Gut microbiota and its implications in small bowel transplantation / 医学前沿

The gut microbiota is mainly composed of a diverse population of commensal bacterial species and plays a pivotal role in the maintenance of intestinal homeostasis, immune modulation and metabolism. The influence of the gut microbiota on solid organ transplantation has recently been recognized. In fact, several studies indicated that acute and chronic allograft rejection in small bowel transplantation (SBT) is closely associated with the alterations in microbial patterns in the gut. In this review, we focused on the recent findings regarding alterations in the microbiota following SBTand the potential roles of these alterations in the development of acute and chronic allograft rejection. We also reviewed important advances with respect to the interplays between the microbiota and host immune systems in SBT. Furthermore, we explored the potential of the gut microbiota as a microbial marker and/or therapeutic target for the predication and intervention of allograft rejection and chronic dysfunction. Given that current research on the gut microbiota has become increasingly sophisticated and comprehensive, large cohort studies employing metagenomic analysis and multivariate linkage should be designed for the characterization of host-microbe interaction and causality between microbiota alterations and clinical outcomes in SBT. The findings are expected to provide valuable insights into the role of gut microbiota in the development of allograft rejection and other transplant-related complications and introduce novel therapeutic targets and treatment approaches in clinical practice.

Influence of gastric acid suppression on the structure and diversity of the jejunal microbiota in a rat model / 肠外与肠内营养

Objective:To investigate the dynamic changes of the luminal microbiota in the jejunum following administration of proton pump inhibitors (PPIs) in a rat model.Methods:Rats were randomized into six groups (n =6 each group).A group of rats were sacrificed just after anesthesia as normal control (0 d) and,other five groups were continuously administered with omeprazole (10 mg/kg twice daily,intraperitoneally) and were euthanized at 5,9,14,21,28 days following the treatment,respectively.Total DNA in the luminal contents of jejunum was extracted and was used for polymerase chain reaction (PCR) amplification with the primer set targeted the hypervariable V3 region of 16S ribosomal RNA genes.Subsequently,the amplicons were separated by denaturing gradient gel electrophoresis (DGGE).After the gels were stained and photographed,the bands were cut out and sequenced to determine the closest bacterial relatives with the BLAST.The DGGE profiles were analyzed to evaluate the shifts of the microbiota composition and diversity following treatments.Results:Changes of the jejunal microbiotas in rats were observed at 5 and 9 days post PPI administration,as characterized by outgrowth of Streptococcus pneumonia,Clostridium saccharolyticum and Lactococcus garvieae compared to those of the controls (0 d).With time extension of PPI treatment,the mictobiotas significantly shifted toward dysbiotic state,in which the opportunistic pathogens,including Ertterococcus faecalis and Clostridium difficile,were strikingly expanded,especially 21 days later.However,the commensals such as Lactobacillus reuteri and Weissella koreensis were markedly declined in PPI-treated animals compared with the controls.The similarity of the jejunal microbiotas between PPI-treated animals and controls was markedly reduced following PPI treatment,reaching (56.1 ± 16.7) ％ at 28 days.Conclusion:Our data demonstrate that the gastric acid suppression could induce shifts of the jejuna microbiota in a rat model.More importantly,long-term use (＞ 14 d) of PPI could lead to the dysbiosis of the jejunal microbiota,which might be related causally to increased susceptibility to enteric infection.

The polyamidoamine induced mineral deposition on dentin surface in vitro / 实用口腔医学杂志

Objective:To evaluate the sealing ability of the 3.0th generation of polyamidoamine dendrimer(3.0 PAMAM)on hu-man dentinal tubules.Methods:1 6 extracted premolars were cut into 2 mm thick dentin slices to establish sensitive dentin model in vitro.Then 2 samples without any treatment were selected randomly into demineralized dentin group,and the remain 1 4 dentine pills were divided into 2 groups by the random number table(n=7).Samples in the experimental group were treated with 3.0 PAMAM, those in the control group were treated with deionized water.After having immersed in the artificial saliva for 2 and 4 weeks respec-tively,the dentin slices were examined by scanning electron microscope(SEM)and X-ray energy dispersive spectroscopy(EDS). Results:SEM showed that the minerals on the surfaces of the dentine disks in experimental group were formed gradually with the time,the dentinal tubules were blocked 4 weeks after treatment.The minerals on the sample surface in control group were less and the dentinal tubules remained open.EDS results showed that Ca/P(1 .49 ±0.1 6)of mineral deposition in the experimental group was higher than that in the control group (1 .1 8 ±0.20)(P<0.05).Conclusion:The 3.0th generation of PAMAMhas the occlu-ding ability by inducing remineralization on the dentine surface and it may be used in the treatment of dentin hypersensitivity.

Determination of Ultratrace Copper in Barium Phosphate Laser Glass by Inductively Coupled Plasma Mass Spectrometry / 分析化学

With the use of high pure HF and HNO3 reagents, and autoclaves made of high purity Rerfluoroalkoxy ( PFA ) material, a solution sample digestion technique effective for phosphate samples, subjected to high temperature fusion, was established. The whole procedure was concise, fast and of low blank value. Key factors such as the amount and ratios of the reagents, the digestion temperature and time, were systematically optimized, it was found that within 0. 5 h at 150 ℃, only 1. 7 mL of total reagent consumption could lead to a complete sample decomposition. Most importantly, the samples were not required to be ground to fine powder, which greatly reduced the risk of contamination. In addition, an effective liquid_liquid extraction procedure based on 5_nonylsalicylaldehyde oxime as the extractant was established for matrix separation and analyte preconcentration. Under the optimal extraction conditions of 5 mL of 15% extractant, 0. 5% HNO3 of extraction acidity and 20% HNO3 of back_extraction acidity, a matrix separation efficiency of over 99. 999% could be realized and a preconctration factor of 10 could be obtained, which resulted in complete elimination of the matrix_induced interference and great enhancement of the analytical sensitivity. After optimization of the operation parameters of ICP_MS, high signal to background detection of Cu in 20%HNO3 at 840 W of plasma power and low sample uptake rate were realized. The detection limits of 2. 5 ng/g, RSD of 3. 3% for six detections of parallel samples, and the recovery of 94. 3% for spike test were obtained, respectively. The method was finally applied to three real samples analysis, and the results agreed well with the data from laser adsorption loss experiment.

Effect of Ca(OH)2 pre-treated on remineralization of the demineralized dentin induced by polyamidoamine dendrime / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To evaluate the remineralization effect of Ca(OH)2 pre-treated with carboxylmodified polyamidoamine dendrimer (PAMAM) on demineralized dentin.</p><p><b>METHODS</b>Thirty-two demineralized dentin models were divided into four groups randomly as follows: control group with no treatment, Ca(OH)2 group pretreated with Ca(OH)2 solution, PAMAM group processed with carboxyl-modified PAMAM, and PAMAM+Ca(OH)2 group processed with carboxyl-modified PAMAM and pretreated with Ca(OH)2 solution. All samples were immersed in artificial saliva for two weeks. The remineralization effects of dentin discs were evaluated by scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and X-ray diffraction (XRD).</p><p><b>RESULTS</b>Observed by the SEM, it was showed that in PAMAM+Ca(OH)2 group almost all the dentinal tubules were occluded by the minerals, however this was not found in other groups. The minerals proved were hydroxyapatite through EDS and XRD tests.</p><p><b>CONCLUSIONS</b>There was potential superiority of the carboxyl-modified PAMAM with Ca(OH)2 solution in promoting the remineralization of initial dentin lesions.</p>

Berberine attenuates impairment of intestinal glutamine transport in sepsis / 肠外与肠内营养

Objective: A marked deficiency of glutamine in clinical critical illness is correlated with mortality in the intensive care unit, and intestinal glutamine transport was reported to be impaired in late sepsis. Berberine was reported to protect against the intestine injury, and improve the survival rate in sepsis. We designed this study to gain further knowledge of the intestinal glutamine transport in early and late sepsis, and to find out whether beberine pretreatment has some effect on glutamine transport in sepsis. Methods: Berberine (50 mg/kg) was given intragastrically once a day for 5 days, and sepsis was induced by cecal ligation and puncture on day 5. The small intestinal samples were collected at 0, 2, 6, 12, 24 h. Intestinal brush border membrane vesicles were prepared by Mg~(2+) aggregation-differential centrifugation techniques, and brush border glutamine transport was studied by a rapid filtration technique. Results: Under control condition, Na~+-dependent glutamine transport accounted for about 90% of the total transport. The relative contributions of ATA2, ATB~(0,+), B~0AT1 were about 12, 25, 63%, respectively. Septic rats showed an early increase and a late decrease in intestinal glutamine transport. ATA2 had an earlier increase in the early stage, while B0AT1 had no significant increase. Berberine pretreated group had a relative less increase in early phase and a less decrease in late phase compared to sepsis group. Conclusion: Rat intestinal glutamine transport showed an early increase and a late decrease in sepsis, and berberine pretreatment could attenuate the impairment of glutamine transport in sepsis. It may provide some information for sepsis treatment.

A study of mesenchymal stem cells decreasing intestinal permeability induced by mesenteric ischemia/reperfusion / 肠外与肠内营养

Objective: To investigate the effect of bone marrow mesenchymal stem cells (MSC) on the variation of intestinal permeability damaged by superior mesenteric artery ischemia and reperfusion. Methods: Bone marrow mesenchymal stem cells were isolated from cavity of tibias and femurs of male Sprague Dawley rat in a sterile condition, and were cultured and proliferated in plastic dishes. 10 week old female Sprague Dawley rats were randomly divided into three groups:group A (sham group), group B (MSC group) and group C (saline group). In group B and group C, the superior mesenteric artery (SMA) of the animals were seperated and occluded by non-invasive vascular clamp for 45 minutes. Immediately after removing the vascular clamp,1×10~7 MSC suspended in 0.5 ml sterile L-DMEM and the same volume of normal saline was submucosally injected into the small intestine at ten different points in group B and group C, respectively. In group A, the animals were only underwent laparotomy without clamping the SMA. 3 days and 6 days after the operation, 100 mg lactulose and 50mg mannitol dissolved in 2 ml distilled water were administrated by oral gavage and urine during 6 h experiment was collected for assaying the L/M ratio before sacrificing the animals. The donor derived MSC was identified by Y chromosome in situ hybridization in ileum tissue, and the serum D-lactate level was determined. Results: The donor derived MSC could home to the ischemia/reperfusion injured intestinal mucosa, and the intestinal permeability was much lower in group B (MSC group) than that in group C (saline group)(P<0.05). Conclusion: Mesenchymal stem cells can reduce the small intestinal mucosal permeability impaired by ischemia/reperfusion, and can participate in the preservation of integrity of the damaged gut mucosal mechanical barrier.

A modified isolation method for mouse intestinal intraepithelial lymphocytes / 肠外与肠内营养

Objective: To explore and modify the isolation method for mouse intestinal intraepithelial lymphocytes. Methods: Epithelium mucosae of mouse small intestine was incubated in iced bath and shaked in PBS containing DTT. The cell suspension was obtained after filtration with 80 and 400- screen mesh trap valve in turn. The yield, viability and purity of intestinal intraepithelial lymphocytes were observed to estimate the feasibility. Results: About (5.6±0.7)×10～6 intestinal intraepithelial lymphocytes were obtained from every 20cm samll intestine. The viabilty of intestinal intraepithelial lymphocytes was (90.46±5.71)% and the purity was (92.21±5.20)%. Conclusion: Compared with other reported isolation methods, the modifled method is convenient and esay to handling.The yield, viability and purity are high enough to be used for intestinal intraepithelial lymphocytes studies.

Lactobacillus acidophilus inhibits expression of IL-6 and IL-8 in Caco-2 cells induced by TNF-α / 中华微生物学和免疫学杂志

Objective To investigate the effect of live Lactobacillus acidophilus on Caco-2 cells to release pro-inflammatory cytokines IL-6 and IL-8.Methods Caco-2 cells were cultured for 2 h with live Lactobacillus acidophilus strain 1950103-12 and examined by reverse transcription-PCR for IL-6 and TNF-α induced IL-8 expression.An enzyme-linked immunosorbent assay was used to quantitate secreted IL-6 and IL-8.Results Lactobacillus acidophilus strain 1950103-12 had no ecffect on the mRNA expression and production of IL-6 and IL-8 in the Caco-2 cells.A significant mRNA expression and production of IL-6 and IL-8 by the Caco-2 cells were detected after exposure to TNF-α.Lactobacillus acidophilus strain 1950103-12 down-regulated IL-6 and IL-8 mRNA expression and inhibited constitutive synthesis by Caco-2 cells of IL-6 and IL-8 that induced by TNF-α.Conclusion Lactobacillus acidophilus strain 1950103-12 has potent direct anti-inflammatory activity on human epithelial cells.

EICOSAPENTAENOIC ACID ALTERS INTERLEUKIN-2 RECEPTOR DISTRIBUTION IN DETERGENT-INSOLUBLE MEMBRANE DOMAIN / 营养学报

Objective: To determine whether EPA exert effectively immunosuppressive function by altering distribution of IL-2R in membrane subdomains. Method: The human Jurkat E6-1 T cells were cultured in EPA-supplemented medium and the cells treated with stearic acid served as control. The effect of EPA on CD25 (IL-2? receptor) expression on the surface of T cells was investigated by flow cytometry. The lipid rafts were isolated by discontinuous sucrose density gradient ultracentrifugation. The localization of IL-2R?, IL-2R?, and IL-2R?c in fractions isolated and the effect of EPA treatment were determined by immunoblot and chemiluminescence. Results: EPA suppressed CD25 expression on the surface of T cells. IL-2R?, IL-2R?, and IL-2R?c were associated with lipid rafts of T cells, and these subunits were partly displaced from lipid rafts of EPA-treated T cells. Conclusion: Lipid rafts are functional subdomains for IL-2R signaling. EPA enrichment modifies distribution of IL-2R?, IL-2R?, and IL-2R?c in lipid rafts and EPA plays immunosuppressive roles probably by partly removing IL-2R from lipid rafts.

Interleukin-2? receptor in membrane lipid rafts / 肠外与肠内营养

Objective: To determine lipid rafts on the membrane of T cells is the functional microdomains for IL-2? receptor. Methods: Flow cytometric analysis was performed for expression of CD25(IL-2R?) on the surface of T cells. Lipid rafts were isolated by discontinuous sucrose density gradient ultracentrifugation. The localization of IL-2R? in fractions isolated from sucrose density gradients was determined by immunoblotting and detected by chemiluminescence. Results: cells were stimulated with IL-2 and expression of CD25(IL-2R?) on the surface of T cells was 37.08%. Immunoblot analysis of fractions from sucrose gradients revealed that a large proportion of IL-2R? was localized in lipid rafts. Conclusions: lipid rafts is the functional microdomains for IL-2? receptors.

Progress in researches on the role of dendritic cells during sepsis / 医学研究生学报

Sepsis is the leading cause of mortality in critically ill patients.Studies indicate that immune suppression in sepsis is more often associated with poor outcome.Dendritic cells may contribute largely to the development of immune suppression during sepsis.This article reviews the emerging data indicating the key role of dendritic cells in sepsis induced immune suppression.A deeper insight into the dendritic cell changes during sepsis may provide a powerful weapon against sepsis.

The Influences of Carvedilol on Cardiac Function and Heart Rate Variability in Patients with Congestive Heart Failure / 中国医师杂志

Objective To observe the effect of carvedilol on cardiac function and heart rate variability(HRV) in patients with congestive heart failure(CHF) . Methods Sixty-three patients with CHF were randomly divided into two groups. 33 cases (carvedilol group) were given Carvedilol titrated from low dose to target dose in addition to standard therapy for CHF. The cardiac fuction and HRV of all patients were examined before and after 6 months therapy. Results After 6-month therapy, LV end-diastolic dimension (LVEDD) and LV end-systolic dimension (LVESD) in carvedilol group were significantly lower than those in control group (P

The adhesive characters of Lactobacillus to enterocyte-like HT-29 cells / 解放军医学杂志

Objective To study the adhesive characters of Lactobacillus to enterocyte-like HT-29 cells.Methods A HT-29 cell culture was employed to investigate the adherent ability of Lactobacillus.Bacterial suspension and HT-29 cells were co-incubated at 37℃ for 1h.The cells with adherent bacteria were Gram-stained,and then examined microscopically under oil immersion.The pH of the medium,bacterial growth phase,co-incubation time,bacterial concentration,D-mannose and type of host cells,which were involved in the process of adherence of Lactobacillus to enterocyte-like HT-29 cells,were also investigated.Results The adherent level increased substantially for Lactobacillus reuteri JCM1081 as the pH decreased from 6.0 to 4.0.Maximum adherence occurred within 90min and remained stable until the end of incubation.The bacterial concentration exerted a certain influence on the adherence of Lactobacillus reuteri JCM1081 to HT-29 cells,and it seemed to be concentration dependent.Maximum adherence occurred in the concentration of 109cfu/ml and remained stable until the end of incubation.Lactobacillus strain that grew into stationary phase showed higher ability to adhere to HT-29 cells than that in logarithmic phase.The addition of D-mannose dramatically decreased the level of Lactobacillus adherence.The Lactobacillus strain adhered in higher levels to the enterocyte-like cells or gastric epithelium cells than other cell origins,and the adhesion of Lactobacillus showed host cells specificity.Conclusion The adhesive characters observed with Lactobacillus suggested that adhesive properties are species and host specific.The pH,bacterial growth phase,co-incubation time,bacterial concentration and D-mannose may influence the adhesion of Lactobacillus to enterocyte-like HT-29 cells.