1/133. Hb chile [beta28(B10)Leu-->Met]: an unstable hemoglobin associated with chronic methemoglobinemia and sulfonamide or methylene blue-induced hemolytic anemia.Among the causes of life-long cyanosis are congenital methemoglobinemia due to M hemoglobins, congenital methemoglobinemia due to methemoglobin reductase deficiency, a small number of low oxygen affinity hemoglobins, and a small number of unstable hemoglobins that spontaneously form methemoglobin in vivo at an accelerated rate. We report an unstable hemoglobin with these characteristics that was observed in a family of indigenous (native American) origin living near Santiago, chile. This variant has the substitution beta28(B10)Leu-->Met, unambiguously corresponding to the dna mutation of CTG-->ATG in beta-globin gene codon 28.- - - - - - - - - - ranking = 1keywords = oxygen, deficiency (Clic here for more details about this article) |
2/133. An unusual case of hypoxia from benzocaine-induced methemoglobinemia.Hypoxemia during bronchoscopy occurs frequently. It can usually be managed by supplemental oxygen and bronchodilators or, in some cases, occasionally stopping the procedure. benzocaine spray is commonly used as a topical anesthetic agent during bronchoscopy. However, it has been associated with the development of methemoglobinemia. The following is a case report of hypoxia during bronchoscopy from benzocaine-induced methemoglobinemia and its management.- - - - - - - - - - ranking = 3.3345971848832keywords = oxygen, hypoxia (Clic here for more details about this article) |
3/133. methemoglobinemia as an uncommon cause of cyanosis.cyanosis is usually caused by decreased arterial oxygen saturation due to pulmonary or cardiac diseases. methemoglobinemia is a rare cause, sometimes with lethal outcome. Two patients are described, both with an unremarkable cardiopulmonary history, presented with severe cyanosis due to aniline-induced methemoglobinemia that developed at work. The symptoms and the treatment of methemoglobinemia are discussed.- - - - - - - - - - ranking = 0.87005023575786keywords = oxygen (Clic here for more details about this article) |
4/133. A case of methemoglobinemia after ingestion of an aphrodisiac, later proven as dapsone.Methemoglobin (MetHb) is an oxidation product of hemoglobin in which the sixth coordination position of ferric iron is bound to a water molecule or to a hydroxyl group. The most common cause of acquired MetHb-emia is accidental poisoning which usually is the result of ingestion of water containing nitrates or food containing nitrite, and sometimes the inhalation or ingestion of butyl or amyl nitrite used as an aphrodisiac. We herein report a case of MetHb-emia after ingestion of an aphrodisiac, later identified as dapsone by gas chromatograph/mass selective detector (GC/MSD). A 24-year old male was admitted due to cyanosis after ingestion of a drug purchased as an aphrodisiac. On arterial blood gas analysis, pH was 7.32, PaCO2 26.8 mmHg, PaO2 75.6 mmHg, and bicarbonate 13.9 mmol/L. Initial pulse oxymetry was 89%. With 3 liter of nasal oxygen supplement, oxygen saturation was increased to 90-92%, but cyanosis did not disappear. Despite continuous supplement of oxygen, cyanosis was not improved. On the fifth hospital day, MetHb was 24.9%. methylene blue was administered (2 mg/kg intravenously) and the patient rapidly improved. We proved the composition of aphrodisiac as dapsone by the method of GC/MSD.- - - - - - - - - - ranking = 2.6101507072736keywords = oxygen (Clic here for more details about this article) |
5/133. methemoglobinemia secondary to topical silver nitrate therapy--a case report.methemoglobinemia is a rare complication in individuals exposed to nitrates or nitrites. Whereas methemoglobinemia is a recognized potential complication in burn patients treated with topical 0.5% silver nitrate solution, no report of methemoglobinemia in burn patients has been present in the literature for more than 15 years. We raise consciousness about this complication with a case report of a 12-month-old child with necrotizing fasciitis resulting from a cutaneous flank infection. The patient developed cyanosis 20 days after initiation of topical treatment with 0.5% silver nitrate solution. Intravenous injection of methylene blue can restore normal blood oxygenation.- - - - - - - - - - ranking = 0.87005023575786keywords = oxygen (Clic here for more details about this article) |
6/133. A novel mutation in the NADH-cytochrome b5 reductase gene of a Chinese patient with recessive congenital methemoglobinemia.Recessive congenital methemoglobinemia due to nicotinamide adenine dinucleotide (NADH)-cytochrome b5 reductase (b5R) deficiency is classified into 2 clinical types: type 1 (erythrocyte type) and type 2 (generalized type). We found a Chinese family with type 1 recessive congenital methemoglobinemia, the patients from which were diagnosed according to clinical symptoms and b5R enzyme activity in the blood cells. To learn the molecular basis of type 1 recessive congenital methemoglobinemia in this Chinese family, we isolated total rna from the peripheral leukocytes of the propositus and b5R complementary dna (cDNA) by reverse transcription- polymerase chain reaction (RT-PCR). The coding region of the b5R cDNA was analyzed by sequencing the cloned PCR products. The results showed that the propositus was homozygous for a G-->A transition at codon 203 in exon 7, changing a cysteine to a tyrosine (Cys203Tyr). To characterize the mutant enzyme, both glutathione S-transferase (GST)-fused wild-type b5R and GST-fused mutant Cys203Tyr b5R were expressed in escherichia coli and affinity purified. The results showed that the catalytic activity of the enzyme was not much affected by this amino acid substitution, but the mutant enzyme exhibited decreased heat stability and increased susceptibility to trypsin. These properties of the mutant enzyme would account for the restricted b5R deficiency and mild clinical manifestations of these type 1 patients. The finding of this novel mutation makes codon 203 the only position within the b5R gene at which more than 1 mutation has been found.- - - - - - - - - - ranking = 0.25989952848427keywords = deficiency (Clic here for more details about this article) |
7/133. metoclopramide-induced methemoglobinemia in an adult.methemoglobinemia is a condition characterized by increased level of methemoglobin in the erythrocytes and brownish cyanosis. Acquired methemoglobinemia is diagnosed by elevated methemoglobin with normal hemoglobin electrophoresis and normal NADH cytochrome b5 reductase. We report a patient who developed lethargy, confusion, and cyanosis during post-operative period. He had arterial methemoglobin level of 40.6% and oxygen saturation of 59%. No other cause could be found for his methemoglobinemia other than metoclopramide, even though it is rarely reported to cause methemoglobinemia in adults compared to infants. He had an excellent clinical response to treatment with methylene blue with which his clinical symptoms improved and the methemoglobin level returned to normal within 24 hours. Here we discuss the clinical features, diagnosis, and treatment of acquired methemoglobinemia induced by metoclopramide.- - - - - - - - - - ranking = 0.87005023575786keywords = oxygen (Clic here for more details about this article) |
8/133. A case of methemoglobinemia type II due to NADH-cytochrome b5 reductase deficiency: determination of the molecular basis.Clinical, biochemical and molecular findings in a patient with methemoglobinemia type II are described. Furthermore, a comparison between methemoglobinemia type I and type II, both caused by a deficiency of NADH-cytochrome b5 reductase (b5R), is made. Although the clinical pictures of type I and II are strikingly different, mutations in the diaphorase (DIA1) gene located on chromosome 22 have been described in both types. In the present patient, two newly identified mutations, both leading to a stop codon in exon 4 (Gln77Ter) and in exon 6 (Arg160Ter), were found. Identification of different mutations at different positions in the DIA1 gene might shed light on the clinical and biochemical differences between methemoglobinemia type I and type II.- - - - - - - - - - ranking = 0.64974882121069keywords = deficiency (Clic here for more details about this article) |
9/133. benzocaine-associated methemoglobinemia following bronchoscopy in a healthy research participant.benzocaine (ethyl aminobenzoate) is a local anesthetic commonly used to achieve topical anesthesia of the skin and mucous membranes prior to endoscopic procedures. methemoglobinemia, a condition in which hemoglobin cannot bind and deliver oxygen normally, has been associated with benzocaine use in various patient populations. This is the first report of benzocaine-associated methemoglobinemia occurring in a healthy research participant. The research participant developed a methemoglobin level of 27% and marked cyanosis. No adverse sequelae other than cyanosis were identified. This report extends the population in which benzocaine-associated methemoglobinemia has been described. Additionally, this report supports the observation that methemoglobin levels approaching 30% may be tolerated in otherwise healthy individuals, producing few clinically important effects. Finally, this case also indicates that, in obtaining informed consent for a procedure in which benzocaine will be administered, patients and research participants should be specifically informed of the risk of benzocaine-induced methemoglobinemia. This information is especially important in those settings in which the manufacturer-recommended dose of benzocaine may either intentionally or inadvertently be exceeded.- - - - - - - - - - ranking = 0.87005023575786keywords = oxygen (Clic here for more details about this article) |
10/133. A Thai boy with hereditary enzymopenic methemoglobinemia type II.Individuals with methemoglobin exceeding 1.5 g/dl have clinically obvious central cyanosis. Hereditary methemoglobinemia is due either to autosomal dominant M hemoglobins or to autosomal recessive enzymopenic methemoglobinemia. Four types of enzymopenic methemoglobinemia have been described. In addition to methemoglobinemia, individuals with type II, which is the generalized cytochrome b5 reductase deficiency, have severe and progressive neurological disabilities. Here we report a 3-year-old Thai boy with type II hereditary enzymopenic methemoglobinemia. He was born to a second-cousin couple. His central cyanosis was first observed around 10 months of age. His neurological abnormalities were seizures beginning at 1 year of age, microcephaly, and inability to hold his head up. His cardiovascular and pulmonary evaluations were unremarkable. Methemoglobin level by spectral absorption pattern was 18 per cent. A qualitative enzymatic assay confirmed the deficiency of the cytochrome b5 reductase enzyme. With this definite diagnosis, a prenatal diagnosis for the next child of this couple will be possible.- - - - - - - - - - ranking = 0.25989952848427keywords = deficiency (Clic here for more details about this article) |
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