Modeling of Growth of Lactobacillus sanfranciscensis and Candida milleri in Response to Process Parameters of Sourdough Fermentation

1998 ◽  
Vol 64 (7) ◽  
pp. 2616-2623 ◽  
Author(s):  
Michael G. Gänzle ◽  
Michaela Ehmann ◽  
Walter P. Hammes
Keyword(s):  
Acetic Acid ◽  
Biological Significance ◽  
Ecological Factors ◽  
Lactobacillus Sanfranciscensis ◽  
Inhibition Of Growth ◽  
The Stability ◽  
Ph Range

ABSTRACT We investigated the effect of the ecological factors pH, temperature, ionic strength, and lactate, acetate, and ethanol levels on Candida milleri and two strains of Lactobacillus sanfranciscensis, organisms representative of the microflora of sourdough. A mathematical model describing the single and combined effects of these factors on the growth of these organisms was established in accordance with the following criteria: quality of fit, biological significance of the parameters, and applicability of the in vitro data to in situ processes. The growth rates of L. sanfranciscensis LTH1729 and LTH2581 were virtually identical under all conditions tested. These organisms tolerated >160 mmol of undissociated acetic acid per liter. Growth occurred in the pH range of 3.9 to 6.7 and was completely inhibited by 4% NaCl. C. milleri had a lower optimum temperature for growth (27°C) than the lactobacilli. The growth of the yeast was not affected by pH in the range of 3.5 to 7, and up to 8% NaCl was tolerated. Complete inhibition of growth occurred at 150 mmol of undissociated acetic acid per liter, but acetate at concentrations of up to 250 mmol/liter exerted virtually no effect. The model provides insight into factors contributing to the stability of the sourdough microflora and can facilitate the design of novel sourdough processes.

scholarly journals Effect of Cavity Disinfectants on Adhesion to Primary Teeth—A Systematic Review

2021 ◽  
Vol 22 (9) ◽  
pp. 4398
Author(s):  
Ana Coelho ◽  
Inês Amaro ◽  
Ana Apolónio ◽  
Anabela Paula ◽  
José Saraiva ◽  
...  
Keyword(s):  
Primary Teeth ◽  
Clinical Success ◽  
Dental Materials ◽  
In Vitro Study ◽  
In Vitro Studies ◽  
Cochrane Library ◽  
Promising Alternative

Some authors have been proposing the use of cavity disinfectants in order to reduce, or even eliminate, the effect of the microorganisms present in a dental cavity before a restoration is placed. The aim of this study was to evaluate the effect of different cavity disinfectants on bond strength and clinical success of composite and glass ionomer restorations on primary teeth. The research was conducted using Cochrane Library, PubMed/MEDLINE, SCOPUS, and Web of Science for articles published up to February 2021. The search was performed according to the PICO strategy. The evaluation of the methodological quality of each in vitro study was assessed using the CONSORT checklist for reporting in vitro studies on dental materials. Sixteen in vitro studies and one in situ study fulfilled the inclusion criteria and were analyzed. Chlorhexidine was the most studied cavity disinfectant, and its use does not compromise dentin bonding. Sodium hypochlorite is a promising alternative, but more research on its use is required to clearly state that it can safely be used as a cavity disinfectant for primary teeth. Although other disinfectants were studied, there is a low-level evidence attesting their effects on adhesion, therefore their use should be avoided.

scholarly journals High temperature structural study of decagonal Al-Cu-Rh quasicrystal.

2014 ◽  
Vol 70 (a1) ◽  
pp. C94-C94
Author(s):  
Pawel Kuczera ◽  
Walter Steurer
Keyword(s):  
Structural Changes ◽  
Configurational Entropy ◽  
Lattice Vibrations ◽  
X Ray Diffraction ◽  
Stabilization Mechanism ◽  
X Ray ◽  
Comparative Structure ◽  
The Stability

The structure of d(ecagonal)-Al-Cu-Rh has been studied as a function of temperature by in-situ single-crystal X-ray diffraction in order to contribute to the discussion on energy or entropy stabilization of quasicrystals (QC) [1]. The experiments were performed at 293 K, 1223 K, 1153 K, 1083 K, and 1013 K. A common subset of 1460 unique reflections was used for the comparative structure refinements at each temperature. The results obtained for the HT structure refinements of d-Al-Cu-Rh QC seem to contradict a pure phasonic-entropy-based stabilization mechanism [2] for this QC. The trends observed for the ln func(I(T1 )/I(T2 )) vs.|k⊥ |^2 plots indicate that the best on-average quasiperiodic order exists between 1083 K and 1153 K, however, what that actually means is unclear. It could indicate towards a small phasonic contribution to entropy, but such contribution is not seen in the structure refinements. A rough estimation of the hypothetic phason instability temperature shows that it would be kinetically inaccessible and thus the phase transition to a 12 Å low T structure (at ~800 K) is most likely not phason-driven. Except for the obvious increase in the amplitude of the thermal motion, no other significant structural changes, in particular no sources of additional phason-related configurational entropy, were found. All structures are refined to very similar R-values, which proves that the quality of the refinement at each temperature is the same. This suggests, that concerning the stability factors, some QCs could be similar to other HT complex intermetallic phases. The experimental results clearly show that at least the ~4 Å structure of d-Al-Cu-Rh is a HT phase therefore entropy plays an important role in its stabilisation mechanism lowering the free energy. However, the main source of this entropy is probably not related to phason flips, but rather to lattice vibrations, occupational disorder unrelated to phason flips like split positions along the periodic axis.

scholarly journals DEVELOPMENT AND EVALUATION OF MUCOADHESIVE NANOGEL OF NEVIRAPINE FOR VAGINAL APPLICATION

2019 ◽  
pp. 144-149
Author(s):  
Sheikh Sofiur Rahman ◽  
ABDUL BAQUEE AHMED
Keyword(s):  
Hiv Infection ◽  
Ex Vivo ◽  
Vaginal Fluid ◽  
Content Uniformity ◽  
Vaginal Mucosa ◽  
Salting Out ◽  
Zero Order Kinetics ◽  
The Stability ◽  
Ph Range

Objectives: The main objective of this study was to develop and evaluate Nevirapine nanoparticle loaded mucoadhesive gel (NVP-Np mucoadhesive gel) for vaginal application for the treatment of HIV infection.  Methods: NVP loaded nanoparticles were prepared by salting out method followed by incorporation in different gel bases to produce NVP-Np mucoadhesive gel The prepared gels were evaluated for their physicochemical parameters, rheological characteristics, mucoadhesion, in-vitro drug release and ex-vivo permeation of drug across porcine vaginal mucosa.  Results: The result of FT-IR and DSC study confirmed the absence of incompatibility of NVP with excipients used in the formulations. The particle size of the prepared NVP-Np was found to be 243.8 ± 3.15 nm, a polydispersity index (PI) of 0.787± 0.002 and zeta potential value -17.12 mV, which revealed the stability of nanoparticles. All the formulations showed good homogeneity, spreadability, physical appearance and content uniformity. The pH of the mucoadhesive gel formulations was in the range of 3.70 ± 0.03 to 4.56 ± 0.02, which lies in the normal pH range of the vaginal fluid.  The cumulative amounts permeated at 6 h were 832.23 ± 63.45 μg/cm2 , 592.13 ± 82.55 μg/cm2 and 941.32 ± 81.10 μg/cm2 from F1(1% Chitosan), F2(1% Carbopol 974P) and F3 (1% HPMC K100M )  respectively. A linear relationship [r2 > 0.9 (0.97 n 0.99)] was observed between the percentage cumulative amount permeated and time, indicating zero order kinetics. Conclusion: In conclusion, NVP-Np mucoadhesive gel was prepared successfully using salting out followed by a homogenization technique for vaginal application of NVP for the prophylaxis of HIV infection.

scholarly journals Fungicidal Activity of Fluconazole against Candida albicans in a Synthetic Vagina-Simulative Medium

2004 ◽  
Vol 48 (1) ◽  
pp. 161-167 ◽  
Author(s):  
Mahomed-Yunus S. Moosa ◽  
Jack D. Sobel ◽  
Hussain Elhalis ◽  
Wenjin Du ◽  
Robert A. Akins
Keyword(s):  
Acetic Acid ◽  
Candida Albicans ◽  
Drug Development ◽  
Carboxylic Acids ◽  
Fungicidal Activity ◽  
Vaginal Candidiasis ◽  
Ph Range ◽  
Cure Rates ◽  
Systemic Infections

ABSTRACT Fluconazole (FLZ) has emerged as a highly successful agent in the management of systemic infections of Candida. Cure rates for symptomatic candidiasis following single 150-mg FLZ dose therapy exceed 90%. In vitro, however, FLZ is fungistatic only in a narrow pH range and is not effective at vaginal pH, 4.2. This study evaluated the effect of FLZ on Candida albicans under in vitro conditions resembling the vaginal microenvironment, using vagina-simulative medium (VS). We found that FLZ was fungicidal for C. albicans in VS, but not in other media at the same pH, 4.2. In VS, FLZ was fungicidal at concentrations of ≥8 μg/ml and reduced viability by greater than 99.9%. Analysis of the components of VS indicated that 17 mM acetic acid, a concentration achieved in the vagina, was responsible for the synergistic, fungicidal effect. This effect was not seen at neutral pH. Other substrates were not effective substitutes for acetic acid; however, short-chained carboxylic acids, glyoxylate and malonate, were effective. Most strains of C. albicans that were resistant to FLZ under standard conditions were killed by FLZ plus acetate. Other species of Candida were also killed, except C. krusei and C. glabrata. This study shows that FLZ has fungicidal activity for Candida species under in vitro conditions that mimic the vaginal microenvironment. This raises the possibility that FLZ may also have fungicidal effects during treatment of vaginal candidiasis. Elucidating the mechanism by which FLZ and acetate interact may disclose vulnerable pathways that could be exploited in drug development.

scholarly journals The ESA Permanent Facility for Altimetry Calibration: Monitoring Performance of Radar Altimeters for Sentinel-3A, Sentinel-3B and Jason-3 Using Transponder and Sea-Surface Calibrations with FRM Standards

2020 ◽  
Vol 12 (16) ◽  
pp. 2642
Author(s):  
Stelios Mertikas ◽  
Achilleas Tripolitsiotis ◽  
Craig Donlon ◽  
Constantin Mavrocordatos ◽  
Pierre Féménias ◽  
...  
Keyword(s):  
Objective Assessment ◽  
Ground Truth ◽  
Sea Surface ◽  
Crossover Analysis ◽  
Operational Phase ◽  
The Stability ◽  
Independent Calibration ◽  
Monitoring Performance

This work presents the latest calibration results for the Copernicus Sentinel-3A and -3B and the Jason-3 radar altimeters as determined by the Permanent Facility for Altimetry Calibration (PFAC) in west Crete, Greece. Radar altimeters are used to provide operational measurements for sea surface height, significant wave height and wind speed over oceans. To maintain Fiducial Reference Measurement (FRM) status, the stability and quality of altimetry products need to be continuously monitored throughout the operational phase of each altimeter. External and independent calibration and validation facilities provide an objective assessment of the altimeter’s performance by comparing satellite observations with ground-truth and in-situ measurements and infrastructures. Three independent methods are employed in the PFAC: Range calibration using a transponder, sea-surface calibration relying upon sea-surface Cal/Val sites, and crossover analysis. Procedures to determine FRM uncertainties for Cal/Val results have been demonstrated for each calibration. Biases for Sentinel-3A Passes No. 14, 278 and 335, Sentinel-3B Passes No. 14, 71 and 335, as well as for Jason-3 Passes No. 18 and No. 109 are given. Diverse calibration results by various techniques, infrastructure and settings are presented. Finally, upgrades to the PFAC in support of the Copernicus Sentinel-6 ‘Michael Freilich’, due to launch in November 2020, are summarized.

Determination of mosquito bloodmeal pH in situ by ion-selective microelectrode measurement: implications for the regulation of malarial gametogenesis

Parasitology ◽  
2000 ◽  
Vol 120 (6) ◽  
pp. 547-551 ◽  
Author(s):  
O. BILLKER ◽  
A. J. MILLER ◽  
R. E. SINDEN
Keyword(s):  
Xanthurenic Acid ◽  
Mosquito Vector ◽  
Dependent Manner ◽  
Ph Increase ◽  
Ph Range ◽  
Dose Dependent

Malarial gametocytes circulate in the peripheral blood of the vertebrate host as developmentally arrested intra-erythrocytic cells, which only resume development into gametes when ingested into the bloodmeal of the female mosquito vector. The ensuing development encompasses sexual reproduction and mediates parasite transmission to the insect. In vitro the induction of gametogenesis requires a drop in temperature and either a pH increase from physiological blood pH (ca pH 7·4) to about pH 8·0, or the presence of a gametocyte-activating factor recently identified as xanthurenic acid (XA). However, it is unclear whether either the pH increase or XA act as natural triggers in the mosquito bloodmeal. We here use pH-sensitive microelectrodes to determine bloodmeal pH in intact mosquitoes. Measurements taken in the first 30 min after ingestion, when malarial gametogenesis is induced in vivo, revealed small pH increases from 7·40 (mouse blood) to 7·52 in Aedes aegypti and to 7·58 in Anophěles stephensi. However, bloodmeal pH was clearly suboptimal if compared to values required to induce gametogenesis in vitro. Xanthurenic acid is shown to extend the pH-range of exflagellation in vitro in a dose-dependent manner to values that we have observed in the bloodmeal, suggesting that in vivo malarial gametogenesis could be further regulated by both these factors.

scholarly journals Potential Sustainable Properties of Microencapsulated Endophytic Lactic Acid Bacteria (KCC-42) in In-Vitro Simulated Gastrointestinal Juices and Their Fermentation Quality of Radish Kimchi

2018 ◽  
Vol 2018 ◽  
pp. 1-10
Author(s):  
Chae Eun Song ◽  
Han Hyo Shim ◽  
Palaniselvam Kuppusamy ◽  
Young-IL Jeong ◽  
Kyung Dong Lee
Keyword(s):  
Acetic Acid ◽  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Organic Acids ◽  
Succinic Acid ◽  
Fermentation Medium ◽  
Gastrointestinal Fluid ◽  
Fermentation Quality

The objective of this study was to investigate alginate microencapsulated lactic acid bacteria (LAB) fermentation quality of radish kimchi sample and its potential survivability in different acidic and alkaline environments. Initially, we isolated 45 LAB strains. One of them showed fast growth pattern with potential probiotic and antifungal activities against Aspergillus flavus with a zone of inhibition calculated with 10, 8, 4mm for the 4th, 5th, and 6th day, respectively. Therefore, this strain (KCC-42) was chosen for microencapsulation with alginate biopolymer. It showed potential survivability in in-vitro simulated gastrointestinal fluid and radish kimchi fermentation medium. The survival rate of this free and encapsulated LAB KCC-42 was 6.85 × 105 and 7.48× 105 CFU/ml, respectively; the viability count was significantly higher than nonencapsulated LAB in simulated gastrointestinal juices (acid, bile, and pancreatin) and under radish kimchi fermentation environment. Kimchi sample added with this encapsulated LAB showed increased production of organic acids compared to nonencapsulated LAB sample. Also, the organic acids such as lactic acid, acetic acid, propionic acid, and succinic acid production in fermented kimchi were measured 59mM, 26mM, 14mM, and 0.6mM of g/DW, respectively. The production of metabolites such as lactic acid, acetic acid, and succinic acid and the bacteria population was high in microencapsulated LAB samples compared with free bacteria added kimchi sample. Results of this study indicate that microencapsulated LAB KCC-42 might be a useful strategy to develop products for food and healthcare industries.

scholarly journals Environmental Signals Modulate the Expression of an Indole-3-Acetic Acid Biosynthetic Gene in Erwinia herbicola

1997 ◽  
Vol 10 (4) ◽  
pp. 499-505 ◽  
Author(s):  
Maria T. Brandl ◽  
Steven E. Lindow
Keyword(s):  
Acetic Acid ◽  
Nitrogen Availability ◽  
Natural Habitat ◽  
Biosynthetic Gene ◽  
Erwinia Herbicola ◽  
Environmental Signals ◽  
Acid Pathway ◽  
Indole 3 Acetic Acid

The ipdC gene of Erwinia herbicola strain 299R encodes an indolepyruvate decarboxylase involved in the biosynthesis of indole-3-acetic acid (IAA). Transcriptional fusions of ipdC to an ice nucleation reporter gene (inaZ) were used to study the expression of ipdC in vitro and in situ on plants. ipdC was expressed only at low levels in liquid media and independently of factors such as richness of the medium, pH, nitrogen availability, the presence of l-tryptophan or oxygen, and growth phase of the culture. However, the transcriptional activity of ipdC increased approximately 18-fold under low solute and matric potentials in culture. ipdC was also induced 32-fold on leaves of bean and tobacco and 1,000-fold on pear flowers. This is the first report of the plant-inducible transcription of a bacterial IAA biosynthetic gene. It strongly supports the role of ipdC, and thus that of the indole-3-pyruvic acid pathway, in IAA biosynthesis by strain 299R in situ. The plant induction and apparent regulation of ipdC by low water availability indicate that this gene, and presumably IAA synthesis, are involved in a response to conditions encountered by E. herbicola in its natural habitat on leaves.

scholarly journals The Stability of the Induced Epigenetic Programs

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Maria J. Barrero
Keyword(s):  
Stem Cells ◽  
Somatic Cells ◽  
Cell Types ◽  
Specific Cell ◽  
Cell Type ◽  
Pluripotent Cells ◽  
Potential Applications ◽  
The Stability

For many years scientists have been attracted to the possibility of changing cell identity. In the last decades seminal discoveries have shown that it is possible to reprogram somatic cells into pluripotent cells and even to transdifferentiate one cell type into another. In view of the potential applications that generating specific cell types in the laboratory can offer for cell-based therapies, the next important questions relate to the quality of the induced cell types. Importantly, epigenetic aberrations in reprogrammed cells have been correlated with defects in differentiation. Therefore, a look at the epigenome and understanding how different regulators can shape it appear fundamental to anticipate potential therapeutic pitfalls. This paper covers these epigenetic aspects in stem cells, differentiation, and reprogramming and discusses their importance for the safety of in vitro engineered cell types.

scholarly journals Effects of Bradykinin on Pial Arteries and Arterioles in vitro and in situ

1983 ◽  
Vol 3 (2) ◽  
pp. 231-237 ◽  
Author(s):  
Michael Wahl ◽  
Alan R. Young ◽  
Lars Edvinsson ◽  
Franz Wagner
Keyword(s):  
Maximal Response ◽  
Guinea Pig Ileum ◽  
Response Curves ◽  
Pial Arteries ◽  
Cerebrovascular Resistance ◽  
Resistance Vessels ◽  
Prostaglandin F ◽  
The Stability

The effect of bradykinin on cerebrovascular resistance vessels was investigated by the use of in vitro and in situ preparations. Bradykinin, in the range of 10−10 to 10−5 M, elicited a concentration-dependent vasodilatation on both feline and human pial arteries in vitro; the half-maximal response was found to be approximately at 2.8 × 10−7 M and 1.3 × 10−8 M (EC50), respectively. This dilatatory effect of bradykinin in vitro was found only in arteries preconstricted with prostaglandin F2α or 5-hydroxytryptamine. In order to determine the effects of bradykinin on the diameter of cat pial arteries in situ, perivascular microapplication was employed. The dose-response curves obtained showed vasodilatation; the EC50 and the maximal response (EAm) were 4.4 × 10−7 M and 45.5% at 10−5 M, respectively. Statistically significant (p < 0.01) reactions were observed at 10−7 M and higher concentrations of bradykinin. The observed effects were independent of initial vessel size (80–260 μm). These in situ findings are very similar to those found in vitro. The isolated guinea pig ileum was used to check the stability of the bradykinin solutions. In this instance, a concentration-dependent contraction was found when “freshly prepared” or “5 hours stored” bradykinin was applied, indicating no measurable degradation of bradykinin. We conclude that bradykinin is a powerful vasodilator of both human and feline pial arteries.

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