Identification of the blood component responsible for increased susceptibility to gut-derived infection

It has previously been reported that the transfusion of allogeneic whole blood increases sepsis-related mortality and decreases the ability of the host to kill bacteria that have translocated from the intestinal tract. To determine which blood component contributes to this adverse effect, the impact of the transfusion of white cells (WBCs), red cells (RBCs), and plasma on microbial translocation, bacteria killing, and mortality rate was studied. Blood from C3H/HeJ mice was separated into WBCs, RBCs, and plasma, and these fractions were transfused to Balb/c mice. Controls received sterile saline. Five days after transfusion, all Balb/c mice underwent a 20-percent burn and gavage with 1 × 10(10) Escherichia coli labeled with 14C-glucose. Mortality was observed for 10 days. Four additional groups, receiving the same treatment as above, were sacrificed 4 hours after the burn, and mesenteric lymph nodes, liver, kidney, and blood were harvested aseptically. For each tissue, quantitative colony counts, radionuclide counts, and percentage of translocated bacteria that remained alive were calculated. By radionuclide counts, no difference was observed in the degree of 14C E. coli translocation among the groups. In contrast, the percentage of viable bacteria and the mortality rate were significantly higher in the group receiving allogeneic WBCs than in all other groups (p < 0.05). It is concluded that WBCs are the component in transfused blood that has an adverse effect on host resistance to gut- derived infection.     

Comparison of translocation of different types of microorganisms from the intestinal tract of burned mice

The aim of this study was to compare the ability of various microorganisms to translocate from the intestine to the mesenteric lymph nodes (MLNs), liver, and spleen in a burned mouse model. Balb/c mice were gavaged with 1 x 10(9) or 1 x 10(10) of one of 11 different microorganisms. All animals were then given a 20% burn. Survival after 10 days showed no significant difference between any of the groups at the 10(10) dose. At the 10(9) dose, significantly higher survival rates were found in three of the 11 strains. Microbial translocation (gavage of 10(10) 111In-labeled organisms) and host's ability to kill translocated bacteria (viable bacteria in tissues) were measured followed by burn injury and sacrifice four hours later. Translocation and killing of Staphylococcus epidermidis and Escherichia coli was high in the MLNs compared with all other groups but translocation was lower to the liver. Klebsiella, Pseudomonas, and Serratia translocated more evenly to all the tissues. However, these groups showed very high clearance of bacteria in the liver and spleen except for Klebsiella and one strain of Pseudomonas in the spleen. Candida showed poor translocation to all of the tissues and high clearance. It is concluded that various strains of bacteria translocate from the intestine to a similar degree after injury, but the tissues to which they translocate and the rate at which they are killed are somewhat strain dependent.     

Fungal translocation is associated with increased mortality after thermal injury in guinea pigs

Thermal injury increases the rate of translocation of Candida albicans in guinea pigs, but early enteral feeding can significantly decrease this rate. We studied the combined effects of C. albicans translocation and early feeding on outcome of thermal injury in guinea pigs. Eighty guinea pigs were subjected to a flame burn covering 50% total body surface area. One hour before burn injury, half of the animals underwent gavage with 3 x 10(10) viable C. albicans, a dosage that in previous studies was associated with greater than 90% incidence of yeast translocation to the mesenteric lymph nodes. The other half underwent gavage with an equal volume of saline. After injury, half of each group were randomly selected to receive guinea pig feed ad libitum and the other half were starved for 72 hours. All were allowed access to water ad libitum. Mortality rate was recorded at 3 3 days. The group that underwent gavage with C. albicans and subsequent starvation after burn injury had a significantly higher mortality rate than had any of the other groups. We conclude that induced translocation of C. albicans in guinea pigs increases mortality after burn injury. Moreover, early enteral feeding has a protective effect, presumably by decreasing translocation rates has been shown in previous studies.     

Effect of metronidazole on Escherichia coli in the presence of Bacteroides fragilis: an investigation in mice

The observation that, in rats, metronidazole exhibited antimicrobial activity against resistant Escherichia coli (when this was accompanied by susceptible Bacteroides fragilis) prompted us to attempt to reproduce this phenomenon in another species and under other experimental conditions. In experiment 1, mice injected intraperitoneally with an E. coli/B. fragilis mixture were treated with metronidazole, 250 mg/kg given by mouth at 0 and 10 h, or left untreated. At 24 h, viable counts of bacteria in blood and peritoneal washings were determined. In experiment 2, mice with 5-day-old subcutaneous abscesses containing E. coli and B. fragilis were also either given metronidazole as above or left untreated. At 24 h, viable counts of bacteria in pus were determined. Metronidazole affected neither the frequency with which E. coli persisted at the three sites, nor the viability of E. coli at these sites. This was so despite the fact that, in each of the sites, a significant B. fragilis kill was registered. Thus, pending elucidation of the mechanism by which the phenomenon operates, its non-appearance in these experiments cautions against the extrapolation of the original observations beyond the circumstances under which they were first made.     

Therapy with cefoperazone plus sulbactam against disseminated infection due to cefoperazone-resistant Pseudomonas aeruginosa and Escherichia coli in granulocytopenic mice.

Using a granulocytopenic murine model, we evaluated the efficacy of cefoperazone plus sulbactam against disseminated infection due to isolates of beta-lactamase-producing, cefoperazone-resistant (MIC, > or = 50 micrograms/ml) Escherichia coli and Pseudomonas aeruginosa. Both isolates were susceptible in vitro to cefoperazone plus sulbactam (MIC, < or = 6.3 micrograms/ml). Mice rendered granulocytopenic with cyclophosphamide were divided into three groups: group A--infected, untreated mice (controls); group B--infected, cefoperazone-treated mice (700 mg/kg of body weight); and group C--infected, cefoperazone-plus-sulbactam-treated mice (700 mg plus 350 mg). In the E. coli experiment, survival rates in groups A, B, and C were 25, 46, and 73%, respectively. In the experiment with P. aeruginosa, survival rates in groups A, B, and C were 0, 10, and 50%, respectively (P < 0.001). Highly significant differences also were noted for colony counts in the blood, liver, and spleen of group C mice versus group A or B mice in both experiments. Thus, cefoperazone plus sulbactam appears to be a promising combination for the treatment of infections due to certain cefoperazone-resistant gram-negative bacilli, including P. aeruginosa.     

Hypertonic saline enhances host defense to bacterial challenge by augmenting Toll-like receptors

OBJECTIVE: To determine whether hypertonic saline infusion modulates thermal injury-induced bacterial translocation and host response to bacterial challenge through the augmentation of Toll-like receptors (TLRs). DESIGN: Prospective, experimental study. SETTING: Research laboratory at a university hospital. SUBJECTS: Thermal injury models in the mice. INTERVENTIONS: In experiment 1, mice underwent burn were given with 10 mL/kg hypertonic saline (7.5% NaCl), 10 mg/kg saline (N/S1), or 80 mL/kg saline (N/S2) at 4 or 8 hrs after burn. At 24 hrs after burn, mesenteric lymph nodes were harvested for bacterial translocation assay. In experiment 2, mice receiving hypertonic saline or saline after thermal injury received peritoneal challenge with Escherichia coli, and bacterial clearance was measured. In experiment 3, peritoneal cells from mice receiving hypertonic saline or saline after thermal injury were incubated with E. coli, and bacterial count, TLR2, TLR4, MIP2, CXCR2, pp38, and ERK expression were evaluated. In experiment 4, reactive oxygen species production, CXCR2, MIP2, TLR2, and TLR4 expression of bone marrow neutrophil from mice receiving hypertonic saline or saline treatment after thermal injury were evaluated. In experiment 5, neutrophil were cultured with hypertonic saline or N/S and incubated with E. coli. TLR2 and TLR4 expression and bacterial count were evaluated. In experiment 6, mice were fed with oral antibiotics with or without lipopolysaccharide, a TLR ligand, supplements. At 24 hrs after burn, mesenteric lymph nodes were harvested for bacterial translocation assay, and neutrophils were harvested for TLR2 and TLR4 protein assay. MEASUREMENTS AND MAIN RESULTS: Hypertonic saline decreased thermal injury-induced bacterial translocation. Hypertonic saline increased bacterial clearance, phagocytic activity, and TLR2, TLR4, CXCR2, pp38, and p44/42 expression of peritoneal cells. Hypertonic saline treatment at 4 or 8 hrs after thermal injury decreased reactive oxygen species production of neutrophil. Hypertonic saline injection increased TLR2, TLR4, and pp38 expression of neutrophil. In vitro treatment of neutrophil with hypertonic saline increased phagocytic activity and TLR2 and TLR4 expression. Commensal depletion with oral antibiotics decreased TLR2 and TLR4 expression of neutrophil; lipopolysaccharide increased TLR4 expression of neutrophil and decreased thermal injury-induced bacterial translocation. CONCLUSIONS: Restoration of extracellular fluid in burn shock with hypertonic saline decreased thermal injury-induced bacterial translocation. Hypertonic saline increased the phagocytic activity and TLR2, TLR4, CXCR2, pp38, and P44/42 expression of peritoneal cells. Hypertonic saline decreased reactive oxygen species but increased TLR2, TLR4, and pp38 expression and phagocytic activity of bone marrow neutrophil. Stimulation of the TLRs with lipopolysaccharide in commensal depleted mice increased TLRs expression of neutrophil and decreased thermal injury-induced bacterial translocation. Taken together with the fact that stimulation of TLRs with hypertonic saline increases phagocytic activity of systemic inflammatory cells, we conclude that TLRs play a critical role in the innate immunity by recognizing bacteria and that hypertonic saline enhances host response to bacterial challenge by increasing TLRs of inflammatory cells.     

Sodium arsenite induces the stress response in the gut and decreases bacterial translocation in a burned mouse model with gut-derived sepsis

Bacteria translocation from the bowel to systemic organs after burn injury may contribute to or be a cause of sepsis and multiple organ failure. The stress response confers protection under stressful conditions that would otherwise lead to cell damage or death. We investigated whether prior induction of the stress response by sodium arsenite could affect bacterial translocation after thermal injury. HSP-70, a highly stress-inducible protein, was used as a marker for induction of the stress response. Balb/c mice were intravenously injected with 4 mg/kg of sodium arsenite and killed at selected times post-treatment. Other treated mice were then gavaged with 10(10) E. coil or 10(10) 111In-labeled E. coil followed by a 20% burn. Survival was observed for 10 days. Mice gavaged with radiolabeled E. coil were killed 4 h post-burn to determine the effect of HSP-70 induction on microbial translocation in mesenteric lymph nodes (MLN), liver, and spleen. Sodium arsenite-injected mice showed HSP-70 induction in the ileum that increased in a time-dependent manner with peak expression 12 h post-injection. Treated mice showed a significantly higher survival rate (93%) than controls (46%; P < 0.05), and detection of 111In-labeled E. coli was significantly less in the liver and spleen (P < 0.05). These data show that sodium arsenite induced HSP-70 expression in the small intestine. The stress response was associated with significantly increased survival and significant decrease in detection of 111In-labeled E. coil in the liver and spleen in a burned mouse model with gut-derived sepsis.     

Prevention of IgG2a production as a result of allotype-specific interaction between T and B cells

BALB/c T cells, which can prevent normal C57BL IgG2a allotype (G2) production of Ig-congenic partner mice (C.B mice), are shown capable of preventing the growth and G2 production of a C.B plasmacytoma (CBPC 101). Such cytotoxic or suppressor T cells are clearly allotype-specific (G2 Tcs cells). And since CBPC 101 B cells do not require specific helper T cells in order to grow, we infer that G2-bearing B cells (normal or neoplastic) must be the direct target of G2 Tcs cells. This mode of T cell prevention of allotype production contrasts that reported for suppressor T cells in (BALB/c x SJL)F1 mice.     

Effect of blood transfusion on survival in a mouse bacterial peritonitis model

Allogeneic blood transfusions can result in alloimmunization or immunosuppression. A previous study demonstrated a deleterious effect of allogeneic blood transfusion on tumor growth in mice that was dependent, in part, on the dose of tumor cells with which the host animal was inoculated. The current study examined the effect of a similar allogeneic blood transfusion protocol on survival in a mouse bacterial peritonitis model. C57Bl/6J mice were transfused with 0.2 mL of heparinized fresh whole blood from C57Bl/6J (syngeneic) or Balb/c (allogeneic) mice. Transfusions were given on Days -10 and -7. On Day 0, mice were injected intraperitoneally with 10(7) Escherichia coli. Survival at Day 7 was 61 percent in the allogeneic blood transfusion group and 55 percent in the syngeneic blood transfusion group (p = 0.52). Experiments using different strains of mice, different transfusion protocols, and different doses of bacteria also failed to demonstrate an effect of allogeneic blood transfusion on survival. The results demonstrate that blood transfusion does not influence survival after a septic challenge with bacteria. The data obtained in the present study, together with those obtained in the tumor model, suggest that the mechanisms by which the allogeneic blood transfusion impedes host defense against bacterial infections is different from the mechanisms involved in tumor growth.     

糖尿病患者血清糖化低密度脂蛋白水平研究

目的 分析糖尿病患者检测血清糖化低密度脂蛋白(G-LDL)的意义,探讨G-LDL与血糖、血脂的相关性.方法 随机抽取2008年6月至2010年6月在该院检查的100例糖尿病患者作为实验组,100例健康体检者作为对照组.分别检查两组血清G-LDL、血糖、三酰甘油(TG)、胆固醇(Chol)、低密度脂蛋白胆固醇(LDL-C)等.结果 实验组G-LDL、血糖、TG、Chol水平明显高于对照组,差异有统计学意义(P<0.05);LDL-C水平与对照组比较,差异无统计学意义(P＞0.05).实验组血清G-LDL水平与血糖呈正相关(r=0.627,P<0.05),与LDL-C无关(r=0.326,P＞0.05).结论 糖尿病患者G-LDL水平明显升高,检测G-LDL作为诊断和评价糖尿病的生化指标具有重要指导意义.     

短期胰岛素强化治疗对初诊2型糖尿病患者胰岛B细胞功能的影响

目的观察强化胰岛素治疗对新诊断2型糖尿病(T2DM)患者胰岛B细胞功能的影响,并比较两种强化胰岛素治疗方案的疗效。方法将60例空腹血糖大于11.1mmol/L的初诊2型糖尿病患者分为多次皮下胰岛素注射治疗组(胰岛素注射液)和胰岛素泵组,同期选择健康体检人群30例作为健康对照组,对糖尿病患者进行2周的胰岛素强化治疗,比较强化治疗前后血糖、血三酰甘油(TG)及总胆固醇(TC)、空腹胰岛素原(FPI)、空腹胰岛素(FIns)、FPI/FIns、HomaB功能指数(HBCI)及口服馒头餐—胰岛素释放试验中糖负荷后胰岛素曲线下面积(AUCi)、AUCi/AUCg、糖负荷后30min胰岛素增值与血糖增值的比值(ΔI30'/ΔG30'),并对两个治疗组之间的上述指标进行比较。结果 (1)胰岛素注射组、胰岛素泵组两组血糖、三酰甘油、总胆固醇和糖化血红蛋白(GHbA1c)水平均明显高于健康对照驵,但两组间各指标间差异无统计学意义;(2)胰岛素强化治疗后,FIns、FIns/FBG、HBCI、AUCi和AUCi/AUCg,以及ΔI30'/ΔG30'均较治疗前显著升高(P<0.01或P<0.05),血糖、TG、TC和FPI和FPI/FIns水平较治疗前明显下降(P<0.01或P<0.05);胰岛素泵组每日所用胰岛素总量较胰岛素注射组少,患者血糖达标所需时间缩短,且胰岛素泵组反映胰岛B细胞功能的指标改善更明显(与胰岛素注射组相比,P<0.05)。结论短期胰岛素强化治可明显改善初诊2型糖尿病患者胰岛B细胞功能,胰岛素泵治疗效果相对较好。     

GENETICS OF A NEW IgVH (T15 IDIOTYPE) MARKER IN THE MOUSE REGULATING NATURAL ANTIBODY TO PHOSPHORYLCHOLINE

The idiotype present on the Fab of a phosphorylcholine-binding IgA myeloma protein TEPC 15 (T15) of BALB/c origin was found in normal serum of BALB/c mice. Molecules carrying the T15 idiotype in normal serum could be adsorbed with Sepharose phosphorylcholine beads and R36A pneumococci. The T15 idiotype is absent in germ-free BALB/c but appears when the mice are conventionalized. A survey of normal sera of inbred strains for the T15 idiotype showed it to be present in BALB/c, 129, C57L, C58, and ST and absent or in low levels in CBA, C3H, C57BL/6, C57BL/Ka, C57BL/10, SJL, B10.D2, DBA/2, RIII, A, AL, AKR, NZB, and NH inbred strains of mice. The T15 idiotype is associated with some but not all strains carrying the IgC_H allotypes found in BALB/c. Linkage of genes controlling the T15 idiotype in normal serum to the IgC_H locus of BALB/c was demonstrated in F₂ progeny of a BALB/c and C57BL cross, Bailey's recombinant inbred strains, C x BD, C x BE, C x BG, C x BH, C x BI, C x BJ, C x BK, and CB20 congenic strains. Among these strains, only those possessing the IgC_H locus of BALB/c including the F₂ progeny consisting of BALB/c homozygotes and BALB/c/C57BL heterozygotes and C x BG and C x BJ recombinants showed the T15 idiotype.     

SPF级Balb/c小鼠脏器质量、脏器系数、血常规、血生化指标的测定与比较

背景：实验动物重要基础数据的标准化测定,是实行动物标准化监督管理的重要依据。目的：测定SPF级Balb/c小鼠主要脏器质量、脏器系数、血常规、血生化指标,并进行比较。方法：取18g左右Balb/c小鼠240只,雌雄各半,饲养1周后,精确称量体质量和主要脏器质量,计算脏器系数,并检测血常规及血生化指标。结果与结论：雌性与雄性Balb/c小鼠比较：①肺、脾、双肾、心、膀胱质量差异有显著性意义（P〈0.01或P〈0.05）。②肺、脾、双肾、膀胱脏器系数差异有显著性意义（P〈0.01或P〈0.05）。③白细胞、单核细胞、嗜碱性粒细胞百分比、红细胞、血红蛋白、红细胞平均血红蛋白浓度、红细胞分布宽度、嗜酸性粒细胞百分比差异有显著性意义（P〈0.01或P〈0.05）。④总蛋白、白蛋白、白球比、血糖、肌酐、尿酸、三酰甘油、总胆固醇、低密度脂蛋白、高密度脂蛋白、铁、磷、尿素氮差异有显著性意义（P〈0.01或P〈0.05）。说明性别对SPF级Balb/c小鼠主要脏器、主要脏器系数、血常规、血生化指标有影响。     

Escherichia coli modulates extraintestinal spread of Staphylococcus aureus

Staphylococcus aureus remains one of the most frequent causes of life-threatening systemic infection in surgical and trauma patients. It is understood that S. aureus colonization predisposes to complicating infection, but extraintestinal dissemination of S. aureus from the intestinal lumen to the draining mesenteric lymph nodes has not been systematically studied. After oral inoculation with high numbers of S. aureus, otherwise normal mice had low levels of cecal S. aureus (6.7 log10/g) and the incidence of extraintestinal dissemination was 30%. As expected, parenteral Escherichia coli lipopolysaccharide (LPS) was associated with increased numbers of cecal S. aureus, but the incidence of translocation remained unchanged. Purified LPS had no effect on S. aureus internalization by cultured HT-29 enterocytes and no effect on S. aureus transmigration through confluent enterocytes. To begin to clarify the effect of alterations in cecal bacteria on S. aureus translocation, mice were orally inoculated with E. coli and S. aureus. Compared with mice inoculated with S. aureus alone, these mice had increased numbers of cecal E. coli and S. aureus, and the incidence of S. aureus translocation nearly doubled from 46% to 88%. Experiments with HT-29 enterocytes indicated that viable E. coli had no effect on S. aureus internalization, but viable E. coli was at least 40 times more potent in inducing S. aureus transmigration across confluent enterocytes compared with a corresponding amount of purified LPS. Thus, S. aureus disseminated from the intestinal tract of normal mice by a mechanism that could involve paracellular migration across the intestinal epithelial barrier.     

Donor WBCs can persist and transiently mediate immunologic function in a murine transfusion model: effects of irradiation, storage, and histocompatibility

BACKGROUND: Donor WBCs are responsible for numerous transfusion complications, but little is known concerning the natural history of their clearance following transfusion or of their function in the recipient's circulation. A murine transfusion model was developed to investigate the effects of blood component characteristics and histocompatibility on donor WBC survival kinetics and function. STUDY DESIGN AND METHODS: To investigate the effects of storage and irradiation, fresh whole blood and blood stored for 1, 2, and 6 weeks at 4 degrees C, all from male C57b (H2K(b)) mice, was transfused to female Balb/c (H2K(d)) mice. To study the effect of histocompatibility, blood was also transfused from C57b mice to Balb/c, FVB, C3H, and SW (outbred) mice. To investigate the xenogeneic setting, blood from humans, rats, and rabbits was transfused to Balb/c mice. Samples were collected weekly after transfusion, and the donor WBCs were analyzed, targeting the Y-chromosome with quantitative PCR. To investigate donor WBC function, dinitrochlorobenzene (DNCB) sensitivity was induced in donor and recipient mice, and the transfusion recipients were observed for hypersensitivity to DNCB. RESULTS: Donor WBCs had reduced in vivo survival equivalent to their period of storage ex vivo at 4 degrees C. Irradiation of donor blood produced no observable difference in donor WBC survival. Allogeneic male donor WBCs persisted (100-<1 cell/microL) in female Balb/c recipient mice blood over 6 weeks. Donor WBC survival kinetics displayed an early MHC-dependent phase, which was followed by a more rapid phase that was not influenced by donor-recipient MHC differences. All donor WBCs were cleared within 24 to 48 hours. DNCB sensitivity was passed through transfusion, where it was transiently expressed in naive recipients. CONCLUSION: The clearance of donor WBCs in the murine transfusion model is much slower than that in humans. Allogeneic donor WBC clearance may be biphasic, involving MHC-dependent as well as MHC-independent mechanisms. DNCB sensitivity can be transferred transiently to a naive recipient.     

Effects of a human antiflagellar monoclonal antibody in combination with antibiotics on Pseudomonas aeruginosa infection.

The in vivo activity of human immunoglobulin M monoclonal antibody IN-2A8, which is specific for flagellum type b of Pseudomonas aeruginosa, was evaluated in comparison to anti-O antigen (serotype B) MAb KO-2F2 and in combination with antibiotics. IN-2A8 showed stronger activity than KO-2F2 against subcutaneous infection in burned mice, while it was much less active against intraperitoneal infection in normal mice. In a burn infection model, IN-2A8 inhibited the increase of bacteria in skin lesions weakly and that in blood significantly, suggesting that it strongly suppressed bacterial spread to blood. The activity of IN-2A8 in combination with 10 antipseudomonal antibiotics against intraperitoneal infection was examined. Clear additive effect was observed with a combination of either carbapenem or aminoglycoside antibiotics in terms of mouse survival. The administration of an antibiotic, imipenem-cilastatin, simultaneously with or before that of IN-2A8 gave a combined effect, but the reverse order did not. The combination of IN-2A8 with imipenem-cilastatin decreased numbers of viable bacteria in the peritoneal cavity and blood and kept them low for a longer time than did either treatment alone. These results suggest that an antiflagellar monoclonal antibody would be effective against systemic infection in combination with some kinds of antibiotics.     

抗阻训练对老年2型糖尿病患者糖代谢、脂代谢等方面的影响

目的探讨抗阻训练对老年2型糖尿病患者血糖、血脂、糖化血红蛋白（HbAlC）、胰岛素水平、尿微量白蛋白的影响。方法60例老年2型糖尿病患者随机分为观察组和对照组,每组30例。2组实验前均进行饮食指导,实验期间常规用药不变。对照组保持日常生活习惯,观察组进行抗阻训练。观察2组患者治疗前后空腹血糖（FBG）、餐后2小时血糖（2hBG）、空腹胰岛素（Fins）、餐后2h胰岛素（2hlns）、血脂、HbAlC、尿微量白蛋白（MA）水平。结果观察组治疗后FBG、2hBG、HbAlc水平明显降低。观察组治疗后FBG、2hBG、HbAIc水平明显低于对照组。2组患者治疗后甘油三酯（TG）、总胆固醇（TC）、低密度脂蛋白（LDL—c）水平均明显降低;观察组治疗后TG、TC、LDL—C水平明显低于对照组。2组治疗后Fins、2hIns、MA水平均较治疗前明显降低。观察组治疗后Fins、MA水平均较对照组明显降低。结论抗阻训练在调控老年2型糖尿病患者糖代谢和脂代谢等方面具有明显作用。     

Assessment of the role of antibiotics and enterococcal virulence factors in a mouse model of extraintestinal translocation

OBJECTIVE: To study the relative contribution of antibiotics and bacterial virulence factors in the process of translocation of Enterococcus faecalis from the gut to extraintestinal organs. DESIGN: Prospective controlled animal study. SETTING: Animal experimental laboratory at a university medical center. SUBJECTS: Fifty-two female Balb/c mice. INTERVENTIONS: We developed a mouse model to study the translocation of Enterococcus faecalis from the intestinal tract. Balb/c mice received sterile drinking water or antibiotic combinations to deplete their indigenous intestinal microflora. The animals subsequently were fed genetically engineered enterococci expressing different combinations of the putative enterococcal virulence factors aggregation substance and binding substance. Animals were killed, and their livers, spleens, and mesenteric lymph nodes were aseptically removed and cultured along with fecal samples for enumeration of bacteria. MEASUREMENTS AND MAIN RESULTS: All animals were colonized with the test strains at 2-6 x 109 colony forming units/g of feces; in the antibiotic-treated animals, feces were free from anaerobes and Enterobacteriaceae. In animals fed the identical bacterial mutant, the colony counts in mesenteric lymph nodes were significantly lower in mice not treated with antibiotics than in those treated with antibiotics (p =.016). Multigroup analysis of variance revealed no significant differences of the translocation frequencies for the different mutant strains; however, the differences were statistically significant for all groups receiving antibiotics vs. the group not receiving antibiotics (p <.05-.01). There was a trend (although not statistically significant) for a higher proportion of positive cultures from either spleen or liver in mice that had enterococci recovered from their mesenteric lymph nodes (28%) relative to those that did not have enterococci isolated from the lymph nodes (12%; rate ratio 2.39, p =.30 by logistic regression analysis). CONCLUSIONS: Oral antibiotics can select for extraintestinal translocation of Enterococcus faecalis, and neither aggregation substance nor binding substance seems to be required for this process. The experiments encourage further exploration of host and microbial factors contributing to translocation and may provide a better understanding of the pathogenesis of enterococcal infections in patients in intensive care units.     

Induction of immune tolerance across major histocompatibility complex barrier by transfusion of ultraviolet B-irradiated immature dendritic cells

BACKGROUND: Transfusion of ultraviolet B (UVB)-irradiated peripheral blood mononuclear cells (PBMNCs) induces immunologic tolerance across the major histocompatibility complex (MHC) barrier in a murine model. It is necessary, however, to reduce contaminating platelets (PLTs) to a minimum. Ex vivo preparation of dendritic cells (DCs) offers an opportunity to rid the contaminating PLTs. The use of immature and mature DCs (iDCs and mDCs) with and without UVB irradiation for tolerance induction was therefore investigated. STUDY DESIGN AND METHODS: iDCs and mDCs were prepared by culture of Balb/c (H-2d) mouse marrow cells in the presence of granulocyte-macrophage-colony-stimulating factor and interleukin-4. Different dose schedules of iDCs were tested for tolerance induction in CBA (H-2k) mice. Tolerance induction by UVB-irradiated iDCs and mDCs was compared. Tolerance induction in two additional strains of mice (C3H and C57BL/6) was also studied. The induction of tolerance was tested by challenging transfusions of treated mice with PBMNCs from the donor strain. The induction of negative regulatory CD4+ T cells in tolerized mice was examined. RESULTS: Four weekly transfusions of 5 x 10(4) UVB-irradiated iDCs from Balb/c mice efficiently induced immune tolerance in CBA and C3H mice. iDCs and mDCs without UVB irradiation could not induce immune tolerance. Tolerance induced by transfusions of UVB-irradiated iDCs was associated with the development of CD4+-regulatory T cells as demonstrated by an adoptive transfer study. CONCLUSION: Transfusion of UVB-iDCs induces immune tolerance across the MHC barrier in certain combinations of mouse strains. The results support the idea that iDCs irradiated with UVB may be applied to induce immune tolerance across the MHC barrier.     

糖尿病血管病变患者血清补体C1q和B因子检测的临床意义

目的 测定2型糖尿病血管病变患者血清补体C1q(C1q)和B因子(BF)的水平,分析C1q和BF与糖尿病血管病变患者的相关性。方法 透射免疫比浊法测定155例2型糖尿病血管病变患者、133例单纯性2型糖尿病患者(T2DM)和150例正常对照组的血清C1q和BF水平,并测定各组的生化指标:血糖(Glu)、糖化血红蛋白(HbA1c)、三酰甘油(TG)和总胆固醇(TC),做统计分析。结果 糖尿病血管病变组与T2DM组、对照组比较,C1q和BF均升高,差异有统计学意义(P<0.01),糖尿病血管病变组和T2DM组与对照组比较,C1q和BF均升高,差异有统计学意义(P<0.01); C1q和BF均与Glu,HbA1c,TG,TC呈正相关(C1q:r=0.35,0.40,0.34,0.36; BF:r=0.29,0.38,0.28,0.26)。结论 血清C1q和BF在T2DM及其血管病变的发生和发展过程中可能起重要作用。