• Users Online: 16
  • Print this page
  • Email this page

 
ORIGINAL ARTICLE
Ahead of print publication  

The ratios of estradiol and progesterone to testosterone influence the severity of facioscapulohumeral muscular dystrophy


1 Department of Medical Biology and Genetics, Faculty of Medicine, Akdeniz University, Antalya, Turkey
2 Department of Biostatistics, Faculty of Medicine, Akdeniz University, Antalya, Turkey
3 Department of Biochemistry, Faculty of Medicine, Akdeniz University, Antalya, Turkey
4 Department of Endocrinology, Faculty of Medicine, Akdeniz University, Antalya, Turkey
5 Department of Neurology, Faculty of Medicine, Akdeniz University, Antalya, Turkey
6 Department of Neurology, Faculty of Medicine, Çukurova University, Adana, Turkey

Date of Submission03-Apr-2020
Date of Decision04-May-2020
Date of Acceptance22-Jun-2020
Date of Web Publication06-Oct-2020

Correspondence Address:
Sibel Berker Karauzum,
Department of Medical Biology and Genetics, Faculty of Medicine, Akdeniz University, Konyaalti, Antalya
Turkey
Login to access the Email id

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/NSN.NSN_37_20

  Abstract 


Background: Facioscapulohumeral muscular dystrophy (FSHD) occurs as a consequence of genetic deletion of D4Z4 repeats on chromosome 4q35. Onset of FSHD is earlier in males, suggesting that testosterone may trigger the disease. In accordance, the rapid progression of disease in women after menopause suggests a protective role for estrogen and progesterone. No studies have examined levels of all these hormones in relation with the severity of FSHD. Aims: To evaluate the possible correlation between the severity of FSHD with sex hormones, age, and genetic deletion on chromosome 4q35. Subjects and Methods: D4Z4 repeat units were investigated in 33 patients (19 males/14 females) with FSHD. In the blood samples, luteinizing hormone, follicle-stimulating hormone, free estriol, estradiol, free testosterone and total testosterone, progesterone, 17-OH progesterone, prolactin, albumin, and fibrinogen were measured. The severity of FSHD was identified using a Clinical Severity Score (CSS) scaling system. Spearman's correlation and regression analyses were performed as statistical analyses. Results: Age (P = 0.001, r = 0.541) and total testosterone (P = 0.045, r = 0.351) were positively correlated, and the progesterone/total testosterone (P = 0.025, r = −0.390) and estradiol/total testosterone ratios (P = 0.025, r = −0.389) were negatively correlated with the severity of FSHD. Conclusions: Our results indicate that age, total testosterone, ratios of estradiol and progesterone to total testosterone, but not deletion on chromosome 4q35, have a significant relation with the severity of FSHD. Given that both estrogen and testosterone treatment are considered in therapy, our results suggest that estrogen and progesterone but not testosterone are likely to be more effective on the severity of FSHD.

Keywords: Estradiol, facioscapulohumeral muscular dystrophy, FSHD, progesterone, testosterone



How to cite this URL:
Hangul C, Bozkurt S, Bilge U, Ozdem S, Altunbas H, Uysal H, Koc F, Karauzum SB. The ratios of estradiol and progesterone to testosterone influence the severity of facioscapulohumeral muscular dystrophy. Neurol Sci Neurophysiol [Epub ahead of print] [cited 2020 Oct 28]. Available from: http://www.nsnjournal.org/preprintarticle.asp?id=297425




  Introduction Top


Facioscapulohumeral muscular dystrophy (FSHD) is the third most common dystrophy with an incidence of 1:15,000–1:20,000.[1] Drug studies have been continuing, yet there is no specific treatment for the disease.

D4Z4 repeats located on chromosome 4q35 region have been associated with the disease by linkage studies, and FSHD (OMIM#15890) is an autosomal dominantly inherited genetic disorder. In the normal population, the D4Z4 sequence consists of 11-100 repeats, each of which is 3.3 kb in length. There is a contraction of these repeats in 95% of patients with FSHD, and this group is referred to as FSHD1. The repeat number has been shown to vary between 1 and 10 repeats in individual FSHD cases, and DUX4 has been attributed to be the responsible gene, which is located in each D4Z4 repeat unit.[2] Less than 5% of patients with FSHD have mutations in SMCHD1, DNMT3 and LRIF1 genes, known as FSHD2. These genes act by reducing the levels of methylation on D4Z4 repeats.[3],[4],[5] Clinically, FSHD manifests with asymmetrical progressive loss of strength in face–shoulder–scapular muscles, and less frequently in peroneal muscles.[6],[7] Commonly, onset is around the second and third decades of life.[6] However, there is no typical clinical manifestation; the severity of the disease is rather variable between individuals. In some patients, the disease manifests in their 20s–30s and it progresses over the years making patients wheelchair bound, whereas in others, the disease could be mild, with involvement being limited to a few muscles.

In contrast to autosomal dominant inheritance in which male and female segregation is equal, significant clinical differences between female and male patients have also been identified. In males, the disease manifestation is earlier compared with females,[8],[9] which indicates the role of testosterone in FSHD. In addition, the observation of exacerbations in female patients with FSHD just after menopause indicates a possible effect for estrogen. There is clinical and molecular evidence supporting this hypothesis. Puma et al. showed that patients with FSHD who were taking antiestrogen treatment for breast cancer had an acceleration of muscle scores, whereas other patients with cancer who were treated with common chemotherapy agents did not exhibit this acceleration.[10] On the other hand, in a clinical study that investigated lifetime estrogen exposure on disease severity, no significant relation was identified.[11] The hypothesis that estrogen is thought to have an impact on FSHD had also been tested in molecular studies. Teveroni et al. revealed that there was an epigenetic modulation by estrogen on DUX4 target genes via histone modification.[12] In addition, Banerji et al. showed that PGC1/ERR alpha was related to the muscle wasting of FSHD, and this phenotype was rescued with phytoestrogen (e.g. genistein, daidzein) treatment.[13] Based on our own experience with estrogen treatment invitro, we observed that DUX4 protein was downregulated after estradiol treatment in a primary FSHD cell line,(unpublished data) supporting the protective role of estrogen in FSHD. Based on these studies, it may be considered that sex steroids, especially estrogen, have a relation in the pathophysiology of FSHD. The aim of this study was to reveal whether sex steroids had a role in FSHD by investigating the relation between the severity of the disease and sex steroid levels.


  Subjects and Methods Top


This study was examined by local ethics committee and it is pursuant to the Declaration of Helsinki. This was two-center research study conducted in the universities of Akdeniz and Cukurova.

All patients were genetically tested and diagnosed as having FSHD1. The D4Z4 repeat unit of each patient is given in [Table 1].
Table 1: Clinical severity scores, age, onset, and repeat units of 19 male and 14 female patients with facioscapulohumeral muscular dystrophy

Click here to view


The patients with FSHD were contacted and requested to undergo a physical examination and peripheral blood sampling.

Study design

The severity of the disease was defined: Clinical severity scoring (CSS) was estimated through neurologic physical examinations. Age, D4Z4 repeat number on chromosome 4, age at onset of disease, and duration of the disease (current age-onset) were also incorporated as other indicators of the disease. Peripheral blood samples were collected from 33 patients with FSHD (19 males/14 females) to determine the levels of the endocrinologic parameters. Statistical analysis was performed to evaluate the effect of the hormone levels on clinical severity through correlation analysis with CSS.

Physical examination and CSS calculation

CSS was used to assess the severity of FSHD in the clinical approach.[14],[15] Neurologic physical examinations were performed to estimate the CSS in the control and FSHD groups. The CSS form can be reached from the University of Rochester Medical Center website: https://www.urmc.rochester.edu/MediaLibraries/URMCMedia/fields-center/documents/ClinicalSeverityScoring.pdf.

Endocrinologic parameters and their biochemical analysis

The investigated endocrinologic parameters were as follows: luteinizing hormone (LH), follicle-stimulating hormone (FSH), free estriol, estradiol, free testosterone and total testosterone, progesterone, 17-OH progesterone, prolactin, albumin, and fibrinogen. Hormonal ratios were calculated by simple division. The calculated ratios were estradiol/free testosterone (E/fT), estradiol/total testosterone (E/tT), progesterone/estradiol (P/E), progesterone/free testosterone (P/fT), progesterone/total testosterone (P/tT), 17OH progesterone/estradiol (17OH P/E), 17-OH progesterone/free testosterone (17OH P/fT), 17-OH progesterone/total testosterone (17OH P/tT), and free testosterone/total testosterone (fT/tT).

Peripheral blood samples were collected to analyze the hormone levels of the patients with FSHD. For each male patient, blood sampling was performed once. Furthermore, from eight nonmenstruating females, blood sampling was performed once (one child and women in menopause). Blood samples were obtained twice in seven menstruating women because of the fluctuation of hormone levels, on the 1st and 21st day of menstruation. The mean values of the 1st and 21st day were used for correlation analysis to eliminate a possible bias in hormone levels.

Body mass index (BMI) was calculated using the formula weight/(height2) for each patient.

Measurement methods of biochemical parameters

LH, FSH, total testosterone, estradiol, progesterone, and prolactin levels were measured using an ADVIA Centaur XP (Siemens Healthcare Diagnostics, Forchheim, Germany) system with a commercial chemiluminescent immunoassay kit.

17-OH progesterone was quantified using Shimadzu LCMS-8040 triple quadrupole mass spectrometry (Shimadzu Corporation, Japan).

Free testosterone was determined via a Beckman Coulter (Beckman Coulter, Brea, CA, USA) system using a radioimmunoassay kit.

DHEA-s and free estriol levels were evaluated using a chemiluminescent kit with an Immulite 2000 system (both from Siemens Healthcare Diagnostics, Forchheim, Germany). Free estriol was excluded from the study due to undetectable low levels in all patients with FSHD.

Albumin measurements were performed on a Siemens ADVIA 2400 biochemical autoanalyzer (Siemens Healthcare Diagnostics, Forchheim, Germany) using spectrophotometry.

Fibrinogen levels were measured via a Siemens BCS XP coagulation analyzer (Siemens Healthcare Diagnostics, Forchheim, Germany) using coagulometry.

Statistical analysis

Statistical analyses were performed using the Statistical Package for the Social Sciences ver. 23.0 (SPSS). (IBM, Armonk, New York, USA). The relevance of normal distribution was tested using the Shapiro–Wilk test. Having a restricted number of patients, regression analysis could not be performed for all hormones, thus nonparametric Spearman's analysis were used instead of a parametric test. The Mann–Whitney U-test was used to reveal whether there was a significant difference of CSS between male-female patients with FSHD. Spearman's correlation analysis was used to determine whether endocrinologic parameters were correlated with CSS. After Spearman's analysis, the most powerfully correlated hormone with CSS was investigated via regression analysis together with age and disease duration.

Free estriol was not included in any statistical analysis because it was found to be under the detection limit for each patient.


  Results Top


All clinical (sex, age, onset, and CSS) and genetic (repeat units) parameters of the 33 patients with FSHD are summarized in [Table 1]. Twenty-seven of the patients were from 10 different families in which a minimum of two and maximum of four patients were from the same family. Six patients had no relatives in the study. Before the correlation analysis, the CSS of the male and female patients with FSHD was compared and no significant difference was detected (P = 0.733).

In the correlation analysis, CSS was analyzed with age, age at onset, disease duration, and D4Z4 repeat unit numbers on chromosome 4, hormone levels, and the ratios of these hormone levels. The correlation analysis of the patients with FSHD is summarized in [Table 2]. Age, duration of disease, total testosterone, progesterone ratio to testosterone, estradiol ratio to testosterone, and BMI were found to be correlated with disease severity. Of these, the ratios of progesterone and estradiol to testosterone were the parameters that were negatively correlated with disease severity, the others were correlated positively. Of note, repeat units on chromosome 4q35 D4Z4 had no significant correlation with FSHD severity.
Table 2: Data of Spearman's correlation analysis between CSS and D4Z4 repeat unit number, age, onset, duration of disease, and hormone levels

Click here to view


To observe whether age at onset was affected by sex hormone levels and the D4Z4 repeat number, additional correlation analyses were performed with these factors. The results are given in [Table 3]. As seen in the table, the D4Z4 repeat number of the patients showed no relation with age at onset. 17-OH progesterone and its ratio levels to estradiol and free testosterone were found to have a relation with the beginning of disease symptoms.
Table 3: Components correlated with onset

Click here to view


In the literature, age and repeat unit are accepted as other positively correlated concomitant factors affecting clinical severity. To clarify the independent positive effects of age, repeat unit, and total testosterone, further statistical regression analyses were performed. The results of these regression analyses are given in [Table 4].
Table 4: Results of regression analysis including total testosterone, age, and D4Z4 repeat unit number

Click here to view


As seen in [Table 4], repeat unit number also had no significant effect in the regression analysis (P = 0.429). As a result of regression analysis, it might be calculated as: CSS corresponds to 1.161 constant plus 0.024-fold of age plus 0.044-fold of the total testosterone value. This formulation of 33 patients with FSHD can be summarized as: CSS = 1.161+ (0.024 × Age) + (0.044 × total testosterone).


  Discussion Top


This study explored the correlation of hormonal levels, age, age at disease onset, disease duration, and repeat unit number with clinical severity in 33 patients with FSHD.

In our study, age and duration of disease were correlated with CSS, but age at onset and repeat unit number were not correlated with CSS. The effect of repeat unit number on the severity of FSHD remains controversial. Tawil et al. found a significant (r = 0.92, P < 0.004) correlation between disease severity and the size of the 4q35-associated deletion.[16] In addition, Statland et al. observed a milder phenotype within patients with 7-10 repeats compared with shorter repeat units.[17] However, Klinge et al. observed a discordant case in their sample group.[18] One patient in their study with the largest D4Z4 repeat (21 kb), inversely to all patients with short alleles, displayed a very severe phenotype with the general inverse relationship established between disease severity and the residual D4Z4 repeat size.[18] Importantly, 10% of patients with FSHD have borderline size (9-10 RU), which is also found in healthy people or in a different myopathies,[19] and 5%–10% of patients carry the range of the general population (11 RU or more) on both chromosomes.[20] All these data indicate that the D4Z4 repeat unit on chromosome 4q35 is not specific to characterize FSHD severity. Our study results also support that the D4Z4 repeat unit is not a direct factor that affects the severity of FSHD. Recent literature revealed a more complex interaction of genetic factors including the D4Z4 repeat unit, methylation, and as yet unknown components,[21] as well as other known components including sex hormones.

Onset is variable between patients with FSHD.[22] Including the effect of D4Z4 repeat unit contraction, we investigated whether hormone levels had a relation with the onset of the disease. As a result, we found 17-OH progesterone and its ratio to estradiol and testosterone were important for the beginning of symptoms. Similar to CSS, onset was not found to be correlated with the D4Z4 repeat unit number.

Progression velocity is also variable between patients with FSHD.[22] In male patients with FSHD, onset is earlier and symptoms are more severe.[8],[9] The main responsible protein in the pathogenesis of FSHD, DUX4, is expressed only in the testis of healthy men,[23] where the testosterone is highly expressed, indicating a possible interaction or common pathway between testosterone and DUX4. We found higher total testosterone levels with greater disease severity in patients in whom DUX4 had been expected to be highly expressed. These data draw attention to the fact that testosterone may be one of the trigger factors in FSHD. Paradoxically, there is one ongoing research on recombinant human growth factor and testosterone together for the treatment of FSHD. The trial started on December 18, 2017. This is a study of daily human growth hormone (Genotropin®, 5.0 μg/kg s. c.) and testosterone injections (testosterone enanthate, 140 mg i. m.) every 2 weeks for 24 weeks in men with FSHD with a 12-week washout period.[24] Even though the results of our study indicate testosterone as a trigger factor rather than a treatment option, with the results of the clinical testosterone trial, we will be able to learn more clear and detailed data on the role of testosterone in FSHD.

In female patients with FSHD, there is a clear aggravation of symptoms after menopause.[25] In parallel with this, in women there is a sharp decrease in estradiol levels after menopause.[26] With the overlap between FSHD aggravation and hormonal changes in menopause, estrogen and other hormones have become worthy of further investigation. The protective effect of estrogen on FSHD has also been supported by recent molecular studies. Estradiol was shown to downregulate DUX4 levels (unpublished data) or DUX4 target genes by histone modification[12] in FSHD cell lines. Our results indicate a relative effect of both estradiol and progesterone to total testosterone on the severity of FSHD. These results are also in harmony with clinical disease progression, especially after menopause in women.[25]


  Conclusion Top


In summary, our findings suggest that the increase in disease severity might have a relation with high testosterone levels. On the other hand, a decrease in severity might have a relation with high estradiol, progesterone levels, and the ratios of these two hormones to testosterone.

In the literature, one study has investigated lifetime estrogen exposure on FSHD severity.[11] However, our study is the first pilot research to investigate both estrogen and free testosterone, and total testosterone, progesterone, 17-OH progesterone, prolactin, albumin, fibrinogen levels, and hormonal ratios with disease severity. All the results of our study indicate that estradiol, testosterone, and progesterone orchestrate changes in the severity of FSHD. By finding a correlation, especially with estradiol and progesterone levels relative to testosterone levels, we suggest that studies on FSHD should focus on the balance between these hormone levels rather than the solitary levels of each hormone.

Acknowledgment

Thanks to Professor Rabi Tawil for making their Clinical Severity Score (CSS) (https://www.urmc.rochester.edu/MediaLibraries/URMCMedia/fields-center/documents/ClinicalSeverityScoriCl.pdf) available on website for application. Thanks to Dr. Hakan GÜLKESEN for statistical contribution and Dr. Filiz ÖZCAN for methodologic language contribution.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Statland J, Tawil R. Facioscapulohumeral muscular dystrophy. Neurol Clin 2014;32:721-8, ix.  Back to cited text no. 1
    
2.
Hewitt JE, Lyle R, Clark LN, Valleley EM, Wright TJ, Wijmenga C, et al. Analysis of the tandem repeat locus D4Z4 associated with facioscapulohumeral muscular dystrophy. Hum Mol Genet 1994;3:1287-95.  Back to cited text no. 2
    
3.
de Greef JC, Lemmers RJ, van Engelen BG, Sacconi S, Venance SL, Frants RR, et al. Common epigenetic changes of D4Z4 in contraction-dependent and contraction-independent FSHD. Hum Mutat 2009;30:1449-59.  Back to cited text no. 3
    
4.
Yamanaka G, Goto K, Ishihara T, Oya Y, Miyajima T, Hoshika A, et al. FSHD-like patients without 4q35 deletion. J Neurol Sci 2004;219:89-93.  Back to cited text no. 4
    
5.
Hamanaka K, Sikrova D, Mitsuhashi S, Masuda H, Sekiguchi Y, Sugiyama A, et al. Homozygous nonsense variant in LRIF1 associated with facioscapulohumeral muscular dystrophy. Neurology. 2020;94:e2441-7.  Back to cited text no. 5
    
6.
Pandya S, King WM, Tawil R. Facioscapulohumeral dystrophy. Phys Ther 2008;88:105-13.  Back to cited text no. 6
    
7.
Fitzsimons RB. Retinal vascular disease and the pathogenesis of facioscapulohumeral muscular dystrophy. A signalling message from Wnt? Neuromuscul Disord 2011;21:263-71.  Back to cited text no. 7
    
8.
Zatz M, Marie SK, Cerqueira A, Vainzof M, Pavanello RC, Passos-Bueno MR. The facioscapulohumeral muscular dystrophy (FSHD1) gene affects males more severely and more frequently than females. Am J Med Genet 1998;77:155-61.  Back to cited text no. 8
    
9.
Tonini MM, Passos-Bueno MR, Cerqueira A, Matioli SR, Pavanello R, Zatz M. Asymptomatic carriers and gender differences in facioscapulohumeral muscular dystrophy (FSHD). Neuromuscul Disord 2004;14:33-8.  Back to cited text no. 9
    
10.
Puma A, Garibaldi M, Teveroni E, Deidda G, Moretti FS. Estrogens as a Potential Disease Modifier in FSHD: A Retrospective Clinical Study; 2017.  Back to cited text no. 10
    
11.
Mul K, Horlings CG, Voermans NC, Schreuder TH, van Engelen BG. Lifetime endogenous estrogen exposure and disease severity in female patients with facioscapulohumeral muscular dystrophy. Neuromuscul Disord 2018;28:508-11.  Back to cited text no. 11
    
12.
Teveroni E, Pellegrino M, Sacconi S, Calandra P, Cascino I, Farioli-Vecchioli S, et al. Estrogens enhance myoblast differentiation in facioscapulohumeral muscular dystrophy by antagonizing DUX4 activity. J Clin Invest 2017;127:1531-45.  Back to cited text no. 12
    
13.
Banerji CR, Panamarova M, Pruller J, Figeac N, Hebaishi H, Fidanis E, et al. Dynamic transcriptomic analysis reveals suppression of PGC1 alpha/ERR alpha drives perturbed myogenesis in facioscapulohumeral muscular dystrophy. Human Molecular Genetics 2019;28:1244-59.  Back to cited text no. 13
    
14.
Ricci E, Galluzzi G, Deidda G, Cacurri S, Colantoni L, Merico B, et al. Progress in the molecular diagnosis of facioscapulohumeral muscular dystrophy and correlation between the number of KpnI repeats at the 4q35 locus and clinical phenotype. Ann Neurol 1999;45:751-7.  Back to cited text no. 14
    
15.
van Overveld PG, Enthoven L, Ricci E, Rossi M, Felicetti L, Jeanpierre M, et al. Variable hypomethylation of D4Z4 in facioscapulohumeral muscular dystrophy. Ann Neurol 2005;58:569-76.  Back to cited text no. 15
    
16.
Tawil R, Forrester J, Griggs RC, Mendell J, Kissel J, McDermott M, et al. Evidence for anticipation and association of deletion size with severity in facioscapulohumeral muscular dystrophy. The FSH-DY Group. Ann Neurol 1996;39:744-8.  Back to cited text no. 16
    
17.
Statland JM, Donlin-Smith CM, Tapscott SJ, Lemmers RJ, van der Maarel SM, Tawil R. Milder phenotype in facioscapulohumeral dystrophy with 7-10 residual D4Z4 repeats. Neurology 2015;85:2147-50.  Back to cited text no. 17
    
18.
Klinge L, Eagle M, Haggerty ID, Roberts CE, Straub V, Bushby KM. Severe phenotype in infantile facioscapulohumeral muscular dystrophy. Neuromuscul Disord 2006;16:553-8.  Back to cited text no. 18
    
19.
Butz M, Koch MC, Müller-Felber W, Lemmers RJ, van der Maarel SM, Schreiber H. Facioscapulohumeral muscular dystrophy. Phenotype-genotype correlation in patients with borderline D4Z4 repeat numbers. J Neurol 2003;250:932-7.  Back to cited text no. 19
    
20.
van Overveld PG, Lemmers RJ, Sandkuijl LA, Enthoven L, Winokur ST, Bakels F, et al. Hypomethylation of D4Z4 in 4q-linked and non-4q-linked facioscapulohumeral muscular dystrophy. Nat Genet 2003;35:315-7.  Back to cited text no. 20
    
21.
Salsi V, Magdinier F, Tupler R. Does DNA methylation matter in FSHD? Genes (Basel) 2020;11:258.  Back to cited text no. 21
    
22.
Mul K, van den Boogaard ML, van der Maarel SM, van Engelen BG. Integrating clinical and genetic observations in facioscapulohumeral muscular dystrophy. Curr Opin Neurol 2016;29:606-13.  Back to cited text no. 22
    
23.
Young JM, Whiddon JL, Yao Z, Kasinathan B, Snider L, Geng LN, et al. DUX4 binding to retroelements creates promoters that are active in FSHD muscle and testis. PLoS Genet 2013;9:e1003947.  Back to cited text no. 23
    
24.
Heatwole CR. Study of Testosterone and rHGH in FSHD: A Proof-of-Concept Study. 2017-2021. Available from: http://grantome.com/grant/NIH/R01-NS095813-01A1. [Last accessed on 2020 Jan 24].  Back to cited text no. 24
    
25.
Sacconi S, Salviati L, Desnuelle C. Facioscapulohumeral muscular dystrophy. Biochim Biophys Acta 2015;1852:607-14.  Back to cited text no. 25
    
26.
Jiroutek MR, Chen MH, Johnston CC, Longcope C. Changes in reproductive hormones and sex hormone-binding globulin in a group of postmenopausal women measured over 10 years. Menopause 1998;5:90-4.  Back to cited text no. 26
    



 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4]



 

 
Top
 
 
  Search
 
     Search Pubmed for
 
    -  Hangul C
    -  Bozkurt S
    -  Bilge U
    -  Ozdem S
    -  Altunbas H
    -  Uysal H
    -  Koc F
    -  Karauzum SB
    Access Statistics
    Email Alert *
    Add to My List *
* Registration required (free)  

 
  In this article
Abstract
Introduction
Subjects and Methods
Results
Discussion
Conclusion
References
Article Tables

 Article Access Statistics
    Viewed134    
    PDF Downloaded5    

Recommend this journal