Showing posts with label PubMed. Show all posts
Showing posts with label PubMed. Show all posts

Saturday, February 22, 2014

'Save the Date's + Resources

Some 'Save the Date's:

1. ASM Meeting, Boston, MAY 2014:
Speaker: Christen Rune Stensvold 
Session Title: Passion for Parasites! Current Topics in Medical Parasitology 
Session Date/Time:  5/18/2014 8:00:00 AM 
Presentation Title: Blastocystis Clinical Relevance: More Common and Important than You Think

2. ICOPA, Mexico City, AUGUST 2014:
3. 1st International Blastocystis Symposium, Ankara, 28-29 MAY 2015:

Please go here for more information.

Just found out that out of 1065 Blastocystis papers in PubMed, 269 are can be downloaded for free! If you enter 'Blastocystis' in the search box, you'll see the 1065 or so hits, but if you go to the right side bar, you have the option of having the Free Full Text (269) display.

I have disabled Google+ comments for now due to repetitive abuse. However, it is still possible to comment on blog posts, only now comments will be reviewed and potentially moderated by me prior to publishing.

In case there should be readers who think that I'm trying to propagate the view that Blastocystis is pathogenic, I hope that after going through my blog posts they will realise that I'm not; in fact, I'm much more trying to be the devil's advocate: Blastocystis is 'innocent' unless proven otherwise. In my opinion we have very little clinical evidence of pathogenicity. And at our lab, we generally do not recommend treating patients with Blastocystis. In fact, we really don't know HOW to treat Blastocystis, - and maybe that's one of the most fundamental issues in Blastocystis research. I know that many treatment regimens are currently in use for Blastocystis despite the absence of clinical guidelines, and some of them are used systematically at various clinics it seems, but off the top of my head I cannot think of one single randomised controlled treatment study that have explored the microbiological and clinical effect of treatment. Such studies are critical to our understanding of  the role of the parasite in health and disease, although even this type of studies have limitations such as non-specific drug actions that will blur our ability to point out Blastocystis as the culprit, and also some drugs may have adverse effects that mimic symptoms potentially caused by Blastocystis, including symptoms related to intestinal dysbiosis. I hope that those who have extensive experience with Blastocystis treatment will soon take to sharing their knowledge.

But I guess that what we are currently trying in various fields is to get a differentiated view of Blastocystis - for instance: can colonisation turn into infection, and is there any such thing as a Blastocystis infection at all? Can, and if so, when does Blastocystis carriage lead to pathology/disease? Which are the interactions between Blastocystis and the remaining microbiota? What host factors may be responsible for potential differences in Blastocystis-mediated disease susceptibility?

Don't miss the February issue of 'This Month In Blastocystis Research' which will be available in a week or so.

Friday, April 26, 2013

This Month in Blastocystis Research (APR 2013)

I've been extremely bored all day writing up my evaluation of a (not so interesting) PhD thesis, and I thought I'd spice up my day by introducing a new series of posts on this blog inspired by so many other blogs, namely: This Month in Blastocystis Research! A place for me to go through some of the most recent papers on Blastocystis.

There is paper out by Gould and Boorom who look at the stability of Blastocystis surface antigen over time. They show that detection of Blastocystis by an immunofluorescense assay (IFA) is not hampered after1 year of storage of faecal material in formalin compared to results immediately after the sampling point. Detection of Blastocystis by IFA is something that is not often used (that's my impression, anyway), but makes sense in cases where laboratory analyses can be performed only weeks-months after sample collection (e.g. during field work), in which case samples need to be preserved. We usually, however, recommend storing faecal material in (70%) ethanol (in the relationship 1 part faecal sample to 4 parts of ethanol), where the sample is mixed with the ethanol initially by vortexing the tube (typically a 2 mL Eppendorf tube) for 5-10 min, and subsequently keeping the tubes away from light until further processing. Importantly, in contrast to formalin-fixed stool, ethanol-fixed stool can be made highly suitable for PCR by just washing the samples x3 in PBS prior to DNA extraction. An example of this methodology can be seen in our study of Blastocystis in members of the Tapirapé tribe in Mato Grosso, Brazil (go here for a free download).

I'd wish that Gould and Boorom had validated their findings by running a PCR on the samples too (specificity and sensitivity testing). The IFA assay was also used in a publication from 2010 by Dogruman-Al et al., who found a diagnostic sensitivity of the IFA assay of 86.7% compared to culture; also here, adding PCR would have been relevant to better determine the diagnostic qualities of the IFA assay.

I was lucky to be involved in field work in the Lao PDR in 2003 conducted by regional WHO authorities; preserving and analysing faecal samples for parasites by microscopy (Kato Katz) and - later - PCR was what we did!

Adding to the endless row of cross-sectional prevalence papers, there is an article out just now by Abdulsalam et al. (2013) on Prevalence, predictors and clinical significance of Blastocystis sp. in Sebha, Libya (free for download here). The study used culture (Jones' medium) as diagnostic modality and confirmed the existence of frequent asymptomatic carriage. The authors used questionnaire info and multivariate statistical analysis to identify risk factors for Blastocystis carriage among 380 individuals aged 1-75, and what I find really interesting is that they found that participants aged > 18 years were much more prone to having Blastocystis than participants < 18 years (P < 0.001). This is something that we see in Denmark too, and I'm currently trying to collect "sufficient proof"! Whether this is an age accumulation effect due to the chronicity of colonisation remains to be investigated. The authors also found that carriers were more likely to experience symptoms than those who were not carriers (P < 0.001), mainly abdominal pain (P < 0.001), but notably not diarrhoea (P = 0.117).
It's a pity that molecular data was not included the study from Libya. Incidentally, our group recently published subtype data from Sebha, Libya, and it appears that Blastocystis found in humans in Libya mainly belongs to ST1, whereas ST3 is often the most common subtype in most other countries, and what is more: ST4 appears virtually absent in Libya and the rest of Africa... But let's see: The investigators might have more data up their sleeve waiting to be published...

May I also again draw your attention to our recent paper on Blastocystis in non-human primates, in which we find that despite the fact that there is a great overlap of subtypes in human and non-human primates, it appears that ST1 and ST3 strains found in non-human primates differ genetically from those found in humans, indicating cryptic host specificity. We have additional data supporting the theory that Blastocystis in humans is a result of human-to-human transmission (anthroponotic) rather than animal-to-human (zoonotic) transmission. Which is really interesting, since the theory of zoonotic transmission of Blastocystis has been heavily (I dare not say purported, so I'll say) propagated. Having said that, I think we still need to look much deeper into barcoding of Blastocystis from pets and other synanthropic animals before we can make more poignant conclusions.

And, finally, yet another add for our recent review on Recent Development in Blastocystis Research!

Please note that I'm happy to take suggestions for future posts, and I'd also like to encourage guest blogging!

Suggested reading:

Abdulsalam AM, Ithoi I, Al-Mekhlafi HM, Khan AH, Ahmed A, Surin J, & Mak JW (2013). Prevalence, predictors and clinical significance of Blastocystis sp. in Sebha, Libya. Parasites & Vectors, 6 PMID: 23566585

Alfellani MA, Jacob AS, Perea NO, Krecek RC, Taner-Mulla D, Verweij JJ, Levecke B, Tannich E, Clark CG, & Stensvold CR (2013). Diversity and distribution of Blastocystis sp. subtypes in non-human primates. Parasitology, 1-6 PMID: 23561720

Alfellani MA, Stensvold CR, Vidal-Lapiedra A, Onuoha ES, Fagbenro-Beyioku AF, & Clark CG (2013). Variable geographic distribution of Blastocystis subtypes and its potential implications. Acta Tropica, 126 (1), 11-8 PMID: 23290980

Clark CG, van der Giezen M, Alfellani MA, & Stensvold CR (2013). Recent developments in Blastocystis research. Advances in Parasitology, 82, 1-32 PMID: 23548084

Dogruman-Al F, Simsek Z, Boorom K, Ekici E, Sahin M, Tuncer C, Kustimur S, & Altinbas A (2010). Comparison of methods for detection of Blastocystis infection in routinely submitted stool samples, and also in IBS/IBD Patients in Ankara, Turkey. PloS One, 5 (11) PMID: 21124983 

Gould R, & Boorom K (2013). Blastocystis surface antigen is stable in chemically preserved stool samples for at least 1 year. Parasitology research PMID: 23609598

Malheiros AF, Stensvold CR, Clark CG, Braga GB, & Shaw JJ (2011). Short report: Molecular characterization of Blastocystis obtained from members of the indigenous Tapirapé ethnic group from the Brazilian Amazon region, Brazil. The American Journal of Tropical Medicine and Hygiene, 85 (6), 1050-3 PMID: 22144442

Wednesday, April 10, 2013

Blastocystis Hits The 1,000 Entry Mark In PubMed

Yesterday, the number of Blastocystis entries in PubMed reached 1,000! PubMed is a public resource comprising more than 22 million citations for biomedical literature from MEDLINE, life science journals, and online books.

In comparison, there are currently 7,641 entries on Entamoeba, 6,630 on Cryptosporidium and 235 entries on Dientamoeba.

I plan to introduce the "Hall of Fame in Blastocystis Research" in a future post, but already now I can reveal that the researcher with most Blastocystis-related publications is Dr Hisao Yoshikawa according to Web of Science (WoS), which currently returns 895 hits on a search on Blastocystis; Dr Yoshikawa has at least 43 publications on Blastocystis alone (WoS), and at least 37 Blastocystis-specific peer-reviewed journal articles (PubMed) since 1987.