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pathology coursework exam > practical 2- carbohydrates and PAS staining > Flashcards

practical 2- carbohydrates and PAS staining Flashcards

1
Q

what are carbohydrates

A

sugars and their derivatives

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2
Q

in preserved (fixed) cells and tissues, which carbohydrates are available for demo

A

polysaccharides, proteoglycans and glycoproteins (mucosubstances)

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3
Q

what is meant by mucosubstances

A

macromolecular compounds composed of only carbs or partially of carbs

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4
Q

what do polysaccharides consist of, give 2 examples

A

entirely of carbohydrates

glycogen and cellulose

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5
Q

what do proteoglycans consist of, give 3 examples

A

long polysaccharide chains attaches to smaller protein core

decorin, heparin and heparin in sulphate proteoglycans

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6
Q

what do glycoproteins consist of, give 3 examples

A

proteins bearing numerous covalently bound oligosaccharide chains

serum proteins, collagen, aggrecan

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7
Q

why must the tissue remain intact when exploring methods to test for carbohydrates

A

because interest is in the precise location of the mucosubstance in the tissue/cell

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8
Q

what are the 3 different methods to test for carbohydrates

A

direct staining using cationic dyes (e.g. alcian blue)

direct staining using chemical tests (e.g. periodic acid and schiffs stain)

use of lectins (e.g. concanavalin A)

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9
Q

how does the periodic acid (PA) test work

A

PA oxidises glycols to aldehydes by breaking up the vicinial diols into monosaccharides with a pair of aldehydes at the 2 free ends of the monosaccharide ring

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10
Q

what is schiffs (S) reagent

A

mixture of pararosaniline and sodium metabisulphate

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11
Q

what is the schiffs (S) test

A

s reagent is mixed with the dialdehydes which produces an insoluble magenta compound

(because the S reagent produced a pararosaniline adduct which stains glycol-containing cellular elements pink to red)

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12
Q

what is the schiffs reagent used for

A

to identify specific tissue structures or pathological alterations depending on tissue content

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13
Q

what does PAS stand for

A

periodic acid-schiff

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14
Q

what is the experimental procedure used to identify mucosubstances

A

counterstain using haematoxylin to identify cell nuclei

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15
Q

in PAS staining, how is the section dewaxed

A

using histoclear

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16
Q

in PAS staining, how is the sample hydrated

A

immerse in decreasing concentrations of alcohol

absolute (100%) alcohol
90% alcohol
70% alcohol

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17
Q

in PAS staining, how is the sample oxidised

A

in 1% periodic acid

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18
Q

in PAS staining, how is the sample actually stained

A

immerse in schiffs reagent

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19
Q

in PAS staining, how is the nuclei stained

A

use mayers haematoxylin

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20
Q

in PAS staining, how is the sample dehydrated

A

immerse in increasing concentrations of alcohol

70% alcohol
90% alcohol
absolute (100%) alcohol

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21
Q

in PAS staining, what are the final 2 steps

A

clear in histoclear

mount in DePeX and dry in fume cupboard

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22
Q

in PAS staining, what colour would neutral mucosubstances appear

A

red

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23
Q

what 4 cells are found in seminiferous tubules

A

spermatogonia
spermatids
spermatozoa
sertoli cells

24
Q

in the test booklet for practical 2, label A and B on the diagram for cells in rat testis

A

A- spermatids

B- spermatogonium, sertoli cells (primary and secondary spermatocytes)

25
Q

name the interstitial cells in rat testis

A

leydig cells

26
Q

what is the function of the leydig and where is it located in a cell

A

production of testosterone

nuclei towards the bottom of the cell

27
Q

what does the haematoxylin stain identify

A

DNA/nucleus

28
Q

which of the following would not be positively stained by PAS

a. polynucleotides
b. polysaccharides
c. proteoglycans
d. glycoproteins

A

a. polynucleotides

29
Q

in the testes, where are the leydig cells found

a. adjacent to the basement membrane of the seminiferous tubule
b. centre of seminiferous tubule
c. adjacent to ST
d. in the wall of the ST

A

c. adjacent to ST

30
Q

which of the following is the correct sequence for PAS staining with Haematoxylin counter stain

a. rehydrate, periodic acid, schiffs, haematoxylin, dehydrate
b. rehydrate, schiffs, haematoxylin, periodic acid, dehydrate
c. rehydrate, schiffs, periodic acid, haematoxylin, dehydrate
d. rehydrate, periodic acid, haematoxylin, schiffs, dehydrate

A

a. rehydrate, periodic acid, schiffs, haematoxylin, dehydrate

31
Q

what is HER2

A

epidermal growth factor (EGR)

plasma membrane receptor

32
Q

where is HER2 coded

A

on proto-oncogene on chromosome 17

33
Q

human EGR receptor 2 is involved in signalling of what

A

embryogenesis
cell growth
cell differentiation
apoptosis

34
Q

where is HER2 located

A

in epithelium of breast, lung, bladder and ovary cells

35
Q

why is HER2 important in breast cancer

A

HER2 is over expressed in 10-20% of breast cancers

over expression can either due to increased gene amplification or altered status

over expression of HER2 indicates poor prognosis

36
Q

what is herceptin

A

humanised mouse monoclonal antibody, which targets HER2

37
Q

when is herceptin used

A

when a patient shows an over expression of HER2

38
Q

how does HER2 grading of samples take place

A

formalin fixed paraffin sections are used for immunocytochemical and FISH assessment

39
Q

what 2 things is HER2 grading dependent on

A

intensity

completeness of staining cell membrane

40
Q

in HER2 grading, what is the staining like in grade 0 samples

A

no staining/very slight partial membrane staining in <10% tumour cells

41
Q

in HER2 grading, what is the staining like in 1+ grade samples

A

faint barely perceptive membrane in >10% tumour cell, cells stained in part of the membrane

42
Q

in HER2 grading, what is the staining like in 2+ grade samples

A

weak to moderate complete membrane staining in >10% TC

43
Q

in HER2 grading, what is the staining like in 3+ grade samples

A

strong complete membrane staining >30% TC

44
Q

in HER2 staining, state whether treatment is used in each grade

A

0 and 1+ no treatment used
2+ referred for FISH (fluorescent in situ hybridisation)
3+ herceptin treatment is used

45
Q

when taking breast specimen samples, how does a needle core biopsy work

A

needle inserted into lump to draw sample fluid and tissue

may be difficult if needle deflects

46
Q

when taking breast specimen samples, how does a lympectomy/open biopsy work

A

surgical procedure to remove all/part of a lump

tissue surrounding lump is also removed

47
Q

when taking breast specimen samples, how does a mastectomy work

A

removal of breast tissue and axillary lymph nodes

48
Q

when taking breast specimen samples, how does a sentinel lymph node biopsy work

A

sentinel lymph nodes are removed

49
Q

why may a HER IHC profile alter between different methods of obtaining a breast specimen

A

may be result of:

exhibiting an altered genetic/protein profile during tumour development

preoperative chemotherapy

time of specimen to fixative

time of specimen in fixative

specimen processing type and schedule

50
Q

how are tissue samples fixed

A

using buffered formalin and paraffin wax

51
Q

what is meant by invasive breast cancer

A

cancer grows into healthy tissue

52
Q

what is meant by in situ breast cancer

A

cancer stays within milk ducts/lobules

53
Q

why would a DCIS (ductal carcinoma in situ) not be treated with herceptin

A

because it is located within the milk ducts

54
Q

what is FISH

A

fluorescent in situ hybridisation

55
Q

how does FISH work

A

centromeric region of Ch17 is marked with green fluorescent signal

HER2 is marked with red

assess 20-60 cells, ratio of red: green is calculated

diagnosis is dependent on ratio of gene: chromosome

positive = >2.2
negative = <1.8
equivocal = 1.8-2.2 (in this case assess more cells and IHC)
56
Q

what is CISH

A

chromogenic in situ hybridisation

similar to FISH but allows chromogenic visualisation of HER2 on Ch17

either reported as direct count of signal cluster

57
Q

what are the 3 main tests to identify carbohydrates

A

direct staining using cationic dyes (e.g. alcian blue)

direct staining using chemical tests (e.g. periodic acid schiffs stain)

use of lectins (e.g. concanavalin)

pathology coursework exam (5 decks)

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