Investigation of the Biosynthetic Potential of Endophytes in Traditional Chinese Anticancer Herbs

Traditional Chinese medicine encompasses a rich empirical knowledge of the use of plants for the treatment of disease. In addition, the microorganisms associated with medicinal plants are also of interest as the producers of the compounds responsible for the observed plant bioactivity. The present study has pioneered the use of genetic screening to assess the potential of endophytes to synthesize bioactive compounds, as indicated by the presence of non-ribosomal peptide synthetase (NRPS) and polyketide synthase (PKS) genes. The total DNA extracts of 30 traditional Chinese herbs, were screened for functional genes involved in the biosynthesis of bioactive compounds. The four PCR screens were successful in targeting four bacterial PKS, six bacterial NRPS, ten fungal PKS and three fungal NRPS gene fragments. Analysis of the detected endophyte gene fragments afforded consideration of the possible bioactivity of the natural products produced by endophytes in medicinal herbs. This investigation describes a rapid method for the initial screening of medicinal herbs and has highlighted a subset of those plants that host endophytes with biosynthetic potential. These selected plants can be the focus of more comprehensive endophyte isolation and natural product studies

The effects of β-glucan on human immune and cancer cells

Non-prescriptional use of medicinal herbs among cancer patients is common around the world. The alleged anti-cancer effects of most herbal extracts are mainly based on studies derived from in vitro or in vivo animal experiments. The current information suggests that these herbal extracts exert their biological effect either through cytotoxic or immunomodulatory mechanisms. One of the active compounds responsible for the immune effects of herbal products is in the form of complex polysaccharides known as β-glucans. β-glucans are ubiquitously found in both bacterial or fungal cell walls and have been implicated in the initiation of anti-microbial immune response. Based on in vitro studies, β-glucans act on several immune receptors including Dectin-1, complement receptor (CR3) and TLR-2/6 and trigger a group of immune cells including macrophages, neutrophils, monocytes, natural killer cells and dendritic cells. As a consequence, both innate and adaptive response can be modulated by β-glucans and they can also enhance opsonic and non-opsonic phagocytosis. In animal studies, after oral administration, the specific backbone 1→3 linear β-glycosidic chain of β-glucans cannot be digested. Most β-glucans enter the proximal small intestine and some are captured by the macrophages. They are internalized and fragmented within the cells, then transported by the macrophages to the marrow and endothelial reticular system. The small β-glucans fragments are eventually released by the macrophages and taken up by other immune cells leading to various immune responses. However, β-glucans of different sizes and branching patterns may have significantly variable immune potency. Careful selection of appropriate β-glucans is essential if we wish to investigate the effects of β-glucans clinically. So far, no good quality clinical trial data is available on assessing the effectiveness of purified β-glucans among cancer patients. Future effort should direct at performing well-designed clinical trials to verify the actual clinical efficacy of β-glucans or β-glucans containing compounds

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

The student experience of problem-based learning in medical education in different national contexts

One of the important goals of society is to keep the population healthy. At the basis of this is the preparation of well-trained doctors who keep the health of members of our societies in check. From 1970 onwards, in response to comprehensive reviews of existing medical programmes an international transition commenced with a change of approach in medical education to problem-based learning (PBL) medical programs. Some research into PBL suggests that certain context-specific learning stereotypes exist which may account for the lack of evidence-based success of PBL programs in different national contexts. This thesis argues that the reasons why PBL medical education may or may not be successful in different national contexts is a more complex and sophisticated set of associations and relationships than the country in which it occurs. Student learning research in the last four decades has provided evidence that qualitatively better learning outcomes are closely related to a number of key variables including student conceptions of learning, how they approach learning and their awareness and perceptions of key aspects of the learning context. These variables will be investigated in the two PBL research sites in this thesis. Two similar undergraduate PBL medical programs, at The University of Hong Kong and at The University of Newcastle in Australia, were investigated both qualitatively and quantitatively by employing research methodologies from seminal research into student learning in higher education. This thesis provides significant discussion and evidence about those aspects of the student experience of PBL which seem to transcend national boundaries, and those aspects which appear to be more embedded in the contexts in which the programmes are run. The implications from the results of the thesis will be relevant for educators responsible for designing and improving the teaching and learning of new and existing problem-based medical education in different contexts

Ganoderma lucidum (Reishi mushroom) for cancer treatment (review)

Background: Ganoderma lucidum is a natural medicine that is widely used and recommended by Asian physicians and naturopaths for its supporting effects on immune system. Laboratory research and a handful of preclinical trials have suggested that G. lucidum carries promising anticancer and immunomodulatory properties. The popularity of taking G. lucidum as an alternative medicine has been increasing in cancer patients. However, there is no systematic review that has been conducted to evaluate the actual benefits of G. lucidum in cancer treatment. Objectives: To evaluate the clinical effects of G. lucidum on long-term survival, tumour response, host immune functions and quality of life in cancer patients, as well as adverse events associated with its use. Search methods: We searched an extensive set of databases including the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, NIH, AMED, CBM, CNKI, CMCC and VIP Information/Chinese Scientific Journals Database was searched for randomised controlled trials (RCTs) in October 2011. Other strategies used were scanning the references of articles retrieved, handsearching of the International Journal of Medicinal Mushrooms and contact with herbal medicine experts and manufacturers of G. lucidum. For this update we updated the searches in February 2016. Selection criteria: To be eligible for being included in this review, studies had to be RCTs comparing the efficacy of G. lucidum medications to active or placebo control in patients with cancer that had been diagnosed by pathology. All types and stages of cancer were eligible for inclusion. Trials were not restricted on the basis of language. Data collection and analysis: Five RCTs met the inclusion criteria and were included in this review. Two independent review authors assessed the methodological quality of individual trials. Common primary outcomes were tumour response evaluated according to the World Health Organization (WHO) criteria, immune function parameters such as natural killer (NK)-cell activity and T-lymphocyte co-receptor subsets, and quality of life measured by the Karnofsky scale score. No trial had recorded long-term survival rates. Associated adverse events were reported in one study. A meta-analysis was performed to pool available data from the primary trials. Results were gauged using relative risks (RR) and standard mean differences (SMD) for dichotomous and continuous data respectively, with a 95% confidence interval (CI). Main results: The methodological quality of primary studies was generally unsatisfying and the results were reported inadequately in many aspects. Additional information was not available from primary trialists. The meta-analysis results showed that patients who had been given G. lucidum alongside with chemo/radiotherapy were more likely to respond positively compared to chemo/radiotherapy alone (RR 1.50; 95% CI 0.90 to 2.51, P = 0.02). G. lucidum treatment alone did not demonstrate the same regression rate as that seen in combined therapy. The results for host immune function indicators suggested that G. lucidum simultaneously increases the percentage of CD3, CD4 and CD8 by 3.91% (95% CI 1.92% to 5.90%, P < 0.01), 3.05% (95% CI 1.00% to 5.11%, P < 0.01) and 2.02% (95% CI 0.21% to 3.84%, P = 0.03), respectively. In addition, leukocyte, NK-cell activity and CD4/CD8 ratio were marginally elevated. Four studies showed that patients in the G. lucidum group had relatively improved quality of life in comparison to controls. One study recorded minimal side effects, including nausea and insomnia. No significant haematological or hepatological toxicity was reported. Authors' conclusions: Our review did not find sufficient evidence to justify the use of G. lucidum as a first-line treatment for cancer. It remains uncertain whether G. lucidum helps prolong long-term cancer survival. However, G. lucidum could be administered as an alternative adjunct to conventional treatment in consideration of its potential of enhancing tumour response and stimulating host immunity. G. lucidum was generally well tolerated by most participants with only a scattered number of minor adverse events. No major toxicity was observed across the studies. Although there were few reports of harmful effect of G. lucidum, the use of its extract should be judicious, especially after thorough consideration of cost-benefit and patient preference. Future studies should put emphasis on the improvement in methodological quality and further clinical research on the effect of G. lucidum on cancer long-term survival are needed. An update to this review will be performed every two years.39 page(s

Culturable endophytes of medicinal plants and the genetic basis for their bioactivity

The bioactive compounds of medicinal plants are products of the plant itself or of endophytes living inside the plant. Endophytes isolated from eight different anticancer plants collected in Yunnan, China, were characterized by diverse 16S and 18S rRNA gene phylogenies. A functional gene-based molecular screening strategy was used to target nonribosomal peptide synthetase (NRPS) and type I polyketide synthase (PKS) genes in endophytes. Bioinformatic analysis of these biosynthetic pathways facilitated inference of the potential bioactivity of endophyte natural products, suggesting that the isolated endophytes are capable of producing a plethora of secondary metabolites. All of the endophyte culture broth extracts demonstrated antiproliferative effects in at least one test assay, either cytotoxic, antibacterial or antifungal. From the perspective of natural product discovery, this study confirms the potential for endophytes from medicinal plants to produce anticancer, antibacterial and antifungal compounds. In addition, PKS and NRPS gene screening is a valuable method for screening isolates of biosynthetic potential

Phylogeny of bacterial type I PKSs.

<p>Relationships inferred by maximum likelihood analysis of bacterial PKS ketosynthase domain fragments, using the LG substitution model. Branch length indicates inferred divergence of amino acid sequences and numbers adjacent to the nodes indicate aLRT support, with support values >50% considered significant. The accession numbers for all sequences obtained from GenBank are indicated. The scale bar represents 0.2 amino acid changes.</p

PCR primers and reaction conditions used in the screening of total DNA extracts from TCM plants.

*<p>Altered from standard PCR procedures described.</p

PKS and NRPS genes identified with degenerate PCR primers.

1<p>In silico prediction of the amino acid substrate recognized by putative NRPS fragments <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0035953#pone.0035953-Rausch1" target="_blank">[28]</a>.</p>2<p>ND =  not done.</p

Phylogeny of bacterial NRPS sequences.

<p>Relationships inferred by maximum likelihood analysis of bacterial NRPS adenylation domain fragments using the LG substitution model. Branch lengths indicate inferred divergence of amino acid sequences. Numbers adjacent to the nodes indicate aLRT support, with support values >50% considered significant. The accession numbers for all sequences obtained from GenBank are indicated. The scale bar represents 0.5 amino acid changes.</p