Letter to the Editor

Abstract

Re: Heidar Tavilani, Amir Fattahi, Maryam Esfahani, Iraj Khodadadi, Jamshid Karimi, Elham Bahrayni, et al. (2014) Genotype and phenotype frequencies of paraoxonase 1 in fertile and infertile men. Syst Biol Reprod Med 60(6):361–366.

Dear Editor,

We read with great interest the article by Tavilani et al. entitled “Genotype and phenotype frequencies of paraoxonase-1 in fertile and infertile men” in which the investigators reported that higher paraoxonase-1 (PON-1) activity and lower malondialdehyde content were detected in fertile males compared with infertile subjects [Tavilani et al. 2014]. They suggested that decreased activity of PON1 may be a risk factor for male infertility. However, we wish to make some comments on paraoxonase-1 (PON-1), which was evaluated in their study.

PON-1 hydrolyzes organophosphate substrate paraoxon and aromatic esters, such as phenylacetate and has been shown to inhibit LDL oxidation. Previous studies showed that certain diseases such as psoriasis, chronic renal failure, inflammatory bowel diseases, hypertension, Parkinson’s disease, Alzheimer disease, vascular dementia, chronic liver disease, systemic lupus erythematosus, hyperlipidemia, and acute phase response status could affect serum PON-1 activity [Costa et al. 2005; Ferre et al. 2002]. The authors did not mention such contributing factors. In this regard, simple laboratory tests as routine biochemistry tests, erythrocyte sedimentation rate, C reactive protein, and complete blood count could be achieved to exclude potential confounders. In addition, dietary supplements such as vitamin C, vitamin E, iron, zinc, and flavonoids can alter PON-1 activity [Rantala et al. 2002]. Also, other factors such as alcohol intake, smoking, pregnancy, and exercise status have to be stated to provide meaningful data [Costa et al. 2005].

Serum PON-1 activity increased during the day between 08:00 to noon, followed by a decrement between 16:00 to 04:00 [Hayek et al. 2014]. The authors did not define the sampling time. Standardizing sampling time is important to obtain reliable data. In this regard, the authors should define when the samples were taken.

Another contributing factor for PON-1 activity is medicine use. Authors stated just lipid lowering drugs as an exclusion criterion in terms of medicine. But, aspirin, fenofibrate, dexametazon, phenobarbital, and hormone replacement therapy also affect PON-1 activity [Mackness et al. 1985].

There is no data about mean ages of study groups. It is reported that PON-1 activity progressively decrease in elderly subjects [Costa et al. 2005]. Therefore, it is an important contributing factor which should be stated.

In conclusion, though this study contributes valuable information to the medical literature, clarifying these concerns will certainly provide a clearer picture when interpreting PON-1 activity among participants.

Letter to the Editor ResponseE-mail: [email protected]

Re: Heidar Tavilani, Amir Fattahi, Maryam Esfahani, Iraj Khodadadi, Jamshid Karimi, Elham Bahrayni, et al. (2014) Genotype and phenotype frequencies of paraoxonase 1 in fertile and infertile men. Syst Biol Reprod Med 60(6):361–366.

Dear Editor,

The authors thank Agilli et al. for their interesting remarks and valuable comments in the Letter to the Editor. Agilli et al. suggested that since diseases such as psoriasis, chronic renal failure, inflammatory bowel disease, Parkinson's disease, Alzheimer disease, acute phase responses, systemic lupus erythematosus, and etc. could affect serum PON1 activity, it is required to asses all relevant biological parameters as well as determination of vitamins, iron, zinc, and other dietary supplements in all participants. However, respectfully it should be noted that all aforementioned diseases basically can be excluded by completion of a simple questionnaire addressing existence of the history of any chronic or major acute illnesses during the subject enrolment without the requirement of performing biological tests. Additionally we were aware of the effect of factors such as pathological conditions, pharmacological, life style, antioxidant status, and age on PON1 activity, therefore in our study participants were examined by a physician and subjects with no history of previous disease were included. Pharmacological status including any report of hormone therapy or administration of phenobarbital, phenofibrate, and aspirin were also determined and individuals were excluded from the study, according to the report of the physician.

Moreover, there are conflicting reports in the literature about the impact of modulating factors such as vitamin C and E on PON1 activity, thereby and initial evidences have not been confirmed by further studies [Costa et al. 2005]. Although an inverse correlation of PON1 activity and age has been reported in some studies [Seres et al. 2004, Milochevitch and Khalil 2001], this observation has exclusively been made in elderly subjects indicating a reduced PON1 activity in subjects aged over 46 years compared with subjects less than 45 years of age. Since people get less fertile as they get older, subjects aged less than 45 years were only enrolled in our study to eliminate biases affecting the results. However, we think further investigations are required to fully understand the physiological and/or pathological conditions which may affect the assessment of PON1 status.