Characteristics and Immunological Roles of Surface Layer Proteins in Clostridium difficile

Clostridium difficile is a major causative agent of antibiotic-associated diarrhea and has become the most common pathogen of healthcare-associated infection worldwide. The pathogenesis of C. difficile infection (CDI) is mediated by many factors such as colonization involving attachment to host intestinal epithelial cells, sporulation, germination, and toxin production. Bacterial cell surface components are crucial for the interaction between the bacterium and host cells. C. difficile has two distinct surface layer proteins (SLPs): a conserved high-molecular-weight SLP and a highly variable low-molecular-weight SLP. Recent studies have shown that C. difficile SLPs play roles not only in growth and survival, but also in adhesion to host epithelial cells and induction of cytokine production. Sequence typing of the variable region of the slpA gene, which encodes SLPs, is one of the methods currently used for typing C. difficile. SLPs have received much attention in recent years as vaccine candidates and new therapeutic agents in the treatment of C. difficile-associated diseases. Gaining mechanistic insights into the molecular functions of C. difficile SLPs will help advance our understanding of CDI pathogenesis and the development of vaccines and new therapeutic approaches. In this review, we summarize the characteristics and immunological roles of SLPs in C. difficile.

Detection and genotyping of moxifloxacin-resistant Clostridium difficile by multiplex polymerase chain reaction / 中华传染病杂志

Objective To develop a multiplex polymerase chain reaction (PCR )method for detecting and genotyping moxifloxacin-resistant Clostridium difficile (C.difficile)isolates.Methods Specific PCR primers of slpA genotypes gr,hr,fr,gc08 and 078 were designed according to the differences of slpA nucleotide sequences in different C.difficile genotypes,and the house-keeping gene tpi specific PCR primers were also added for the construction of multiplex PCR method.Nine common intestinal normal and pathogenic strains were used to verify the specificity of slpA multiplex PCR for the detection of C.difficile.Forty-six C.difficile reference strains,belonging to 11 slpA genotypes,were used to verify the ability of the multiplex PCR method for dectecting and genotyping.Thirty-nine moxifloxacin-resistant clinical isolates were genotyped by the multiplex PCR,and its clinical value was evaluated by comparing with slpA sequence typing (slpA ST)method.Results All the 9 intestinal normal and pathogenic strains were negative when detected by the multiplex PCR.And tpi of 46 C. difficile reference strains were positive,and 36 strains belonging to slpA genotypes gr,hr,fr,gc08 and 078 were genotyped correctly.Other 10 strains which belonged to other 6 genotypes were non-typeable. Among 39 moxifloxacin-resistant clinical isolates,all were positive of tpi,and 32 isolates were typed correctly by the multiplex PCR method,including 22 slpA genotypes gc08,6 genotypes hr,2 genotypes fr,and 2 genotypes 078,which were consistent with slpA ST.However,7 isolates could not be typed by multiplex PCR,which were identified as other genotypes not included in the multiplex PCR by slpA ST. Conclusions A convenient and rapid multiplex PCR method for the detection of C.difficile is established successfully,which can distinguish among five slpA genotypes.slpA genotype gc08 is the common genotype of moxifloxacin-resistant clinical isolates.

Modification of surface pretreatment of white spot lesions to improve the safety and efficacy of resin infiltration / 대한치과교정학회지

OBJECTIVE: A low-viscosity resin (infiltrant) was used to inhibit the progression of white spot lesions (WSLs) and resolve associated esthetic issues. An alternative pretreatment was explored to increase the pore volume of the surface layer of the WSLs. Also, the penetration effects of the infiltrant were evaluated for various pretreatments. METHODS: Sixty two artificial lesions were fabricated on bovine teeth. As a positive control, 15% HCl gel was applied for 120 seconds. Further, 37% H3PO4 gel was applied for 30 seconds using three methods. The samples were divided as follows: H3PO4 only group, H3PO4 sponge group, and H3PO4 brush group. The acid was gently rubbed with the applicators (i.e., a sponge or brush) throughout the application time. To compare the effects of resin infiltration, twenty paired halves of specimens were treated with an infiltrant (ICON(R)). RESULTS: Thicknesses of the removed surface layers and infiltrated areas were evaluated by confocal laser scanning microscope. The positive control and the 37% H3PO4 brush group failed to show significant differences in the removed thickness (p > 0.05); however, the mean percentage of the infiltrated area was higher in the 37% H3PO4 brush group (84.13 +/- 7.58%) than the positive control (63.51 +/- 7.62%, p < 0.001). Scanning electron microscope observations indicate higher pore volumes for the 37% H3PO4 brush group than for the positive control. CONCLUSIONS: Application of 37% H3PO4 with a brush for 30 seconds increased the pore volume of WSL surface layers and the percentage of infiltrated areas in comparison to the use of 15% HCl for 120 seconds.

Research progress of lactobacillus surface layer protein / 肠外与肠内营养

Lactobacillus can maintain the stability of microbiological environment in intestine and its surface layer protein controls the biological function of intestinal epithelia cells. The mechanism of adhering had been studied. In this article, we review the progress of surface layer protein in the study of the isolation, identification and the biological reaction with the intestinal epithelia cells .

Relationship between enamel demineralization and ultrastructure of surface layer under driving forces of dental plaque fluid / 第三军医大学学报

Objective To evaluate the effect of driving forces similar to those found in dental plaque fluid on the enamel demineralization and ultrastructure of surface layer.Methods The sections of human enamel were exposed to lactic acid solutions with degree of saturation with respect to enamel and degree of saturation with respect to fluoroapatite for 96 h at 25 ℃,using the deionized water as control in the same conditions.Enamel demineralization was monitored using SEM and confocal laser scanning microscopy(CLSM).Results Only was enamel subsurface demineralization detected in solutions with DS_(EN)(0.1-0.3).Enamel mineral loss and micropores of surface layer decreased significantly with increasing DS_(EN) and DS_(FA) values.However,no mineral loss and micropores of surface layer was observed in sections of enamel exposed to solutions with DS_(EN) values of 0.4 and 0.5,which were covered with homogeneous remineralization layer.Conclusion The demineralization driving forces similar to dental plaque fluid under different DS_(EN) and DS_(FA) have significant effects on the surface layer of enamel and the subsurface demineralization process.

Peritoneal vibration increases peritoneal permeability and damages the peritoneal surface layer / 中国病理生理杂志

AIM: To investigate the effect of peritoneal vibration on the peritoneal permeability and the peritoneal surface layer. METHODS: Peritoneal transport rate was examined in twelve male SD rats. Six (S group) were put on an electronic shaker and the other six were used as control (C group). After that, the peritoneum was examined by electron microscopy (EM). RESULTS: The net ultrafiltration volume (NUF) in the S group was lower than that in the C group. This difference in NUF was due to both a significantly higher peritoneal fluid absorption rate and a significantly lower transcapillary ultrafiltration rate in S group as compared to C group. The peritoneal direct lymphatic absorption rate was higher in S group. The transport rates of small solutes were also significantly higher in S group. EM showed that the thickness of the peritoneal surface layer was significantly decreased in S group. CONCLUSION: Our results suggest that the peritoneal surface layer may be an important layer in modulating the peritoneal transport rate.