matix/ECM disease Flashcards
why is a negative control necessary in immunohistochemisrty
A negative control can demonstrate that the (primary) antibodies used in immunohistochemistry were specific only to the epitopes present. This allows the assessment of affinity of the epitopes and paratropes involved and enables correct interpretation of results
> neg slide would show either no staining or evidence of NONSPECIFIC backgorund staiing
why is a polyclonal antibody less specific
polyclonalantibodies can recognise many epitopes on a surface whilst monoclonal only recognise 1
so polyclonal are less specific and its harder to distinguish between 2 types of molecules if they express the same epitopes
poly - less expensive, less skill and less time to make but will have batch variability
what is the most abundant ECM molecule? what does it do?
collagen - makes up 25% of total protein mass in mammals
key structural protein and can help to organise and shape of tissue, cell differentiaton and migration
what is the 2nd most abundatn eECM molecule? what do they do?
it is proteoglycan (protein core + a sulphated GAG)
they can be sulphated or unsulphated (hyaluronic acid). and are highly charged molecules so can retain water creating a large swelling pressure making ECM compression resistant and gives stiffness to tissue!
> loss of PG linked to aging = increased pain of joints as no longer compression resistant
> hyaluronic acid can be found in synovial fluid enabling frictionless joint movement
what is hepari?n
its an anticoagulant in the blood, synthesized and secreted by mast cells
> useful for medicinal use as it can prevent blood clotting
good for haemostasis
what do lamins and fibronectins do?
lamin good for cell-cell adhesions, migration of cells and regulate the inflammatory reponse
fibronectin - receptor can bind to other ECM molecules so good for cell signalling
what are the 4 main tissue types in the (mammals) body?
connective tissues
muscle tissue
nervous tissue
epithelial tissue
what is the most common subcatergory of collagens? A beaded filaments collagens B fibrous or fibrilar collagen C multiplexin collegen D MACIT
fibrililar and Fibrilar associated collagen with interupted triple helix most common
they are involved in structure of ECM and can form strucutral proteins
the other types are involved in cell adhesions and interactions
what is the role of multiplexin subset of collagen?
expressed in Vascular endothelial cells and basement membrane so regulate cell function
> they are NON fibrilar!
what is a heterotypic fibres?
a collagen fibre made up of many different types of collagen fibrils and can enhance physical characteristics of tissue
> e.g in articular cartilage there is type2,9,11 which help with tensile strength, shear strenght and diameter of the fibril fibre
for example the bone is made up of type1 and type2 collagens
how is cartilidge homeostasis controlled?
via matrix metalloprotreases + ADAMT which degradE cartlidge and require a metal ion to be activated, maximum activity at a neutal pH
> THEY can remodel the ECM
but if excess =OA so are normally secreted in their inactive form (proenzyme/zymogen)
which joint is most likely to develop OA? A hip B shoulder C knee D waist
the knee
higher prevelance in women of getting OA than men due to a loss of cartilidge and then there is bone to bone contact and
in OA what causes this uncontrolled degradation of cartilige/waht causes upregulation of MMP expressin?
there is a disruption to chondrocyte metabolism so there is release of inflammatory mediators like ROS and cytokines
they upregulate NF-Kappa signalling which then upregulates MMP transcription and eventual secretion into the ECM
what is the difference between autologous, heterologous/allogenic and xengenenic cells ?
auto - own cell/ genetically identical
hetero/allogenic - from the same species but genetically different
xenogenic - different species
