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Biochemistry Pulmonology > GlycoBio: Clinical > Flashcards

GlycoBio: Clinical Flashcards

1
Q

HbA1C and Type II Diabetes

A

Most common gylcated Hb = HbA1C

HbA1C forms spontaneously proportional to the blood glucose conc.

Good indicator for blood glucose over the preceding 6-8 weeks

Normal levels = 5%

Pre-diabetic = 5.7-6.4

Diabetic > 6.5

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2
Q

Hemaggulinin

A

Sialic acid binding lectin

Found in envelope protein of H1N1

Along with neuraminidase

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3
Q

Mechanism of H1N1 (swine flu)

A

Interaction #1:

Hemagglutinin on the viral surface with a host receptor (sialic acid) on host membrane surface….respiratory epithelial cell

Result = cell entry

Interaction #2: inside cell

Replicates

Eventually the cell will rupture and virus can escape

(H) on new viral particle attaches to dead cell membrane (SA)

(N) cleaves SA from membrane…so the virus can leave that area and infect other cells

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4
Q

Oseltamivir (Tamiflu) and Zanamivir (Relenza)

A

Neuraminidase inhibitors

So H1N1virus cannot spread after rupturing cell

So stops spreading…not initial infection

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5
Q

Mucopolysacchardoses (MPS)

General

A

Caused by deficiency of enzymes for the degradation of GAGs

Symptoms:

Coarse facial features

Hepatospenomegaly

Bone deformity

Mental retardation

Most common types:

Hurler/Schei (MPS I) - AR

Hunter (II) - X-link

Sanfilippo (III) - AR

Morquio (IV) - AR

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6
Q

Hurler Syndrome (MPS I)

A

GAGs: DS and HS

Enzyme: alpha-L-Iduronidase

Reaction: 2nd step in the degradation process of these GAGs

Involves the removal of the Iduronic acid after the sulfate group was removed (1st step)

TREATMENT: ERT (adlurazyme, laronidase) - non-neuro symptoms only

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7
Q

Hunter Syndrome (MPS II)

A

GAGs: DS and HS

Enzyme: Iduronate sulfatase

Reaction: removal of the sulfate group on the 2-S-L-IdoA….need to do this in order to remove that acid all together

TREATMENT: enzyme replacement therapy (Elaprase, idusulfase)…only non-neuro symptoms

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8
Q

Sanfillipo Syndrome (MPS III)

A

GAGs: HS (2-S-L-IdoA successfully cleaved away)

Enzyme: Heparan N-sulfatase (Type A), Acetyl-CoA acetyl transferase (Type C), alpha-N-acetylglucosaminidase (Type B)

1st reaction: removal of sulfate group

2nd reaction: acetyl group is added to the xposed NH2 group to form a terminal GlcNAc

3rd reaction: GlcNAc removed

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9
Q

Morquio Syndrome (MPS IV)

A

GAGs: KS (terminal Gal-6S)

Enzyme: N-acetylgalactosamine-6-sulfatase (Type A), beta-galactosidase (Type B)

1st reaction: removal of sulfate group generating a terminal galactose residue

2nd reaction: terminal galactose is removed

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10
Q

Morquio Type B

Vs.

Krabbe Disease

A

Both are a due to a defect in a galactosidase

But the enzymes are from 2 different loci, distinct from one another
—> so enzymes are not the same…active sites and substrates are not the same

Morquio Type B:

  • substrate = KS
  • terminal galactose connected to a N-acetylglucosamine in a GAG (MPS)

Krabbe:

  • substrate = galactocerebroside
  • terminal galactose is bound to ceramide (lipid)
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11
Q

Morquio Type B

Vs.

GM1-gangliosidosis

A

Defect in cleaving a terminal galactose (beta1,3) is the issue in both

ALSO, in both KS (Morquio) and GM1…

The terminal galactose is bound to a GalNAc
(N-acetylgalactosamine)

THEREFORE, the same enzyme is involved in both….so if that enzyme is defective…can cause a buildup in both KS and GM1

Still considered two separate diseases though

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12
Q

The 4 common sphingolipidoses (abnormal GSLs)

A

Fabry

Gaucher

Krabbe

Tay-Sachs

**all recessive except Fabry (X-linked)

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13
Q

Fabry Disease

A

Gb3 catabolism disorder…accumulation in kidney, heart, skin, and other visceral organs

Symptoms: hemizygous male with skin lesions, fever, burning pain

Death occurs in adult life from renal and cardiac failure

Mutation of alpha-galactosidase A

ERT (Fabrazyme)= may be good for slowing progression….otherwise dialysis or kidney transplants

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14
Q

Gaucher disease

A

Most common LSD

Deficiency in glucocerebrosidase (beta-glucosidase)

Accumulation of GlcCer is tissue macrophages…which become engorge Gaucher Cells

Type 1 = adult form, non neuropathic

Type 2 = acute neuropathic form

Type 3 = subacture neuropathic form

ERT = only effective for Type 1 because no neuro

General symptoms

Hepatosplenomegaly

Osteoporesis of long bones

CNS impairment in rare infantile and juvenile forms

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15
Q

Krabbe Disease

A

= globoid cell leukodystrophy

Severe demyelination of the CNS and PNS

Deficiency in lysosomal galactocerebrosidase (GALC or beta-galastosidase)

Needed to catabolize GalCer —> Gal + Cer

***NO accumulation of GalCer

Instead the galactosylsphingosine (psychosine) is elevated in the brain

—> leads to early destruction of oligodendroglia (which produce much of the GalCer)

GALC degrades psychosine too…

Symptoms:

Mental and motor retard

Blindness and deafness

Near total loos of myelin

Globoid bodes in white matter of brain

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16
Q

Classical Tay Sachs (GM2-gangliosidosis)

A

The terminal GalNAc in GM2 is hydrolyzed by HexA (not HexB)

Therefore caused by a HexA deficiency…which is a heterodimer (Hex B is a homodimer

Variants of TAY can be caused by deficiency in Hex A, B, or GM2 activator

Symptoms:

  • rapid progessive neuro shit
  • blindness
  • cherry red macula
  • muscular weakness
  • seizures
17
Q

Tay Sachs Variant B

A

Defect in alpha chain…so HexA is only one affected

Cannot digest GM2

HexB and cofactor are fine

18
Q

Tay Sachs variant O (Sandoff)

A

Beta chain —> both HexA and B are affected

cofactor is fine

…cannot digest both Gb4 and GM2

Can also have issues digesting GalNAc from glycoproteins as well as GalNAc containing GSLs

More severe than classical but similar symptoms

  • same neuro as classical…but now visceral is involved as well
19
Q

Variant AB

Tay sachs

A

GM2 activator fucked

HexA and B are fine

Cannot digest GM2

Can digest Gb4

20
Q

Blood group A

A

Possess the A antigen on RBC surface

Antibodies against antigen B

Can accept from A or with apcked RBCs (no plamsa) from O

21
Q

Blood group B

A

Antigen B on surface

Anti-antigen A antibodies

Can accept from B or O (no plasma)

22
Q

Blood group AB

A

Possess A and B on surface

Neither antibody

Accept from AB and packed RBCs from A, B, and O

‘Universal recepient’

23
Q

Blood group O

A

Possess H antigens on the surface

Both antibodies expressed

Can only accept from O

Can donate to any (universal donor)

24
Q

The major phosphoglycerides involved in neonatal respiratory distress syndrome (RDS)

A

DPPC and PC

-give mother an injection of glucocorticoids to promote surfactant production

25
Q

How is surfactant production measured clinically

A

Look at the Lecithin:Sphingomyelin ration

Control lipid = SM

Measured in fetal amniotic fluid

<1.5 = lungs still immature

1.5-1.9 = transitional

> 2.0 = mature

26
Q

Primary vs secondary RDS

A

Primary = not enough production (usually neonatal)

Secondary = surfactant not allowed to work properly…could be due to edema…surfactant too diluted

27
Q

Zellweger syndrome

A

Defect in peroxisome biogenesis…

Where plasmalogens are made, so their production is compromised

Usually leads to death in 6mo-1yr

28
Q

Sphingomyelinase

A

Cleaves between the ceramide and phosphocholine

Involved in Niemann Pick Type A and B

29
Q

Niemann Pick Type A

A

Most severe

Enlarged liver and spleen

Mental retard

Neurodegeneration

Early death

Excessive build up of SM in CNS

30
Q

Niemann Pick Type B

A

Less severe

Still some sphingomyelinase activity

Usually survive into adulthood

31
Q

Farber disease

A

Ceramidase deficiency

(Cer —> sphingosine + FA)

Accumulation of ceramides

SYMPTOMS:

  • Painful, progressive joint shit
  • subcutaneous nodules of lipid cells
  • hoarse cry
  • tissues show granulomas
32
Q

GM1 gangliosidosis

A

Enzyme: beta-galactosidase

GM1 and KS accumulation

SYMPTOMS:

Neuro shit

Hepatosplenomegaly

Skeletal deformities

Cherry red macula

33
Q

Metachromatic leukodystrophy

A

Arylsulfatase deficiency

(Sulfatide —> desulfation fo galactosylcerbroside)

Accumulations of sulfatide

Symptoms:

Cognitive shit

Demyelination

Progressive paralysis

Dementia in adult form

Nerves stain yellowish brown with cresyl violet (metachromasia)

Biochemistry Pulmonology (12 decks)

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