State the level of COPD that has the lowest FEV.

Explain how a low FEV can be used to indicate emphysema.

State the disease severity group that has the highest range of plasma desmosines.

Evaluate which of the two biomarkers would be the most useful indicator of COPD severity.

Elastin is also an important component of other tissues such as arteries and ligaments. Evaluate how these other sources of elastin could affect the interpretation of the biomarker as an indicator of COPD.

State the relationship between diffusion capacity and urine desmosines.

Other studies on pulmonary diseases have shown a wide variety of results. Apart from age, sex and severity of COPD, list two other factors that may explain the inconsistent results between studies.

Discuss whether measurements of desmosine concentration would be useful for monitoring changes in the health of a patient.

Severe

a. low FEV indicates inability to force out air/adequate volume of air

    OWTTE

b. airflow limitation is the reason for inability to force out air/shortness of breath

c. inability to force out air/shortness of breath indicates emphysema

d. emphysema causes/involves breakdown of alveoli walls «so less elastin»

    The idea that there are fewer alveoli to “push”

[Max 2 Marks]

No disease

a. plasma desmosines

b. neither is very good due to large overlaps of ranges

    OWTTE

    OR

    the range of data for each category is less for plasma desmosines

    OR

    data are more reliable

c. the level of plasma desmosines increases with disease severity

d. easier/less invasive to take urine sample rather than a plasma sample

[Max 2 Marks]

a. degradation of elastin from other tissues may have contributed to the results

b. there is no guarantee that the concentrations of desmosines measured came from the lungs

    OR

    difficult to assess how much lung elastin constitutes the total

c. overlapping ranges makes interpretation difficult

[Max 2 Marks]

inversely correlated

OR

negative correlation

OR

the higher the «urine» desmosine concentration, the lower the diffusion «rate»

a. «small» sample size

    OR

    only studied in one country

b. methods used

c. environment/pollution/workplace exposure

d. race/genetic factors

e. health status/fitness/BMI of volunteers

[Max 2 Marks]

a. positive correlation with COPD severity «as seen in the table»

    OR

    negative correlation with «CO» diffusion capacity «as seen in the graph»

b. not directly proportional/other factors affect it

c. «but» if other factors stay the same in a patient it could be an effective indicator of change

d. because the ranges are high, only change in an individual is useful

e. the measurements may be more useful for one gender than the other as differences seen in the graph

[Max 3 Marks]