"Analysis of immunohistochemical expression of epidermal growth factor receptor in oral squamous cell carcinoma using tissue microarray technology and whole sections:" A comparative study

BACKGROUND

Oral squamous cell carcinoma (OSCC) accounts for more than 90% of all oral cancers. Epidermal growth factor receptor (EGFR) dysregulation is associated with essentially all of the key features of cancer. Tissue microarrays (TMAs) allow the simultaneous analysis of many tumours using small-diameter cores sampled from larger blocks of tissue. Hence present study was taken up to validate TMA technology.

AIMS AND OBJECTIVES

To analyse and compare the immunohistochemical (IHC) expression of EGFR in OSCC using TMA technology and in whole tissue sections.

MATERIALS AND METHODS

Study included 34 cases of OSCC.Three tissue cores, each 1 mm in diameter were placed into a recipient paraffin block using a precision microarray instrument finally containing 102 spots. EGFR expression was analysed. Agreement between whole sections and TMA scores was analysed using Cohen's weighted Kappa.

RESULTS

EGFR expression was seen in 61.8% of whole section cases. In TMA out of 102 cores 75.50 % of the disks were confirmed to represent an adequate amount of tumor tissue. In TMA 48.5% cases showed EGFR expression.The EGFR expression of whole.

CONCLUSION

Some OSCC express high EGFR and this expression may be an independent Wfactor of certain clinico-pathological variables. TMA may be used as an adjunct with conventional method of evaluation of OSCC especially in larger sample sized studies keeping in mind its limitations.

Comparison of frictional resistance of esthetic and semi-esthetic self-ligating brackets

AIM

The frictional resistance encountered during sliding mechanics has been well established in the orthodontic literature, and it consists of complex interactions between the bracket, archwire, and method of ligation the claim of reduced friction with self-ligating brackets is often cited as a primary advantage over conventional brackets. This study was done to compare and evaluate the frictional forces generated between fully esthetic brackets and semi-aesthetic self-ligating brackets, which are of passive form and SEM (scanning electron microscope) study of the Brackets after Frictional evaluation.

MATERIALS AND METHODS

Two types of self-ligating esthetic brackets, Damon clear (Ormco) made of fully ceramic and Opal (Ultradent Products, USA) and, Two types of self-ligating semi-esthetic brackets, Clarity SL (3M Unitek) and Damon 3 (Ormco) both of which are made of ceramic with metal slot. Arch wires with different dimensions and quality 17 × 25, 19 × 25 Titanium Molybdenum Alloy (TMA) and 17 × 25, 19 × 25 stainless steel that came from plain strands of wire were used for frictional comparison test. The brackets used in this study had 0.022 × 0.028 inch slot.

RESULTS

The statistical tests showed significantly smaller amount of kinetic frictional forces is generated by Damon 3 (semi-esthetic self-ligating brackets). For each wire used, Damon 3 displayed significantly lower frictional forces (P ≤ 0.05) than any of the self-ligating system, followed by Opal (fully esthetic self-ligating brackets) which generated smaller amount of frictional forces but relatively on the higher side when compared with Damon 3. Damon clear (fully esthetic self-ligating brackets) generated the maximum amount of kinetic forces with all types of wire dimensions and properties when compared to the other three types of self-ligating system. Clarity SL (semi-esthetic self-ligating brackets) generated smaller amount of frictional forces when compared with Damon clear and relatively higher amount of frictional forces when compared to Opal and Damon 3.

Molecular diversity of HLA-A*19 group of alleles in south Indian population

To determine the genetic diversity of the human leucocyte antigen (HLA)-A*19 group of alleles in the south Indian Tamil population, we studied 100 random healthy unrelated individuals. The frequency of HLA-A*19 was 37% with A*33 (45.9%), A*32 (29.7%), A*31 (16.2%), A*30 (5.4%), A*29 (2.7%) and A*74 (0%). The frequency distribution of the HLA-A*19 alleles was distinct and revealed marked similarities and variations with other populations.