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Multivariate analysis for animal selection in experimental research.

Pinto RM, Campos DH, Tomasi LC, Cicogna AC, Okoshi K, Padovani CR - Arq. Bras. Cardiol. (2015)

Bottom Line: Then, the variance matrix of the set was submitted to principal components analysis (PCA), aiming at reducing the parametric space and at retaining the relevant variability.The allocation of the animals in the new system and the construction of the confidence region revealed six spurious animals as compared to the homogeneous batch of 109 animals.The biometric criterion presented proved to be effective, because it considers the animal as a whole, analyzing jointly all parameters measured, in addition to having a small discard rate.

View Article: PubMed Central - PubMed

Affiliation: Departamento de Bioestatística, Instituto de Ciências Biológicas, Universidade Estadual Paulista, Botucatu, São Paulo, Brazil.

ABSTRACT

Background: Several researchers seek methods for the selection of homogeneous groups of animals in experimental studies, a fact justified because homogeneity is an indispensable prerequisite for casualization of treatments. The lack of robust methods that comply with statistical and biological principles is the reason why researchers use empirical or subjective methods, influencing their results.

Objective: To develop a multivariate statistical model for the selection of a homogeneous group of animals for experimental research and to elaborate a computational package to use it.

Methods: The set of echocardiographic data of 115 male Wistar rats with supravalvular aortic stenosis (AoS) was used as an example of model development. Initially, the data were standardized, and became dimensionless. Then, the variance matrix of the set was submitted to principal components analysis (PCA), aiming at reducing the parametric space and at retaining the relevant variability. That technique established a new Cartesian system into which the animals were allocated, and finally the confidence region (ellipsoid) was built for the profile of the animals' homogeneous responses. The animals located inside the ellipsoid were considered as belonging to the homogeneous batch; those outside the ellipsoid were considered spurious.

Results: The PCA established eight descriptive axes that represented the accumulated variance of the data set in 88.71%. The allocation of the animals in the new system and the construction of the confidence region revealed six spurious animals as compared to the homogeneous batch of 109 animals.

Conclusion: The biometric criterion presented proved to be effective, because it considers the animal as a whole, analyzing jointly all parameters measured, in addition to having a small discard rate.

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Related in: MedlinePlus

Placement of the silver clip in the aortic valve
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Related In: Results  -  Collection

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f01: Placement of the silver clip in the aortic valve

Mentions: Aortic stenosis was induced according to a previously described method4-7. The three- to four-week-old animals, weighing 70-90 g, underwentanesthesia with the association of ketamine chloride (60 mg/kg) and xylidine chloride(10 mg/kg), by intraperitoneal (ip) route. Then median thoracotomy was performed, theascending aorta dissected and a silver clip (inner diameter of 0.6 mm) placedapproximately 3 mm from its root (Figure 1).The thoracic wall was closed, and the sternum, muscle layers and skin were suturedwith 5.0-mononylon thread. During surgery, the animals were manually ventilated withpositive pressure, 100% oxygen. After the end of surgery, they received,subcutaneously, 1 mL of warm saline solution, and were placed on a warm surface torecover from anesthesia.


Multivariate analysis for animal selection in experimental research.

Pinto RM, Campos DH, Tomasi LC, Cicogna AC, Okoshi K, Padovani CR - Arq. Bras. Cardiol. (2015)

Placement of the silver clip in the aortic valve
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4375652&req=5

f01: Placement of the silver clip in the aortic valve
Mentions: Aortic stenosis was induced according to a previously described method4-7. The three- to four-week-old animals, weighing 70-90 g, underwentanesthesia with the association of ketamine chloride (60 mg/kg) and xylidine chloride(10 mg/kg), by intraperitoneal (ip) route. Then median thoracotomy was performed, theascending aorta dissected and a silver clip (inner diameter of 0.6 mm) placedapproximately 3 mm from its root (Figure 1).The thoracic wall was closed, and the sternum, muscle layers and skin were suturedwith 5.0-mononylon thread. During surgery, the animals were manually ventilated withpositive pressure, 100% oxygen. After the end of surgery, they received,subcutaneously, 1 mL of warm saline solution, and were placed on a warm surface torecover from anesthesia.

Bottom Line: Then, the variance matrix of the set was submitted to principal components analysis (PCA), aiming at reducing the parametric space and at retaining the relevant variability.The allocation of the animals in the new system and the construction of the confidence region revealed six spurious animals as compared to the homogeneous batch of 109 animals.The biometric criterion presented proved to be effective, because it considers the animal as a whole, analyzing jointly all parameters measured, in addition to having a small discard rate.

View Article: PubMed Central - PubMed

Affiliation: Departamento de Bioestatística, Instituto de Ciências Biológicas, Universidade Estadual Paulista, Botucatu, São Paulo, Brazil.

ABSTRACT

Background: Several researchers seek methods for the selection of homogeneous groups of animals in experimental studies, a fact justified because homogeneity is an indispensable prerequisite for casualization of treatments. The lack of robust methods that comply with statistical and biological principles is the reason why researchers use empirical or subjective methods, influencing their results.

Objective: To develop a multivariate statistical model for the selection of a homogeneous group of animals for experimental research and to elaborate a computational package to use it.

Methods: The set of echocardiographic data of 115 male Wistar rats with supravalvular aortic stenosis (AoS) was used as an example of model development. Initially, the data were standardized, and became dimensionless. Then, the variance matrix of the set was submitted to principal components analysis (PCA), aiming at reducing the parametric space and at retaining the relevant variability. That technique established a new Cartesian system into which the animals were allocated, and finally the confidence region (ellipsoid) was built for the profile of the animals' homogeneous responses. The animals located inside the ellipsoid were considered as belonging to the homogeneous batch; those outside the ellipsoid were considered spurious.

Results: The PCA established eight descriptive axes that represented the accumulated variance of the data set in 88.71%. The allocation of the animals in the new system and the construction of the confidence region revealed six spurious animals as compared to the homogeneous batch of 109 animals.

Conclusion: The biometric criterion presented proved to be effective, because it considers the animal as a whole, analyzing jointly all parameters measured, in addition to having a small discard rate.

Show MeSH
Related in: MedlinePlus