration Time ◽  
Acidic Conditions

AbstractMild steel (MS) corrosion is a worldwide issue that greatly affects the industrial and natural environment. To extend the lifespan of appliances, the control of MS corrosion is necessary. To shield MS from corrosion, specifically from acidic conditions, one of the practical and finest approaches is the application of inhibitors. Triazole derivatives are eco-friendly corrosion inhibitors (CIs) having inconsequential toxicities, excellent inhibition efficiencies (IEs) against corrosion of MS, and extremely high cost-effectiveness. This critical review discusses the general effect of temperature, concentration, time after the application of CI, and type of acid on the IE of triazole derivatives. Further, the review provides an adequate amount of information about the features of excellent CIs; a summary of the reported properties of triazole-based inhibitors, CIs in industries, and current requirements of industries; and recommendations and implications for researchers to improve IE. Additionally, the review also illustrates the mechanisms of action and the IEs, which are evaluated from potentiodynamic polarization parameters, in various acidic media and concentrations of triazole inhibitors. By IE correlation with numerous concentrations and acidic conditions, this review is advantageous and helpful for synthetic chemists to expand the diversity and complexity of a class of triazole derivatives by synthesizing new triazole derivatives.

scholarly journals A New pH-Dependent Macrocyclic Rhodamine B-Based Fluorescent Probe for Copper Detection in White Wine

Sensors ◽  
2019 ◽  
Vol 19 (20) ◽  
pp. 4514 ◽  
Author(s):  
Nour Doumani ◽  
Elias Bou-Maroun ◽  
Jacqueline Maalouly ◽  
Maya Tueni ◽  
Adrien Dubois ◽  
...  
Keyword(s):  
Rhodamine B ◽  
White Wine ◽  
Green Solvent ◽  
Acidic Media ◽  
One Pot ◽  
Acidic Conditions ◽  
Ph Conditions ◽  
Ph Dependent ◽  
Copper Detection ◽  
Color Emission

For efficiently measuring copper (II) ions in the acidic media of white wine, a new chemosensor based on rhodamine B coupled to a tetraazamacrocyclic ring (13aneN4CH2NH2) was designed and synthesized by a one-pot reaction using ethanol as a green solvent. The obtained chemosensor was characterized via NMR, UV and fluorescent spectra. It was marked with no color emission under neutral pH conditions, with a pink color emission under acidic conditions, and a magenta color emission under acidic conditions where copper (II) ions were present. The sensitivity towards copper (II) ions was tested and verified over Ca2+, Ag+, Zn2+, Mg2+, Co2+, Ni2+, Fe2+, Pb2+, Cd2+, Fe3+, and Mn2+, with a detection limit of 4.38 × 10−8 M in the fluorescence spectrum.

Tensile, physical, and microstructure properties of glycine treated cotton fibers

2017 ◽  
Vol 88 (12) ◽  
pp. 1356-1366 ◽  
Author(s):  
Rechana Remadevi ◽  
Stuart Gordon ◽  
Xungai Wang ◽  
Rangam Rajkhowa
Keyword(s):  
Linear Density ◽  
Cotton Fibers ◽  
Acidic Ph ◽  
Alkaline Ph ◽  
X Ray Diffraction ◽  
Density Measurements ◽  
X Ray ◽  
Acidic Conditions ◽  
Improved Strain ◽  
Control Samples

In this paper, the effect of aqueous glycine treatments at different pH on the tensile properties of cotton fibers is reported. The effects on linear density and X-ray diffraction crystallinity were also evaluated. Glycine treated fibers at alkaline pH (i.e. at pH 11) produced fibers with higher linear density than control (untreated) and glycine treatments at acidic pH. The same treatment also increased strain values in cotton fibers by as much as 36%. Interestingly, similar changes in strain were observed under acidic conditions, especially at pH4, although the changes were smaller. Specific stress values normalized by the linear density measurements were not significantly different from control samples. The results of this research demonstrated improved strain properties of cotton fibers after aqueous glycine treatment at suitable conditions.

scholarly journals Morphology-tunable and pH-responsive supramolecular self-assemblies based on AB2-type host–guest-conjugated amphiphilic molecules for controlled drug delivery

2019 ◽  
Vol 15 ◽  
pp. 1925-1932 ◽  
Author(s):  
Yang Bai ◽  
Cai-ping Liu ◽  
Di Chen ◽  
Long-hai Zhuo ◽  
Huai-tian Bu ◽  
...  
Keyword(s):  
Drug Delivery ◽  
Self Assembly ◽  
Controlled Drug Delivery ◽  
Transition Process ◽  
Hydrodynamic Diameter ◽  
Cancer Cell Proliferation ◽  
Acidic Ph ◽  
Stimuli Responsive ◽  
Amphiphilic Molecules ◽  
Acidic Conditions

Although stimuli-responsive supramolecular self-assemblies have been constructed, the controlled drug delivery induced by morphology transitions of these supramolecular self-assemblies on the basis of host–guest-conjugated monomers (HGCMs) are few reported. In this paper, the self-assembly behaviors of AB2-type HGCMs, e.g., β-cyclodextrin-benzimidazole2 (β-CD-BM2), were investigated at neutral and acidic pH conditions, respectively. Specifically, β-CD-BM2 first self-assembled into fan-shaped supramolecular self-assemblies with a hydrodynamic diameter of 163 nm at neutral pH, whereas they were further dissociated into spherical supramolecular self-assemblies with a size of 52 nm under acidic conditions. This morphology transition process was utilized to conduct a two-stage DOX delivery under neutral and acidic pH. Basic cell experiments demonstrated that the drug-loaded β-CD-BM2-based supramolecular self-assemblies with varied morphology could inhibit cancer cell proliferation, indicating their potential application in the field of drug delivery.

Troponin I isoforms and differential effects of acidic pH on soleus and cardiac myofilaments

1995 ◽  
Vol 268 (2) ◽  
pp. C323-C330 ◽  
Author(s):  
J. Wattanapermpool ◽  
P. J. Reiser ◽  
R. J. Solaro
Keyword(s):  
Troponin I ◽  
Troponin C ◽  
Binary Complex ◽  
Acidic Ph ◽  
Differential Effects ◽  
Adult Rat ◽  
Effects Of Ph ◽  
Isoform Switching ◽  
Acidic Conditions ◽  
Tension Generation

Differences in pH sensitivity of tension generation between developing and adult cardiac myofilaments, which contain the same isoform of troponin C (TnC), have been proposed to be due to troponin I (TnI) isoform switching from the slow skeletal (ss) to cardiac (c) TnI isoforms (21). We investigated the effects of acidic pH on Ca(2+)-activation of force in chemically skinned preparations of adult rat trabeculae and single soleus fibers that also share the same TnC isoform. Compared with the soleus fibers, trabeculae demonstrated a greater suppression of tension and a rightward shift in pCa50 (-log half-maximally activating molar Ca2+ concentration) when pH was decreased from 7.0 to 6.2. The pH-induced shift in pCa50 in soleus fibers did not change with sarcomere length. Troponin subunit interactions were also investigated, using cardiac troponin C (cTnCIA) labeled with a fluorescent probe, 2-(4'-iodoacetamidoanilino)-naphthalene-6-sulfonic acid. Under acidic conditions, cTnCIA demonstrated a decrease in Ca(2+)-affinity. This decrease was amplified both in the binary complex cTnCIA-cTnI and in the complex cTnCIA-cTnI-cTnT-tropomyosin to the same extent. In contrast, substitution of ssTnI for cTnI in these complexes produced the same decrease in Ca2+ affinity in response to acidic pH as cTnCIA alone. These results support our hypothesis that differential effects of pH on tension generation and Ca2+ sensitivity between soleus fibers and trabeculae are due to the presence of different isoforms of TnI.

A 2,7-diamino-1,4,8-triazanaphthalene derivative selectively binds to cytosine bulge DNA only at a weakly acidic pH

2017 ◽  
Vol 15 (6) ◽  
pp. 1313-1316 ◽  
Author(s):  
H. Aikawa ◽  
A. Yano ◽  
K. Nakatani
Keyword(s):  
Acidic Ph ◽  
Dna Duplex ◽  
Ph Profile ◽  
Selective Binding ◽  
Absorption Change ◽  
Bulge Dna ◽  
Acidic Conditions

2,7-Diamino-1,4,8-triazanaphthalene (azaDANP) shows selective binding to a cytosine bulge DNA duplex under weakly acidic conditions, and the absorption change of azaDANP on binding to the target is very sensitive to environmental pH with a bell-shaped absorption–pH profile.

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