IL-10 plays an important role in the control of inflammation but not in the bacterial burden in S. epidermidis CNS catheter infection.

BACKGROUND: Shunt infection is a frequent and serious complication in the surgical treatment in hydrocephalus. Previous studies have shown an attenuated immune response to these biofilm-mediated infections. We proposed that IL-10 reduces the inflammatory response to Staphylococcus epidermidis (S. epidermidis) CNS catheter infection. METHODS: In this study, a murine model of catheter-associated S. epidermidis biofilm infection in the CNS was generated based on a well-established similar model for S. aureus. The catheters were pre-coated with a clinically derived biofilm-forming strain of S. epidermidis (strain 1457) which were then stereotactically implanted into the lateral left ventricle of 8-week-old C57BL/6 and IL-10 knockout (IL-10 knockout) mice. Bacterial titers as well as cytokine and chemokine levels were measured at days 3, 5, 7, and 10 in mice implanted with sterile and S. epidermidis-coated catheters. RESULTS: Cultures demonstrated a catheter-associated and parenchymal infection that persisted through 10 days following infection. Cytokine analysis of the tissue surrounding the catheters revealed greater levels of IL-10, an anti-inflammatory cytokine, in the infected group compared to the sterile. In IL-10 KO mice, we noted no change in bacterial burdens, showing that IL-10 is not needed to control the infection in a CNS catheter infection model. However, IL-10 KO mice had increased levels of pro-inflammatory mediators in the tissues immediately adjacent to the infected catheter, as well as an increase in weight loss. CONCLUSIONS: Together our results indicate that IL-10 plays a key role in regulating the inflammatory response to CNS catheter infection but not in control of bacterial burdens. Therefore, IL-10 may be a useful therapeutic target for immune modulation in CNS catheter infection but this should be used in conjunction with antibiotic therapy for bacterial eradication.

Reflections on year one of a new residency program: Lessons for future leaders from residents and educators.

This article was migrated. The article was marked as recommended. As the number of graduating medical students increases, the number of primary care residency positions is not keeping pace. One solution to this problem is the creation and accreditation of new residencies, although there is little literature describing the perspectives of the residents and educators who found new programs. Seven out of ten resident physicians who served as the inaugural interns in a new residency training program in pediatrics provide their reflection on the distinctive perspective they had from this experience. They have identified consensus themes in topic areas of strengths, challenges, and lessons learned from training in a new program. Themes applying to strengths of participating in a new residency training program were the opportunity to shape the program, individualized learning experience, and enthusiastic faculty. Challenges of a new program included missing upper level residents, diverse faculty expectations, and morale. Themes under lessons learned included resident engagement, expectations and feedback, and wellness. Each theme was then considered in the context of the medical education literature, underscoring the important balance that new program leaders must strike between structure and flexibility. This inaugural resident class has identified key challenges and opportunities to inform education leaders who are planning new GME training programs.

Improved siRNA/shRNA functionality by mismatched duplex.

siRNA (small interfering RNA) and shRNA (small hairpin RNA) are powerful and commonly used tools in biomedical research. Currently, siRNAs are generally designed as two 21 nt strands of RNA that include a 19 nt completely complementary part and a 2 nt overhang. However, since the si/shRNAs use the endogenous miRNA machinery for gene silencing and the miRNAs are generally 22 nt in length and contain multiple internal mismatches, we tested if the functionality can be increased by designing the si/shRNAs to mimic a miRNA structure. We systematically investigated the effect of single or multiple mismatches introduced in the passenger strand at different positions on siRNA functionality. Mismatches at certain positions could significantly increase the functionality of siRNAs and also, in some cases decreased the unwanted passenger strand functionality. The same strategy could also be used to design shRNAs. Finally, we showed that both si and miRNA structured oligos (siRNA with or without mismatches in the passenger strand) can repress targets in all individual Ago containing cells, suggesting that the Ago proteins do not differentiate between si/miRNA-based structure for silencing activity.

Alternative processing of primary microRNA transcripts by Drosha generates 5' end variation of mature microRNA.

BACKGROUND: It is generally believed that the miRNA processing machinery ensures the generation of a mature miRNA with a fixed sequence, particularly at its 5' end. However, we and others have recently noted that the ends of a given mature miRNA are not absolutely fixed, but subject to variation. Neither the significance nor the mechanism behind the generation of such miRNA polymorphism is understood. miR-142 is an abundantly expressed miRNA in hematopoietic cells and exhibits a high frequency of 5' end polymorphism. METHODOLOGY/PRINCIPAL FINDINGS: Here we show that a shift in the Drosha processing of pri-miRNA generates multiple forms of miR-142s in vivo with differing 5' ends that might target different genes. Sequence analysis of several pre-miRNA ends cloned from T cells reveals that unlike many other pri-miRNAs that are processed into a single pre-miRNA, pri-miR-142 is processed into 3 distinct pre-miR-142s. Dicer processing studies suggest that each of the 3 pre-miR-142s is processed into a distinct double-stranded miRNA, giving rise to 4 mature miRNA variants that might regulate different target gene pools. CONCLUSIONS/SIGNIFICANCE: Thus, alternative Drosha processing might be a novel mechanism for diversification of the miRNA target gene pool.