• Users Online: 85
  • Print this page
  • Email this page


 
 
Table of Contents
ORIGINAL ARTICLE
Year : 2022  |  Volume : 27  |  Issue : 4  |  Page : 385-391

Fluid aspirates of ameloblastoma: Types, prevalence, and prognostic relevance


Department of Oral Pathology & Oral Medicine, Faculty of Dentistry, University of Nigeria, Enugu, Enugu State, Nigeria

Date of Submission16-Feb-2022
Date of Decision06-Jun-2022
Date of Acceptance15-Jun-2022
Date of Web Publication22-Sep-2022

Correspondence Address:
Mark C Nwoga
Department of Oral Pathology and Oral Medicine, Faculty of Dentistry, University of Nigeria, Enugu 400221, Enugu State
Nigeria
Login to access the Email id

Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijmh.ijmh_41_22

Rights and Permissions
  Abstract 

Background: Ameloblastoma is a benign cystic odontogenic tumor common in Nigeria. The cystic cavities frequently contain tumor fluids, which may be obtained by needle aspiration. The tumor fluids help in the clinical differential diagnosis. The types, prevalence, and relevance of ameloblastoma fluid aspirates have been mostly unreported. Objectives: The aim of this study was to identify the types and prevalence of fluid aspirates of ameloblastoma and evaluate its prognostic relevance. Materials and Methods: This was a 7-year retrospective study of consecutive patients with ameloblastoma at a tertiary hospital in Enugu, Nigeria. The tumor fluids obtained by needle aspiration are categorized based on visual appearance. The data retrieved from case files, biopsy forms, histopathologic reports, and other records in the departmental archives were analyzed with IBM SPSS Statistics, version 24.0. Results: Tumor fluid aspirate yield was positive in 80.4% ((n=74) of patients with ameloblastoma. There were aspirates from 82.4% (n=61) cases of primary ameloblastoma and 17.6% (n=13) cases of recurrent ameloblastoma. The aspirates obtained were dark-brown 41.9%, straw-colored 37.8%, serosanguinous 10.8%, and purulent 9.5%. The type of aspirate was influenced by the primary or recurrent status of ameloblastoma (P = 0.04). Straw-colored aspirate was obtained from 92.9% of primary ameloblastoma and in 73.1% of patients <20 years of age. Recurrent ameloblastoma typically yielded dark-brown aspirates in 76.9% of recurrences. Conclusion: The association of some tumor fluids with primary and recurrent ameloblastoma could improve the understanding of the recurrence potential of the disease and influence treatment planning.

Keywords: Primary ameloblastoma, recurrent ameloblastoma, tumor fluid


How to cite this article:
Nwoga MC. Fluid aspirates of ameloblastoma: Types, prevalence, and prognostic relevance. Int J Med Health Dev 2022;27:385-91

How to cite this URL:
Nwoga MC. Fluid aspirates of ameloblastoma: Types, prevalence, and prognostic relevance. Int J Med Health Dev [serial online] 2022 [cited 2022 Oct 1];27:385-91. Available from: https://www.ijmhdev.com/text.asp?2022/27/4/385/356632




  Introduction Top


Ameloblastoma is a benign, epithelial jaw tumor commonly diagnosed as peripheral, unicystic, multicystic, and metastasizing.[1] It has been reported as the most frequently diagnosed odontogenic tumor in Nigeria.[2] The tumor is mostly slow-growing but could present with large disfiguring jaw swellings, malocclusion, loosening of teeth, buccal and lingual bone expansion, cortical perforation with soft-tissue invasion, and unilocular or multilocular radiolucency.[1] Intraosseous ameloblastoma could present with cystic cavities which develop from degenerations of epithelial tumor islands.[1] Jaw swellings often prompt clinicians to perform chair-side needle aspirations to exclude or affirm its solid, cystic, or vascular nature. Such simple clinical procedures result in positive or negative tumor fluid yields.[3]

Visual examinations of fluid aspirates from tumors histologically diagnosed as ameloblastoma have been variously described as straw-colored,[4] brownish,[5] blood-tinged straw-colored,[6] straw fluid,[7] and brownish-yellow.[8],[9]

Few studies known to the author and in English literature have investigated the types, prevalence, categories, and prognostic relevance of ameloblastoma tumor fluids.[5],[6],[8],[9] A most recent report of ameloblastoma in children and adolescents only categorized the types of tumor fluid aspirates as straw, serosanguinous, dark-brown, and purulent.[10] There is a possibility that fluids obtained from ameloblastoma could give insight into its biological behavior and guide management. This study evaluates the types, frequency, and prognostic relevance of the fluid aspirates of primary and recurrent ameloblastoma.


  Materials and Methods Top


This was a retrospective review of consecutive patients who presented at the Oral and Maxillofacial Surgery/Pathology clinics with histologically confirmed diagnoses of ameloblastoma from 2012 to 2018.

The archived records of case files, biopsy forms, and histopathology reports of the patients with ameloblastoma were retrieved. The information regarding age, gender, site, aspirate type, and histopathology reports of primary and recurrent ameloblastoma cases were extracted. Other factors assessed included the history of pain, age at onset, age at presentation, and duration of tumor. Age-at-tumor onset instead of age-at-presentation of tumor, best reflects the date of tumor origin from the patient’s perspective. The age-at-onset was obtained by subtracting the tumor duration from the patient’s age at clinic presentation.

Inclusion criteria

All jaw tumors with positive aspirate yield and histologic confirmation of ameloblastoma were included. Cases with complete documentation in case files, histology report, biopsy form, tissue blocks, and slides were also included in the study.

Exclusion criteria

All other jaw tumors not diagnosed as ameloblastoma were excluded. All cases of ameloblastoma without a record of tumor fluid aspiration or recorded with negative aspirate yield were excluded. Cases with incomplete case file documentation, poorly filled biopsy form, loss of some tissue blocks, and slides were also excluded from the study.

Collection of aspirates

The aspirates were aseptically obtained using a sterile 5-mL syringe with a 27-G disposable needle. Institutional ethical approval from the affiliate institution where the study was done was obtained.

Aspirates were categorized according to the color and nature of their appearance. The color ranges used in this study were drawn from those reported in the literature: straw,[4] serosanguinous,[6] and dark-brown.[5] The straw-colored aspirates included those described as yellow-straw[7] and brownish-yellow.[8],[9] The blood-tinged straw aspirate was classified as serosanguinous type. The aspirates clinically described as “chocolate brown” or “dirty brown” were included in the dark-brown category. Some cases of infected ameloblastoma yielded purulent aspirates. Such aspirates were categorized as “purulent.”

The age-at-onset was categorized into four groups: ≤20 years, 21–40 years, 41–60 years, and >60 years.

Statistics

The data were analyzed with IBM SPSS Statistics, version 24.0. The frequencies and percentages were calculated for the descriptive variables. The means and standard deviations of continuous variables, the frequency tables of categorical variables, and the associations using chi-square tests were determined. The test of significance was set at P ≤ 0.05.


  Results Top


There were 191 odontogenic tumors with 115 cases of ameloblastoma, out of which 92 cases were selected. The prevalence of positive tumor fluid yield was 74 (80.4%) and negative yield was 18 (19.6%).

Age

Among the 74 cases with positive aspirate yield, the mean age at tumor onset was 28.9 ± 18.4 years (range, 6 years and 79 years). The mode was 12 years and the median was 23 years.

Those in the ≤20 years age group at onset of ameloblastoma 32(43.2%) were the highest group that yielded tumor aspirates followed by those in the 21–40 years age group with 23(31.1%) cases. Twelve patients (16.2%) in the 41–60 age group had aspirates, whereas the least number of cases with tumor aspirates were in the >60 years age group.

The mean age at clinical presentation of tumors with aspirates was 32.7 ± 19.0 years (range 6 to 81 years). The median and mode for the age at clinical presentation were 26.0 and 22.0 years, respectively. The mean duration of the swellings was 3.8 ± 2.0 years (range, 1 and 11 years).

Age-at-onset of tumors was found to be significantly associated with the aspirate type, P = 0.01.

Gender

There was equal gender distribution of 50 (50%) male and 50 (50%) female with a ratio of 1:1.

Site

The ameloblastoma cases were all intraosseous with 71(95.9%) cases located on the mandible: anterior 31 (41.9%), posterior 40 (54.1%), and the maxilla with 3(4.1%) of cases. [Figure 1] shows a clinical photo of a large mandibular ameloblastoma. [Figure 2] shows a cut section of mandibular excision specimen showing multicystic cavities where tumor fluid usually accumulated.
Figure 1: Ameloblastoma with expansion of the mandibular cortical bones and intraoral mass

Click here to view
Figure 2: Excisional specimen of mandibular ameloblastoma. The cut section shows cystic cavitations that may contain tumor fluid

Click here to view


Clinical history

Pain was frequently reported by 39(52.7%) of the patients with positive aspirate yield. A total of 61(82.4%) cases were primary ameloblastoma in contrast to 13(17.6%) cases of recurrent ameloblastoma. The histologic diagnoses were reported as follows: Solid/multicystic ameloblastoma 61(82.4%) and unicystic ameloblastoma 13(17.6%).

Aspirates

Primary ameloblastoma cases yielded 61(82.4%) tumor fluid aspirates, whereas 13(17.6%) aspirates were obtained from cases of recurrent ameloblastoma. [Table 1] shows four types of aspirates identified as dark-brown, straw, serosanguinous, and purulent.
Table 1: Summary of aspirate fluid type and prevalence in ameloblastoma (n = 74)

Click here to view


The primary or recurrent status of ameloblastoma

[Table 2] shows that the primary or recurrent status of ameloblastoma is significantly associated with the type of aspirate (P = 0.04). This explained why recurrent ameloblastoma predominantly yielded dark brown aspirates and rarely straw aspirates.
Table 2: Association of aspirate type and recurrence status of ameloblastoma

Click here to view


Dark-brown aspirate

Although primary ameloblastoma presented all types of aspirates, recurrent tumors showed dark-brown aspirates as the most frequent feature. The aspirates from 13 recurrent ameloblastoma cases were mostly dark-brown 76.9% (10). [Table 3] shows that 12 (52.2%) out of 23 aspirates were found among those in the 21–40 years age group. Of all dark-brown aspirates in the study, 40.0% (12/30) were found in the onset age group 21–40 [Table 3].
Table 3: Association of aspirate type and age-at-onset of ameloblastoma (n = 72a)

Click here to view


Straw aspirate

[Table 2] shows that straw-colored aspirate was significantly observed in primary ameloblastoma, 92.9% (26/28), P = 0.037. Out of a total of 28 ameloblastoma cases with straw aspirates, 92.9% (26) of the straw yield was observed in primary ameloblastoma as against 7.1% (2) noted in recurrent ameloblastoma. [Table 3] indicates that more than half of the 13 cases of unicystic ameloblastoma (53.8%) yielded straw aspirates (P = 0.107).

Serosanguinous aspirate

[Table 2] shows that all the cases (n = 7) of serosanguinous aspirates in this series were observed only in primary ameloblastoma, P = 0.037. The serosanguinous aspirate was also not observed in recurrent tumors, nor in patients less than 20 years of age (P = 012) [Table 3].

Purulent aspirates

[Table 4] shows that all seven cases of purulent aspirates were from conventional multicystic ameloblastoma. The majority of purulent aspirates, 85.7% (6/7) were found in primary ameloblastoma, whereas only one case 14.3% was observed in recurrent ameloblastoma [Table 2].
Table 4: Association of aspirate type and histological types of ameloblastoma

Click here to view


There was no significant relationship of type of aspirate with age-at-presentation (P = 0.057), gender (P = 0.98), history of pain (P = 0.19), duration groups (P = 0.30), and histological types of ameloblastoma (0.11).


  Discussion Top


This study identified types and prevalence of fluid aspirates of ameloblastoma as dark-brown 41.9%, straw-colored 37.8%, serosanguinous 10.8%, and purulent 9.5%. Ameloblastoma tumor aspirates were recently reported in children and adolescents, as straw aspirates 61.3%, dark-brown aspirates 25.8%, purulent 9.7%, and purulent 3.2%.[10] Previous reports of such aspirates had given varied descriptions such as brownish,[5] blood-tinged and brownish-yellow,[8],[9] without categorizing them. Semi-solid cavity contents too thick to be needle-aspirated and placement of an aspirating needle outside of a tumor fluid cavity could explain the negative aspirate yields of 19.6% in this study.

The mean age of 28.9 years at onset of ameloblastoma from this study contrasts with the 34 years reported in the Western literature,[1] due to the methodology of using the age of tumor onset as more representative of the epidemiological data.[10] The age at clinical presentation is unreliable in our environment due to the unpredictable periods of delay before presenting at the hospital. In this study, ameloblastoma showed a predilection for children and adolescents with predominant occurrence in the age group of ≤20 years. This contrasts with the reported predilection for the 20–29 years age group from a large-scale Nigerian study of ameloblastoma using age at clinical presentation.[2]

The equal gender distribution and mandibular predilection of ameloblastoma is consistent with other published reports,[1] but contrasts with a Nigerian study that reported a male predilection in a ratio of 1.2:1.[2]

The predominant mandibular location of ameloblastoma occurrence of 95.9% and its intraosseous site are features commonly reported in many studies.[1],[2],[10] Aspiration of tumor fluid was possible in intraosseous types of ameloblastoma because of development of cystic cavities in unicystic and multicystic types of ameloblastoma.[1],[10]

Pain was frequently reported by 52.7% of the patients at time of clinical presentation. This observation contrasts with the report that ameloblastoma is a painless tumor.[1] The reasons for the pain in ameloblastoma in this series could be due to the delay in presentation, the tumor size, tumor infection, the mandibular predilection, and close relation with the inferior alveolar nerve. However, there is no statistically significant relationship of pain and tumor aspirate in this study.

Types of fluid aspirates of ameloblastoma were sparsely referenced in earlier literature.[6],[7],[8],[11] Consequently, understanding their role in the tumor development and prognosis was not investigated. Tumor fluid aspirates from ameloblastoma cavities are extracellular fluid and part of the tumor interstitial fluid (TIF) which constitutes the tumor microenvironment.[12],[13] The tumor fluid accumulates over the course of the disease and has regulatory roles in cellular growth and tumor behavior[12],[13] They are reported to form reactive interstitium with increased angiogenesis as the tumor progressed.[14],[15],[16] The reactive interstitium increases the quantities of vascular endothelial growth factor (VEGF-A),[17] endothelial cells, fibroblasts,[15],[18] epidermal growth factors,[19] and inflammatory cells including tumor-associated macrophages (TAMs).[20] This is corroborated by the report of inflammatory exudates and cells during the cytologic examination of ameloblastoma fluid aspirate.[7],[21] Similar observations have been reported in fluids from other tumors that gave rise to reactive TIF, association with increased vascular stroma formation, increased microvascular permeability, and extravasations of plasma proteins.[21],[22]

The order of appearance of tumor fluid types is not known to the author. It may be a dynamic process or static throughout the course of the tumor, unless an infection supervenes. The factors determining the type of tumor fluid that the ameloblastoma starts with may depend on multiple factors that include biological behavior of the tumor, age at onset, and primary of recurrent status among others. A tumor at onset could probably start with accumulation of any of the tumor fluid types, become purulent following an infection process, or end up semisolid or with blood clots.[11]

Recurrence of a tumor could indicate aggressive behavior and an increase in morbidity. This is important especially in ameloblastoma where frequent recurrences could be associated with malignant transformation.[23] Recurrence in ameloblastoma could therefore affect the type and nature of the TIF and the fluid aspirate.

Dark-brown fluid aspirates in recurrent ameloblastoma could suggest increased recurrence potential or aggressive tumor behavior. A previous surgical treatment followed by recurrence of ameloblastoma appears to favor the development of dark-brown aspirate fluid. Dark brown aspirate was also observed in primary ameloblastoma, especially among those between 20 and 40 years at tumor onset. The implication of this is that whenever dark-brown aspirate is present in primary ameloblastoma, similar to recurrent ameloblastoma, it suggests a greater potential for frequent recurrence and increasing morbidity.

This study observed that straw aspirates were predominant in those below 20 years of age, and the significant relationship (P = 0.01) of age-at-onset of tumors with the aspirate type could indicate that the type of tumor fluids are determined early at the beginning of tumor occurrence. The result also showed that if straw aspirates are observed in ameloblastoma, it is most likely to be in a primary tumor. This finding concurs with a similar report in a recent study of ameloblastoma in children and adolescents.[10]

Straw aspirates are also frequent findings in non-invasive odontogenic cysts such as dentigerous cysts,[7] and could indicate less aggressive ameloblastoma similar to these odontogenic cysts. Further studies would be required to evaluate any difference in rate of recurrence between primary ameloblastoma with straw aspirates and those with dark-brown aspirates.

Serosanguinous aspirates are common features of primary ameloblastoma because all the seven cases of serosanguinous aspirates in this series were obtained only in primary ameloblastoma. The absence of serosanguinous aspirate in recurrent ameloblastoma could suggest it is less aggressive than the dark-brown aspirate. The non-occurrence of serosanguinous aspirate in patients less than 20 years of age was found to be statistically significant, P = 012 and could suggest it is a transition tumor fluid after the stage of straw fluid appearance. The other clinical relevance of the observation of serosanguinous aspirate could not be explained by the author.

Purulent aspirates were seen only in multicystic ameloblastoma in this series. It was also found mostly (6/7) in primary ameloblastoma, and therefore considered a sequelae of supervening tumor infection. Purulence was secondary to an infection that masked the prior tumor fluid type. The reason for the low infection rates in recurrent ameloblastoma could be the probable antimicrobial effects of dark brown tumor fluid with reactive interstitium and vascularizations.[16],[17],[18]

The new knowledge contributed by this study includes the types and prevalence of fluid aspirates of ameloblastoma, the significant association with age-at-onset of ameloblastoma and the recurrent status. The significant association of dark brown aspirates with the recurrent status implies the presence of a recurrence potential. This knowledge can influence the clinical evaluation, recommendation for a more aggressive treatment of primary tumors with dark-brown aspirates, and prognostic considerations of ameloblastoma.

This study was limited by evaluating a few cases of recurrent ameloblastoma and categorization of tumor aspirates based only on the clinical appearance and capacity for color observation. One of the strengths of this study is the large number of primary ameloblastoma cases with documentation of their fluid aspirates.

In conclusion, this study noted that when straw aspirates were present, they were commonly observed in primary ameloblastoma. Comparatively, when recurrent ameloblastoma yields tumor aspirate, it is frequently associated with dark-brown aspirate.

This study proposes the examination of tumor fluid aspirate as complementary to the histologic diagnosis of ameloblastoma in planning the management and prognosis. The dark-brown aspirate could be considered a clinical indicator of increased recurrence potential in a histologically confirmed ameloblastoma. Other important factors affecting the management and prognosis of ameloblastoma would include anatomical site, histopathologic type, treatment approach, the proliferation of residual tumor, and iatrogenic implantation.[7],[24] The association of some tumor fluids with primary and recurrent ameloblastoma improves the understanding of the recurrence potential of some tumors and could influence treatment planning.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Not applicable.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Takata T, Slootweg PJ Odontogenic and maxillofacial bone tumors. In: El-Naggar AK, Chan JKC, Grandis JR, Takata T, Slootweg PJ, editors. WHO classification of head and neck tumors. 4th ed. Lyon: IARC Press; 2017. pp. 203-60.  Back to cited text no. 1
    
2.
Okoh DS, Akinshipo AO, Butali A, Omitola OG, Sigbeku OF, Soyele OO, et al. Descriptive epidemiology of odontogenic tumors in Nigeria: An African oral pathology research consortium multicenter study. Niger J Clin Pract 2020;23:1695-701.  Back to cited text no. 2
[PUBMED]  [Full text]  
3.
Agrawal M, Weihsin H, Garg B, Sood R, Singh M Atypical proliferative ameloblastoma with a rare histopathological feature and review of literature. Oral Maxillo-fac Pathol J 2015;6:582-85.  Back to cited text no. 3
    
4.
Zain RB Unicystic ameloblastoma: A new entity? Med J Malaysia 1986;41:370-3.  Back to cited text no. 4
    
5.
Bhagwat AU Intraluminal unicystic ameloblastoma: A case report. Int J Dent Med Res 2015;1:119-21.  Back to cited text no. 5
    
6.
Kavitha M, Raj RR, Anuradha G, Vijayakumar V Intraluminal plexiform unicystic ameloblastoma: A report of a rarity in an 8-year-old boy. IJSS Case Reports & Review 2015;1:52-4.  Back to cited text no. 6
    
7.
Saravanakumar B, Parthiban J, Aarthi N.V, Sarumathi T, Prakash CA Unicystic ameloblastoma of the mandible: Report of two cases with review of literature. J Clin Diagn Res 2014;8:ZD07-9.  Back to cited text no. 7
    
8.
Nagalaxmi V, Sangmesh M, Maloth KN, Kodangal S, Chappidi V, Goyal S Unicystic mural ameloblastoma: An unusual case report. Case Rep Dent 2013;2013:957418.  Back to cited text no. 8
    
9.
Nadendla LK Unusual imaging appearance of unicystic ameloblastoma. Contemp Clin Dent 2012;3:475-7.  Back to cited text no. 9
    
10.
Nwoga MC Ameloblastoma in Children and Adolescents: A Seven-year Study in Enugu, Nigeria. J Paediatr Dent Res Pract 2021;2:23-8.  Back to cited text no. 10
    
11.
Cankurtaran CZ, Branstetter BF 4th, Chiosea SI, Barnes EL Jr. Best cases from the AFIP: Ameloblastoma and dentigerous cyst associated with impacted mandibular third molar tooth. Radiographics 2010;30:1415-20.  Back to cited text no. 11
    
12.
Lu P, Weaver VM, Werb Z The extracellular matrix: A dynamic niche in cancer progression. J Cell Biol 2012;196:395-406.  Back to cited text no. 12
    
13.
Miles FL, Sikes RA Insidious changes in stromal matrix fuel cancer progression. Mol Cancer Res 2014;12:297-312.  Back to cited text no. 13
    
14.
Kalluri R, Zeisberg M Fibroblasts in cancer. Nat Rev Cancer 2006;6:392-401.  Back to cited text no. 14
    
15.
Fukumura D, Xavier R, Sugiura T, Chen Y, Park EC, Lu N, et al. Tumor induction of VEGF promoter activity in stromal cells. Cell 1998;94:715-25.  Back to cited text no. 15
    
16.
Mantovani A, Allavena P, Sica A, Balkwill F Cancer-related inflammation. Nature 2008;454:436-44.  Back to cited text no. 16
    
17.
Brown LF, Guidi AJ, Schnitt SJ, Van De Water L, Iruela-Arispe ML, Yeo TK, et al. Vascular stroma formation in carcinoma in situ, invasive carcinoma, and metastatic carcinoma of the breast. Clin Cancer Res 1999;5:1041-56.  Back to cited text no. 17
    
18.
Junttila MR, de Sauvage FJ Influence of tumor micro-environment heterogeneity on therapeutic response. Nature 2013;501:346-54.  Back to cited text no. 18
    
19.
Woo SR, Corrales L, Gajewski TF Innate immune recognition of cancer. Annu Rev Immunol 2015;33:445-74.  Back to cited text no. 19
    
20.
Sica A, Mantovani A Macrophage plasticity and polarization: In vivo veritas. J Clin Invest 2012;122:787-95.  Back to cited text no. 20
    
21.
Chaudhary Z, Sangwan V, Pal US, Sharma P Unicystic ameloblastoma: A diagnostic dilemma. Natl J Maxillofac Surg 2011;2:89-92.  Back to cited text no. 21
    
22.
Dvorak HF, Sioussat TM, Brown LF, Berse B, Nagy JA, Sotrel A, et al. Distribution of vascular permeability factor (vascular endothelial growth factor) in tumors: Concentration in tumor blood vessels. J Exp Med 1991;174:1275-8.  Back to cited text no. 22
    
23.
Hertog D, Bloemena E, Aartman IH, van-der-Waal I Histopathology of ameloblastoma of the jaws: Some critical observations based on a 40 years single institution experience. Med Oral Patol Oral Cir Bucal 2012;17:e76-82.  Back to cited text no. 23
    
24.
Prakash R, Shyamala k, Girish HC, Murgod S, Singh S, Rani PSV Comparison of components of odontogenic cyst fluids: A review. J Med Radiol Pathol Surg 2016;2: 15-17.  Back to cited text no. 24
    


    Figures

  [Figure 1], [Figure 2]
 
 
    Tables

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



 

Top
 
  Search
 
    Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
 Related articles
    Access Statistics
    Email Alert *
    Add to My List *
* Registration required (free)  

 
  In this article
Abstract
Introduction
Materials and Me...
Results
Discussion
References
Article Figures
Article Tables

 Article Access Statistics
    Viewed94    
    Printed0    
    Emailed0    
    PDF Downloaded13    
    Comments [Add]    

Recommend this journal