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Cell Pathology > L.7 Carbohydrates > Flashcards

L.7 Carbohydrates Flashcards

1
Q

What is glycogen?

A

Storage form of sugar found in liver, muscle, and cervical epithelium

Glycogen serves as a key energy reserve in the body.

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2
Q

What are glycoproteins?

A

Proteins with covalently attached carbohydrate chains, commonly referred to as mucins when secreted.

Glycoproteins play vital roles in various biological processes.

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3
Q

What are the functions of glycoproteins/mucins?

A
  • Facilitate cell-cell communication
  • Act as structural components
  • Provide lubrication to epithelial surfaces
  • Offer protection from enzymes and pathogens

Their functions are crucial for maintaining tissue integrity and function.

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4
Q

What is the primary stain for detecting glycogen in tissues?

A

Periodic Acid-Schiff (PAS)

PAS highlights aldehyde groups produced after oxidation of sugars, giving a magenta color.

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5
Q

What does PAS staining indicate when glycogen is present?

A

It gives a magenta color indicating the presence of carbohydrates, including glycogen.

This color change is a key diagnostic feature in histological studies.

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6
Q

What is the significance of diastase sensitivity in glycogen identification?

A

If PAS staining disappears after diastase treatment, it confirms the material was glycogen.

Diastase digestion test differentiates glycogen from other PAS-positive substances.

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7
Q

What is the diastase digestion test used for?

A

To confirm the presence of glycogen by using enzymes like salivary amylase or malt diastase.

This test is crucial for accurate histological diagnosis.

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8
Q

What is Best’s Carmine used for?

A

Stains glycogen red.

It provides an alternative method for visualizing glycogen in tissue samples.

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9
Q

What is Methenamine Silver used for?

A

Can be used for carbohydrates, though less specific for glycogen.

It is a versatile stain in histochemistry.

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10
Q

What are mucins?

A

A type of glycoprotein that is secreted by epithelial cells.

Mucins are important for lubrication and protection in epithelial tissues.

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11
Q

How do glycoproteins change in disease states?

A

Their type and quantity often change, making them valuable diagnostic markers in histology.

This characteristic is utilized in clinical diagnostics.

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12
Q

What are the two broad categories of mucins?

A

Acidic Mucins and Neutral Mucins

Mucins are classified based on their chemical composition and histochemical behavior.

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13
Q

What characterizes Acidic Mucins?

A

Contain carboxyl and sulphate groups, stain with acid mucin-specific dyes

Example of an acid mucin-specific dye is Alcian Blue at pH 2.5.

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14
Q

Where are Acidic Mucins predominantly found?

A
  • Gastrointestinal tract
  • Respiratory epithelium
  • Connective tissue

Hyaluronic acid is a non-sulphated mucin found in connective tissue, epithelium, and neural tissue.

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15
Q

What characterizes Neutral Mucins?

A

Lack acidic groups, stain PAS-positive but Alcian Blue-negative

PAS stands for Periodic Acid-Schiff, a staining method used in histology.

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16
Q

Where are Neutral Mucins commonly found?

A
  • GI tract
  • Squamous epithelium (e.g., cervix)
  • Bronchial glands
  • Prostate
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17
Q

What is meant by ‘Mixed Mucin Content’ in tissues?

A

Some tissues contain a combination of acid and neutral mucins

This requires dual-staining techniques for accurate identification.

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18
Q

Provide an example of a tissue with Mixed Mucin Content.

A

Salivary glands

Salivary glands contain both neutral mucins (from serous cells) and acidic mucins (from mucous cells).

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19
Q

What do acid mucins contain that gives them an overall negative charge?

A

Carboxyl and/or sulphate groups

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20
Q

What type of dye is Alcian Blue?

A

Cationic (basic) dye

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21
Q

At pH 2.5, which types of mucins are stained by Alcian Blue?

A

Most acidic mucins (both sulphated and carboxylated)

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22
Q

Which tissues are associated with Alcian Blue staining at pH 1.0–1.5?

A

Epithelial tissues (e.g., large intestine)

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23
Q

At pH < 1 (e.g., 0.2), which mucins are stained by Alcian Blue?

A

Only strongly sulphated mucins

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24
Q

What is the role of magnesium chloride concentration in Alcian Blue staining?

A

Fine-tunes the selectivity of the staining solution

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25
What do neutral mucins lack?
Sulphate or carboxyl groups
26
How do neutral mucins react to Alcian Blue?
Do not react with Alcian Blue
27
What is the appearance of neutral mucins when stained with PAS?
Magenta
28
What does the PAS (Periodic Acid-Schiff) reaction detect?
Neutral mucins, glycogen, basement membranes, and other carbohydrates
29
What happens to glycogen during the diastase digestion step in PAS?
Glycogen is digested and disappears
30
What remains PAS-positive after glycogen is digested?
Neutral mucins
31
What is the purpose of the Alcian Blue-Periodic Acid Schiff dual staining method?
To provide a broader view of mucin distribution in tissues containing both types of mucins
32
What color indicates acid mucins in dual staining?
Blue
33
What color indicates neutral mucins in dual staining?
Magenta
34
What color indicates tissues containing a mix of both acid and neutral mucins?
Purple/Violet
35
What is heparin?
A sulphated glycoprotein secreted by mast cells ## Footnote Best visualized by toluidine blue and exhibits metachromatic properties indicating high sulphate content.
36
What does metachromatic staining indicate?
High sulphate content ## Footnote Metachromatic staining is when a substance appears purple instead of blue.
37
What is the application of mucin histochemistry?
Studying normal mucin distribution and diagnosing mucin-related abnormalities ## Footnote Particularly in cancers and metabolic disorders.
38
Which cancers commonly show increased mucin production?
* Adenocarcinomas of the colon * Stomach * Pancreas * Bronchus * Ovary ## Footnote Increased mucin production is a common feature in these malignancies.
39
What is Barrett’s Oesophagus?
A change from squamous to glandular epithelium due to acid reflux ## Footnote Shows an increase in acid mucins, which is an early warning sign for malignancy.
40
What condition leads to mucin accumulation in the liver?
Alpha-1-antitrypsin deficiency ## Footnote This deficiency impairs protein degradation.
41
What is Hurler syndrome?
A lysosomal storage disorder with accumulation of mucopolysaccharides ## Footnote It is characterized by various physical and cognitive symptoms.
42
How do mucin stains assist in fungal infections?
They help highlight fungal capsules in tissue ## Footnote This is important for diagnosing fungal infections.
43
What are basement membrane alterations used for?
Assessing epithelial invasiveness, especially in cancers ## Footnote Changes in the basement membrane can indicate tumor progression.
44
What does AB/PAS stand for?
Alcian Blue/Periodic Acid-Schiff ## Footnote It is a combined staining method used to differentiate acidic and neutral mucins.
45
What is the basic dye used in the AB/PAS staining method?
Alcian Blue ## Footnote It stains acid mucins blue.
46
What does the PAS method detect?
Neutral mucins, glycogen, and other carbohydrates ## Footnote It involves a two-step reaction for specificity.
47
What is the purpose of diastase digestion in the PAS method?
Removes glycogen to confirm specificity ## Footnote This step is essential when glycogen is suspected.
48
What is the sequence of the combined AB/PAS technique?
* Alcian Blue → stains acid mucins blue * PAS → stains neutral mucins magenta ## Footnote Areas with both stains appear purple/violet.
49
What are technical considerations in the AB/PAS staining method?
* Tissue preservation and fixation (formalin) * Use of diastase control slide * Counterstains and mounting media ## Footnote These considerations are crucial for accurate results.
50
What are carbohydrates widely found in tissue?
Glycogen, mucins, glycoproteins, basement membranes ## Footnote These structures are important in various diseases.
51
What does PAS (Periodic Acid-Schiff) stain detect?
Neutral mucins, glycogen, fungal walls, basement membranes ## Footnote It is crucial for diagnosing several conditions.
52
List applications of PAS stain.
* Glycogen storage disorders * Fungal infections (Candida, Aspergillus) * Basement membrane thickening in kidney (e.g., diabetic nephropathy) * Adenocarcinomas – PAS-positive mucin ## Footnote These applications highlight its diagnostic relevance.
53
What is the purpose of Diastase-PAS (PAS-D) stain?
To confirm glycogen presence by enzymatically removing it ## Footnote It helps differentiate glycogen from mucins.
54
List applications of Diastase-PAS (PAS-D) stain.
* Liver biopsies in suspected glycogen storage disease * Differentiating glycogen from mucins ## Footnote These applications are critical in liver pathology.
55
What does Alcian Blue (AB) stain detect?
Acid mucins in epithelial tissues ## Footnote It is significant in various gastrointestinal and respiratory conditions.
56
List applications of Alcian Blue (AB) stain.
* Barrett’s oesophagus – intestinal metaplasia * Ulcerative colitis – goblet cell depletion * Respiratory and GI tract tumors * Identifying capsules of some bacteria (e.g., Klebsiella) ## Footnote These applications are important for diagnosing specific diseases.
57
What is the purpose of the AB/PAS combination stain?
To evaluate tissues containing both mucin types ## Footnote This combination is useful in complex cases.
58
List applications of the AB/PAS combination stain.
* Adenocarcinomas of colon, lung, pancreas * Cervical pathology – glandular differentiation * Evaluating metastatic mucin-producing tumors ## Footnote These applications assist in cancer diagnosis and treatment.
59
What is Best's Carmine stain specific for?
Glycogen ## Footnote It is a useful stain in identifying glycogen deposits.
60
What does Methenamine silver stain detect?
Basement membranes and fungal walls ## Footnote This stain is crucial for identifying fungal infections.
61
What does Toluidine Blue stain target?
Sulphated mucins (heparin) ## Footnote It is a metachromatic stain used in various histological examinations.
62
What can different mucin profiles suggest?
* Malignancy vs benign conditions * Site of origin of metastatic tumors * Help in monitoring treatment response (e.g., mucin depletion) ## Footnote Understanding mucin profiles is important for prognosis and treatment strategies.

Cell Pathology (28 decks)

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