双歧三联活菌胶囊对结肠癌术后化疗相关性腹泻患者 肠黏膜通透性的影响及疗效观察

目的探讨双歧三联活菌胶囊对结肠癌术后化疗相关性腹泻患者肠黏膜通透性的影响及疗效观察。方法选取70例结肠癌术后行辅助化疗发生化疗相关性腹泻患者,随机分为观察组和对照组,每组35例。两组患者均予以口服蒙脱石散、静脉补液或口服补液和纠正水电解质酸碱平衡紊乱等常规治疗。观察组患者加用双歧三联活菌胶囊420 mg/次,3次/d,温开水溶解后口服。观察两组患者治疗前和治疗72 h后血清二胺氧化酶（DAO）和肿瘤坏死因子-α（TNF-α）水平的变化,并比较临床疗效及药物不良反应。结果治疗72 h后,两组患者DAO和TNF-α水平均有不同程度下降（P〈0.05或P〈0.01）,且观察组下降程度较对照组更明显（P〈0.05）;同时观察组患者临床总有效率（94.29%）明显高于对照组（74.29%）（χ2=5.29,P〈0.05）,两组患者治疗期间无明显的药物不良反应。结论双歧三联活菌胶囊用于治疗结肠癌术后化疗相关性腹泻具有较好的疗效及安全性,能降低血清DAO和TNF-α水平,具有降低肠黏膜的通透性功能。     

Polyamine metabolism and function in brain

Putrescine, spermidine and spermine are simple alipathic polycations of ubiquitous occurrence. The pathways of biosynthesis and catabolism, and changes of the concentrations of these compounds in brain under various conditions are discussed.The pharmacological properties of the polyamines have not yet revealed functions which are characteristic only for the CNS, but preliminary evidence suggests structural roles in membranes and a modulatory function in certain neuronal systems.     

The role of Cys108 in Trigonopsis variabilisd-amino acid oxidase examined through chemical oxidation studies and point mutations C108S and C108D

Oxidative modification of Trigonopsis variabilisd-amino acid oxidase in vivo is traceable as the conversion of Cys108 into a stable cysteine sulfinic acid, causing substantial loss of activity and thermostability of the enzyme. To simulate native and modified oxidase each as a microheterogeneity-resistant entity, we replaced Cys108 individually by a serine (C108S) and an aspartate (C108D), and characterized the purified variants with regard to their biochemical and kinetic properties, thermostability, and reactivity towards oxidation by hypochlorite. Tandem MS analysis of tryptic peptides derived from a hypochlorite-treated inactive preparation of recombinant wild-type oxidase showed that Cys108 was converted into cysteine sulfonic acid, mimicking the oxidative modification of native enzyme as isolated. Colorimetric titration of protein thiol groups revealed that in the presence of ammonium benzoate (0.12 mM), the two muteins were not oxidized at cysteines whereas in the wild-type enzyme, one thiol group was derivatized. Each site-directed replacement caused a conformational change in d-amino acid oxidase, detected with an assortment of probes, and resulted in a turnover number for the O₂-dependent reaction with D-Met which in comparison with the corresponding wild-type value was decreased two- and threefold for C108S and C108D, respectively. Kinetic analysis of thermal denaturation at 50 °C was used to measure the relative contributions of partial unfolding and cofactor dissociation to the overall inactivation rate in each of the three enzymes. Unlike wild-type, C108S and C108D released the cofactor in a quasi-irreversible manner and were therefore not stabilized by external FAD against loss of activity. The results support a role of the anionic side chain of Cys108 in the fine-tuning of activity and stability of d-amino acid oxidase, explaining why C108S was a surprisingly poor mimic of the native enzyme.     

Polyamine metabolism and in vitro cell multiplication and differentiation in leaf explants of Chrysanthemum morifolium Ramat

Arginine decarboxylase (ADC), ornithine decarboxylase (ODC), diamine oxydase (DAO) free amine and conjugated amine titers were estimated in leaf explants of Chrysanthemum morifolium Ramat. var. Spinder cultivated in vitro in relation to hormone treatment. Addition of benzyladenine (BA) to a basal medium caused the formation of buds on the explants. BA plus 2,4 dichlorophenoxyacetic acid (2,4 D) caused callus formation and proliferation. Formation of roots was obtained by addition of indolylacetic acid (IAA). Arginine decarboxylase (ADC) ornithine decarboxylase (ODC) and diamine oxidase (DAO) activities increased during the first days of culture when cell multiplication was rapid, followed by a sharp decline as the rate of cell division decreased and differentiation took place. DAO activities increased rapidly in proliferating and growing organs and decreased during maturity. This increase was concomitant with ADC and ODC activities and polyamine content (free and conjugated polyamines). The biosynthesis and oxidation of polyamines which occurred simultaneously in physiological states of intense metabolism such as cell division or organ formation were directly correlated. In callus cultures DAO activity was blocked throughout development and regulated neither the cellular levels of polyamines nor polyamine conjugates. Levels of polyamine conjugates were high in callus cultures throughout development. In foliar explants cultivated on a medium promoting callus, inhibition of ODC activity by DFMO (-DL-difluoromethylornithine, a specific enzyme-activated ODC inhibitor) resulting in an amide deficiency facilated the expression of differentiated cell function; substantial activation of DAO was observed until the emergence of the buds. On a medium promoting bud formation, -OH ethylhydrazine (DAO inhibitor) promoted callus formation without differentiation. In this system DAO activity was blocked and there were high levels of polyamines, especially polyamine conjugates, throughout the culture period. The relationship among free and conjugated polyamines related biosynthetic enzyme activities, DAO activities, cell division and organ formation is discussed.Abbreviations ADC = arginine decarboxylase - ODC = ornithine decarboxylase - DOA = diamine oxidase - DFMA = -DL-difluoromethylarginine - DFMO = -DL-difluoromethylornithine - Put = putrescine     

Resonance Raman study on the flavin in the purple intermediates of D-amino acid oxidase

Resonance Raman (RR) spectra were measured for the purple intermediates of D-amino acid oxidase reconstituted with isotopically labelled FAD's, i.e., [4a-13C]-, [4,10a-13C2]-, [2-13C]-, [5-15N]-, and [1,3-15N2]flavin adenine dinucleotides, and compared with those with the native enzyme. The RR lines around 1605 cm-1 with D-alanine or D-proline as a substrate and at 1548 cm-1 with D-alanine undergo isotopic shifts upon [4a-13C]- and [4,10a-13C2]-labelling. These lines are assigned to the vibrational modes associated with C(10a) = C(4a) - C(4) = O moiety of reduced flavin, providing the first assignment of RR lines of reduced flavin and conclusive evidence that reduced flavin is involved in this intermediate.     

Reversal by aminoguanidine of the inhibition of proliferation of human fibroblasts by spermidine and spermine.

The inhibitory effect of the polyamines, spermidine and spermine, on the proliferation of human fibroblasts in culture was found to be reversed by the addition of aminoguanidine (AM), a specific and highly effective inhibitor of diamine oxidase (DAO) present in fetal calf serum (FCS). Aminoguanidine itself in concentration as high as 10(-3) M exhibited no effect upon cell proliferation nor did putrescine at similar concentrations. However, at higher concentrations of putrescine, cell proliferation was inhibited and this inhibition was unaffected by the addition of mM concentrations of AM. These studies support earlier hypotheses on the mechanisms of the toxic effects of polyamines on cell proliferation and establish further that the diamine oxidase-catalyzed metabolism of spermine and spermidine is necessary for their toxic effects in cell culture.     

Biotechnological advances on Penicillin G acylase: Pharmaceutical implications,unique expression mechanism and production strategies

In light of unrestricted use of first-generation penicillins, these antibiotics are now superseded by their semisynthetic counterparts for augmented antibiosis. Traditional penicillin chemistry involves the use of hazardous chemicals and harsh reaction conditions for the production of semisynthetic derivatives and, therefore, is being displaced by the biosynthetic platform using enzymatic transformations. Penicillin G acylase (PGA) is one of the most relevant and widely used biocatalysts for the industrial production of β-lactam semisynthetic antibiotics. Accordingly, considerable genetic and biochemical engineering strategies have been devoted towards PGA applications. This article provides a state-of-the-art review in recent biotechnological advances associated with PGA, particularly in the production technologies with an emphasis on using the Escherichia coli expression platform.     

Deciphering the potential involvement of PXMP2 and PEX11B in hydrogen peroxide permeation across the peroxisomal membrane reveals a role for PEX11B in protein sorting

Peroxisomes have the intrinsic ability to produce and scavenge hydrogen peroxide (H₂O₂), a diffusible second messenger that controls diverse cellular processes by modulating protein activity through cysteine oxidation. Current evidence indicates that H₂O₂, a molecule whose physicochemical properties are similar to those of water, traverses cellular membranes through specific aquaporin channels, called peroxiporins. Until now, no peroxiporin-like proteins have been identified in the peroxisomal membrane, and it is widely assumed that small molecules such as H₂O₂ can freely permeate this membrane through PXMP2, a non-selective pore-forming protein with an upper molecular size limit of 300–600 Da. By employing the CRISPR-Cas9 technology in combination with a Flp-In T-REx 293 cell line that can be used to selectively generate H₂O₂ inside peroxisomes in a controlled manner, we provide evidence that PXMP2 is not essential for H₂O₂ permeation across the peroxisomal membrane, neither in control cells nor in cells lacking PEX11B, a peroxisomal membrane-shaping protein whose yeast homologue facilitates the permeation of molecules up to 400 Da. During the course of this study, we unexpectedly noted that inactivation of PEX11B leads to partial localization of both peroxisomal membrane and matrix proteins to mitochondria and a decrease in peroxisome density. These findings are discussed in terms of the formation of a functional peroxisomal matrix protein import machinery in the outer mitochondrial membrane.     

双歧杆菌三联活菌胶囊对非酒精性脂肪性肝炎患者血清D-乳酸和二胺氧化酶水平的影响

目的探讨双歧杆菌三联活菌胶囊对非酒精性脂肪性肝炎（NASH）患者血清D-乳酸和二胺氧化酶（DAO）水平的影响。方法选取NASH患者88例,随机分为对照组和观察组。对照组患者予以适度的节食、加强休息与适当的体育锻炼,观察组患者加用双歧杆菌三联活菌胶囊420 mg,2次/d,连用8周。观察两组患者治疗前后肝功能指标丙氨酸转氨酶（ALT）和谷氨酰转肽酶（γ-GT）,血清D-乳酸和DAO水平的变化。结果治疗8周后,两组患者ALT和γ-GT水平均较前明显下降（P〈0.05或P〈0.01）,且观察组下降幅度较对照组更明显（P〈0.05）;两组患者血清D-乳酸和DAO水平均较前明显下降（P〈0.05或P〈0.01）,且观察组下降幅度较对照组更明显（P〈0.05）。结论双歧杆菌三联活菌胶囊辅助治疗NASH疗效较好,能降低血清D-乳酸和DAO水平,改善其肝功能指标。     

副干酪乳杆菌N1115对肝硬化患者肠黏膜屏障功能的研究

目的 研究不同剂量副干酪乳杆菌对肝硬化患者肠黏膜屏障的影响。方法 选择我院肝硬化失代偿期患者42例,随机分为对照组和副干酪乳杆菌4 g、8 g、16 g组。各组均给予常规对症治疗。在此基础上,除对照组外,其余各组按相应剂量每日口服补充副干酪乳杆菌,连续2周。所有患者均于治疗前后测血清二胺氧化酶、脂多糖。结果 给予不同剂量副干酪乳杆菌治疗后,各组患者的二胺氧化酶和脂多糖均有所下降,但只有给予16 g副干酪乳杆菌治疗的患者二胺氧化酶和脂多糖与对照组相比差异有统计学意义（t=9.517、10.836,P＜0.05）,同时该组患者疗前后相比差异亦有统计学意义（t=9.445、7.701,P＜0.05）。结论 补充16 g/d副干酪乳杆菌能帮助改善肝硬化患者肠黏膜屏障功能。