Muscle Physiology Data Handling Assignment

There are 5 questions to answer

Question 1.

A group of researchers are looking to identify a novel peptide which could be used to inhibit uterine contractions and help women who are in preterm labour, due to premature uterine contractions.

They present their findings to a group of biotech investors by showing what they describe as typical findings below;

The researchers explain that they have recorded contractions from pieces of human myometrium and then applied the peptide to the tissue and recorded its effects. The time bar underneath the figure indicates 20 minutes of activity and the bar above the trace indicates when the peptide was applied to the contracting tissue.

  1. Roughly calculate what the effect of the peptide is on the amplitude and frequency of contraction, (It may be easier to print this question and use a ruler to measure. Please detail your workings)
  1. What effect to you think the peptide is having on overall uterine activity and how could you calculate this?

Question 2.

In a second experiment, the researchers decide to measure intracellular Ca2+ levels to look at the effect the peptide has on Ca2+ signalling mechanisms in the myometrium. They discuss using Ca2+ indicators to measure this.

In their experiment they decide to use the Ca2+ indicator indo 1-AM. They measured changes in intracellular calcium concentration ([Ca2+]), shown in red below (bottom trace), and concluded that the peptide causes Ca2+ desensitisation in the myometrium: Time bar indicates 10 minutes, force (in mN) is shown in black (top trace).

Do you agree with the researchers that it looks like Ca2+ sensitivity has been altered? Give the reasons for your answer and describe how the extract may be acting in the uterus

Question 3.

Using the relationship between apparent Kd (dissociation constant), ratio value for saturating [Ca2+] (maximal fluorescence, Rmax) and ratio value for zero Ca2+ (minimal fluorescence, Rmin):

[Ca2+] = Kd · (R – Rmin)/(Rmax- R)

calculate the [Ca2+] for an experimentally determined ratio value (R) of Ca2+ at rest of 1.0 and at peak of contraction of 4.4. Give your answers in μM, and use the following values:

Kd is 400nM  Rmax = 5.8 and Rmin = 0.4                                                                                (20 Marks)

Question 4.

Two researchers want to investigate the effect of obesity on preterm birth rate. They are discussing

different types of study designs that they could use and cannot decide between performing ‘case- control’ study and a ‘cohort’ study.

  1. Briefly describe the major differences in the way in which the two types of study are
  2. List two advantages and two disadvantages of a case-control study compared to a cohort

Question 5

Periodontal disease has been linked to a number of conditions including adverse pregnancy outcomes. It has been suggested that treatment of periodontal disease may reduce adverse outcomes including preterm birth and low birth weight (<2500g). A group of researchers carried out a Cochrane review and meta-analysis of randomized trials to assess the effects of treating periodontal disease in pregnant women as a means to reduce or prevent preterm birth and low birth weight.

Below are extracts from the results of their Cochrane review.

Comparison 1: Periodontal treatment versus no treatment Outcome 1: Gestational age (preterm birth)

  1. How many studies were included in the meta-analysis of preterm birth?
  2. Which study had the greatest influence and which study had the least influence on the pooled result? Give reasons for your answers.
  3. Based on the calculated pooled result, does treatment of periodontal disease reduce preterm birth? Give reasons for your answer.
  4. e) In a second meta-analysis, the researchers investigated the effect of treatment of periodontal disease versus no treatment on low birth weight outcome. Their findings are presented below.

Comparison 1: Periodontal treatment versus no treatment Outcome 2: low birth weight (<2500g)

Do the findings support periodontal treatment to reduce low birth weight? Give reasons for your answer.

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