lecture 4 Flashcards
how was the pepsin measured?
- slot blot ELISA
how does slot blot ELISA work?
- primary specific antibody (anti pepsin)
- secondary antibody (anti sheep goat)
- secondary recognises first, conjugated to peroxidase
- repeat washing
- colour development
- substrate added, dab with H2O2
what did we find?
- pepsin levels low in normal
- chronic cough group have no pepsin
- lung transplant patients have lots of pepsin (significantly high levels)
which group of transplant patients had highest pepsin levels?
- acute rejectors
what is high levels of pepsin linked with?
- acute rejection
why do BOS patients not have high pepsin levels?
- patients are showing damage to lungs
- BOS development causes leaky lungs so any pepsin escapes from lungs
why no pepsin in the chronic cough group?
- coughed up so no pepsin in actual lungs
- aspirate doesn’t get down through lungs
what results were shown from isografts with aspiration?
- more T killer cells when lungs damaged with reflux
- large number of lymphocytes
how is the rejection process accelerated?
- chronic aspiration of gastric fluid
- damage to lungs
- aspiration as immune response stimulated
what is the effect of gastric juice on rat lung allografts?
- pH 2.5 rat gastric juice = damage, open spaces disappeared,
- low pH isn’t only damaging factor
what is aspiration a source of?
- injury
what antibiotic prevents deterioration of allografts?
- azithromycin
- FEV is shown to increase
- not antimicrobial effect
- reduces amount of neutrophils
what does azithromycin do?
- effects gastric motility
- prevents reflux by increasing gastric emptying
- no contents in stomach to reflux as easy
what does azithromycin reduce levels of?
- C reactive protein (inflammatory linked plasma protein)
is azithromycin effective still in patients with lung transplants and BOS?
- bile acid aspiration reduces the survival
- if bile acid present, deterioration always occurs
what diseases have high pepsin and no other obvious cause?
- OME
- non-allergic rhinitis
- sinusitis
- hoarseness
- chronic cough
what pH is acid damaging below?
- pH 3.5
how is pepsin reactivated?
- when trapped in tissue reactivated by second exposure to acid
how is chronic cough and reflux related?
- by reflux to top of oesophagus and pepsin in sputum
what is low impedance?
- easy flow through the machine
what factors are significant in terms of reflux and chronic cough?
- age
- pepsinspit
- gender
what is pepsinspit?
- cough up and measure pepsin in sputum
what is full column?
- where the refluxate has gone passed all the rings
- not known if goes out, but like yes cant say for definite
why are the pepsin levels in lung lavages low?
- pepsin doesnt reach lungs as cough as soon as exits oesophagus?
what does the leading edge of waveform indicate?
- retrograde bolus movement
- levels gone up
what happens when the reflux event passes the rings?
- fall of impedance
what shows the height of the reflux?
- multiple channels
what does the trialing edge of waveform indicate?
- clearance of the bolus
does stopping reflux by anti-reflux surgery benefit the patient?
- after fundoplication the reflux symptom index decreases
- heartburn and other symptoms decrease
- quality of life improves
what does a reflux symptom index of 13 mean?
- reflux present
how does FEV1 change after operation?
- improvement
how are bile salt assays tested?
- oxidising them with 3-alpha HSD to remove an OH group so its oxidised
- dehydrogenase
- uses NAD+
what occurs in kit 2 for measuring bile salt assays?
- reaction to oxidised form
- can go bckwards as NADH
- can go forwards too so cycles
- more development of NAD
- measure levels of thio-NADH
what other method is used to measure bile salts?
- mass spec
- more sensitive
what is the hypothesis of profiles of sputum and gastric juice in cystic fibrosis?
- gastric and lung microbiomes are related
how do cystic fibrosis patients become reinfected with the same bacteria?
- present/hiding in stomach
- found on proton pump inhibitors
- pH high so bacterial overgrowth
what were the results from the experiment?
- 9/14 non CF grew bacteria/funghi (stomach isn’t sterile)
- all CF sputa and gastric juice grew bacteria/funghi
- p.aeruginosa in 11/14 CF patients
why does non CF patients have more microbial species ?
- most CF patients on long term antibiotic treatment
what are the conclusions?
- stomach acts as resiviour for microbes which can be refluxed and aspirated into lungs
what can be an issue following this discovery?
- PPIs as reduce acidity of stomach so add to further overgrowth
- antibiotics
how does reflux and covid-19 link?
-
how does covid enter cells?
- uses ACE2 receptor
- converts angiotensin from 1 to 2 to affect blood pressure
what GI symptoms support clinical diagnosis of covid-19?
- nausea
- vomitting
- diarrhoea
what theory was made linking covid-19 and reflux?
- reflux and aspiration damages lungs
- damaged tissue present
- allows covid access
- so can infect lungs
how was reflux identified?
- uses reflux symptom index (level over 13=reflux)
- measure salivary pepsin levels using ELISA
what results linked pepsin and severe covid?
- pepsin of more than 76ng/ml
- RSI greater than 13
how does severe covid link?
- pepsin levels increasing from mild to severe
- severity based on pepsin and high reflux
