The tripeptide GHG as an unexpected hydrogelator triggered by imidazole deprotonation

Soft Matter ◽  
2020 ◽  
Vol 16 (17) ◽  
pp. 4110-4114
Author(s):  
Morgan Hesser ◽  
Lavenia Thursch ◽  
Todd Lewis ◽  
David DiGuiseppi ◽  
Nicolas J. Alvarez ◽  
...  
Keyword(s):  
Critical Concentration ◽  
Imidazole Group

The tripeptide glycyl-histidyl-glycine (GHG) self-assembles into long, crystalline fibrils forming a strong hydrogel (G′ ∼ 50 kPa) above a critical concentration of 40 mM upon the deprotonation of its imidazole group.

An equation for the empirical design of anoxic zones used to eliminate rising sludges at nitrifying activated sludge plants

1996 ◽  
Vol 33 (3) ◽  
pp. 185-194 ◽  
Author(s):  
M. Sarioglu ◽  
N. Horan
Keyword(s):  
Activated Sludge ◽  
Empirical Equation ◽  
Nitrate Nitrogen ◽  
Critical Concentration ◽  
Settling Tank ◽  
Limited Information ◽  
Batch Experiments ◽  
Anoxic Zone ◽  
Secondary Settling ◽  
Anoxic Zones

Anoxic zones are designed for the removal of nitrogen in nitrifying activated sludge plants. This can be carried out either to achieve a nitrogen discharge consent or to eliminate the problem of rising sludges. The rising sludge problem is mostly encountered in medium and small size plants in warm conditions and there is limited information as to the appropriate design of anoxic zones to protect against rising sludges in the secondary sedimentation tanks. Therefore a series of batch experiments were undertaken in order to establish the critical concentration of nitrate-nitrogen which causes rising sludge in the secondary settling tank and the effect of environmental factors such as temperature (15°C to 30°C) and residual carbon source (100 to 600 mg/1 COD) were examined. Based on the results of these experiments an empirical equation was presented which can be used to size an anoxic zone to eliminate rising sludges. The application of this equation at full-scale plants is discussed.

Serum Carboxypeptidase N1 Serves as a Potential Biomarker Complementing CA15-3 for Breast Cancer

2020 ◽  
Vol 20 (17) ◽  
pp. 2053-2065
Author(s):  
Ranliang Cui ◽  
Chaomin Wang ◽  
Qi Zhao ◽  
Yichao Wang ◽  
Yueguo Li
Keyword(s):  
Breast Cancer ◽  
Metastatic Breast Cancer ◽  
Critical Concentration ◽  
Tumour Size ◽  
Clinical Stage ◽  
Metastatic Breast ◽  
Breast Cancer Patients ◽  
Potential Biomarker ◽  
Incidence And Mortality ◽  
Combined Detection

Background: The incidence and mortality of breast cancer are increasing annually. Breast cancer seriously threatens women's health and quality of life. We aimed to measure the clinical value of CPN1, a new serum marker of breast cancer and to evaluate the efficacy of CPN1 in combination with CA15-3. Methods: Seventy samples of breast cancer with lymph node metastasis, seventy-three samples of nonmetastatic breast cancer and twenty-five samples of healthy human serum were collected. Serum CA15-3 concentration was determined by Roche Elecsys, and serum CPN1 concentration was determined by ELISA. Results: In breast cancer patients, serum CPN1 concentration was positively correlated with tumour size, clinical stage and CA15-3 concentration (r = 0.376, P<0.0001). ROC curve analysis showed that the optimal critical concentration of CPN1 for breast cancer diagnosis was 32.8pg/ml. The optimal critical concentration of CPN1 in the diagnosis of metastatic breast cancer was 66.121pg/ml. CPN1 has a greater diagnostic ability for breast cancer (AUCCA15-3=0.702 vs. AUCCPN1=0.886, P<0.0001) and metastatic breast cancer (AUCCA15-3=0.629 vs. AUCCPN1=0.887, P<0.0001) than CA15-3, and the combined detection of CA15-3 and CPN1 can improve the diagnostic efficiency for breast cancer (AUCCA15-3+CPN1=0.916) and for distinguishing between metastatic and non-metastatic breast cancer (AUCCA15-3+CPN1=0.895). Conclusion: CPN1 can be used as a new tumour marker to diagnose and evaluate the invasion and metastasis of breast cancer. The combined detection of CPN1 and CA15-3 is more accurate and has a certain value in clinical application.

scholarly journals Importance of beta-lactamase inhibitor pharmacokinetics in the pharmacodynamics of inhibitor-drug combinations: studies with piperacillin-tazobactam and piperacillin-sulbactam.

1997 ◽  
Vol 41 (4) ◽  
pp. 721-727 ◽  
Author(s):  
P D Lister ◽  
A M Prevan ◽  
C C Sanders
Keyword(s):  
Antibacterial Activity ◽  
Critical Concentration ◽  
Specific Inhibitor ◽  
Logarithmic Phase ◽  
Critical Ratio ◽  
Beta Lactamase ◽  
Beta Lactam ◽  
Dosing Regimens ◽  
Lactamase Inhibitor

An in vitro pharmacokinetic model was used to study the pharmacodynamics of piperacillin-tazobactam and piperacillin-sulbactam against gram-negative bacilli producing plasmid-encoded beta-lactamases. Logarithmic-phase cultures were exposed to peak antibiotic concentrations observed in human serum after the administration of intravenous doses of 3 g of piperacillin and 0.375 g of tazobactam or 0.5 g of sulbactam. Piperacillin and inhibitor were either dosed simultaneously or piperacillin was dosed sequentially 0.5 h after dosing with the inhibitor. In studies with all four test strains, the pharmacodynamics observed after simultaneous dosing were similar to those observed with the sequential regimen. Since the ratio between piperacillin and tazobactam was in constant fluctuation after sequential dosing, these data suggest that the pharmacodynamics of the piperacillin-inhibitor combinations were not dependent upon maintenance of a critical ratio between the components. Furthermore, when regrowth was observed, the time at which bacterial counts began to increase was similar between the simultaneous and sequential dosing regimens. Since the pharmacokinetics of the inhibitors were the same for all regimens, these data suggest that the length of time that the antibacterial activity was maintained over the dosing interval with these combinations was dictated by the pharmacokinetics of the beta-lactamase inhibitor in the combination. The antibacterial activity of the combination appeared to be lost when the amount of inhibitor available fell below some critical concentration. This critical concentration varied depending upon the type and amount of enzyme produced, as well as the specific inhibitor used. These results indicate that the antibacterial activity of drug-inhibitor combinations, when dosed at their currently recommended ratios, is more dependent on the pharmacokinetics of the inhibitor than on those of the beta-lactam drug.

scholarly journals The bulk of unpolymerized actin in Xenopus egg extracts is ATP-bound.

1995 ◽  
Vol 6 (2) ◽  
pp. 227-236 ◽  
Author(s):  
J Rosenblatt ◽  
P Peluso ◽  
T J Mitchison
Keyword(s):  
Actin Polymerization ◽  
Critical Concentration ◽  
Large Fraction ◽  
Nucleotide Exchange ◽  
Chromatography Analysis ◽  
Thymosin Beta 4 ◽  
Egg Extracts ◽  
Xenopus Egg ◽  
Xenopus Egg Extracts

Non-muscle cells contain 15-500 microM actin, a large fraction of which is unpolymerized. Thus, the concentration of unpolymerized actin is well above the critical concentration for polymerization in vitro (0.2 microM). This fraction of actin could be prevented from polymerization by being ADP bound (therefore less favored to polymerize) or by being ATP bound and sequestered by a protein such as thymosin beta 4, or both. We isolated the unpolymerized actin from Xenopus egg extracts using immobilized DNase 1 and assayed the bound nucleotide. High-pressure liquid chromatography analysis showed that the bulk of soluble actin is ATP bound. Analysis of actin-bound nucleotide exchange rates suggested the existence of two pools of unpolymerized actin, one of which exchanges nucleotide relatively rapidly and another that apparently does not exchange. Native gel electrophoresis of Xenopus egg extracts demonstrated that most of the soluble actin exists in complexes with other proteins, one of which might be thymosin beta 4. These results are consistent with actin polymerization being controlled by the sequestration and release of ATP-bound actin, and argue against nucleotide exchange playing a major role in regulating actin polymerization.

scholarly journals The Chemical Composition of Cometary Nuclei

1972 ◽  
Vol 45 ◽  
pp. 265-270
Author(s):  
L. M. Shul'man
Keyword(s):  
Chemical Composition ◽  
Cosmic Rays ◽  
Organic Molecules ◽  
Solid Phase ◽  
Critical Concentration ◽  
Energy Output ◽  
Time Interval ◽  
Nuclear Surface ◽  
Solar Cosmic Rays ◽  
Cometary Nuclei

The probable parent-molecules of radicals such as C3 and N2+ are discussed, and it is concluded that cometary nuclei may contain complicated organic molecules, such as C3H4, CH2N2, and C4H2. It is suggested that these molecules are formed by radiation synthesis in solid phase. In a time interval of order 107 to 109 yr bombardment from cosmic rays would be expected to transform the chemical composition to a depth of 1 m. Solar cosmic rays do not penetrate as far, and as a result the surface layer of the nucleus can be enriched with unsaturated hydrocarbons. After a critical concentration of this explosive material is reached a further burst of solar cosmic rays can initiate an explosion and thus an outburst in the comet's brightness. This mechanism is the only one advanced to date that can explain the synchronism of the energy output over the whole nuclear surface.

scholarly journals Study of the Optimal Dosage of Celullose Ash as a Contribution Filler in Asphalt Mixtures Based on Its Adhesiveness under Moisture Conditions

2021 ◽  
Vol 13 (2) ◽  
pp. 854
Author(s):  
Diana Movilla-Quesada ◽  
Aitor C. Raposeiras ◽  
Manuel Lagos-Varas ◽  
Osvaldo Muñoz-Cáceres ◽  
Valerio-Carlos Andrés-Valeri ◽  
...  
Keyword(s):  
Latin American ◽  
Critical Concentration ◽  
Resource Scarcity ◽  
Wear Loss ◽  
Optimal Dosage ◽  
Bituminous Mixtures ◽  
Forestry Sector ◽  
Natural Aggregates ◽  
Moisture Conditions ◽  
By Products

Chile is the first Latin American country to begin an “ecological overdraft”, as established by the Global Footprint Network (GFN). This implies that the country’s ecological footprint has exceeded the global average bio-capacity. The consumption of natural aggregates for construction in Chile has grown by around 6.6% in the last year, with around 120 million tons being extracted. Given the above, it is important to seek alternatives that help to minimize the problem of resource scarcity, as well as the recovery of industrial by-products and/or waste. The Chilean forestry sector has also grown in recent years, generating approximately 4000 metric tons of waste in 2018, which was deposited in landfills or disposed of on forest roads. The present research is focused on the reuse and possible recovery of ash from the incineration of cellulose as a filler in bituminous mixtures. We analyze the adhesiveness of the filler/bitumen system in dry and wet states, based on the Cantabro wear loss test. The results obtained show that the limit of the relation between the volumetric concentration and critical concentration (Cv/Cs) is 1 for the addition of ash and that concentrations lower than or equal to this value present controlled losses, with 1.00 being the optimal (Cv/Cs) ratio that allows better behavior against the effect of water.

Prolonged response of skeletal muscle in the absence of penetrating anions

1960 ◽  
Vol 198 (2) ◽  
pp. 289-299 ◽  
Author(s):  
Gertrude Falk ◽  
Jorge F. Landa
Keyword(s):  
Action Potentials ◽  
Critical Concentration ◽  
Relaxation Oscillations ◽  
Plateau Phase ◽  
Slow Oscillations ◽  
Mechanical Responses ◽  
External Potassium ◽  
Prolonged Response ◽  
Plateau Level ◽  
Potassium Addition

Replacement of Ringer's chloride by a variety of nonpenetrating anions results in prolonged electrical and mechanical responses of muscle to stimulation. The ‘negative after-potential’ is characterized by a slowly increasing secondary depolarization which reaches a stable plateau lasting as long as 2 minutes. After-discharge frequently occurs during early depolarization. In most fibers repolarization is relatively abrupt, but in some, slow oscillations resembling relaxation oscillations arise following the plateau, grow gradually in amplitude and, only when they are of sufficient amplitude, does the membrane repolarize. Prolonged depolarization can still be produced when the spike has failed. At times, fibers may respond with short-duration action potentials, but may be primed to give prolonged responses by previous stimuli or by increase of external potassium. Addition of chloride has no effect below a critical concentration. Reduction of sodium to 25% of normal does not change plateau level or duration. Duration of the plateau phase is decreased by potassium.

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