• Applied Microscopy
• /
• 제19권2호
• /
• pp.43-58
• /
• 1989

To investigate the effects of hexavalent chromium on mitochondrial respiration of rat kidney, various hexavalent chromium concentrations were treated, then respiration and electron transfer enzyme activities were measured. Ultrastructural changes at state IV respiration of mitochondria were also observed. Then, to investigate protective role against hexavalent chromium in the body, low-molecular-weight, chromium-binding substances (LMCr) were purified from livers of rabbits 2hr after intravenously administrated with sodium dichromate at a dose of 74mg per kg body weight. And then, respiration rates of mitochondria treated with LMCr, hexavalent chromium containing 0.7mM chromium were measured. Hexavalent chromium decreased state IV respiration rates and electron transfer enzyme activities of mitochondria, and increased labile membrane and swelling. And partial inhibitions of condensed to orthodox conformational change were observed. Respiration rates of mitochondria treated with LMCr containing 0.7mM chromium did not differ from that of the non-treated mitochondria. But respiration rates of 0.7mM hexavalent chromium-treated mitochondria decreased by 42%, compared to non-treated mitochondria. These results suggest that LMCr may play an important role in detoxification of toxic hexavalent chromium.

• 한국독성학회:학술대회논문집
• /
• 한국독성학회 2002년도 Current Trends in Toxicological Sciences
• /
• pp.67-67
• /
• 2002

According to the epidemiological studies in chromium workers, hexavalent chromium is associated with the risk of lung cancer. Genotoxicity such as chromosome aberration, and cellular oxidative damages by reactive oxygen species produced by hexavalent chromium exposure may play an important role in the carcinogenesis process.(omitted)

• 한국환경성돌연변이발암원학회지
• /
• 제22권4호
• /
• pp.279-288
• /
• 2002

According to the epidemiological studies in chromium workers, hexavalent chromium is associated with the risk of lung cancer. Cellular oxidative damages by reactive oxygen species produced by hexavalent chromium exposure may play an important role in the carcinogenesis process. We investigated the availabilities of malondialdehyde measurement for the assessments of oxidative damages from chromium exposure with an experimental inhalation study in vivo. Lipid peroxidation, one kind of cellular oxidative damage, was measured in blood plasma of the rats which inhaled the hexavalent chromium mist for 1, 2 and 3 weeks. The concentrations of malondialdehyde (MDA), the metabolite of lipid peroxidation, in all exposed groups were higher than those of controls with dose-dependant manner. The levels of MDA were also correlated with urine chromium levels of the rats. Therefore, MDA as an indicator of lipid peroxidation could be proper biologic marker for the assessment of the oxidative damage from chromium exposure, which might be involved in carcinogenesis.

• 한국식품영양과학회지
• /
• 제33권4호
• /
• pp.762-768
• /
• 2004

인슐린 작용을 강화시키는 LMWCr의 발견과 크롬 결핍과 관련 있는 포도당 불내성(glucose intolerance)이 크롬 투여 시 반응을 보여준 임상적 증명 이후, 크롬은 확실한 필수 영양소로 인식되고 보조제로 사용되고 있다. 시험관 실험에서 고농도의 3가 크롬을 배양 세포에 노출 시, 일부 연구 결과에서 염색체이상 유발과 변이원성 효과가 발견되긴 하였으나 이는 비타민 A, D, 니코틴산, 셀레늄 등과 같은 많은 다른 영양소의 과잉 섭취 시 독성 효과를 나타내는 정도로 해석되며, 시험관 실험 결과들이 발암성의 증거로 해석되지는 않는다. 3가 크롬을 경구 보조제로 투여된 임상 치료에서 환자들은 독성효과를 보이지 않았으며, 혈장 내 크롬 수치가 비 투여된 사람들에 비하여 조금 높았다. 크롬을 TPN 형태로 투여받은 환자들에게서도 우려했던 신체ㆍ정신적 효과와의 상관 관계가 없었으며 신기능부전을 나타낸 경우는 신장 독성을 주는 약들을 함께 복용한 경우로서, 우려되는 부작용은 없는 것으로 인정된다. 임상학적, 실험적으로 사용된 3가 크롬의 용량은 ESADDI 규정된 범위 50∼200 $\mu$g/day에서 전혀 독성을 나타내지 않았으며, 일반적인 사용에 기준이 될 것이다. EPA는 모든 관련 자료들을 검토한 후에 크롬의 참고용량 (RfD) 수치를 70 mg/day로 결론지었으며, 다른 영양소들의 용량과 비교했을 때 대단히 넓은 수치이다. 3가 크롬은 당뇨병, 임신성 당뇨병, 인슐린 내성, 비정상적 지방대사를 개선시키기 위한 영양소로서 가능성을 가진다. 또한 크롬의 보충은 제II형 당뇨병과 다양한 심혈관계 질환을 예방하거나 치료하는데 가장 유용한 것으로 밝혀졌다. 앞으로는 크롬 보조제 사용 시, 일부 연구자들이 3가 크롬 1000 $\mu$g/day의 안전성을 입증한 것과 같이 용량을 늘려 임상실험을 시도한 후 안전과 효능을 증명하는 것이 필요하다.

• 한국독성학회:학술대회논문집
• /
• 한국독성학회 2001년도 International Symposium on Dietary and Medicinal Antimutgens and Anticarcinogens
• /
• pp.121-122
• /
• 2001

According to the epidemiological studies in chromium workers, hexavalent chromium is associated with the risk of lung cancer. Genotoxicity such as chromosome aberration, and cellular oxidative damages by reactive oxygen species produced by hexavalent chromium exposure may play an important role in the carcinogenesis process. We investigated the availabilities of several kinds of biological markers to assess the genotoxicity and oxidative damages from chromium exposure in Korean chromium plating workers.(omitted)

• 대한금속재료학회지
• /
• 제46권10호
• /
• pp.652-661
• /
• 2008

Reduction of NOx in emission gas, improvement of engine efficiency, and extension of warranty period has made demands for developing materials more corrosively resistant to the inner-muffler environments or predicting the lifetime of materials used in muffler more precisely. The corrosion inside muffler has been explained with condensate corrosion mainly though thermal oxidation experiences prior to condensate corrosion. Hence, the aim of this study is to describe how the thermal oxidation affects the corrosion of stainless steel exposed to the inner-muffler environments. Auger electron spectroscopy and electrochemical tests were employed to analyze oxide scale and to evaluate corrosion resistance, respectively. Thermal oxidation has different role of condensate corrosion depending on the temperature: inhibiting condensate corrosion below $380^{\circ}C$ and enhancing condensate corrosion above $380^{\circ}C$. The low temperature oxidation causes to form compact oxide layer functioning a barrier for penetrating condensate into a matrix. Although though thermal oxidation caused chromium-depleted layer between oxide layer and matrix, the enhancement of the condensate corrosion in high temperature oxidation resulted from corrosion-induced crevice formed by oxide scale rather than corrosion in chromium-depleted layer. It was proved by aids of anodic polarization tests and measurements of pitting corrosion potentials. By the study, the role of high temperature oxidation layer affecting the condensate corrosion of stainless steels used as muffler materials was well understood.

• Environmental Analysis Health and Toxicology
• /
• 제18권3호
• /
• pp.165-174
• /
• 2003

Cr (Ⅵ) - containing compounds are well-established carcinogens, although the mechanism for chromium - induced carcinogenesis is still not well understood. The reduction of Cr (Ⅵ) to its lower oxidation states, par ticularly Cr (V) and Cr (IV), is an important step for the production of chromium-mediated reactive oxygen species (ROS). The persistent oxidative stress during the reduction process may play a key role in the mechanism of Cr (Ⅵ) -induced carcinogenesis. This paper summarizes recent studies on (1) the reduction of Cr (Ⅵ) to Cr (III) occur by a multiplicity of mechanisms depending on the nature of reducing agents including ascorbate, diol-and thiol-containing molecules, certain flavoenzymes, cell organelles, intact cells, and whole animals; (2) free-radical production with emphasis on hydroxy radical generation via Fenton or Haber-Weiss type reactions; and (3) free radical - induced cellular damage, such at DNA strand breaks, hydroxylation of 2'-deoxyguanosine, and activation of nuclear transcription factor kB.

• 한국환경보건학회지
• /
• 제23권4호
• /
• pp.9-15
• /
• 1997

This experiment was carried out to examine the roles of selenium in arsenic- and chromium-induced oxidative stress, which results in chromosomal damage, such as sister chromatid exchange (SCE) and chromosomal aberration (CA). For this purpose, the frequency of CA and SCE related to the level of 0xidative stress were analyzed. Selenium decreased the frequency of CA induced by As. In order to evaluate the effect of selenium on clastogenic factors, media from As- and Cr-treated cells were ultrafiltered and added again to cells in the presence or absence of selenium. Selenium decreased the frequency of SCE by As and Cr. This observation indicates the possibility of presence of clastogenic factor. In addition, the clastogenic factor would be involed in oxidative stress since selenium decreased the level of oxidative stress. Thus, it is suggested that selenium may play a role as an anti-clastogenic effector by preventing the oxidative stress, thereby decreasing the frequency of Asand Cr-induced chromosomal damage.

• 대한용접접합학회:학술대회논문집
• /
• 대한용접접합학회 2005년도 춘계학술발표대회 개요집
• /
• pp.48-50
• /
• 2005

Advanced hard materials based on diamond are in common use. In this study our main goal was employed to analyze, the mechanisms for the rich phases and chromium carbide, interface of a diamond grits brazed to a Ni-based brazing filler metal matrix. When Ni-7Cr-3Fe-3B-4Si (wt. %) was utilized as the brazing alloy, an isothermal holding resulted in the various products(Ni-rich/Cr-rich domains, carbide). According to these results, the chemical compounds and chromium carbides products is considered to play an important role in brazing temperature and time. Especially chromium carbide has an influence on brazing junction properties.

• 한국독성학회:학술대회논문집
• /
• 한국독성학회 2001년도 International Symposium on Signal transduction in Toxicology
• /
• pp.151-151
• /
• 2001

According to the epidemiological studies in chromium workers, hexavalent chromium is associated with the risk of lung cancer. Reactive oxygen species produced by hexavalent chromium exposure may play an important role in the carcinogenesis process. We measured one kind of oxidative DNA damages, 8-hydroxydeoxyguanosine (8-OHdG) and its repair activities as an indicators of cellular oxidative stress in rat lungs by the repeated inhalation exposure to sodium chromate.(omitted)