methemoglobin

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Related to Methaemoglobin: carboxyhemoglobin, Blue baby syndrome

methemoglobin

[met‚hē·mə′glō·bən]
(biochemistry)
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Toxic methaemoglobin concentrations in premature infants after application of a prilocaine containing cream and peridural prilocaine.
Due to deficiency of enzyme nicotinamide adenine dinucleotide NADH cytochrome b5 reductase, which helps in conversion of methaemoglobin to functional haemoglobin.
According to WHO (2004), nitrate is reduced to nitrite in the stomach of infants, and nitrite is able to oxidize hemoglobin (Hb) and methaemoglobin, which is unable to transport oxygen around the body.
Increased levels of catecholamines, as well as increased release of metmyoglobin from damaged muscle and interaction of metmyoglobin and methaemoglobin with peroxides during exercise also have been proposed as mediators of ROS generation (4, 19).
G6PD status was determined using the standard methaemoglobin reduction test.
So nitrite accumulates, absorbed and in blood it reacts with haemoglobin and convert it into methaemoglobin incapable of oxygen transport and resultant anoxia causing respiratory distress.
Tender are invited for supply of Equipments & Instruments (1 Monitor for Continuous Measurement of Cardiac Function (2 Monitor for continuous measurement of body tissue oxygenation and oxygen delivery status (3 Brain Function Monitor for depth of anesthesia (4 Instant Hand held blood pH and Lactate monitor (5 Lumber Puncture Simulator with Epidural block trainer (6 Spinal Injection Trainer (7 Central Venous Catheter Simulator (8 Cricotracheotomy trainer (9 Peripheral Nerve Stimulator/ Locator (10 Multi-frequency based deep heat generator (11 Airway management Trainer: (12 Handheld instant hemoglobinometer with facility to measure Methaemoglobin at Department of anesthesiology (manicktala)
If the accumulation of nitrite was occured, the nitrite ions would be absorbed into the blood, and when they were in contact with erythrocytes, nitrite would oxidize [Fe.sup.+2] in hemoglobin (Hb) into [Fe.sup.3+] to form methaemoglobin (MetHb).
These results might be due to the decrease number of RBC or due to the conversion of nitrate to nitrite ions which can convert ferrous ions of hemoglobin into ferric form (methaemoglobin) resulting in tissue anoxia which may be responsible for renal and hepatic damage[16].Total protein and albumin concentrations were significantly decreased in the nitrated treated group.
Methaemoglobin (MetHb) or Metmyoglobin (MetMb) reacts with hydrogen peroxide or lipid hydroperoxides to generate ferryl heme protein radicals, which can abstract hydrogen from polyunsaturated fatty acids thus initiating lipid oxidation (Miller et al., 1997).
The globe may be hyperintense on T1-weighted images; this may represent either subhyaloid or subretinal fluid with blood degradation products (methaemoglobin) or high protein content (see Figure 1b).
[11] Because sensitivity of MRI to blood flow and to the paramagnetic effects of iron (in the form of methaemoglobin) is superior to that of CT, differentiation between flowing blood, acute thrombus (<1 week old) and subacute thrombus (between 1 week and 1 month) is possible.