MetHb Levels Research Articles

Does Exposure to Nitrate in Drinking Water Contribute Anything the Effect of Water Chlorination on Children Methemoglobin Levels?

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.

Risk Factors for Delayed Neuropsychiatric Sequelae in Carbon Monoxide Poisoning: Ten Years' Experience in a Pediatric Emergency Department

Objective: The occurrence of Delayed Neuropsychiatric Sequelae (DNS) after Carbon Monoxide (CO) poisoning is uncommon in children. Early identification of risk factors for the development of DNS in pediatric emergency departments is important. The objective of this study was to analyze risk factors for DNS after CO poisoning. Methods: We retrospectively analyzed children with CO poisoning admitted to the pediatric emergency department from 2001 to 2010. Clinical, demographic, and laboratory data were collected; chi-square and univariate analyses were performed to assess risk factors for DNS. Results: Among 68 children with CO poisoning, seven (10.3%) developed DNS. Clinical parameters such as Glasgow Coma Scales (GCS), Methemohemoglobin (MetHb), troponin-I, CPK level, myocardial injury, and neuroimaging abnormalities, were important associated risk factors for DNS. Decreased GCS level (OR = 0.701) and Methemohemoglobin (MetHb) ≥ 0.8% (OR = 19.54) are associated with DNS. Carboxyhemoglobin, and inadequate HBO therapy were not risk factor. Conclusions: Prompt treatment of CO poisoning and identify risk factor for DNS is still challenge in PED. Our data demonstrate that decreased GCS level and increased MetHb level were independent risk factors associated with DNS. Early recognition and prompt treatment is important to prevent further neurological damage.

Inhibition of Dapsone-Induced Methaemoglobinaemia by Cimetidine in the Rat During Chronic Dapsone Administration

Dapsone undergoes N-acetylation to monoacetyl dapsone as well as N-hydroxylation to a hydroxylamine which is responsible for the haemotoxicity (i.e. methaemoglobinaemia; Met Hb) of the drug. Since dapsone is always given chronically, we have investigated the ability of cimetidine to inhibit Met Hb formation caused by repeated dapsone administration. The drug was given (i.p.) to four groups (n = 6 per group) of male Wistar rats, 300-360 g. Group I received 10 mg kg-1 at 1, 24, 48 and 72 h. Group II received 10 mg kg-1 at 1, 8, 24, 32, 48, 56, 72 and 80 h. Groups III and IV received the drug as for groups I and II, respectively, as well as cimetidine (50 mg kg-1) 1 h before each dose of dapsone. Twice daily dapsone administration (Group II) resulted in a significantly greater (P less than 0.05) Met Hb AUC (757 +/- 135 vs 584 +/- 115% Met Hb h), dapsone AUC (140 +/- 17.5 vs 113 +/- 13.0 micrograms h mL-1) and monoacetyl dapsone AUC (48.2 +/- 18.3 vs 10.8 +/- 4.6 micrograms h mL-1) compared with a single daily dapsone dose (group I). The administration of cimetidine before the once daily dose of dapsone (group III) resulted in a significant (P less than 0.05) fall in Met Hb (302 +/- 179 vs 584 +/- 115% Met Hb h) and an increase in both the dapsone (151 +/- 22.2 vs 113 +/- 13.0 micrograms h mL-1) and monoacetyl dapsone AUC values (33.6 +/- 5.8 vs 10.8 +/- 4.0 micrograms h mL-1) compared with a single daily dose of dapsone (group I).(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of nitrite exposure on functional haemoglobin levels, bimodal respiration, and swimming performance in the facultative air-breathing fish Pangasianodon hypophthalmus

In this study we investigated nitrite (NO 2 −) effects in striped catfish, a facultative air-breather. Fish were exposed to 0, 0.4, and 0.9 mM nitrite for 0, 1, 2, 4, and 7 days, and levels of functional haemoglobin, methaemoglobin (metHb) and nitrosyl haemoglobin (HbNO) were assessed using spectral deconvolution. Plasma concentrations of nitrite, nitrate, chloride, potassium, and sodium were also measured. Partitioning of oxygen consumption was determined to reveal whether elevated metHb (causing functional hypoxia) induced air-breathing. The effects of nitrite on maximum oxygen uptake (MO 2max) and critical swimming speed ( U crit) were also assessed. Striped catfish was highly tolerant to nitrite exposure, as reflected by a 96 h LC 50 of 1.65 mM and a moderate nitrite uptake into the blood. Plasma levels of nitrite reached a maximum after 1 day of exposure, and then decreased, never exceeding ambient levels. MetHb, HbNO and nitrate (a nitrite detoxification product) also peaked after 1 day and then decreased. Only high levels of nitrite and metHb caused reductions in MO 2max and U crit. The response of striped catfish contrasts with that seen in most other fish species and discloses efficient mechanisms of combating nitrite threats. Furthermore, even though striped catfish is an efficient air-breather, this species has the ability to sustain aerobic scope and swimming performance without air-breathing, even when faced with nitrite-induced reductions in blood oxygen carrying capacity. Our study is the first to confirm that high levels of nitrite and metHb reduce MO 2max and thereby aerobic scope, while more moderate elevations fail to do so. Further studies are needed to elucidate the mechanisms underlying the low nitrite accumulation in striped catfish.

Nitric oxide reduces sickle hemoglobin polymerization: Potential role of nitric oxide-induced charge alteration in depolymerization

We previously demonstrated that inhaling nitric oxide (NO) increases the oxygen affinity of sickle red blood cells (RBCs) in patients with sickle cell disease (SCD). Our recent studies found that NO lowered the P 50 values of sickle hemoglobin (HbS) hemolysates but did not increase methemoglobin (metHb) levels, supporting the role of NO, but not metHb, in the oxygen affinity of HbS. Here we examine the mechanism by which NO increases HbS oxygen affinity. Because anti-sickling agents increase sickle RBC oxygen affinity, we first determined whether NO exhibits anti-sickling properties. The viscosity of HbS hemolysates, measured by falling ball assays, increased upon deoxygenation; NO treatment reduced the increment. Multiphoton microscopic analyses showed smaller HbS polymers in deoxygenated sickle RBCs and HbS hemolysates exposed to NO. These results suggest that NO inhibits HbS polymer formation and has anti-sickling properties. Furthermore, we found that HbS treated with NO exhibits an isoelectric point similar to that of HbA, suggesting that NO alters the electric charge of HbS. NO–HbS adducts had the same elution time as HbA upon high performance liquid chromatography analysis. This study demonstrates that NO may disrupt HbS polymers by abolishing the excess positive charge of HbS, resulting in increased oxygen affinity.

Susceptibility of channel catfish (Ictalurus punctatus) fed with dietary sodium chloride to nitrite toxicity

Juvenile channel catfish (Ictalurus punctatus) were fed with nutritionally complete, basal diets supplemented with NaCl at 0, 10, 20 or 40 g kg−1 diet (0, 1, 2, or 4%) to apparent satiation twice daily for 10 weeks. Catfish were exposed to nitrite after six (7.70 mg L−1 nitrite-N) and ten (7.18 mg L−1 nitrite-N) weeks of feeding to determine the effect of dietary NaCl supplementation on resistance to nitrite toxicity. Fish were sampled before (baseline, pre-exposure) and after 24-h nitrite exposure to determine the effects of dietary NaCl on haematology (haematocrit, haemoglobin and methaemoglobin) and plasma electrolyte dynamics (nitrite, chloride, sodium and potassium). Mortality from nitrite toxicity was also determined. Mortality from nitrite exposure tended to decrease with increasing NaCl in the diet at 6 weeks and was significantly lower in the 40 g kg−1 NaCl group (12.5%) compared to the control group (57.5%). A similar trend in mortality occurred at 10 weeks as well; however, the differences among dietary treatments were not significant. The improvements in blood MetHb (non-significant), chloride and nitrite levels in catfish may at least in part be responsible for the improved survival after nitrite exposure, which trended in support of the prevailing hypotheses for the positive effects of NaCl on nitrite toxicity.

Blood Levels of Methemoglobin in Patients with Aluminum Phosphide Poisoning and its Correlation with Patient’s Outcome

Although methemoglobinemia following aluminum phosphide (AlP) intoxication has been reported, probable effect of blood level of methemoglobin (Met-Hb) on outcome of AlP-poisoned patients has not yet been investigated. This study aimed to evaluate blood levels of methemoglobin in patients with AP intoxication and its correlation with patient's outcome. This prospective study was carried out at the Loghman-Hakim poison hospital from April 2009 to August 2009. All patients aged >12 years who had ingested AlP and were admitted at the hospital were enrolled in the study. Using the co-oximetry, blood Met-Hb level was measured at the time of admission and 24 h later if the patient survived. Forty-eight patients with AlP intoxication including 24 males were evaluated. Mean age of the patients was 25.5±9.5 years. There was significant association between blood level of Met-Hb at the time of admission and mortality (2.4%±7.1% in survivors versus 15.2%±13.5% in non-survivors, P<0.001). The same association was found at the 2nd day of admission (2.9%±8.2% in survivors versus 26.5%±9.9% in non-survivors, P=0.02). The present study found an association between blood level of Met-Hb and mortality in patients with AlP intoxication. Effect of administration of vitamin C and methylene blue on outcome of patients with AlP intoxication should be investigated in future studies.

Anaerobic storage of red blood cells.

Anaerobic storage of red blood cells.

Is threshold for treatment of methemoglobinemia the same for all? A case report and literature review

Acquired methemoglobinemia (MetHb) is a rare complication of exposure to toxic chemicals or drugs, most commonly topical anesthetic agents. This condition occurs when the rate of methemoglobin production exceeds the rate of methemoglobin reduction. Topical anesthetics have been reported to cause MetHb, but this adverse event is extremely rare and is not usually listed as one of the possible complications of transesophageal echocardiography (TEE). However, the number of published case reports of TEE-associated MetHb has recently increased. Benzocaine (ethyl aminobenzoate) is a topical anesthetic widely used for oropharyngeal anesthesia before TEE. Health care providers who are not familiar with the association of TEE and benzocaine-induced MetHb may not recognize the idiosyncratic and often nonspecific characteristics of this condition. Recognition is critical, as clinically important symptoms may occur at relatively low MetHb levels. If left untreated, MetHb can lead to cardiopulmonary compromise, severe neurologic impairment, and even death. The current report documents a case of TEE-associated MetHb from a high-volume (3000 cases per year including 300-350 TEEs per year) echo laboratory. Our patient was symptomatic and severely distressed, despite a MetHb level of only 10.8%. This case report emphasizes the importance of early recognition and treatment of MetHb, as it represents a medical emergency and can be severely symptomatic, especially in young children and the elderly, even with low MetHb levels.

Pharmakokinetik von Articain in der Tumeszenz lokalanästhesie

SummaryTumescence local anaesthesia (TLA) is being increasingly used in varicose vein surgery. However, this requires doses of local anaesthetics that exceed the licensed limits. Whilst data exist for lidocaine and prilocaine, the literature rarely contains those for the local anaesthetic articaine. Patients, methods: Postoperative levels of methaemoglobin as well as plasma concentrations of articaine hydrochloride (articaine HCl) and articaine acid were measured in 100 patients who underwent varicose vein surgery under TLA after subcutaneous infiltration of 2.86 to 19.56 mg articaine pro kg body weight. With the first 20 patients, several blood samples for each parameter were collected at two-hour intervals to construct the plasma concentration versus time curves. In the following 80 patients, the plasma concentrations of methaemoglobin (MetHb), articaine HCl and articaine acid were each measured once only at the time of the previously determined average peak. Patient satisfaction, pre-, intra- and postoperative pain were recorded with the aid of questionnaires and the visual analogue scale (VAS). Results: Maximum concentrations of articaine HCl (n = 100) in plasma were 0.0034 to 0.5800 μg/ml (median: 0.0517 μg/ml) and were observed one hour after the start of infiltration. Values considered toxicologically harmful are &gt;5 μg/ml. Levels of MetHb ranged from 0.19 to 1.90% (median: 0.78%) and were always normal. The median score on the VAS for the pain caused by TLA and the operation was 5 (0–10; n =4 3). Preoperative administration of 500 mg ibuprofen reduced the score to 3 (0–10; n = 40). Ibuprofen was well tolerated by the patients. Without ibuprofen, the patients were free of post-operative pain for 2 hours (0–10), while with ibuprofen, they were pain-free for 3.0 hours (0.5–9). Patient satisfaction was extremely high. 91.75% would agree to the same stripping operation being carried out in the same way again. Plasma concentrations of articaine acid, as the inert product of articaine HCl metabolism, peaked after 8 hours and were between 0.92 and 14.58 μg/ml (median: 3.95 μg/ml). Conclusion: The use of doses of up to 20 mg/kg body weight articaine in TLA appears to be a safe technique with high patient satisfaction. In comparison with prilocaine, the risk of methaemoglobinaemia is nil. Due to its structure, the use of articaine has none of the carcinogenic potential of the lidocaine metabolite, 2,6-dimethylalanine. The disadvantage of articaine is its rapid metabolism, which gives it a shorter duration of action and hence a shorter postoperative analgesia compared with prilocaine and lidocaine.

Large scale production of vesicles by hollow fiber extrusion: a novel method for generating polymersome encapsulated hemoglobin dispersions.

Vesicles, which include both liposomes and polymersomes (polymer vesicles), are being developed as therapeutic drug carriers. In this study, we present a fully scalable low pressure extrusion methodology for preparing vesicles. Vesicles were generated by continuous extrusion through a 200 nm pore diameter hollow fiber (HF) membrane. The first half of this study describes a method for generating empty polymersomes composed of different molecular weight amphiphilic poly(butadiene-b-ethylene oxide) (PBD-b-PEO) diblock copolymers on a large scale (50-100 mL) using a HF membrane. Monodisperse empty polymersomes were formed with particle diameters slightly less than 200 nm, which were close to the rated 200 nm pore size of the HF membrane. The second half of this study describes the successful encapsulation of hemoglobin (Hb) inside the aqueous core of polymersomes using the HF extrusion methodology. We demonstrate that polymersome encapsulated hemoglobin (PEH) particles formed by this technique had similar oxygen affinity, cooperativity coefficient, and methemoglobin (metHb) level compared to PEH particles formed by the 1 mL volume small scale manual extrusion method. Most notably, Hb encapsulation inside the polymer vesicles formed by the HF extrusion method increased 2-fold compared to the manual extrusion method. This work is important, since it will enable facile scale-up of homogeneous vesicle dispersions that are typically required for preclinical and clinical studies as well as industrial use.

Lipid status, anti-oxidant enzyme defence and haemoglobin content in the blood of long-term clozapine-treated schizophrenic patients

Despite clozapine's unique effectiveness in patients with schizophrenia, a number of adverse effects have been recognised including abnormalities in lipid and glucose metabolisms. A high clozapine level in red blood cells (RBCs) and disturbed anti-oxidant enzyme activities in blood from schizophrenic patients prompted us to investigate lipid status and anti-oxidant enzyme defence in the blood of chronic schizophrenic patients on long-term clozapine therapy. Plasma lipids, RBC anti-oxidant enzyme activities and haemoglobin (Hb) content were measured using established procedures in a group of eighteen chronically-medicated (average 630 days of therapy) schizophrenic patients receiving clozapine (average dose of 295 mg/day) and data were compared with those from a group of eighteen well-matched normal controls. Significantly higher levels of plasma triglycerides (by 47%, p<0.01) and total cholesterol and phospholipids (by 8% and 11%, respectively p<0.05) in patients were found. CuZn-superoxide dismutase (SOD1) activity was markedly higher (by 35%, p<0.001) while selenium-dependent glutathione peroxidase (GSH-Px1) activity was markedly lower (by 41%, p<0.001) in patients. In addition, metHb and HbA1c levels in patients were significantly higher (by 58% and 25%, respectively p<0.001). SOD1 activity was negatively correlated (p<0.001) to GSH-Px1 activity in patients. The findings support the view that ongoing oxidative stress may be a mechanism by which clozapine induces some adverse effects that increase the risk of diabetes and metabolic syndrome. If valid, this would indicate that in parallel with long-term clozapine treatment, schizophrenic patients could be encouraged to make some lifestyle changes to limit the detrimental effects of the medication.

The quaternary structure of tetrameric hemoglobin regulates the oxygen affinity of polymerized hemoglobin

This study focuses on the effect of the initial quaternary structure of bovine hemoglobin (Hb) on the physical properties of glutaraldehyde polymerized Hb (PolyHb) solutions. Tense (T) state PolyHb was synthesized by maintaining the pO(2) of Hb before and after polymerization at 0 mm Hg. In contrast, relaxed (R) state PolyHb was generated by maintaining the pO(2) of Hb before and after polymerization to >749 mm Hg. PolyHb solutions were characterized by measuring the pO(2), methemoglobin (metHb) level, molecular weight distribution, O(2) affinity and cooperativity coefficient. The metHb level of all PolyHb solutions was low (<2%). Analysis of the molecular weight distribution of PolyHb solutions indicates that in general, the molecular weight of PolyHb solutions increased with increasing cross-link density. T-state PolyHb solutions exhibited lower O(2) affinity compared to unmodified Hb, whereas R-state PolyHb solutions exhibited higher O(2) affinity compared to unmodified Hb. In addition, the polymerization reaction resulted in a significant decrease in cooperativity that was more pronounced at higher cross-link densities. All of these results were explained in terms of the quaternary structure of Hb. Taken together, our results yield more insight into the importance Hb's quaternary structure plays in defining the physical properties of glutaraldehyde PolyHb solutions. This information will be useful in designing optimized glutaraldehyde PolyHb oxygen carriers for various applications in transfusion medicine.

Exposure of petrol station attendants and auto mechanics to premium motor sprit fumes in Calabar, Nigeria.

A population-based-cross-sectional survey was carried out to investigate the potential risk of exposure to premium motor spirit (PMS) fumes in Calabar, Nigeria, among Automobile Mechanics (AM), Petrol Station Attendants (PSA) and the general population. Structured questionnaire was administered on the randomly chosen subjects to elicit information on their exposure to PMS. Duration of exposure was taken as the length of work in their various occupations. Venous blood was taken for methaemoglobin (MetHb) and packed cells volume (PCV). Mean MetHb value was higher in AM (7.3%) and PSA (5.8%) than in the subjects from the general population (2.7%). PCV was lower in PSA (30.8%), than AM (33.3%) and the subjects from the general population (40.8%). MetHb level was directly proportional, and PCV inversely related, to the duration of exposure. The study suggested increased exposure to petrol fumes among AM, PSA, and MetHb as a useful biomarker in determining the level of exposure to benzene in petrol vapour.

Effects of magnesium supplementation on the glutathione redox system in atopic asthmatic children

Our aim was to investigate the effects of 12-week oral magnesium (Mg) supplementation on the RBC redox system in stable, persistent, moderately asthmatic children (N = 40, 24 boys, 16 girls) aged 4-16 years in a randomized, double-blind, placebo-controlled study. Oxidized (GSSG) and reduced (GSH) glutathione, oxyhaemoglobin, methaemoglobin (metHb), hemichrome and bilirubin levels before and after treatment were determined, and GSH stability tests were performed. The GSH concentration was significantly higher in the Mg-treated than in the placebo-treated patients after the treatment period. There was a positive correlation between the decreased plasma metHb and hemichrome levels and the decreased plasma haemoglobin concentrations in the Mg-treated patients at the end of the study. Mg in the given doses exerts antioxidant activity and influences the glutathione redox system.

Reduction and suppression of methemoglobin loaded in the polymeric nanoparticles intended for blood substitutes

Oxidation of hemoglobin (Hb) to nonfunctional methemoglobin (metHb) is a main challenge for the fabrication of an ideal Hb-based blood substitute. In this study, a novel nonenzymatic reduction and suppression route, combined with a fast prereduction, optimized double emulsion preparation, and a second sustaining postreduction, was developed to control the metHb in Hb-loaded nanoparticles (HbP) with porous microstructure to a desirable level. In the prereduction, the metHb in the raw Hb was effectively reduced from over 90% to 1.2% using sodium dithionite following gel filtration separation. During the preparation, higher the emulsion strength performed, higher was the extent of Hb oxidized. PEGylated polymer and addition of miscible solvent, such as acetonitrile, into the oil phase could pronouncedly suppress metHb formation. The resultant metHb level in HbP under the optimal fabrication was about 5.6%, which could be further reduced to 1.4% by the model reducing agents in human plasma with the help of superoxide dismutatse and catalase system, which are capable of sustaining postreduction. The oxygen dissociation curve of the HbP was close to that of native Hb, indicating that the oxygen-carrying ability of the Hb, despite initially losing this function due to the severe oxidation, recovered and retained well. The results achieved are promising for the fabrication of blood substitutes with controlled metHb level, which can fulfill the binding/delivering oxygen to tissues in vivo for future trials.

Biocompatible and Biodegradable Polymersome Encapsulated Hemoglobin: A Potential Oxygen Carrier

This work describes the development of polymersome-encapsulated hemoglobin (PEH) self-assembled from biodegradable and biocompatible amphiphilic diblock copolymers composed of poly(ethylene oxide) (PEO), poly(caprolactone) (PCL), and poly(lactide) (PLA). In the amphiphilic diblock, PEO functions as the hydrophilic block, while either PCL or PLA can function as the hydrophobic block. PEO, PCL, and PLA are biocompatible polymers, while the last two polymers are biodegradable. PEH dispersions were prepared by extrusion through 100 nm pore radii polycarbonate membranes. In this work, the encapsulation efficiency of human and bovine hemoglobin (hHb and bHb) in polymersomes was adjusted by varying the initial concentration of Hb. This approach yielded Hb loading capacities that were comparable to values in the literature that supported the successful resuscitation of hamsters experiencing hemorrhagic shock. Moreover, the Hb loading capacities of PEHs in this study can also be tailored simply by controlling the diblock copolymer concentration. In this study, typical Hb/diblock copolymer weight ratios ranged 1.2-1.5, with initial Hb concentrations less than 100 mg/mL. The size distribution, Hb encapsulation efficiency, oxygen affinity (P 50), cooperativity coefficient (n), and methemoglobin (metHb) level of these novel PEH dispersions were consistent with values required for efficient oxygen delivery in the systemic circulation. Taken together, our results demonstrate the development of novel PEH dispersions that are both biocompatible and biodegradable. These novel dispersions show very good promise as therapeutic oxygen carriers.

Pro-oxidative effects of Chinese herbal medicine on G6PD-deficient erythrocytes in vitro

Glucose-6-phosphate dehydrogenase (G6PD)-deficient subjects are susceptible to chemical-induced oxidative haemolysis. Little is known concerning the haemolytic properties of Chinese herbal medicine on G6PD-deficient subjects. Our objective was to investigate the pro-oxidative effect of 18 commonly used Chinese herbal medicine (CHM) on human G6PD-deficient red blood cells. G6PD-deficient (n=10) and normal (n=10) whole blood samples were incubated with water extracts of CHM. The resulting levels of reduced glutathione (GSH) and methaemoglobin (MetHb) were determined by biochemical assays. Rhizoma Coptidis significantly reduced GSH level by 48.9+/-5.4% (at 1 mg/mL) in the G6PD-deficient erythrocytes (P<0.001) compared with the respective control group without challenge. Similar dose-dependent responses were observed at higher concentrations of Cortex Moutan, Radix Rehmanniae, Radix Bupleuri, Rhizoma Polygoni Cuspidati and Flos Chimonanthi (P<0.01, 5-10 mg/mL). In addition, the levels of MetHb were elevated significantly when challenged with Rhizoma Coptidis (2.8 fold at 5 mg/mL) and Cortex Moutan (3.4 fold at 10 mg/mL). This is the first report on the pro-oxidative action of CHM on G6PD-deficient blood samples in vitro as demonstrated by the decrease of GSH and increase of MetHb. G6PD-deficient subjects should restrain from excessive consumption of these pro-oxidative herbs.

Dapsone induced methemoglobinemia: Intermittent vs continuous intravenous methylene blue therapy

The study compares the decline in blood methemoglobin (MetHb) level in children of dapsone intoxication treated with intermittent and continuous methylene blue therapy. Eleven children with history of accidental dapsone ingestion and suggestive clinical features of dapsone intoxication were studied. Patients were randomized into two groups: Gr I (n=5) received intermittent methylene blue therapy, while Gr II (N=6) as continuous infusion. The dose of methylene blue was same in both groups. MetHb level in blood was assessed by spectrophotometer at admission and thereafter 12hrly up to 72 hrs. The decline in MetHb was statistically analyzed with student t-test. Six patients had history of seizure and altered sensorium. Severe anemia was observed in 2 patients. The mean levels of MetHb in Gr II was statistically significant after 12, 24, 36, 48 and 72 hrs of methylene blue therapy as compared to Gr I. Continuous I.V methylene blue therapy causes significant decline in MetHb level and is more effective in treatment of methemoglobinemia as compared to intermittent regimen.

Methemoglobin level as an indicator for disease severity in sepsis

The objective of our study was to investigate how methemoglobin (MetHb) levels reflect the occurrence and severity of sepsis. MetHb is generated of nitric oxide (NO) through interaction with hemoglobin in a variety of patients [1]. This includes patients in sepsis with a potentially higher NO generation.