Quantitative Trait Locus Studies of Ventilator Induced Lung Injury

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Quantitative Trait Locus Studies of Ventilator
Induced Lung Injury

• William Tolliver

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BACKGROUND
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ALI Acute Lung Injury

• ALI (Acute Lung Injury) is a syndrome of
  widespread lung inflammation and increased
  pulmonary vascular permeability depicted by
  pulmonary edema and hypoxia
• Approximately 190,000 cases/yr with a mortality
  rate of 30-40
• Cause remains unknown but ALI is secondary to
  sepsis, trauma, drug overdose
• Iatrogenic contributions include supplemental
  oxygen and mechanical ventilation

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VILI Ventilator Induced Lung Injury

• Characterized by excessive alveolar distension
  which causes the tight junction of the alveolar
  wall to rupture
• Caused when the lungs are directly damaged by
  over ventilating

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Mechanical Ventilation

• Necessary method used to mechanically support
  people who have ALI
• If ventilation is used improperly, or is done for
  too long, it can lead to VILI

Normal 5 mins. 20 mins.
Fig. Normal Rat Lungs and Rat Lungs after
Receiving High-Pressure Mechanical Ventilation at
a Peak Airway Pressure of 45 cm of Water.
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Control
HTV
Fig. HE staining of mouse lungs with
non-ventilation (Control) and ventilated with
high tidal volume (HTV).
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Heterogeneity in susceptibility and outcome

• Why do only some patients with sepsis develop
  ALI?
• Why do some patients with ALI develop
  multi-organ failure?
• Why is low tidal ventilation of great benefit
  only in some patients?

Genetic Predisposition

• Genetic susceptibility to acute lung injury.
• - Crit Care Med. 2003 Apr31(4
  Suppl)S272-5.
• Genomic insights into acute inflammatory lung
  injury.
• - Am J Physiol Lung Cell Mol Physiol. 2006
  Dec291(6)L1113-7.
• Genetic susceptibility to irritant-induced acute
  lung injury in mice.
• - Am J Physiol Lung Cell Mol Physiol. 2000
  Sep279(3)L575-82.

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AIM OF OUR STUDY
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AIM 1
AIM 2
QTL Analysis of Genetic Susceptibility to VILI
Identification of VILI- Sensitive and VILI-
Resistant mouse strains
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VILI Animal Model
ventilator
EBA
trachea
jugular vein
sensor
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Lung Injury Evaluation

• Alveolar-Capillary Permeability
• Found by measuring either accumulation of protein
  in Bronchoalveolar Lavage or Albumin bound to
  Evans Blue

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Evans Blue Albumin (EBA)

• Used to measure pulmonary leakage
• More EBA leak into the alveoli during lung
  injury.

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Evans Blue Measurement
Homogenize lung in 2 ml of PBS
Incubate with formamide at 60?C for 18 hrs
Centrifuge for 30 mins.
Measure Evans Blue absorbance in lung by
spectrophotometric method (620, 740nm)
Measure Evans Blue absorbance in plasma
Permeability index ( EB Lung /Lung Weight ) / EB
Plasma
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RESULTS
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IN CONCLUSION
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Research Conclusion

• Mice are a good model for VILI
• Inbred strains show variable sensitivity
• Evans Blue or BAL protein are useful phenotypic
  markers of VILI
• This approach will support future quantitative
  trait locus analysis of genes accounting for
  sensitivity to VILI

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My Experience

• Research
• Knowledge about ALI, ARDS and VILI
• Animal anesthesia and animal surgery
• Animal Rights
• Repetition is Key
• Time-Consuming
• Love/Hate Relationship
• How to analysis data
• Summer
• Made Friends
• Had Fun
• Broadened Horizons to Medical Field

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!!!ThAnK yOu!!!

• Thank you for your attention!
• Thank You
• HuiHua Li
• Bruce Pitt
• Karla Wasserloos
• Mackenzie Mosher
• Lindsay Wright
• Antonia Nemec
• George Leikauf
• Liming Zhang
• Dasan Thambiayya

ThAnKs
ThAnKs