Pathophysiological Role of Nucleic Acid-Sensing Pattern Recognition Receptors in Inflammatory Diseases

Pattern recognition receptors (PRRs) play critical roles in recognizing pathogen-derived nucleic acids and inducing innate immune responses, such as inflammation and type I interferon production. PRRs that recognize nucleic acids include members of endosomal Toll-like receptors, cytosolic retinoic acid inducible gene I-like receptors, cyclic GMP–AMP synthase, absent in melanoma 2-like receptors, and nucleotide binding oligomerization domain-like receptors. Aberrant recognition of self-derived nucleic acids by these PRRs or unexpected activation of downstream signaling pathways results in the constitutive production of type I interferons and inflammatory cytokines, which lead to the development of autoimmune or autoinflammatory diseases. In this review, we focus on the nucleic acid-sensing machinery and its pathophysiological roles in various inflammatory diseases.

Inhibition of lipopolysaccharide-induced inflammatory responses by 1'-acetoxychavicol acetate

Lipopolysaccharide on gram negative bacteria can be detected by Toll-like receptor 4 (TLR4) to elicit a series of innate immune responses, leading to inflammation to eliminate the targeted pathogen. However, dysregulation in the responses results in excessive inflammation. The 1'-acetoxychavicol acetate (ACA) is a bioactive compound originated from Alpinia species known to have anti-inflammatory and apoptosis-inducing properties. Here, we found that ACA inhibits lipopolysaccharide-induced expression and production of proinflammatory cytokines such as interleukin 6 and TNFα by macrophages. ACA suppresses the activation of NF-κB and MAP kinases in TLR4 signaling. Moreover, ACA also inhibits TLR4-mediated induction of type I interferon by suppressing IRF3 activation. In lipopolysaccharide-challenged mice, ACA treatment successfully increased the survival of mice and alleviated inflammation in the lung. Thus, ACA is a potential anti-inflammatory agent to regulate excessive inflammation. This article is protected by copyright. All rights reserved.

Exploration of Pattern Recognition Receptor Agonists as Candidate Adjuvants

Adjuvants are used to maximize the potency of vaccines by enhancing immune reactions. Components of adjuvants include pathogen-associated molecular patterns (PAMPs) and damage-associate molecular patterns (DAMPs) that are agonists for innate immune receptors. Innate immune responses are usually activated when pathogen recognition receptors (PRRs) recognize PAMPs derived from invading pathogens or DAMPs released by host cells upon tissue damage. Activation of innate immunity by PRR agonists in adjuvants activates acquired immune responses, which is crucial to enhance immune reactions against the targeted pathogen. For example, agonists for Toll-like receptors have yielded promising results as adjuvants, which target PRR as adjuvant candidates. However, a comprehensive understanding of the type of immunological reaction against agonists for PRRs is essential to ensure the safety and reliability of vaccine adjuvants. This review provides an overview of the current progress in development of PRR agonists as vaccine adjuvants, the molecular mechanisms that underlie activation of immune responses, and the enhancement of vaccine efficacy by these potential adjuvant candidates.

Molecular Characterization of Avian Infectious Bronchitis Virus Isolated in Malaysia during 2014-2016

Avian Infectious Bronchitis (IB) is a highly contagious disease which can cause huge economic losses to the poultry industry. Forty five IB viruses (IBV) were isolated from poultry in Malaysia during 2014-2016. Phylogenetic analysis of the spike glycoprotein 1 (S1) gene revealed that all isolates were clustered into five distinct groups. The predominant type of IBV isolated was QX strains (47%), second was 4/91 type (27%), followed by Malaysian strain MH5365/95 (13%), Massachusetts type (11%) and finally Taiwanese strains (2%). Four types of S1 protein cleavage recognition motifs were found among the isolates which includes HRRRR, RRSRR, RRFRR and RRVRR. To our knowledge, this is the first report describing the motif RRVRR and are unique to Malaysian strains. Six IBVs were grouped in Malaysian MH5365/95 strains. Among these, one isolate was different from others where it only shared 82% identity with MH5365/95 and to others. It formed its own branch in the Malaysian cluster suggesting it may be a variant unique to Malaysia. Alignment analysis of the S1 amino acid sequences indicated that point mutations, insertions and deletions contribute to the divergence of IB variants. This study indicated at least five groups of IBV are circulating in Malaysia with most of the isolates belonged to QX strains. As new IBV variants continue to emerge, further study need to be carried out to determine whether the current available vaccine is able to give protection against the circulating virus.

An investigation of arsenic contamination in Peninsular Malaysia based on Centella asiatica and soil samples

The first objective of this study was to provide data of arsenic (As) levels in Peninsular Malaysia based on soil samples and accumulation of As in Centella asiatica collected from 12 sampling sites in Peninsular Malaysia. The second objective was to assess the accumulation of As in transplanted C. asiatica between control and semi-polluted or polluted sites. Four sites were selected which were UPM (clean site), Balakong (semi-polluted site), Seri Kembangan (semi-polluted site) and Juru (polluted site). The As concentrations of plant and soil samples were determined by Instrumental Neutron Activation Analysis. The As levels ranged from 9.38 to 57.05 μg/g dw in soils, 0.21 to 4.33 μg/g dw in leaves, 0.18 to 1.83 μg/g dw in stems and 1.32-20.76 μg/g dw in roots. All sampling sites had As levels exceeding the CCME guideline (12 μg/g dw) except for Kelantan, P. Pauh, and Senawang with P. Klang having the highest As in soil (57.05 μg/g dw). In C. asiatica, As accumulation was highest in roots followed by leaves and stems. When the As level in soils were higher, the uptake of As in plants would also be increased. After the transplantation of plants to semi-polluted and polluted sites for 3 weeks, all concentration factors were greater than 50 % of the initial As level. The elimination factor was around 39 % when the plants were transplanted back to the clean sites for 3 weeks. The findings of the present study indicated that the leaves, stems and roots of C. asiatica are ideal biomonitors of As contamination. The present data results the most comprehensive data obtained on As levels in Malaysia.

Evaluation of problem-based learning: a lecturer's perspective

INTRODUCTION

The exponential growth in medical/dental knowledge and the ever-expanding influence and sophistication of information technologies have placed a burden of responsibilities on dental educators to fashion out a curriculum that can prepare students to face the coming challenges in the new millennium. Consequently, a curriculum reform took place in the Faculty of Dentistry, National University of Singapore in 1997. Problem-based learning (PBL) was first introduced to the Faculty in 1996 as a pilot project to the 4th year. The purpose of this project was to evaluate the 4-year experience in PBL teaching and learning from the lecturers' point of view.

MATERIALS AND METHODS

All 12 lecturers, who had been involved in the PBL teaching, participated in this questionnaire survey, which was composed of 17 questions with a 5-digit Likert scale. Data analysis was carried out using the Spearman's correlation, t-test, and the Mann-Whitney U test.

RESULTS

Six female, 5 male and 1 unidentified lecturers were recruited into this survey with a 100% response rate. In general, lecturers learned more in teaching PBL and significantly took pleasure in the interactive learning and self-directed learning modes inherent to PBL (P = 0.004). Compared to the male lecturers, female lecturers had a greater propensity to feel that PBL teaching might not be cost-effective (P = 0.03). Senior lecturers felt more fulfilled compared with the younger ones (P = 0.026). Those lecturers who enjoyed the interactive learning experience in PBL seemed to like the self-directed learning and felt more fulfilled through teaching PBL compared to the traditional teaching (TT) (P < 0.01). They also felt that PBL may be cost-effective (P < 0.01). Lecturers did not have difficulties in being a facilitator (P = 0.04). Interestingly, lecturers who found difficulties in being a facilitator for the PBL class seemed to learn more in teaching PBL classes than in TT (P < 0.05). Overall, lecturers would like to suggest more PBL to be incorporated into the curriculum (P = 0.02). Nevertheless, lecturers were concerned about the knowledge gaps in students learning with PBL (P = 0.01) and the time constraint of students (P = 0.002).

CONCLUSION

The results of this study reveal the pros and cons of the current PBL teaching method and may thus provide proper guidelines to shape the further development of PBL in our faculty.

Methods of proximal amalgam overhang removal--a comparison of different techniques

It is widely accepted that the overhanging restoration is an aggravating factor in the initiation and progression of periodontal disease, and when detected, the overhang should be removed. Some methods for removing proximal amalgam overhangs are the EVA reciprocating motor driven system, roto-pro, flame-shaped steel bur, diamond bur and sonic scaler. This article illustrates the trimmed surface after overhang removal with photographs taken at 1:1 magnification. The smoothest surface was produced by EVA system where the overhang was removed with a diamond tip followed by polishing with prophylaxis paste using the plastic tip. The roughest surface was produced by the sonic scaler, whilst the others were intermediate. Of the single step methods, the instrument which combined speed while leaving a reasonable surface was the rotopro.