BACKGROUND The common cause of sodium nitrite poisoning has shifted from previous accidental intoxication by exposure or ingestion of contaminated water and food to recent alarming intentional intoxication as an emplo...BACKGROUND The common cause of sodium nitrite poisoning has shifted from previous accidental intoxication by exposure or ingestion of contaminated water and food to recent alarming intentional intoxication as an employed method of suicide/exit.The subsequent formation of methemoglobin(MetHb)restricts oxygen transport and utilization in the body,resulting in functional hypoxia at the tissue level.In clinical practice,a mismatch of cyanotic appearance and oxygen partial pressure usually contributes to the identification of methemoglobinemia.Prompt recognition of characteristic mismatch and accurate diagnosis of sodium nitrite poisoning are prerequisites for the implementation of standardized systemic interventions.CASE SUMMARY A pregnant woman was admitted to the Department of Critical Care Medicine at the First Affiliated Hospital of Harbin Medical University due to consciousness disorders and drowsiness 2 h before admission.Subsequently,she developed vomiting and cyanotic skin.The woman underwent orotracheal intubation,invasive mechanical ventilation(IMV),and correction of internal environment disturbance in the ICU.Her premature infant was born with a higher-than-normal MetHb level of 3.3%,and received detoxification with methylene blue and vitamin C,supplemental vitamin K1,an infusion of fresh frozen plasma,as well as respiratory support via orotracheal intubation and IMV.On day 3 after admission,the puerpera regained consciousness,evacuated the IMV,and resumed enteral nutrition.She was then transferred to the maternity ward 24 h later.On day 7 after admission,the woman recovered and was discharged without any sequelae.CONCLUSION MetHb can cross through the placental barrier.Level of MetHb both reflects severity of the sodium nitrite poisoning and serves as feedback on therapeutic effectiveness.展开更多
Previous studies showed contradictory findings regarding the relationship between nitrate in drinking well-water and abnormal methemoglobin (MetHb) level (>2%) among children. We studied the effect of water chlorin...Previous studies showed contradictory findings regarding the relationship between nitrate in drinking well-water and abnormal methemoglobin (MetHb) level (>2%) among children. We studied the effect of water chlorination in this relationship in children aged up to 7. 240 subclinical children participated in this cross-sectional study. Water nitrate was analyzed for each participant, and so was blood MetHb. Analysis of two water nitrate exposure levels (50 mg/L as )-other extraneous factors (Breslow-Day-Test for interaction), bivariate and multivariate analyses were performed. Abnormal MetHb levels (up to 7.9%) were associated (p-value = 0.020) with exposure to drinking water nitrate. Only water chlorination was an effect modifier. Among those who do not disinfect water, the prevalence of ab- normal MetHb for those with nitrate level >50 mg/L was 4.95 (p-value = 0.001, 95% CI = [1.92 - 12.79]) times the prevalence for those with nitrate level <50 mg/L. Whereas, among those who do disinfect water, the prevalence for those with high nitrate levels was only 1.38 (p-value = 0.435, 95% CI = [0.62 - 3.07]) times the prevalence of those with low nitrate levels. The biological plausibility of a relationship between waterborne microorganisms, drinking water nitrate, drinking water chlorination, and development of an abnormal MetHb level needs to be further explored.展开更多
Understanding the mechanism of oxidative stress is likely to yield new insights regarding the pathogenesis of Alzheimer’s disease (AD). Our earlier work focused on the difference between hemoglobin and methemoglobin ...Understanding the mechanism of oxidative stress is likely to yield new insights regarding the pathogenesis of Alzheimer’s disease (AD). Our earlier work focused on the difference between hemoglobin and methemoglobin degradation, respectively leading to ferrous (Fe2+) iron, or ferric (Fe3+) iron. Methemoglobin has the role of carrier, the donor of cytotoxic and redox-active ferric (Fe3+) iron, which can directly accumulate and increase the rate of capillary endothelial cell apoptosis, and may cross into the brain parenchyma, to the astrocytes, glia, neurons, and other neuronal cells (neurovascular unit). This supposition helps us to understand the transport and neuronal accumulation process of ferric iron, and determine how iron is transported and accumulated intracellularly, identifiable as “Brain rust”. Earlier research found that the incidences of neonatal jaundice (p = 0.034), heart murmur (p = 0.011) and disorders such as dyslalia and learning/memory impairments (p = 0.002) were significantly higher in those children born from mothers with methemoglobinemia. Our hypothesis suggests that prenatal iron abnormalities could lead to greater neuronal death, the disease ageing process, and neurodegenerative disorders such as AD and other neurodegenerative diseases.展开更多
Reticulocytosls in rats was induced by repetitive bleeding. Both the in vitro and the in vivo studies showed that the detected reductive speed of methemoglobin of the bleeding group was faster than that of the control...Reticulocytosls in rats was induced by repetitive bleeding. Both the in vitro and the in vivo studies showed that the detected reductive speed of methemoglobin of the bleeding group was faster than that of the control group at all time intervals. At the same time, the NADH-cytochrome b5 methemoglobin reductase activity and the molybdenum content in erythrocytes of the bleeding group were significantly increased. Regressional analysis showed that there was a significantly positive correlation between the enzyme activity and the molybdenum content. It is proposed that molybdenum might be required for the enzyme activity展开更多
基金Supported by the National Natural Science Foundation of China,No.82372172the Key Research and Development Plan Project of Heilongjiang Province,No.GA23C007+3 种基金the Heilongjiang Province Postdoctoral Start-up Fund,No.LBH-Q20037the Research Project of Heilongjiang Provincial Health Commission,No.20231717010461the Special Fund for Clinical Research of Wu Jie-ping Medical Foundation,No.320.6750.2022-02-16the Scientific Research Innovation Fund of the First Affiliated Hospital of Harbin Medical University,No.2021M08.
文摘BACKGROUND The common cause of sodium nitrite poisoning has shifted from previous accidental intoxication by exposure or ingestion of contaminated water and food to recent alarming intentional intoxication as an employed method of suicide/exit.The subsequent formation of methemoglobin(MetHb)restricts oxygen transport and utilization in the body,resulting in functional hypoxia at the tissue level.In clinical practice,a mismatch of cyanotic appearance and oxygen partial pressure usually contributes to the identification of methemoglobinemia.Prompt recognition of characteristic mismatch and accurate diagnosis of sodium nitrite poisoning are prerequisites for the implementation of standardized systemic interventions.CASE SUMMARY A pregnant woman was admitted to the Department of Critical Care Medicine at the First Affiliated Hospital of Harbin Medical University due to consciousness disorders and drowsiness 2 h before admission.Subsequently,she developed vomiting and cyanotic skin.The woman underwent orotracheal intubation,invasive mechanical ventilation(IMV),and correction of internal environment disturbance in the ICU.Her premature infant was born with a higher-than-normal MetHb level of 3.3%,and received detoxification with methylene blue and vitamin C,supplemental vitamin K1,an infusion of fresh frozen plasma,as well as respiratory support via orotracheal intubation and IMV.On day 3 after admission,the puerpera regained consciousness,evacuated the IMV,and resumed enteral nutrition.She was then transferred to the maternity ward 24 h later.On day 7 after admission,the woman recovered and was discharged without any sequelae.CONCLUSION MetHb can cross through the placental barrier.Level of MetHb both reflects severity of the sodium nitrite poisoning and serves as feedback on therapeutic effectiveness.
文摘Previous studies showed contradictory findings regarding the relationship between nitrate in drinking well-water and abnormal methemoglobin (MetHb) level (>2%) among children. We studied the effect of water chlorination in this relationship in children aged up to 7. 240 subclinical children participated in this cross-sectional study. Water nitrate was analyzed for each participant, and so was blood MetHb. Analysis of two water nitrate exposure levels (50 mg/L as )-other extraneous factors (Breslow-Day-Test for interaction), bivariate and multivariate analyses were performed. Abnormal MetHb levels (up to 7.9%) were associated (p-value = 0.020) with exposure to drinking water nitrate. Only water chlorination was an effect modifier. Among those who do not disinfect water, the prevalence of ab- normal MetHb for those with nitrate level >50 mg/L was 4.95 (p-value = 0.001, 95% CI = [1.92 - 12.79]) times the prevalence for those with nitrate level <50 mg/L. Whereas, among those who do disinfect water, the prevalence for those with high nitrate levels was only 1.38 (p-value = 0.435, 95% CI = [0.62 - 3.07]) times the prevalence of those with low nitrate levels. The biological plausibility of a relationship between waterborne microorganisms, drinking water nitrate, drinking water chlorination, and development of an abnormal MetHb level needs to be further explored.
文摘Understanding the mechanism of oxidative stress is likely to yield new insights regarding the pathogenesis of Alzheimer’s disease (AD). Our earlier work focused on the difference between hemoglobin and methemoglobin degradation, respectively leading to ferrous (Fe2+) iron, or ferric (Fe3+) iron. Methemoglobin has the role of carrier, the donor of cytotoxic and redox-active ferric (Fe3+) iron, which can directly accumulate and increase the rate of capillary endothelial cell apoptosis, and may cross into the brain parenchyma, to the astrocytes, glia, neurons, and other neuronal cells (neurovascular unit). This supposition helps us to understand the transport and neuronal accumulation process of ferric iron, and determine how iron is transported and accumulated intracellularly, identifiable as “Brain rust”. Earlier research found that the incidences of neonatal jaundice (p = 0.034), heart murmur (p = 0.011) and disorders such as dyslalia and learning/memory impairments (p = 0.002) were significantly higher in those children born from mothers with methemoglobinemia. Our hypothesis suggests that prenatal iron abnormalities could lead to greater neuronal death, the disease ageing process, and neurodegenerative disorders such as AD and other neurodegenerative diseases.
文摘Reticulocytosls in rats was induced by repetitive bleeding. Both the in vitro and the in vivo studies showed that the detected reductive speed of methemoglobin of the bleeding group was faster than that of the control group at all time intervals. At the same time, the NADH-cytochrome b5 methemoglobin reductase activity and the molybdenum content in erythrocytes of the bleeding group were significantly increased. Regressional analysis showed that there was a significantly positive correlation between the enzyme activity and the molybdenum content. It is proposed that molybdenum might be required for the enzyme activity
