• Journal of Life Science
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• v.33 no.7
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• pp.586-592
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• 2023

Oxidative stress is a critical factor affecting the quality and viability of sperm during boar semen storage. Oxidative stress is also a significant concern during the process of freezing semen. The process of semen storage involves exposing the sperm to various stressors, including temperature changes, cryoprotectants, and extended periods of incubation. In addition, oxidative stress can lead to the production of reactive oxygen species (ROS) within the sperm, resulting in oxidative damage to cellular components, such as lipids, proteins, and DNA. Striking a balance between ROS production and the antioxidant defense system is crucial for maintaining sperm viability and functionality during semen storage. Moreover, the prolonged storage of boar semen leads to an increase in ROS levels, which can impair sperm motility, membrane integrity, and DNA integrity. ROS-induced lipid peroxidation affects the fluidity and stability of sperm membranes, leading to decreased sperm motility. Moreover, oxidative damage to the DNA can result in DNA fragmentation, compromising the genetic integrity of the sperm. In conclusion, oxidative stress is a significant challenge in maintaining sperm quality during boar semen storage. Understanding the mechanisms underlying oxidative stress and their impacts on sperm function is crucial for developing effective strategies to minimize oxidative damage and improve sperm storage outcomes.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.3
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• pp.411-418
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• 1998

The thickness dependence of stress electric filed oxide currents has been measured in oxides with thicknesses between 10 nm and 80 nm. The oxide currents were shown to be composed of stress current and transient current. The stress current was composed of stress induced leakage current and dc current. The stress current was caused by trap assisted tunneling through the oxide. The transient current was caused by the tunneling charging and discharging of the trap in the interfaces. The stress current was used to estimate to the limitations on oxide thicknesses. The transient current was used to the data retention in memory devices.

• The Korean Journal of Pharmacology
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• v.31 no.1 s.57
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• pp.95-102
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• 1995

The pathogenesis of diabetic nephropathy is still not completely understood while renal disease is one of the most common disabling complications of diabetes. We, in the present study, investigated the possible involvement of oxidative stress in the development of diabetic nephropathy. To hasten the development of diabetic nephropathy, streptozotocin was injected to unilaterally nephrectomized rats (NEPH-STZ). Eight weeks later, NEPH-STZ rats developed severe hyperglycemia, proteinuria, and hypertension. The kidneys of these rats showed compensatory hypertrophy and mesangial expansion. In contrast, the rats with streptozotocin injection alone (STZ) did not increase urinary protein excretion. Nephrectomized non-diabetic rats (NEPH) developed increased urine protein excretion, but without prominent renal morphological changes. However, oxidation of renal cortical tissue protein significantly increased in all 3 groups of NEPH, STZ and NEPH-STZ in comparison to control rats (CONT). The result indicates the non-specificity of the oxidative tissue damage and suggests that the oxidative damage is hardly a sole mechanism leading to the development of the diabetic nephropathy. However, it would still be a contributing factor considering that the oxidative stress is a common final pathway mediating tissue damages in chronic diabetic complications and other serious illness.

• The Korean Journal of Pharmacology
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• v.32 no.3
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• pp.335-345
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• 1996

A critical role of oxygen-derived free radicals has been implicated in ischemia/reperfusion (I/R)-induced brain damage. In this study, we have produced experimental I/R to the brains of Mongolian gerbil (Meriones unguiculatus) by a transient occlusion and release of the common carotid arteries. We have attempted to determine whether the oxidative stress is generated upon I/R and whether this oxidative stress is linked to the cell damage. Since hippocampus has been suggested as one of the most vulnerable regions of the brain to the oxidative stress, we analyzed samples from hippocampus in comparison with those from cortex. In addition, we have examined the expression of heat shock protein 70kD species (HSP70) in these regions in order to evaluate a possible role of this protein in I/R-induced brain damage. To determine whether the oxidative stress is produced upon I/R, we measured the glutathione oxidation, GSSG/ (GSH + 2xGSSG), as an index of oxidative stress. We found an increase of the glutathione oxidation primarily in hippocampus upon I/R. To determine whether this oxidative stress is linked to the cell damage, we measured the degree of lipid peroxidation upon I/R. We found an increase of lipid peroxidation in both regions. However, the magnitude of increases was greater in hippocampus than in cortex. In addition, we found that changes in both the magnitude and the temporal patterns of glutathione oxidation closely correlated with those of lipid peroxidation. Our study provides biochemical evidences that the oxidative stress is generated upon I/R and this oxidative stress is linked to the oxidative cell damage. Our study also provides evidences that the degree of oxidative stress as well as oxidative cell damage is greater in hippocampus than in cortex. We could not find difference in the basal level of HSP70 expression between hippocampus and cortex, indicating that the intrinsic vulnerability of hippocampus cannot be explained by the lower level of HSP70 expression. We did find, however, that the induction of HSP70 expression upon I/R was impaired in the hippocampus. This impairment appeared to be at the transcriptional level. These results suggest that the measurement of HSP70 induction may be employed as a useful predictor of differential cellular susceptibilities to the I/R-induced brain damage.

• Journal of Life Science
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• v.25 no.3
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• pp.263-268
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• 2015

Coelomocytes are specialized cells that continually and nonspecifically scavenge fluid from the body cavity through endocytosis in Caenorhabditis elegans. Our previous study revealed that coelmocytes were specifically required for dietary-restriction-induced longevity in C. elegans. In the present study, we examined the effect of coelomocyte ablation on the response to environmental stressors and reproduction in C. elegans. Coelomocytes were ablated using diphtheria toxin specifically expressed in coelomocytes. After exposing worms to 20 J/cm²/min of ultraviolet irradiation in vivo, the survival of the worms was monitored daily. To examine their response to heat stress, their survival after 10 h of 35℃ heat shock was measured. Oxidative stress was induced using paraquat, and the susceptibility to oxidative stress was compared between wild-type control and coelomocyte-ablated worms. The total number of progeny produced was counted, and the time-course distribution of the progeny was determined. The worms with ablated coelomocytes showed reduced resistance to ultraviolet irradiation, but the ablation of coelomocytes had no effect on their response to heat or oxidative stress. The number of progeny produced during the gravid period was significantly decreased in the coelomocyte-ablated worms. These findings suggest that coelomocytes specifically modulate the response to ultraviolet irradiation and are required for normal reproduction in C. elegans. The findings could contribute to understanding of the mechanisms underlying dietary-restriction-induced longevity.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.8
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• pp.285-291
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• 2013

In this paper, MOS-Capacitor and MOSFET devices with a Low Level Leakage Current of oxide thickness, channel width and length respectively were to investigate the reliability characterizations mechanism of ultra thin gate oxide films. These stress induced leakage current means leakage current caused by stress voltage. The low level leakage current in stress and transient current of thin silicon oxide films during and after low voltage has been studied from strss bias condition respectively. The stress channel currents through an oxide measured during application of constant gate voltage and the transient channel currents through the oxide measured after application of constant gate voltage. The study have been the determination of the physical processes taking place in the oxides during the low level leakage current in stress and transient current by stress bias and the use of the knowledge of the physical processes for driving operation reliability.

• Journal of Nutrition and Health
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• v.36 no.6
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• pp.570-576
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• 2003

The remarkable change of phenomenon induced by stress increase energy metabolism that can induce many reactive oxygen species (ROS) production. ROS can peroxidize cellular macromolecules including lipid and protein. The object of this study was to investigate whether stress may induce cellular damage by producing ROS and whether vitamin E, as a strong lipid-soluble antioxidant, can protect cells against reactive oxygen species produced by noise and immobilization stress in SD rats. The stress group increased 5-hydroxyindole aceti acid (5-HIAA) , one of the stress hormone, in brain tissue and free fatty acid in plasma. Vitamin I treatment had no effect on 5-HIAA but free fatty acid contents decreased with a fortified vitamin I diet. Furthermore, the body weight of vitamin I-treated rats increased more than that of the stress group. Lipid peroxidation and protein degradation as an index of oxidative damage in brain tissue decreased with the use of the fortified vitamin I diet supplement. The results suggest that vitamin I supplements have a protective effect against noise and immobilization stress-induced oxidative damage in brain tissue.

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.39 no.4
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• pp.335-340
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• 2002

In this paper, the stress induced leakage currents of thin silicon oxides is investigated in the ULSI implementation with nano structure transistors. The stress and transient currents associated with the on and off time of applied voltage were used to measure the distribution of high voltage stress induced traps in thin silicon oxide films. The stress and transient currents were due to the charging and discharging of traps generated by high stress voltage in the silicon oxides. The transient current was caused by the tunnel charging and discharging of the stress generated traps nearby two interfaces. The stress induced leakage current will affect data retention in electrically erasable programmable read only memories. The oxide current for the thickness dependence of stress current, transient current, and stress induced leakage currents has been measured in oxides with thicknesses between 113.4${\AA}$ and 814${\AA}$, which have the gate area $10^3cm^2$. The stress induced leakage currents will affect data retention and the stress current, transient current is used to estimate to fundamental limitations on oxide thicknesses.

• Journal of Korean Ophthalmic Optics Society
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• v.13 no.3
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• pp.103-109
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• 2008

Purpose: This review illustrates an importance of oxidative stress caused by reactive oxygen species (ROS) and reactive nitrogen species (RNS) generation in association with eye disease, especially of cataract, and discusses an important role of lipid peroxide as a mediator of oxidative stress-related ocular dysfunction. Methods: Oxidative stress, resulted from the cellular production of ROS and RNS, is known to cause various forms of cellular damages such as protein oxidation, DNA breaks, apoptosis, and lipid peroxidation. These damages can be developed to human diseases. Accumulating evidence strongly suggests that continuous or constant exposure of eye tissues to oxidative stress is a main cause of cataractogenesis. Therefore, we investigated the action of oxidative stress in ocular dysfunction. Results: The ocular lens is continuously attacked by ROS inevitable generated from the process of cellular metabolism and the chronic exposure to ultraviolet. Excessive generation of ROS, resulting in degradation, oxidation, crosslinking and aggregation of lens proteins, is regarded as an important factor in development of cataract. Conclusions: These oxidative stress and oxidant/antioxidant imbalance produces the excess ROS which can lead to eye dysfunction. Even though known results, it should be noted that there is limited information on the molecular mechanism which can be better defined with the interrelation of oxidative stress and optic abnormalities.

• Journal of the Korean Institute of Telematics and Electronics T
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• v.36T no.1
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• pp.13-18
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• 1999

The trap density by the stress bias in silicon oxides with different thicknesses has been investigated. The trap density by stress bias was shown to be composed of on time current and off time current. The on time trap density was composed of dc current. The off time trap density was caused by the tunneling charging and discharging of the trap in the interfaces. The on time trap density was used to estimate to the limitations on oxide thicknesses. The off time trap density was used to estimate the data retention in nonvolatile memory devices.