scholarly journals Plasticity in organic composition maintains biomechanical performance in shells of juvenile scallops exposed to altered temperature and pH conditions

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Nelson A. Lagos ◽  
Samanta Benítez ◽  
Cristian Grenier ◽  
Alejandro B. Rodriguez-Navarro ◽  
Claudio García-Herrera ◽  
...  
Keyword(s):  
Elevated Temperatures ◽  
Biomechanical Properties ◽  
Low Ph ◽  
Interactive Effects ◽  
Compensatory Mechanism ◽  
Episodic Events ◽  
Physiological Processes ◽  
Scallop Shells ◽  
Ph Conditions ◽  
And Control

AbstractThe exposure to environmental variations in pH and temperature has proven impacts on benthic ectotherms calcifiers, as evidenced by tradeoffs between physiological processes. However, how these stressors affect structure and functionality of mollusk shells has received less attention. Episodic events of upwelling of deep cold and low pH waters are well documented in eastern boundary systems and may be stressful to mollusks, impairing both physiological and biomechanical performance. These events are projected to become more intense, and extensive in time with ongoing global warming. In this study, we evaluate the independent and interactive effects of temperature and pH on the biomineral and biomechanical properties of Argopecten purpuratus scallop shells. Total organic matter in the shell mineral increased under reduced pH (~ 7.7) and control conditions (pH ~ 8.0). The periostracum layer coating the outer shell surface showed increased protein content under low pH conditions but decreasing sulfate and polysaccharides content. Reduced pH negatively impacts shell density and increases the disorder in the orientation of calcite crystals. At elevated temperatures (18 °C), shell microhardness increased. Other biomechanical properties were not affected by pH/temperature treatments. Thus, under a reduction of 0.3 pH units and low temperature, the response of A. purpuratus was a tradeoff among organic compounds (biopolymer plasticity), density, and crystal organization (mineral plasticity) to maintain shell biomechanical performance, while increased temperature ameliorated the impacts on shell hardness. Biopolymer plasticity was associated with ecophysiological performance, indicating that, under the influence of natural fluctuations in pH and temperature, energetic constraints might be critical in modulating the long-term sustainability of this compensatory mechanism.

scholarly journals Activation of Fusion by the SER Virus F Protein: a Low-pH-Dependent Paramyxovirus Entry Process

2003 ◽  
Vol 77 (11) ◽  
pp. 6520-6527 ◽  
Author(s):  
Shaguna Seth ◽  
Annelet Vincent ◽  
R. W. Compans
Keyword(s):  
Elevated Temperatures ◽  
Protein A ◽  
Syncytium Formation ◽  
Simian Virus ◽  
Low Ph ◽  
F Protein ◽  
Simian Virus 5 ◽  
Cytoplasmic Content ◽  
Ph Conditions ◽  
Ph Dependent

ABSTRACT SER virus, a paramyxovirus closely related to simian virus 5, induces no syncytium formation. The SER virus F protein has a long cytoplasmic tail (CT), and truncation or mutations of the CT result in enhanced syncytium formation (S. Seth, A. Vincent, and R. W. Compans, J. Virol. 77:167-178, 2003; S. Tong, M. Li, A. Vincent, R. W. Compans, E. Fritsch, R. Beier, C. Klenk, M. Ohuchi, and H.-D. Klenk, Virology 301:322-333, 2002). We hypothesized that the presence of the long CT serves to stabilize the metastable conformation of the F protein. We observed that the hemifusion, cytoplasmic content mixing, and syncytium formation ability of the wild-type SER virus F coexpressed with the SER virus hemagglutinin-neuraminidase (HN) protein was enhanced, both qualitatively and quantitatively, at elevated temperatures. We also observed enhanced hemifusion, content mixing, and syncytium formation in SER virus F- and HN-expressing cells at reduced pH conditions ranging between 4.8 and 6.2. We have obtained evidence that in contrast to other paramyxoviruses, entry of SER virus into cells occurs by a low-pH-dependent process, indicating that the conversion to the fusion-active state for SER virus F is triggered by exposure to reduced pH.

A Collaborative Study to Establish an International Standard for Alpha-Thrombin

1992 ◽  
Vol 67 (04) ◽  
pp. 424-427 ◽  
Author(s):  
P J Gaffney ◽  
A B Heath ◽  
J W Fenton II
Keyword(s):  
Elevated Temperatures ◽  
Collaborative Study ◽  
World Health Organisation ◽  
Significant Loss ◽  
Thrombin Inhibitors ◽  
World Health ◽  
Expert Committee ◽  
International Standard ◽  
Assay Procedure ◽  
And Control

SummarySince 1975 an International Standard for Thrombin of low purity has been used. While this standard was stable and of value for calibrating thrombins of unknown potency the need for a pure a-thrombin standard arose both for accurate calibration and for precise measurement of thrombin inhibitors, notably hirudin. An international collaborative study was undertaken to establish the potency and stability of an ampouled pure a-thrombin preparation. A potency of 97.5 international units (95% confidence limits 86.5-98.5) was established for the new a-thrombin standard (89/ 588) using a clotting-assay procedure. Stability data at various elevated temperatures indicated that the standard could be transported and stored with no significant loss of potency.Ampoules of lyophilised a-thrombin (coded 89/588) have been recommended as an International Standard for a-thrombin with an assigned potency of 100 international units per ampoule by the International Society for Thrombosis and Haemostasis (Thrombin and its Inhibitors Sub-Committee) in Barcelona, Spain in July 1990 while the Expert Committee on Biological Standardisation and Control of the World Health Organisation will consider its status at its next meeting in Geneva in 1991.

RMI 0.2% Pd

Alloy Digest ◽  
1979 ◽  
Vol 28 (12) ◽  
Keyword(s):  
Corrosion Resistance ◽  
Crevice Corrosion ◽  
Elevated Temperatures ◽  
Pure Titanium ◽  
Heat Treating ◽  
Low Ph ◽  
Commercially Pure Titanium ◽  
Bend Strength ◽  
Commercially Pure ◽  
Minimum Yield

Abstract RMI 0.2% Pd is a grade of commercially pure titanium to which up to 0.2% palladium has been added. It has a guaranteed minimum yield strength of 40,000 psi with good ductility and formability. It is recommended for corrosion resistance in the chemical industry and other places where the environment is mildly reducing or varies between oxidizing and reducing. The alloy has improved resistance to crevice corrosion at low pH and elevated temperatures. This datasheet provides information on composition, physical properties, elasticity, tensile properties, and bend strength. It also includes information on corrosion resistance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: Ti-74. Producer or source: RMI Company.

Association Between Magnesium and Oxidative Stress in Patients with Obesity

2020 ◽  
Vol 16 (5) ◽  
pp. 743-748
Author(s):  
Ana R.S. de Oliveira ◽  
Kyria J.C. Cruz ◽  
Jennifer B.S. Morais ◽  
Juliana S. Severo ◽  
Jéssica B. Beserra ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Thiobarbituric Acid ◽  
Magnesium Concentration ◽  
Control Group ◽  
Compensatory Mechanism ◽  
Thiobarbituric Acid Reactive Substances ◽  
Magnesium Intake ◽  
Significant Difference ◽  
Dietary Magnesium ◽  
And Control

Background: The role of minerals in preventing the generation of oxidative stress in obese individuals has been evaluated. Magnesium is an antioxidant nutrient and a cofactor of enzymes involved in the cell membrane stabilization, attenuating the effects of oxidative stress. Objective: To evaluate the association between magnesium and concentrations of thiobarbituric acid reactive substances (TBARS) in patients with obesity and eutrophic women. Methods: A cross-sectional study was conducted with 73 women, divided into two groups: case group (patients with obesity, n=27) and control group (eutrophic women, n=46). Measurements of body mass index and waist circumference were performed. Dietary magnesium intake was assessed by the three-day food record using the NutWin software. Urinary magnesium concentration was measured by atomic absorption spectrophotometry method. Plasma concentrations of thiobarbituric acid reactive substances (TBARS) were also determined. Results: Mean values of dietary magnesium intake were 161.59 ± 60.04 and 158.73 ± 31.96 for patients with obesity and control group, respectively, with no significant difference between the groups studied (p >0.05). The value of urinary excretion of magnesium was lower than the reference values in both groups, with no significant difference between the groups studied (p >0.05). The plasma concentration of thiobarbituric acid reactive substances was significantly higher in patients with obesity compared to the control group (p <0.001). There was no correlation between levels of magnesium biomarkers and the concentration of TBARS (p >0.05). Conclusion: Patients with obesity showed a reduced dietary magnesium intake which seems to induce hypomagnesuria as a compensatory mechanism. The marker of oxidative stress evaluated in this study was not influenced by magnesium.

scholarly journals Interactive effects between travel behaviour and COVID-19: a questionnaire study

2021 ◽  
Author(s):  
Jinbao Zhang ◽  
Jaeyoung Lee
Keyword(s):  
Early Stage ◽  
Travel Behaviour ◽  
Interactive Effects ◽  
Factors Affecting ◽  
Individual Level ◽  
Passenger Volume ◽  
Spatial Autoregressive ◽  
Railway Passenger ◽  
The Individual ◽  
And Control

Abstract This study has two main objectives: (i) to analyse the effect of travel characteristics on the spreading of disease, and (ii) to determine the effect of COVID-19 on travel behaviour at the individual level. First, the study analyses the effect of passenger volume and the proportions of different modes of travel on the spread of COVID-19 in the early stage. The developed spatial autoregressive model shows that total passenger volume and proportions of air and railway passenger volumes are positively associated with the cumulative confirmed cases. Second, a questionnaire is analysed to determine changes in travel behaviour after COVID-19. The results indicate that the number of total trips considerably decreased. Public transport usage decreased by 20.5%, while private car usage increased by 6.4%. Then the factors affecting the changes in travel behaviour are analysed by logit models. The findings reveal significant factors, including gender, occupation and travel restriction. It is expected that the findings from this study would be helpful for management and control of traffic during a pandemic.

Expression patterns of two carbonic anhydrase genes, Na+/K+-ATPase and V-type H+-ATPase, in the freshwater crayfish, Cherax quadricarinatus, exposed to low pH and high pH

2017 ◽  
Vol 65 (1) ◽  
pp. 50 ◽  
Author(s):  
Muhammad Yousuf Ali ◽  
Ana Pavasovic ◽  
Peter B. Mather ◽  
Peter J. Prentis
Keyword(s):  
Carbonic Anhydrase ◽  
Expression Patterns ◽  
Maximum Level ◽  
Low Ph ◽  
Freshwater Crayfish ◽  
Α Subunit ◽  
Cherax Quadricarinatus ◽  
High Ph ◽  
Internal Ph ◽  
Ph Conditions

Carbonic anhydrase (CA), Na+/K+-ATPase (NKA) and Vacuolar-type H+-ATPase (HAT) play vital roles in osmoregulation and pH balance in decapod crustaceans. As variable pH levels have a significant impact on the physiology of crustaceans, it is crucial to understand the mechanisms by which an animal maintains its internal pH. We examined expression patterns of cytoplasmic (CAc) and membrane-associated form (CAg) of CA, NKA α subunit and HAT subunit a in gills of freshwater crayfish, Cherax quadricarinatus, at three pH levels – 6.2, 7.2 (control) and 8.2 – over 24 h. Expression levels of CAc were significantly increased at low pH and decreased at high pH conditions 24 h after transfer. Expression increased at low pH after 12 h, and reached its maximum level by 24 h. CAg showed a significant increase in expression at 6 h after transfer at low pH. Expression of NKA significantly increased at 6 h after transfer to pH 6.2 and remained elevated for up to 24 h. Expression for HAT and NKA showed similar patterns, where expression significantly increased 6 h after transfer to low pH and remained significantly elevated throughout the experiment. Overall, CAc, CAg, NKA and HAT gene expression is induced at low pH conditions in freshwater crayfish.

scholarly journals An intermediate animal model of spinal cord stimulation

2016 ◽  
Vol 26 (2) ◽  
Author(s):  
Thomas Guiho ◽  
Christine Azevedo Coste ◽  
Claire Delleci ◽  
Jean-Patrick Chenu ◽  
Jean-Rodolphe Vignes ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Animal Model ◽  
Spinal Cord Stimulation ◽  
Spinal Cord Injuries ◽  
Large Animal Model ◽  
Large Animal ◽  
Physiological Processes ◽  
Spinal Roots ◽  
And Control ◽  
Stimulation Of

Spinal cord injuries (SCI) result in the loss of movement and sensory feedback as well as organs dysfunctions. For example, nearly all SCI subjects loose their bladder control and are prone to kidney failure if they do not proceed to intermittent (self-) catheterization. Electrical stimulation of the sacral spinal roots with an implantable neuroprosthesis is a promising approach, with commercialized products, to restore continence and control micturition. However, many persons do not ask for this intervention since a surgical deafferentation is needed and the loss of sensory functions and reflexes become serious side effects of this procedure. Recent results renewed interest in spinal cord stimulation. Stimulation of existing pre-cabled neural networks involved in physiological processes regulation is suspected to enable synergic recruitment of spinal fibers. The development of direct spinal stimulation strategies aiming at bladder and bowel functions restoration would therefore appear as a credible alternative to existent solutions. However, a lack of suitable large animal model complicates these kinds of studies. In this article, we propose a new animal model of spinal stimulation -pig- and will briefly introduce results from one first acute experimental validation session.

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