Apoptosis in macrophages is responsible for immune-depression and pathological effects during malaria. Phagocytosis of PRBC causes induction of apoptosis in macrophages through release of cytosolic factors from infected cells. Heme polymer or β-hematin causes dose-dependent death of macrophages with LC50 of 132 µg/ml and 182 µg/ml respectively. The toxicity of hemin or heme polymer was amplifie...

Methemoglobin is a structurally modified form of hemoglobin incapable binding oxygen, and elevated levels methemoglobin cause tissue hypoxia. Occupational exposure to 2,4,6-trinitrotoluene, commonly called trinitrotoluene, causes methemoglobinemia. This case report describes 27-year-old male sergeant who developed methemoglobinemia upon trinitrotoluene after blast injury while welding the walls...

On the basis of nuclear magnetic resonance spectra, Davis, Charachc, and Ho (1) have recently suggested that the heme groups of the a! and /3 methemoglobin chains are not equivalent. Gibson, Parkhurst, and Geraci (2) have reported biphasic kinetics for the reaction of methemoglobin with a variety of iron-coordinating ligands. These results were also explained assuming nonequivalent heme groups....

We have examined the redox equilibria of azidomethemoglobin (low-spin) and fluoromethemoglobin (high-spin). We have derived a modified Hill equation which includes the tetramer--dimer equilibrium of the oxidized form, and also generalized the two-state model to incorporate ligand binding to the ferriheme. The pH dependence of the redox Hill's constant for fluoromethemoglobin is the same as that...

nitrite intoxication occurs frequently in ruminants and equines. the most common treatment of this disorder is administration of 1% methylene blue, although the use of some antioxidant agents e.g. vitamins and complementary treatment may also be useful. the aim of this study was to evaluate the in vitro antioxidative effects of some vitamins on methemoglobinemia induced by sodium nitrite. for t...

A long-term sodium nitrite infusion is intended for the treatment of vascular disorders. Phase I data demonstrated a significant nonlinear dose-exposure-toxicity relationship within the therapeutic dosage range. This study aims to develop a quantitative systems pharmacology model characterizing nitric oxide (NO) metabolome and methemoglobin after sodium nitrite infusion. Nitrite, nitrate, and m...

Acute formation of methemoglobin is a life-threatening condition caused by multiple medications. In this article we report the first case of methemoglobinemia in a patient with metastatic uterine leiomyosarcoma, after infusion of ifosfamide chemotherapy. The patient recovered after prompt diagnosis and treatment of the condition. A mechanism for the formation of methemoglobin as a result of the...

Methaemogloninemia is a rare condition characterized by elevated levels of methemoglobin levels. We report a case of a young lady who took thinner (a solvent used in paint). Methemoglobinemia was diagnosed on the basis of saturation gap and elevated methemoglobin levels. She recovered after exchange transfusion, which was done due to non-availability of parenteral methylene blue.

A biologically based mathematical model was created to characterize time and dose-dependent relationships between exposure to nitrite and induction of methemoglobinemia. The model includes mass action equations for processes known to occur: oral absorption of nitrite, elimination from the plasma, partitioning between plasma and erythrocytes, binding of nitrite to hemoglobin and methemoglobin, a...