Pseudomonas fluorescens alters epithelial permeability and translocates across Caco-2/TC7 intestinal cells

Background

Pseudomonas fluorescens has long been considered as a psychrotrophic microorganism. Recently, we have shown that clinical strains of P. fluorescens (biovar 1) are able to adapt at a growth temperature of 37°C or above and induce a specific inflammatory response. Interestingly, a highly specific antigen of P. fluorescens, I2, is detected in the serum of patients with Crohn's disease but the possible role of this bacterium in the disease has not yet been explored. In the present study, we examined the ability of a psychrotrophic and a clinical strain of P. fluorescens to modulate the permeability of a Caco-2/TC7 intestinal epithelial model, reorganize the actin cytoskeleton, invade the target cells and translocate across the epithelium. The behaviour of these two strains was compared to that of the well known opportunistic pathogen P. aeruginosa PAO1.

Results

Both strains of P. fluorescens were found to decrease the transepithelial resistance (TER) of Caco-2/TC7 differentiated monolayers. This was associated with an increase in paracellular permeability and F-actin microfilaments rearrangements. Moreover, the invasion and translocation tests demonstrated that the two strains used in this study can invade and translocate across the differentiated Caco-2/TC7 cell monolayers.

Conclusions

The present work shows for the first time, that P. fluorescens is able to alter the intestinal epithelial barrier function by disorganizing the F-actin microfilament network. Moreover, we reveal that independently of their origins, the two P. fluorescens strains can translocate across differentiated Caco-2/TC7 cell monolayers by using the transcellular pathway. These findings could, at least in part, explain the presence of the P. fluorescens specific I2 antigen in the serum of patients with Crohn's disease.     

移植脾组织血管神经生成规律的动态观察

目的：观察自体脾组织大网膜内移植后，移植脾组织血管神经再生过程中血管内皮细胞生长因子、血管内皮细胞生长因子受体及神经肽Y表达的动态变化，分析自体移植脾组织血管神经生成规律。方法：实验于2004—09／2006—10在解放军第三军医大学基础部外科应用解剖与手术学教研室实验室完成。①选用Wistar大鼠70只，按随机数字表法分为7个时相组，每组10只。②行脾切除自体脾组织大网膜内移植，分别于术后7，14，30，60，90，120，180d，采用免疫组化血管内皮细胞生长因子、血管内皮细胞生长因子受体、神经肽Y阳性神经纤维抗体染色方法，应用光镜、电镜、图像分析观测自体移植脾组织。结果：70只大鼠全部进入结果分析，无脱失。①自体脾组织移植术后7d即有血管长入移植脾组织，180d再生血管接近正常；术后30d神经开始再生，180d趋于正常。②术后7，14d血管内皮细胞生长因子、血管内皮细胞生长因子受体阳性染色细胞密度迅速升高，60d达高峰，随后逐渐降低；术后30d。出现神经肽Y阳性神经纤维。术后180d血管内皮细胞生长因子、血管内皮细胞生长因子受体阳性染色细胞密度趋于正常；术后120，180d神经肽Y阳性神经纤维广泛分布。结论：自体移植脾组织再生过程中移植脾组织再生血管神经来源于大网膜内的神经。自体移植再生脾组织内血管内皮细胞生长因子、血管内皮细胞生长因子受体表达量早期开始升高，移植脾组织先出现血管再生，后出现神经再生。     

二氧化碳和氦气气腹对幼猪红细胞免疫及腹腔液中肿瘤坏死因子α的影响

目的:分别以二氧化碳、氦气模拟气腹动物模型,观察其红细胞免疫功能及腹腔液中肿瘤坏死因子α含量的变化,探讨腹腔镜手术中气腹状态对机体红细胞免疫功能的影响。方法:实验于2004-12/2006-12在西京医院实验外科完成。①实验动物:清洁级幼猪30只,随机数字表法分为3组:二氧化碳气腹组、氦气气腹组、正常对照组,10只/组。②实验方法:幼猪麻醉后,于剑突下正中作小切口,刺入气腹针后连接气腹机,二氧化碳气腹组、氦气气腹组分别注入二氧化碳和氦气,保持气腹压力为1.33～1.60kPa,气体流量为0.3L/min,持续性膨腹30min。正常对照组未进行造模。③实验评估:造模后1,4d,ELISA法检测各组幼猪腹腔灌洗液中细胞数量及其释放肿瘤坏死因子α的含量。各组幼猪分别于造模前1d、造模后1,4d采集外周静脉血,测定红细胞C3b受体花环率(高倍镜下计数200个红细胞,以1个红细胞上结合2个或2个以上酵母菌为阳性花环)、红细胞免疫复合物花环率(结果判断同前)、肿瘤红细胞花环率(高倍镜下计数100个癌细胞,以结合3个或3个以上红细胞为阳性花环)。结果:幼猪30只全部进入结果分析。①腹腔液细胞数量及肿瘤坏死因子α含量检测:造模后氦气气腹组腹腔液中细胞数明显多于二氧化碳气腹组、正常对照组[(10628±326),(5721±271),(5648±262)个/L;t=1.7×10-23,P均<0.05]。与正常对照组腹腔细胞释放肿瘤坏死因子α的含量比较,二氧化碳气腹组明显减少,氦气气腹组明显增多[(462±51),(273±28),(785±68),P均<0.05]。②红细胞免疫功能检测:造模前各组红细胞C3b受体花环率、红细胞免疫复合物花环率、肿瘤红细胞花环率均基本相似(t=0.61～0.92,P均>0.05);造模后1,4d,二氧化碳气腹组红细胞C3b受体花环率、红细胞免疫复合物花环率、肿瘤红细胞花环率均显著低于氦气气腹组和正常对照组(t=8.22×10-5～1.2×10-3,P均<0.05)。二氧化碳气腹组造模后1,4d红细胞C3b受体花环率、红细胞免疫复合物花环率、肿瘤红细胞花环率均明显低于造模前(t=1.9×10-6,1.7×10-4,6.12×10-4,P均<0.05)。结论:不同气体产生的气腹对机体及腹腔内局部免疫功能影响各异,二氧化碳气腹对红细胞免疫功能和腹腔细胞释放肿瘤坏死因子α功能强于氦气气腹。     

How to obtain excellent response rates when surveying physicians

This paper outlines ways to maximize response rates to surveysby summarizing the most relevant literature to date and demonstratinghow these techniques have resulted in consistently high ratesof return in family practice research. We describe the methodologyused in recent surveys of physicians conducted by the Centrefor Studies in Family Medicine through its Thames Valley FamilyPractice Research Unit, located in London, Ontario, Canada andfunded by the Ontario Ministry of Health and Long-Term Care.The identification and implementation of these techniques tomaximize response rates is critical, as primary health careresearchers often rely on information gathered through questionnairesto study physicians' practice profiles, experiences and attitudes.Four separate and distinct mailed surveys of physicians usinga modified Dillman approach were conducted from 2001 to 2004.The sampling strategies, topics, types of questions and responseformats of these surveys varied. The first survey did not useany incentives or recorded delivery/registered mail and receiveda response rate of 48%. In sharp contrast, the other three surveysobtained responses rates of 76%, 74%, 74%, respectively, achievedthrough the use of gift certificates and recorded delivery/registeredmail. Sending a survey by recorded delivery/registered mailtends to result in the survey package being given priority inthe physicians' incoming mail at the practice. Gift certificatespartially compensate physicians for time spent completing thesurvey and recognition of the time required is appreciated.The response rates achieved provide strong evidence to supportthe use of monetary incentives and recorded delivery/registeredmail (along with the Dillman approach) in survey research. Itis anticipated that this evidence will be used by other researchersto justify requests for funding to cover the costs associatedwith incentives and recorded delivery/registered mail. We recommendthe use of these strategies to maximize response rates and improvethe quality of this type of primary health care research. Keywords. Response rates, surveys, physicians.     

Men develop more intraabdominal obesity and signs of the metabolic syndrome after hyperalimentation than women

We prospectively studied the effects of fast food-based hyperalimentation on insulin sensitivity and components of the metabolic syndrome and analyzed this with respect to sex. Twelve nonobese men and 6 nonobese women (26 ± 6.6 years old), and an age-matched control group were recruited. Subjects in the intervention group aimed for 5% to 15% weight increase by doubling their regular caloric intake based on at least 2 fast food meals a day while also adopting a sedentary lifestyle for 4 weeks (<5000 steps a day). Weight of subjects in the intervention group increased from 67.6 ± 9.1 to 74.0 ± 11 kg (P < .001), with no sex difference with regard to this or with respect to changes of total abdominal fat volumes or waist circumferences. Fasting insulin (men: before, 3.8 ± 1.7 μU/mL; after, 7.4 ± 3.1 μU/mL; P = .004; women: before, 4.9 ± 2.3 μU/mL; after, 5.9 ± 2.8 μU/mL; P = .17), systolic blood pressure (men: before, 117 ± 13 mm Hg; after, 127 ± 9.1 mm Hg; P = .002; women: before, 102 ± 5.1 mm Hg; after, 98 ± 5.4 mm Hg; P = .39), serum low-density lipoprotein cholesterol, and apolipoprotein B increased only in the men of the intervention group. The sex differences in the metabolic responses to the intervention were linked to a considerable difference in the fat accumulation pattern; 41.4% ± 9.2% of the increase of the fat volume in the abdominal region was accumulated intraabdominally in men and 22.7 ± 6.5% in women (P < .0001). This study thus showed that women are protected, compared with men, against developing intraabdominal obesity when adopting a standardized obesity-provoking lifestyle. Our findings suggest that it is not different lifestyles and/or behaviors that underlie the fact that men have a higher cardiovascular risk at the same level of percentage of body fat than women.     

Periodontal disease and systemic health: current status

The relationship between poor oral health and systemic diseases has been increasingly recognized over the past two decades. Indeed, the clichés "You cannot have good general health without good oral health", "The mouth is part of the body" and "Floss or die", are gaining an increasing momentum. A large number of epidemiological studies have now linked poor oral health with cardiovascular diseases, poor glycaemic control in diabetics, low birthweight preterm babies and a variety of other conditions. The majority have shown an association, although not always strong. As a result, a number of meta-analyses have been conducted and have confirmed the associations and at the same time cautioned that further studies are required, particularly with regard to the effect of periodontal treatment in reducing risk. A number of biologically plausible mechanisms have been put forward to explain the association and there is accumulating evidence in support of them, although at this stage, insufficient to establish causality. Nevertheless, the relationship between poor oral health and systemic diseases has become a significant issue, such that adult oral health can no longer be ignored in overall health strategies. This review provides an update on current understanding of the contribution of poor oral health to systemic diseases, the possible mechanisms involved and the relevance of this for general dental practitioners.     

Mapping of an autosomal dominant gene for Dupuytren's contracture to chromosome 16q in a Swedish family

Mapping of an autosomal dominant gene for Dupuytren's contracture to chromosome 16q in a Swedish family.Dupuytren's contracture (DC) (OMIM 126900) is the most common connective tissue disease of mankind and has both heritable and sporadic forms. The inherited form is most frequently observed among the xanthochroi peoples of Northern Europe where its most common manifestations are thickening of the palmar fascia and contracture of the fingers. We ascertained a five-generation Swedish family in which DC is inherited in an autosomal dominant manner with high, but incomplete, penetrance by the end of the fifth decade. Blood was collected from all affected and informative unaffected family members for the performance of a genome-wide scan at a resolution of approximately 8 cM for all autosomes. Linkage was established to a single 6 cM region between markers D16S419 and D16S3032 on chromosome 16. A maximal two-point logarithm of odds (LOD) score of 3.18 was achieved at microsatellite marker D16S415 with four other markers in the region producing LODs of >1.5.