人参内生菌的研究进展

内生菌由细菌、真菌、古菌和原生生物组成，它们生活在植物的活体组织中，具有丰富的次级代谢产物多样性。人参内生菌在人参的生长发育、次级代谢产物的生成和环境适应等方面均有重要的促进作用，对人参的产量和品质有较大影响。随着人们在微生物领域研究的深入，高通量测序技术已经成为研究植物内生菌的重要方法。文章主要从人参内生菌分离与鉴定研究方法、人参内生菌的多样性、人参内生菌及其次级代谢产物的活性、人参内生菌对宿主的影响等4个方面对人参内生菌近年来的研究进展进行讨论，并对其发展方向提出展望，以期为药用植物内生菌研究和品质改良提供新思路、新方法。     

Using gas chromatography and mass spectrometry to determine 25-hydroxyvitamin D levels for clinical assessment of vitamin D deficiency

Vitamin D is responsible for multiple metabolic functions in humans. Rickets are the most common disease caused by vitamin D deficiency. It is caused by poor calcium intake resulting in poor serum-ionized calcium. The purpose of this study is to develop a rapid, sensitive, and feasible method to determine the 25-hydroxy-vitamin D3 (25(OH)D3) levels in blood samples for clinical assessment. In this study, gas chromatography coupled mass spectrometry with trimethylsilyl derivatization (TMS-GC-MS) is the most suitable protocol for quantitative analyses of 25(OH)D3. Performance of method was evaluated and compared with liquid chromatography and immunoassay. Method validation has been carried out with plasma specimens. The limit of quantitation of TMS-GC-MS method is 1.5 ppb with good linear correlation. Furthermore, the dietary intake and nutritional status of vegetarian and non-vegetarians in Taiwan were assessed by our validated method. As a result, this vitamin D nutrition survey demonstrates that most Taiwanese people have insufficient vitamin D. Due to dietary habits; the male vegans may have the highest risk of vitamin D deficiency.     

Host–microbiome interactions: the aryl hydrocarbon receptor as a critical node in tryptophan metabolites to brain signaling

ABSTRACT

Tryptophan (Trp) is not only a nutrient enhancer but also has systemic effects. Trp metabolites signaling through the well-known aryl hydrocarbon receptor (AhR) constitute the interface of microbiome-gut-brain axis. However, the pathway through which Trp metabolites affect central nervous system (CNS) function have not been fully elucidated. AhR participates in a broad variety of physiological and pathological processes that also highly relevant to intestinal homeostasis and CNS diseases. Via the AhR-dependent mechanism, Trp metabolites connect bidirectional signaling between the gut microbiome and the brain, mediated via immune, metabolic, and neural (vagal) signaling mechanisms, with downstream effects on behavior and CNS function. These findings shed light on the complex Trp regulation of microbiome-gut-brain axis and add another facet to our understanding that dietary Trp is expected to be a promising noninvasive approach for alleviating systemic diseases.     

2003-2005年新生儿感染常见致病菌及耐药性的变迁

目的了解本地区新生儿2003至2005年感染常见致病菌的种类及耐药的现状，以指导临床合理应用抗生素。方法收集我院新生儿科2003年1月至2005年12月收治的613份体液培养阳性（痰液、血液、分泌物、胃液等标本）的患儿资料，对常见检出菌及其耐药性的变迁情况进行分析。结果共检出40种613株病原菌，以革兰阴性杆菌为主约占57．6％，而肺炎克雷伯菌和大肠埃希菌分别位于前二位，其产ESBLs菌株检出率分别为78．1％和82．6％。药敏结果显示，常见致病菌对青霉素、第一、二代头胞类抗生素、红霉素类耐药性显著增加，但对第三代头胞类抗生素如头孢曲松、头孢噻肟（凯福隆）、头孢他啶（复达欣）及B内酰胺酶抑制剂复方制剂、碳青霉烯类、万古霉素等较敏感。产ESBLs菌仅对亚胺培南及B内酰胺酶抑制剂复方制剂敏感。结论革兰阴性杆菌特别是肺炎克雷伯菌和大肠埃希菌是新生儿感染主要病原菌，产ESBLs菌比例增加应引起高度重视。碳青霉烯类、哌拉西林／三唑巴坦和头孢哌酮／舒巴坦，可作为新生儿严重医院感染经验用药，应尽量根据药敏试验调整抗生素。     

Sphingolipid metabolites in neural signalling and function

Sphingolipid metabolites, such as ceramide, sphingosine, sphingosine-1-phosphate (S1P) and complex sphingolipids (gangliosides), are recognized as molecules capable of regulating a variety of cellular processes. The role of sphingolipid metabolites has been studied mainly in non-neuronal tissues. These studies have underscored their importance as signals transducers, involved in control of proliferation, survival, differentiation and apoptosis. In this review, we will focus on studies performed over the last years in the nervous system, discussing the recent developments and the current perspectives in sphingolipid metabolism and functions.     

败血症98例临床分析

目的：探讨近年来败血症病原菌变迁和对常用抗菌药物的敏感状况以及影响败血症预后的因素。方法：回顾性分析1998～2004年的98例经血培养和临床资料证实的败血症。结果：98例败血症患者血培养共分离出致病菌102株，属社区获得性败血症81例（82．7％），医院获得性17例（17．3％）。革兰阳性菌、革兰阴性菌和真菌感染分别占34．3％、60．8％、4．9％。社区获得性败血症以大肠埃希菌为主，其次是金黄色葡萄球菌和肺炎克雷伯菌。医院获得性败血症以大肠埃希菌、真菌和不动杆菌为主。23抹金葡菌中苯唑西林耐药率39．1％，未发现对万古霉素耐药的菌株；31株大肠埃希菌对氨苄西林、阿米卡星和左氧氟沙星耐药率分别占90．3％、61．3％和45．2％，但对头孢三代、四代及酶抑制剂耐药率较低（12．9％～19．1％），未发现对亚胺培南-西司他丁耐药菌株。院内感染、血小板下降、血糖升高及休克增加了败血症患者病死率。结论：院内感染败血症病原菌中真菌和不动杆菌呈上升趋势，大肠埃希菌和金葡菌感染首选亚胺培南-西司他丁和万古霉素，大肠埃希菌院外败血症可首选头孢三代或亚胺培南-西司他丁。     

Identification of cytotoxic principles from Fusarium avenaceum using bioassay-guided fractionation

The cytotoxicity of extracts from rice cultures of five Fusarium avenaceum strains against the porcine epithelial kidney cell-line PK-15 was investigated using the Alamar Blue™ assay. After the identification of known fungal metabolites, cytotoxic extracts were fractionated using semi-preparative reversed-phase HPLC and normal phase LC, and the fractions were tested for cytotoxicity. In this way, two different groups of metabolites were identified as the major cytotoxic principles of the extracts. High concentrations of enniatins, especially enniatins B and B1, inhibited the metabolic activity of PK-15 cells. Furthermore, an unidentified metabolite, produced in high amounts by a strain that produced relatively small amounts of enniatins, was also found to be cytotoxic to PK-15 cells. This study shows that enniatins, a group of cyclic depsipeptides, which have been ignored as significant contributors to the toxicity of fungal extracts, may account for most of the observed effect for F. avenaceum.     

Effect of pentoxifylline on veno-occlusive priapism-induced corporeal tissule lipid peroxidation in a rat model

Objective: To investigate whether pentoxifylline could play a role in attenuation of the hazardous effects of ischemia/reperfusion on corporeal tissue in a rat model of veno-occlusive priapism (VOP). Materials and methods: Placebo and pentoxifylline were given to eight groups of rats prior to priapism being induced by a vacuum constrictive device for durations of 6 and 12 h, respectively. Half of the groups of rats that underwent the same duration of priapism (ischemic) were subjected to 1 h of detumescence after band removal (reperfusion). One group underwent no manipulation and no drug administration and served as a baseline determination (control). Corporeal homogenates were examined for lipid peroxidation (LP) derived malondialdehyde (MDA) accumulation via thiobarbituric acid assay. Results: MDA concentration differed significantly between VOP rats and controls (P < 0.001) but did not differ significantly between ischemic-only groups and reperfused groups (P > 0.05). In the pentoxifyllinepretreated groups, although MDA accumulation tended to be slightly lower than in the placebo groups, the difference was not statistically significant (P > 0.05) either in the 6- or 12-h duration priapic groups. Conclusions: LP, an indicator of radical oxygen metabolite (ROM) induced injury, occurs in rat corporeal tissue during and after abolishment of VOP. Single-dose pentoxifylline pretreatment failed to exert a protective effect on corporeal tissue in a rat model of VOP in terms of attenuation of LP.     

Tacrolimus metabolite cross-reactivity in different tacrolimus assays

Objectives: Tacrolimus (FK506) is an immunosuppressive drug with great clinical promise. There is a controversy regarding the role of tacrolimus metabolites in immunosuppression and toxicity, and immunoassays and immunophilin binding assays have not been adequately tested for metabolite cross-reactivity. Methods are limited to HPLC and HPLC-MS for quantifying the parent drug. Mixed lymphocyte culture assay (MLC) is the preferred functional bioassay for the measurement of parent drug and active metabolites but it is not practical for routine laboratory use. Due to differences in assay methods and reagent specificity, the concentration of tacrolimus in a given specimen may vary among different assay kit manufacturers. The objective of this study was to evaluate the degree of cross-reactivity or interference of the three first-generation tacrolimus metabolites [13-O-demethyl (M-I), 31-O-demethyl (M-II) and 15-O-demethyl (M-III)] among two different tacrolimus immunoassays (Immunoassay: PRO-Trac II FK506, Abbott IMx tacrolimus-II); and the radioreceptor assays (RRA) using minor immunophilins (14, 37, and 52 kDa immunophilins) and tacrolimus binding protein (FKBP12).

Methods: First-generation tacrolimus metabolites (M-I, M-II, and M-III) spiked in drug-free whole blood were assayed with RRA using three minor immunophilins (14, 37, and 52 kDa) and two commercial immunoassay procedures (Incstar PRO-Trac II tacrolimus, Abbott IMx tacrolimus II). The results were compared to previously published FKBP-12 RRA data and their immunosuppressive potency.

Results and conclusion: The first generation tacrolimus metabolites (M-I, M-II, and M-III) were tested using concentrations of 10 and 20 ng/mL. The significance of the metabolite interference (% of the total interference) was calculated based on the relative concentration of each metabolite present at steady-state trough concentrations in renal transplant recipients [22]. Metabolite I, which has no functional immunosuppressive activity showed minimal interference compared to M-II and M-III in all assays except the 14 kDa RRA. The Incstar PRO-Trac II tacrolimus assay showed the least M-I interference. Metabolite-II, which has a pharmacologic potency similar to the parent drug, showed a significant interference in the immunoassays and significant interference in radioreceptor assays. Metabolite III, which is pharmacologically inactive, produces 3–10% interference in the different assays if its presence in the blood is 6% of the parent drug. The total interference from these three metabolites was greater in the immunoassays than in the receptor assays. Receptor assays for tacrolimus provide results closer to the target value than do immunoassays.     

Cerebrospinal fluid purine metabolites after complex febrile convulsions

Adenosine monophosphate, inosine monophosphate, inosine, adenosine, guanosine, adenine, guanine, hypoxanthine, xanthine and uric acid were determined in cerebrospinal fluid (CSF) of 15 children after complex febrile seizures (CFS) and in 27 after simple febrile seizures (SFS), and compared with those in a control group of 63 children. There was no statistically significant difference between the groups for any of these metabolites, suggesting that CFS and SFS neither significantly disturb the metabolism of nucleotides, nucleosides or bases nor significantly deplete neuron adenosine triphosphate levels.