Carboxylesterase catalyzed 18O-labeling of carboxylic acid and its potential application in LC-MS/MS based quantification of drug metabolites

LC-MS quantification of drug metabolites is sometimes impeded by the availability of internal standards that often requires customized synthesis and/or extensive purification. Although isotopically labeled internal standards are considered ideal for LC-MS/MS based quantification, de novo synthesis using costly isotope-enriched starting materials makes it impractical for early stage of drug discovery. Therefore, quick access to these isotope-enriched compounds without chemical derivatization and purification will greatly facilitate LC-MS/MS based quantification. Herein, we report a novel ¹⁸O-labeling technique using metabolizing enzyme carboxylesterase (CES) and its potential application in metabolites quantification study. Substrates of CES typically undergo a two-step oxygen exchange with H₂¹⁸O in the presence of the enzyme, generating singly- and doubly-¹⁸O-labeled carboxylic acids; however, unexpected hydrolytic behavior was observed for three of the test compounds – indomethacin, piperacillin and clopidogrel. These unusual observations led to the discovery of several novel hydrolytic mechanisms. Finally, when used as internal standard for LC-MS/MS based quantification, these in situ labeled compounds generated accurate quantitation comparable to the conventional standard curve method. The preliminary results suggest that this method has potential to eliminate laborious chemical synthesis of isotope-labeled internal standards for carboxylic acid-containing compounds, and can be developed to facilitate quantitative analysis in early-stage drug discovery.     

The effects of grass pollen allergoid immunotherapy on clinical and immunological parameters in children with allergic rhinitis

Allergoid immunotherapy is a new form of allergen immunotherapy allowing safe administration of high allergen doses. There is limited information on the effects of allergoid immunotherapy in children with allergic rhinitis. To investigate the immunological and clinical effects of allergoid immunotherapy in children with allergic rhinitis due to grass pollen allergy. Children with allergic rhinitis were assigned to allergoid immunotherapy (n = 27) or control (n = 26, no immunotherapy) groups. Children in the immunotherapy group received seven injections of grass pollen allergoid immunotherapy before grass pollen season and continued to receive maintenance immunotherapy for 27 months. All patients were offered a pharmacotherapy regimen to be used on demand during the pollen seasons. Clinical and laboratory parameters were compared between the immunotherapy and control groups. The rhinoconjunctivitis symptom-medication score and asthma symptom score were lower in the immunotherapy group after 1 yr of maintenance immunotherapy (p < 0.01 for both). Skin test reactivity and nasal reactivity as determined by nasal provocation testing for grass pollen were significantly decreased after 1 yr of immunotherapy (p < 0.001 for both). The seasonal increase in bronchial reactivity and nasal lavage eosinophil cationic protein levels were prevented after the first year of immunotherapy (p < 0.05 for both). The seasonal increase in immunoglobulin (Ig)E decreased (p < 0.05) and grass-specific IgG, IgG(1) and IgG(4) increased significantly already at the end of the seven-injection build-up therapy (p < 0.001, for all). Interleukin (IL)-4 levels in the culture supernatants showed a steady decline from baseline at first and second year of immunotherapy (p < 0.001) but remained unchanged in the control group. Allergoid immunotherapy is an effective method in the treatment of grass pollen-induced allergic rhinitis in children and prevents the seasonal increase in bronchial hyper-reactivity. Changes in specific IgE and IgG levels and decreased IL-4 production in peripheral blood mononuclear cell culture supernatants may account for the observed clinical effects.     

Regulation of fibroblast-induced collagen gel contraction by interleukin-1β

Fibroblasts incorporated within collagen gels induce a cell-mediated contraction of the gel to form a three-dimensional, tissue-like structure by a mechanism thought to mimic wound contraction in vivo . In this study a gel contraction model was used to investigate the ability of fibroblasts derived from adult gingiva, adult skin and fetal skin to organise a collagen matrix. In addition the effects of interleukin-1β (IL-1β) on the contraction process was also investigated. Over the concentration range 5-50 U/ml, IL-1β induced a statistically significant inhibition of gel contraction in all fibroblast cell types ( P <0.05), although fetal fibroblasts appeared least responsive and gingival fibroblasts most responsive to the inhibitory effects of this cytokine. Comparison of gel contraction by the different fibroblast strains indicated that fetal and gingival fibroblasts shared similar contraction kinetics. For the adult skin fibroblasts, three of five strains studied showed significantly diminished levels of gel contraction compared to fetal and gingival cells. This apparent difference in fibroblast phenotype may, at least in part, explain the fetal-like wound healing pattern seen in the oral mucosa.     

The effect of interleukin-1 on iron metabolism in rats

The effect of interleukin-1 on iron metabolism in rats was evaluated. Plasma iron decreased from 184 +/- 16 micrograms/dl (mean +/- SE) to 24 +/- 12 at 6 hours after interleukin-1 intramuscular administration in non-fasting rats and 109 +/- 6 micrograms/dl to 12 +/- 1 micrograms/dl in fasting rats, which was significantly lower than in control rats. Ferrokinetic studies showed a more rapid disappearance rate and lower iron turnover in interleukin-1-injected rats. The release of iron from the mononuclear phagocyte system to plasma was studied at 3 h after interleukin-1 administration. Although the percent of radioactivity in plasma of the total injected dose was 3.2 +/- 0.6% in interleukin-1, which was significantly lower than in the control rats (5.4 +/- 0.6%) at 9 h after intravenous injection of 59Fe chondroitin ferrous sulfate, there was no difference between the amount of 59Fe released from the mononuclear phagocyte system over the first 9 h in interleukin-1 and control rats. These data appear to imply that iron release is unimpaired but that, for some reason, there is an enhanced rate of clearance of the 59Fe once it has been released from the mononuclear phagocyte system into the plasma.     

18氟-氟化脱氧葡萄糖在下咽部肿瘤诊断中的作用

目的：研究^18氟—氟化脱氧葡萄糖(^18F-FDG)在下咽部肿瘤诊断中的作用。方法：20例下咽部肿瘤患者均接受^18F-FDG检查及CT、全组内镜(食管、咽喉、气管镜)检查。结果：20例下咽部肿瘤患者^18F-FDG检查结果显示：2例阴性；18例肿瘤原发部位有同位素浓集，其中5例伴异位同位素浓集。对此5例患者进一步临床、病理检查证实：1例食管部占位，2例肺部病变，2例为良性改变。^18F-FDG检查结果显示的病变范围与CT、内镜检查相符。结论：^18F-FDG检查可以提高下咽部肿瘤、尤其是隐匿的并发肿瘤诊断的准确性，明确病变范围，为临床治疗提供依据；同时又是一个简单、易行的下咽部肿瘤的随访检查手段。     

IL-4与IL-10联合诱导异种骨移植免疫耐受的体外研究

目的　探讨 IL - 4和 IL - 10在诱导异种骨移植免疫耐受中的作用。方法　反应细胞为 BAL B/c小鼠脾淋巴细胞 ,刺激细胞为新西兰白兔血淋巴细胞 ,刺激抗原为兔骨上清液。采用经典的混合淋巴细胞培养法及骨上清液与淋巴细胞混合培养法作为异种骨移植的体外实验模型。在各培养液中分别加入 IL - 4、IL - 10及两者联合应用 ,通过测定其 3H- Td R掺入率 ,观察不同细胞因子对刺激淋巴细胞增殖的影响。结果　无论在细胞刺激组还是骨上清液刺激组 ,IL- 4对淋巴细胞增殖均有显著抑制作用 (P<0 .0 0 1和 P<0 .0 5 ) ,IL- 10未表现出抑制作用 (P>0 .0 5 )。在两组 IL- 4和 IL - 10联合应用均产生比 IL - 4单独应用更为明显的细胞增殖抑制作用 (P<0 .0 0 1和 P<0 .0 5 )。结论　 IL - 4对由细胞或骨上清液刺激产生的淋巴细胞增殖均有很好的抑制作用 ,IL- 10没有表现出抑制作用 ;IL- 4与 IL- 10联合应用有协同抑制作用。     

Association between cord blood IgE and genetic polymorphisms of interleukin-4, the β-subunit of the high-affinity receptor for IgE, lymphotoxin-α, and tumor Necrosis factor-α

High cord blood immunoglobulin E (cbIgE) is known to be associated with increased risks of atopic diseases in childhood. The relationship between genetic polymorphisms and high cbIgE has not been well documented. A cross-sectional study was conducted to assess the association between cbIgE and genetic polymorphisms of interleukin (IL)-4 -590C/T, the beta-subunit of the high-affinity receptor for IgE (FcepsilonRI-beta) E237G, lymphotoxin (LT)-alphaNcoI alleles, and tumor necrosis factor (TNF)-alpha -308G/A. A total of 320 mother-neonate pairs were recruited from four maternity hospitals from different locations of Taiwan. Cord blood was obtained and assayed for cbIgE. Polymerase chain reaction followed by restriction fragment length polymorphism was used to assess the genotypes. Three hundred pairs of mothers and neonates were included in the final analysis. Infants with IL-4 -590 C allele were found to have higher risk of elevated cbIgE (> or =0.35 IU/ml, 24.3%) (p = 0.004). After adjusting for gender, birth order, maternal age, and history of allergic disease in maternal and paternal families, odds ratios for CC and CT genotypes were 4.41 and 3.16 (95% confidence interval 0.78-22.67, and 1.66-6.13), respectively, using TT genotype as reference. The genotypes of FcepsilonRI-beta, LT-alpha, and TNF-alpha were not associated with cbIgE before or after the adjustment. Our finding suggested a significant association of cbIgE with genetic polymorphism of IL-4 -590C/T, but not with the genotypes of FcepsilonRI-beta, LT-alpha, and TNF-alpha.     

Inadequate Erythropoietin Response to Anaemia in HIV Patients: Relationship to Serum Levels of Tumour Necrosis Factor-Alpha, Interleukin-6 and Their Soluble receptors

Severe anaemia is a frequent complication in advanced HIV infection. In our study we investigated the interaction between cytokine network, HIV infection and erythropoietin (Epo) response with increasing anaemia levels. No correlations could be established between circulating tumour necrosis factor (TNF)-alpha and any of the examined parameters. However, a negative correlation was found between haemoglobin values and soluble TNF receptor levels (sTNF-R-I: r  = −0.54; P  < 0.001; sTNF-R II: r  = −0.47; P  < 0.001) as well as interleukin-6 levels ( r  = −0.29; P  < 0.001). In contrast, no significant increase in log[Epo], counterbalancing haemoglobin decline and paralleling the rise in sTNF receptors, was found. In patients classified as stage III, according to the Centers for Disease Control (CDC) classification, the erythropoietin response was significantly more impaired than in patients from CDC groups I and II ( P  < 0.001). The results of this study suggest that similar to its action in vitro , activation of the TNF/TNF-R system may impair erythropoietin production in HIV-associated anaemia. Due to the brief half-life of TNF-α, this activation is particularly reflected by elevations of soluble TNF receptor levels.