• Journal of Animal Science and Technology
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• v.63 no.2
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• pp.319-331
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• 2021

Heat stress (HS) causes adverse impacts on pig production and health. A potential biomarker of HS is required to predict its occurrence and thereby better manage pigs under HS. Information about the saliva metabolome in heat-stressed pigs is limited. Therefore, this study was aimed to investigate the effects of acute HS on the saliva metabolome and identify metabolites that could be used as potential biomarkers. Growing pigs (n = 6, 3 boars, and 3 gilts) were raised in a thermal neutral (TN; 25℃) environment for a 5-d adaptation period (CON). After adaptation, the pigs were first exposed to HS (30℃; HS30) and then exposed to higher HS (33℃; HS33) for 24 h. Saliva was collected after adaptation, first HS, and second HS, respectively, for metabolomic analysis using 1H-nuclear magnetic resonance spectroscopy. Four metabolites had significantly variable importance in the projection (VIP > 1; p < 0.05) different levels in TN compared to HS groups from all genders (boars and gilts). However, sex-specific characteristics affected metabolites (glutamate and leucine) by showing the opposite results, indicating that HS was less severe in females than in males. A decrease in creatine levels in males and an increase in creatine phosphate levels in females would have contributed to a protective effect from protein degradation by muscle damage. The results showed that HS led to an alteration in metabolites related to energy and protein. Protection from muscle damage may be attributed to the alteration in protein-related metabolites. However, energy-related metabolites showed opposing results according to sex-specific characteristics, such as sex hormone levels and subcutaneous fat layer. This study had shown that saliva samples could be used as a noninvasive method to evaluate heat-stressed pigs. And the results in this study could be contributed to the development of a diagnostic tool as a noninvasive biomarker for managing heat-stressed pigs.

• Asian-Australasian Journal of Animal Sciences
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• v.33 no.5
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• pp.778-787
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• 2020

Objective: This study was conducted to investigate the effects of normal and heat stress environments on growth performance and, selected physiological and immunological parameters, caecal microflora and meat quality in Cobb 500 and Ross 308 broilers. Methods: One-hundred-and-twenty male broiler chicks from each strain (one-day-old) were randomly assigned in groups of 10 to 24 battery cages. Ambient temperature on day (d) 1 was set at 32℃ and gradually reduced to 23℃ on d 21. From d 22 to 35, equal numbers of birds from each strain were exposed to a temperature of either 23℃ throughout (normal) or 34℃ for 6 h (heat stress). Results: From d 1 to 21, strain had no effect (p>0.05) on feed intake (FI), body weight gain (BWG), or the feed conversion ratio (FCR). Except for creatine kinase, no strain×temperature interactions were observed for all the parameters measured. Regardless of strain, heat exposure significantly (p<0.05) reduced FI and BWG (d 22 to 35 and 1 to 35), immunoglobulin Y (IgY) and IgM, while increased FCR (d 22 to 35 and 1 to 35) and serum levels of glucose and acute phase proteins (APPs). Regardless of temperature, the Ross 308 birds had significantly (p<0.05) lower IgA and higher finisher and overall BWG compared to Cobb 500. Conclusion: The present study suggests that the detrimental effects of heat stress are consistent across commercial broiler strains because there were no significant strain×temperature interactions for growth performance, serum APPs and immunoglobulin responses, meat quality, and ceacal microflora population.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.5
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• pp.733-739
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• 2020

Olive flounder Paralichthys olivaceus (total weight 216.4±14.6 g, total length 28.4±1.7 cm) were exposed to different pH levels (3, 4, 5, 6, 7, 8, and 9) for 96 h. At pH 4, hemoglobin decreased significantly, while plasma calcium, glucose, cholesterol, and ALP increased significantly. Exposure to pH 4 also induced stress responses, as evidenced by a significant decrease in heat shock protein 70 (HSP 70) and a significant increase in cortisol. The results of this study indicate that acute exposure to acidic or alkaline pH (pH 3 or 9) induced significant mortality, while exposure to pH 4significantly affected hematological parameters and stress responses in P. olivaceus.

• Journal of the Korean Society for Heat Treatment
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• v.6 no.3
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• pp.159-165
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• 1993

Creep tests of the TiC particulate reinforced Al composite have been conducted in the temperature ranges from 200 to $500^{\circ}C$. The steady-state cree rate of the composite depended strongly on the temperature and ap' plied stress. The stress exponent for the steady state creep rate of the composites was approximately 17.5 and the activation anergy was calculated to be 390KJ/mol. The steady-state creep equation could be written as $\acute{\varepsilon}_{ss}$ $$(s^{-1})=1.5{\times}10^{-9}\;{\sigma}^{17.5}\exp(-390000/RT)$$. Fracture surface examination showed that the fracture mode of the particulate reinforced composite was ductile by plastic tearing of the aluminum matrix and TiC particle interfaces were offered as sites for crack.

• Journal of Microbiology and Biotechnology
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• v.22 no.1
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• pp.118-125
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• 2012

Heat shock proteins (Hsps) play a key role in the cellular defense response to diverse environmental stresses. Here, the role of Hsp genes in the acquisition of thermotolerance in the cyanobacterium Microcystis aeruginosa NIES-298 was investigated. Twelve Hsp-related genes were examined to observe their modulated expression patterns at different temperatures (10, 15, 25, and $35^{\circ}C$) over different exposure periods. HspA and HtpG transcripts showed an up-regulation of expression at low temperatures (10 and $15^{\circ}C$) and high temperature ($35^{\circ}C$), compared with the control ($25^{\circ}C$). To examine their effects upon thermotolerance, we purified recombinant HspA and HtpG proteins. During a thermotolerance study at $54^{\circ}C$, the HspA-transformed bacteria showed increased thermotolerance compared with the control. HtpG also played a role in the defense response to acute heat stress within 30 min. These findings provide a better understanding of cellular protection mechanisms against heat stress in cyanobacteria.

• Structural Engineering and Mechanics
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• v.60 no.1
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• pp.1-19
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• 2016

In this study, the supersonic panel flutter of doubly curved composite sandwich panels with variable thickness is considered under aerothermoelastic loading. Considering different radii of curvatures of the face sheets in this paper, the thickness of the core is a function of plane coordinates (x,y), which is unique. For the first time in the current model, the continuity conditions of the transverse shear stress, transverse normal stress and transverse normal stress gradient at the layer interfaces, as well as the conditions of zero transverse shear stresses on the upper and lower surfaces of the sandwich panel are satisfied. The formulation is based on an enhanced higher order sandwich panel theory and the vertical displacement component of the face sheets is assumed as a quadratic one, while a cubic pattern is used for the in-plane displacement components of the face sheets and the all displacement components of the core. The formulation is based on the von $K{\acute{a}}rm{\acute{a}}n$ nonlinear approximation, the one-dimensional Fourier equation of the heat conduction along the thickness direction, and the first-order piston theory. The equations of motion and boundary conditions are derived using the Hamilton principle and the results are validated by the latest results published in the literature.

• Asian-Australasian Journal of Animal Sciences
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• v.5 no.1
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• pp.81-90
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• 1992

Five buffaloes kept in normal ambient temperature ($30^{\circ}C$) showed no significant changes in the heart rate, respiratory rate, packed cell volume, plasma constituents and renal hemodymics during intravenous infusion of urea for 4 h. The rate of urine flow, fractional urea excretion, urinary potassium excretion and osmolar clearance significantly decreased while the renal urea reabsorption markedly increased during urea infusion. The decrease of fractional potassium excretion was concomitant with the reduction of the rate of urine flow and urine pH. In animals exposed to heat ($40^{\circ}C$) the rectal temperature heart rate and respiratory rate significantly increased while no significant changes in GFR and ERPF were observed. An intravenous infusion of urea in heat exposed animals caused the reduction of the rate of urine flow with no changes in renal urea reabsorption, urine pH and fractional electrolyte excretions. During heat exposure, there were marked increases in concentrations of total plasma protein and plasma creatinine whereas plasma inorganic phosphorus concentration significantly decreased. It is concluded that an increase in renal urea reabsorption during urea infusion in buffaloes kept in normal ambient temperature depends on the rate of urine flow which affect by an osmotic diuretic effect of electrolytes. The limitation of renal urea reabsorption in heat stressed animals would be attributed to an increases in either plasma pool size of nitrogenous substance or body metabolism.

• Korean Journal of Pharmacognosy
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• v.10 no.2
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• pp.61-67
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• 1979

Two pure saponin components, Panax saponin C (protopanaxatriol derivative, ginsenoside Re) and Panax saponin E (protopanaxadiol derivative, ginsenoside $Rb_l$) were isolated from Panax ginseng root and their acute toxicities in mice and antistress effects in rats were investigated. Average lethal doses $(LD_{50})$ of ginsenoside Re were 130mg/kg (i.v.), more than 1,000mg/kg (i.p.) and more than 1,500mg/kg (s.c.), respectively. Average lethal dose of ginsenoside $Rb_{1}$ was 243mg/kg intravenously. Adrenal ascorbic acid and cholesterol contents were significantly decreased when normal rats were exposed to heat $(40^{\circ}C)$ for 30 min. The reduction of the adrenal ascorbic acid and cholesterol contents in rats was partially prevented when the rats received the ginseng saponins prior to exposure to heat stress and most pronounced effects were observed in rats received ginsenoside Re. However, it was found that administration of ginseng alone, without stress, did not significantly change the ascorbic acid and cholesterol contents in adrenal glands. Eosinophil counts in the blood of the rats were elevated when the rats were exposed to the heat stress, and the elevation of the eosinophil counts were prevented with the ginseng saponins under the stress, but the changes were all insignificant statistically.

• Steel and Composite Structures
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• v.25 no.2
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• pp.177-186
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• 2017

In this work, the model of magneto-thermoelasticity based on memory-dependent derivative (MDD) is applied to a one-dimensional thermal shock problem for a functionally graded half-space whose surface is assumed to be traction free and subjected to an arbitrary thermal loading. The $Lam{\acute{e}}^{\prime}s$ modulii are taken as functions of the vertical distance from the surface of thermoelastic perfect conducting medium in the presence of a uniform magnetic field. Laplace transform and the perturbation techniques are used to derive the solution in the Laplace transform domain. A numerical method is employed for the inversion of the Laplace transforms. The effects of the time-delay on the temperature, stress and displacement distribution for different linear forms of Kernel functions are discussed. Numerical results are represented graphically and discussed.

• Tuberculosis and Respiratory Diseases
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• v.52 no.4
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• pp.355-366
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• 2002

Background : The heat shock protein (HSP) 70 families are known to protect cells against the irreversible tissue injury induced by stress and to induce the recovery of cell function during stress. Heat pretreatment was reported to decrease the acute lung injury (ALI) of rats induced by lipopolysaccharide (LPS). However, the role of heat shock with LPS co-treatmenton ALI is unclear. The purpose of this study was to investigate the effect of heat treatment, which was given immediately after the beginning of ALI induced by LPS intratracheally administered in rats. Methods : Either saline (saline group) or LPS was intratracheally instilled without heat treatment (LPS group). In addition, heat was conducted 18 hours prior to the instillation of LPS (pre-treatment group) and conducted immediately after instillation of LPS (co-treatment group). Six hours after the LPS or saline treatment, blood, bronchoalveolar lavage (BAL) fluid and lung tissue samples were obtained. The myeloperoxidase (MPO) activity and the heat shock protein expression in the lung tissue, the differential counts of the polymorphonuclear leukocytes (PMN) in the BAL fluids, and the LDH, protein, $IL-1{\beta}$, $TNF-{\alpha}$ and IL-10 levels in BAL fluid and serum were measured. Results : 1) The MPO activity, the differential PMN counts in the BAL fluid, BAL fluid and serum cytokines were higher in the LPS, the heat pre-treatment and co-treatment group than those of the saline group (p value <0.05). 2) The MPO activity and the protein level in the BAL fluid from the heat co-treatment group were similar to those of the LPS group. 3) The serum $TNF-{\alpha}$ level of the heat co-treatment group was significantly higher than that of the LPS group (p=0.01). Conclusion : Heat shock response administered immediately after a LPS instillation did not attenuate the ALI in this model.