Review for 10.1186/1471-230X-10-35 (2010)

Reviewer's report
Title:Bax Inhibitor-1 down-regulation in the progression of chronic liver diseases
Version: 2Date:27 January 2010
Reviewer: Thomas Bock
Reviewer's report:
Dr. Kotsafti and co-workers have presented a retrospective study in which they
aimed to show that Bax Inhibitor-1 gene expression may correlate with the
progression of chronic liver diseases. In general, this an interesting study using
adequate methods, however, there are some limitations which decreases the
impact of the manuscript and should be addressed.
Major Compulsory Revisions:
1) The authors stated in their abstract that the modulation of Bax and BI-1
expression due to HCV and HBV infection will be determined but did not show
any data for HBV infections.
2) The authors conclude that BI-1 expression, which includes mRNA as well as
protein expression, is down-regulated as liver damage progresses. However,
from their findings BI-1 protein expression is not modulated in contrast to BI-1
mRNA expression. An explanation for this discrepancy is needed.
3) With regard to BI-1 protein expression the authors describe as result from the
Western Blot analysis shown in Fig. 3A that there is no difference in BI-1 protein
expression. This is confusing because the Western Blot clearly shows
differences.
4) In the Result section Kotsafti et al describe differences in HCV-genotype
related activation of Bax mRNA expression but did not show it. In this regard a
figure is missing.
Minor essential revision:
The statistical analyses of the manuscript give the impression to need
verification. The presented values used in the relative real-time PCR are between
approx. 200 and approx. 1000 giving a concentration of mRNA molecules which
may not differ much. Additionally, the dimension/unit is not given. Furthermore,
the calculation of P-values shown by Fig. 2B was done using CH HCV instead of
the control. In other words, what is the overall significance of the presented data?
Minor comments:
1. In the Methods section the regional origin of the patients are not described.
2. Methods section, page 9, third para, the term “absolute” to determine mRNA
concentrations is not correct. It should read “relative”
3. Method section, page 11, 2nd para. There is a typing error in lane 4. Instead of
“2P” value it must read “P” value.
4. Figure 1 and 2, the term “absolute” real-time PCR (see above) is incorrect for
the used experiments to determine gene expression. It must read “relative”
real-time PCR. (see also Methods section)
5. Figure 1 and 2, what is the dimension/unit of the abscissas? Is it, e.g., “relative
concentration …”? This is also true for Figures 3 and 4.
6. A figure to show differences of BI-1 and Bax mRNA modulation by HCV-
genotype infection would be of great interest.
7. Page 14, in the discussion section the authors discuss the drop of BI-1 mRNA
due to the progression of liver damage. However, they did not discuss their
findings that BI-1 protein expression was not altered in contrast to mRNA levels.
8. Figure 5 is more confusing than explaining and did not add any new
information. Furthermore, the findings of the presented study are not adequately
embedded in the drawing. Therefore I suggest omitting figure 5.
9. Table 1 did not add any relevant information and can be omitted.
Level of interest: An article of importance in its field
Quality of written English: Acceptable
Statistical review: Yes, but I do not feel adequately qualified to assess the
statistics.
Declaration of competing interests:
I declare that I have no competing interests