Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0348321 (Haemophilus)
 15,372 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Patients with IgG2 deficiency have recurrent sinopulmonary infections caused by Pneumococcus and Hemophilus. Hereditary and selective IgG2 deficiency was suspected in two Japanese siblings whose serum IgG2 levels were under detection limits, while other serum levels of immunoglobulin subclasses were within normal ranges. Expression level of spontaneous germline Cgamma2 transcript was normal, but that of the spontaneous mature Cgamma2 transcript was greatly decreased in the patients' PBMCs, suggesting the presence of a defect at or after the class switch to Cgamma2. We sequenced the Cgamma2 gene region, and in both patients a homozygous one-base insertion (1793insG) was present in exon 4 of the Cgamma2 gene, just upstream from the alternative splice site for M exons. The mutant membrane-bound gamma2 heavy chain loses the transmembrane domain and the evolutionarily conserved cytoplasmic domain. Considering several lines of evidence showing that intact expression of the membrane-bound heavy chain is essential for a normal response of B cells and production of secreted immunoglobulin in mice, we concluded that 1793insG is responsible for selective and complete IgG2 deficiency in these two siblings. This is the first documentation of a mutation in human selective IgG2 deficiency.
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PMID:Molecular basis of selective IgG2 deficiency. The mutated membrane-bound form of gamma2 heavy chain caused complete IGG2 deficiency in two Japanese siblings. 944 2

IgG2 deficiency is clinically characterized by sinopulmonary infections caused by pneumococcus and Hemophilus. We reported homozygous one-base insertion (1793insG) in the C(gamma)2 gene in two Japanese siblings in whom serum IgG2 levels were under detection limits. The 1793insG was present in exon 4, just upstream from the alternative splice site for M exons; the result being a complete amino acid change in transmembrane and cytosolic parts of membrane-bound gamma2 heavy chain (m gamma 2HC). To determine why this mutation caused selective and complete IgG2 deficiency, we constructed expression vectors of normal and mutant membrane-bound chimeric IgG heavy chain cDNAs. Stable transformants, Ag8N-L and Ag8M-L, expressing either normal and mutant chimeric IgG heavy chain with light chain respectively were obtained using P3X63Ag8653 as recipient cells. Of the Ag8N-L, 22.1% were surface IgG+; however, none of the Ag8M-L were surface IgG+. Addition of an anti-human IgG antibody induced cell death of Ag8N-L and we considered that the expressed chimeric IgG protein on Ag8N-L might function as the Ig receptor for signal transduction. However, Ag8M-L did not express mutant IgG on its surface nor did it secrete this mutant into culture medium. The mutant chimeric IgG protein was rapidly degraded within Ag8M-L. Thus, the mutated IgG2 heavy chain in our patient could not be expressed on the cell surface because of loss of the transmembrane domain and the evolutionally conserved cytoplasmic domain. In humans, B cells expressing surface IgG are indispensable for secretion of IgG.
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PMID:Fate of the mutated IgG2 heavy chain: lack of expression of mutated membrane-bound IgG2 on the B cell surface in selective IgG2 deficiency. 1115 58

Our medical institution does not have a bacterial culture facility, requiring outsourcing of bacterial culture tests. Due to the time elapsed from the time of specimen collection to culturing, the identification of causative bacteria in respiratory tract infections tends to be difficult. We therefore used transport medium for sputum bacteria examinations. Expectorated purulent or purulent-mucous sputum specimens were collected from 32 patients with lower respiratory tract infection. We divided each of the sputum specimens into the two treatment groups: transport medium (Seedswab gamma2) ndar and stad disinfection container. Paired samples prepared from each patient were sent out for bacterial culture together. The time elapsed from collection to delivery to the lab were as follows: day 0 (same day, n = 14 patients), day 1 (n = 15), day 2 (n = 2), and day 3 (n = 1). The identified causative bacteria were Streptococcus pneumoniae (n = 6 patients), Haemophilus influenzae (n =5), Pseudomonas aeruginosa (n = 4), Staphylococcus aureus (n = 2), Moraxella catarrhalis (n = 2), Klebsiella pneumoniae (n = 1), and Streptococcus agalactiae (n = 1). Samples prepared by each of the two methods gave similar results. The utility of transport medium for examination of general bacteria for lower airway infection from sputum samples was not demonstrated. The rate of detection of bacteria decreased, when the transport of samples was delayed. Therefore, we need to send the sputum specimens as quickly as possible.
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PMID:[Use of transport medium in sputum bacterial culture examination of lower airway infection]. 1684 12