平颏海蛇皮中新型硫酸皮肤素的分离纯化和结构表征

目的 从平颏海蛇皮中提取分离糖胺聚糖(GAGs),并对其结构进行初步表征。方法 对海蛇皮进行脱脂处理后,采用木瓜蛋白酶和胰蛋白酶联合酶解提取粗多糖,采用氯代十六烷基吡啶(CPC)沉淀和Q-Sepharose Fast Flow离子交换树脂对粗多糖进行分离纯化。运用醋酸纤维素薄膜电泳分析其GAGs种类,采用1-苯基-3-甲基-5-吡唑啉酮(PMP)衍生高效液相色谱(HPLC)法分析其单糖组成,利用硫酸软骨素酶降解结合质谱和强阴离子交换色谱(SAX-HPLC)法分析其2糖组成。结果 获得了2种GAGs纯化组分,并对其中1种含量较高的纯化组分(HSAP-2)进行了初步结构表征。HSAP-2中含有4种2糖,主要为单硫酸化2糖(4S和6S)和少量2硫酸化2糖(46S)、非硫酸化2糖(0S);单糖组成中含有葡萄糖醛酸(GlcA)和乙酰氨基半乳糖(GalNAc);是1种高度杂合的新型硫酸皮肤素(DS)。结论 从平颏海蛇皮中分离纯化获得了1种结构新颖的DS,为平颏海蛇多糖结构与生物活性的深入研究提供了基础。     

Heparin-derived disaccharides modulate proliferation and Erb-B2-mediated signal transduction in colon cancer cell lines

Organ-specific extracellular matrix (ECM) determines metastasis formation by regulating tumor cell proliferation. Hepatocyte-derived ECM enhances proliferation of colon cancer cell lines by increasing expression of tyrosine kinase receptors of the erb-B family. The active components in the ECM are the heparan sulfates, which are highly heterogeneous in their chemistry and size. We determined the effect of heparan sulfate disaccharides, of defined chemistry and present in high amounts in the liver heparan sulfate chains, on the proliferation of colon cancer cell lines and investigated the mechanism involved. The low-metastatic cell line KM12 was stimulated to proliferate by a highly sulfated disaccharide, found in the highest amounts in hepatocyte-derived heparan sulfate. Growth of the highly metastatic cell line KM12SM was inhibited by the second most common disaccharide in hepatocyte-derived heparan sulfate. The effect of both disaccharides was not accompanied by changes in the expression of erb-B1, erb-B2, erb-B3 or heregulin-alpha. We determined whether the disaccharides modified the signal-transduction pathways mediated by the erb-B receptors. The erb-B2-specific tyrosine kinase inhibitor AG825 abolished the enhancement of KM12 cell proliferation by the stimulatory disaccharide. This disaccharide increased tyrosine phosphorylation of erb-B1 and erb-B2 receptors, effects that were abolished by AG825. Moreover, the disaccharide caused increased expression of cyclin D1 and of activated MAP kinase, again reduced in the presence of the inhibitor AG825. The growth-inhibitory disaccharide reduced phosphorylation of erb-B1, but not of erb-B2, receptors in KM12SM cells. In conclusion, not only hepatocyte-derived heparan sulfate but also disaccharide molecules derived from heparan sulfate can affect colon cancer cell proliferation. Their effect is mediated by modulation of the erb-B signal transduction.     

Disaccharide analysis of chondroitin sulfate in peri-implant sulcus fluid from dental implants

We collected peri-implant sulcus fluid by capillary tubes from sites around titanium osseointegrated implants and determined the chondroitin sulfate released into the peri-implant sulcus fluid by high-performance liquid chromatography. Chondroitin sulfate was found in all peri-implant sulcus fluid samples, and its content was similar to that in gingival crevicular fluid obtained around natural teeth. The predominant unsaturated disaccharide isomer was ΔDi-OS, followed by ΔDi-4S. ΔDi-6S was present in trace amounts. The amount of ΔDi-OS was greater in peri-implant sulcus fluid than in gingival crevicular fluid. Assaying chondroitin sulfate disaccharides in peri-implant sulcus fluid may be an effective method of monitoring the peri-implant condition of dental implants.     

Trehalose activates autophagy and decreases proteasome inhibitor‐induced endoplasmic reticulum stress and oxidative stress‐mediated cytotoxicity in hepatocytes

Aim

Endoplasmic reticulum stress is associated with the pathophysiology of various liver diseases. Endoplasmic reticulum stress mediates the accumulation of abnormal proteins and leads to oxidative stress, cytoplasmic inclusion body formation, and apoptosis in hepatocytes. Autophagy is a bulk degradation pathway for long‐lived cytoplasmic proteins or damaged organelles and is also a major degradation pathway for many aggregate‐prone and disease‐causing proteins. We previously reported that rapamycin, a mammalian target of rapamycin inhibitor, activated autophagy and decreased proteasome inhibitor‐mediated ubiquitinated protein accumulation, cytoplasmic inclusion body formation, and apoptosis in hepatocytes. Trehalose is a non‐reducing disaccharide that has been shown to activate autophagy. It has been reported to decrease aggregate‐prone proteins and ameliorate cytotoxicity in neurodegenerative disease models. However, the effects of trehalose in hepatocytes are unclear.

Methods

We show here that trehalose activated autophagy and reduced endoplasmic reticulum stress, cytoplasmic inclusion body formation, and apoptosis in proteasome inhibitor‐treated liver‐derived cultured cells.

Conclusion

To our knowledge, this is the first report showing that trehalose activates autophagy and has cytoprotective effects in hepatocytes. Our findings suggest that trehalose can become a therapeutic agent for endoplasmic reticulum stress‐related liver diseases.     

Dietary treatment of irritable bowel syndrome: current evidence and guidelines for future practice

The aim of this literature review is to produce guidelines for dietetic practice in irritable bowel syndrome (IBS) by evaluating the research available. In this area randomized control trials (RCT) only account for a small proportion of the literature and have been concentrated in the modification of dietary fibre in patients with IBS. The bulk of the literature is mainly observational trials from which no indisputable conclusions can be extracted. In this review, the evidence available has been interpreted within the context of the current knowledge base. Conclusions are drawn to facilitate the development of guidelines, enabling a starting point for discussion and an evaluation of current practice. The literature available on therapeutic dietary manipulation in IBS patients is centred around non-starch polysaccharides (NSPs), mono and disaccharide sensitivity and food intolerance. The production of these guidelines has focused on research examining the role of dietary components in the therapeutic management of patients with IBS. However, where there is a deficiency in the literature directly relating dietary intake to management of IBS patients, physiological function in relation to dietary components has been relied upon to produce practical guidelines which can be applied realistically in a clinical environment. An interpretation of the evidence has revealed a limited role for exclusion diets, a move away from high-fibre diets towards the manipulation of fibre fractions in the diet, an evaluation of the effects of caffeine on gut function and the necessity for individual dietary assessment to identify dietary issues pertinent to the patient's symptoms. These guidelines outline a positive role for dietitians in the treatment of IBS patients which draws on the unique skills possessed by dietitians regarding the assessment of habitual eating habits and therapeutic dietary manipulation.     

大籽獐牙菜中大籽獐牙菜甙的结构

本文报道从大籽獐牙菜Swertia macrosperma C.B.Clark的全草中分离得到的另外四个化合物Ⅰ～Ⅳ。经光谱及化学方法鉴定,化合物Ⅰ是一种咖啡酸双糖酯类化合物,其结构为反式咖啡酸-1-O-芦丁糖酯(trans caffeic acid-1-O-rutinose ester),系首次从天然界得到的一种新化合物,命名为大籽獐牙菜甙(swertiamacroside);化合物Ⅱ～Ⅳ为已知的(口山)酮衍生物,分别鉴定为芒果甙(mangiferin,Ⅱ),bellidifodin(Ⅲ)及bellidifodin-8-O-β-D-glucopyranoside(Ⅳ)。     

Combined LDI/SAT test to evaluate intestinal lactose digestion and mucosa permeability

BACKGROUND: Intestinal mucosal damage causes impaired digestive capacity and increased mucosal permeability. Quantification of damage can be used to improve treatment options. Currently, the Lactose Digestion Index (LDI) and the Sugar Absorption Test (SAT) are used for evaluation. The investigation studied whether both tests could be combined to provide a useful multifunctional test and whether measurements in blood (LDI) could be replaced by measurements in urine. MATERIALS AND METHODS: The LDI (25 g 13C-lactose, 0.5 g 2H-glucose), the SAT (5 g lactulose, 1 g L-rhamnose) and the LDI/SAT combination test were performed in seven lactose-digesting and eight lactose-maldigesting adults. Plasma glucose 13C-enrichment was determined by gas-chromatography/combustion/isotope ratio mass-spectrometry (GC/C/IRMS), 2H enrichment determined by gas-chromatography/mass-spectrometry (GC/MS) and urinary sugars by gas-chromatography (GC). RESULTS: The results of the separate LDI test were not different from those of the LDI/SAT in the lactose-digester group (0.82 +/- 0.06 vs. 0.81 +/- 0.09), nor in the lactose-maldigester group (0.36 +/- 0.12 vs. 0.35 +/- 0.06). A significant correlation was found between the 10-h urinary-lactose/lactulose ratio and the LDI (R2 = 0.71, P < 0.01). There were no differences in the lactulose/L-rhamnose ratio between lactose-digesters and lactose-maldigesters using both the SAT and LDI/SAT tests. CONCLUSION: The LDI/SAT test is a reliable method of measuring digestion and permeability simultaneously. The 10-h period urinary lactose/lactulose excretion ratio following lactose consumption reflects lactose digestive capacity.     

Antiallergic activity of a disaccharide isolated from Sanguisorba officinalis

The antiallergic activity of the natural disaccharide, 5-O-alpha-D-(3-C-hydroxymethyl)lyxofuranosyl-beta-D-(2-C-hydroxymethyl)arabinofuranose was evaluated using both in vivo and in vitro experimental models. Intravenously administered compound inhibited the passive cutaneous anaphylaxis response in rats in a dose-dependent manner (ED(50) = 9.6 mg/kg). The compound inhibited histamine release evoked by both compound 48/80 and calcium ionophore A23187 in rat peritoneal mast cells indicating that mast cell stabilization is the major mechanism of action for its antiallergic activity. In passively sensitized isolated guinea-pig hearts, an in vitro anaphylaxis model in which histamine release plays a key role for functional deterioration, the compound markedly diminished both coronary flow reduction and histamine release on challenge to the antigen. These data demonstrate that this antiallergic natural disaccharide exerts its effect via inhibition of mast cell mediator release.     

Sensory neuropathy with monoclonal IgM binding to a trisulfated heparin disaccharide

We studied clinical and serological features of five patients with polyneuropathy and serum immunoglobulin M (IgM) binding to the trisulfated disaccharide IdoA2S-GlcNS-6S (TS-HDS), the most abundant disaccharide component of heparin oligosaccharides. The patients all had painful, predominantly sensory polyneuropathies. Sensory loss was distal and panmodal. Electrophysiological and pathological studies were consistent with axonal loss, especially of unmyelinated axons. Immunohistochemistry showed IgM and kappa light chains deposited around the rim of intermediate-sized veins in the perimysium and epineurium. Serum IgM binding to TS-HDS was selective, present in high titer (>12,000), and limited to kappa light chains. We conclude that TS-HDS is a newly identified target carbohydrate antigen of some IgM M-proteins. Monoclonal IgM binding to TS-HDS is associated with a painful, predominantly sensory, polyneuropathy syndrome with axonal loss and deposition of IgM in veins. The role of IgM binding to TS-HDS in the pathogenesis of the neuropathy remains to be determined.     

Enhancement of paracellular transport of heparin disaccharide across Caco-2 cell monolayers

The enhancement of paracellular transport of heparin disaccharide using several absorption enhancers across Caco-2 cell monolayers was tested. The cytotoxicity of these enhancers was also examined. The enhancing effects by Quillaja saponin, dipotassium glycyrrhizinate, 18beta-glycyrrhetinic acid, sodium caprate and taurine were determined by changes in transepithelial electrical resistance (TEER) and the amount of heparin disaccharide transported across Caco-2 cell monolayers. Among the absorption enhancers, 18beta-glycyrrhetinic acid and taurine decreased TEER and increased the permeability of heparin disaccharide in a dose-dependent and time-dependent manner with little or negligible cytotoxicity. Our results indicate that these absorption enhancers can widen the tight junction, which is a dominant paracellular absorption route of hydrophilic compounds. It is highly possible that these absorption enhancers can be applied as pharmaceutical excipients to improve the transport of macromolecules and hydrophilic drugs having difficulty in permeability across the intestinal epithelium.