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Nutrition Flashcards

1
Q

Describe what happens in T1DM on cellular level and in general

A
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2
Q

How can we name these 2 regions of set points

What are the curves ABCD

Why there is a dotted line at 5

Why there is dots higher and lower at the same lysine intake

The result of this study was

What was the requirement for lysine that they established and what was th real one

A

The one on the left are deficient and the one on the right are normal

2) we try to draw statistically lines between these curves,so every dot will be sowewhat on its trajectory , different models
3) we knwo that there are miscelenoeus losses of protein, so we should be aiming for 0 nitrogen balance,but higher-> 5-7
4) individual variability
5) AA and protein requirements from 1950s to 2003
6) they established at 10 mg, but they did not account for miscleneous losses, so thus it should be 28 mg , all EAR

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3
Q

What was the design of the study in 1950s

A

Protein was given as individual AAs in a crystalline form

So in the experiment one AAs was given at 7 grams and other at the requirement and looked how the body responded in 3 days

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4
Q

Why there are difficulties in designing protein studies

A

because crystallized AAs are very expensive

They taste disgusting

You are not real foods, but a milkshake-> subjects miss the texture of food

No dietary fiber->hard stool of any

Carry “the bottle” with them to collect urine, feces

Usually only on healthy males, not pregnant, not women, not elderly , a lot on sick babies, but on healthy ones

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5
Q

Why subjects are asked to go on the diet before the study as well

A

Because liver ( where urea cycle occurs)

Then all the urea is going to be redestributed in all water in the body before being eliminated

It takes several days for equilibration

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6
Q

What are 3 stages in study modelling

A

Clinical/Metabolic

Analytical

Modelling

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7
Q

What is clinical/metabolic part of the study

analytical

A

Clinical/Metabolic
• COMPLETE intake and collections
• Adaptation of urea pool

Analytical (easy peasy)
• Routine analysis of total Nitrogen

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8
Q

What moments should be remembered in modelling stage of the study

A

Modelling
• Misc losses would increase reqt
• Sensitivity: small number calculated from 2 large and similar
numbers
• Curvilinear response as balance approaches zero
• Between‐subject variance is high therefore repeated
measurements on each subject needed…but adaptation issue-> so it is better to have a study on the same subject and test on different levels and AAs-> takes month

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9
Q

In what conditions Arginine becomes indispensable

A

Infants and under severe health conditions

They are making it , but not enough

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10
Q

Name indispensible, conditionally indispensable and dispensible AAs

A
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11
Q

Phe and Tyr, as well as meth and cysteine are considered together

A

Because Tyr is synthesized from Phe

Methionine and cysteine are sulphur AAs, cysteine is synthesized from methionine

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12
Q

What was the old EAR for essential amino acids and the new one

the new one is generally 2 to 3 times higher, why wass that

A

when nitrogen balance was recalcualteed with misceleneous losses, the requiremtn increased

the new model was created

Methionine and cysteine did not go up , because of the clerekal error

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13
Q

What is flow of the tracer

A

Tracer infusion rate/tracer concentration on pool

Low flow rate-> darket the “dye”

You sample the blood and then you test how much of AA there is in the pool

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14
Q

Tracer dilution principles of data experiment : what assumptions are made

A
  1. System at a steady state( not going through fed-fast cycles, so eating should be done little but steadily through the period) Rate of appearance (diet)= rate of disappearance(catabolism)- no storage
  2. Homogenety of pool
  3. Massless tracer
  4. No tracer recycling ( so if you label AAs, it does not get resynthesized)
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15
Q

what do we know here when giving the tracer AA in the diet

A

We know diet intake, we can meaure AA oxidation, thus we can calculate

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16
Q

What are naturally occuring isotopes of C, H,N,O,S

A

Carbon 13,Hydrogen 2 (deuterium),nitrogen 15,oxygen 18,sulphur 34

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17
Q

what is the advantage of isotope

A

That we can measure it+ we can put isotope on any position

Labeling carbon skeleton, so we can trace CO2 in breath -> measure amino acids oxidation

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18
Q

How does Gas Chromatograph Mass Spectrometer works

A

1 microlitre is onjected into the oven, as the oven heats up it seperates all AAs or all compounds

There is a vaccum pump through which molecules come, so there is nothing in there , except the sampe

Separate gas molecule comes into the ion source and it shoots electrons together and smash molecules apart.

Different parts of the molecules can be ionized. They are shot through the lenses into the quadrupole mass analyzer. A certain voltage is applied on this poles, so ions of the certain mass spiral down to the electron multiplier, where it can get detect the molecule at less than pico grams

Mass spectrum result in graph of fingerprint, which you cna look after in the database to identify what is it

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19
Q

What is nutritional indispensable

A

A nutritionally indispensable AA cannot be
synthesized by the animal organism out of
materials ordinarily available to the cells at a speed
commensurate with the demands for normal
growth.

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20
Q

What is metabolically essential amino acids

A

They can’t be synthesized even when precursors are supplied

Leucine can converted reversibly to its ketoacid (amino group goes to something else)

We can give synthetically synthesized ketoacid of leucine and then amino group will be given to push the synthesize towards leucine

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21
Q

What AAs are strictly metabolically indispensible

A

Lysine, Threoine and tryptophan

Others we can synthesize from ketoacids, if they would be available ( 6 other nutritional essential, are not metabolically essential )

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22
Q

What is a cofactor for transaminase

A

Pyridoxine - vitamin b6

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23
Q

What is the chicken that laid the golden egg study

A

All CO2 is radiactove labelled-> it is catched by photosynthesisof algae->radiactive protein. This protein is fed to chicken for month->make eggs-> take egg that are radioactive-> feed subjects

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24
Q

What we can see from the graph

A

Phe has 9 carbon item

As there is no Phe between Phe 0 and Phe with 9 radioactive atoms -> no Phe was synthesized by the chicke, all came from algae

Liver,kidney,spleem,gut,heart are very metabolically active. They synthesized

In humans muscle synthesize is very slow ( turning over)

But because it there is so much of it, it requires a lot. Liver is the small organ

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25
Q

What is GLX and why it is important

A

Glutamine and Glutamate- fuel for the gut , nout glucose unlike other tissues

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26
Q

what can we conclude from this graph

A

All the glutamate is made in the body, function to transport amino groups ultimately to the liver

Even after the month there is hardly any GLX that is all radioactively labelled

Can be synthesized in the body, precursors came from the carbon atoms not from algae- most of them

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27
Q

Why would a food company invest in research about utilization of glutamate

A

MSG, then it can be proved that is not used by the body-> safe

But some people have diverse effects against it . Probably this is because gut converts it into something else that causes the effect. maybe when added to stir fry glutamate becomes unstable and is converted to something else-> symptoms

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28
Q

How can we measure AA requirement

A

growth (weight) ( the graph looks like nitrogen balance)- limited usefulness , because not really applicable to adults

Nitrogen balance

Plasma AA response (the same graph as nitrogen balance), will be low when we are deficient, but not really efficient becuase this pool does not change dramatically, even in protein deficiency, it does not change much

Direct AA oxidation

Indicator AA oxidation

24h AA balance (requires a lot of subject compliance)

or measure of organ or system function

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29
Q

Every subject should be studies at ___ test AA intake levels above and below requirement, to test for

A

more than 6

Test for individual variability

Better to measure 5 people on different levels, rather than a lot of people on different energy requirements and different levels

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30
Q

All methods should give ___

A

The same answer

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31
Q

Why plasma concentrations is not accepted as a measure of AA change

A

Endpoint should show clear response to change in test AA intake, plasma do not change much, wont see the end

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32
Q

For how long CO2 should be measured

A

CO2 if carbon is labelled ( hours to a couple of days)

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33
Q

Why men are willing to participate in the studies

A

Do not need to shop, to cook, free

Female- does not like the taste, the smell

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34
Q

Where it is better to take blood sample for analysis

A

Better from the artery, because mixed blood and does not reflect the metabolized

But not ethical

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35
Q

Why subjects get little money for the study

A

You can pay for the expenses, but usually not paid , because there is not enough money to become a motive

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36
Q

Ethics of doing research in babies

A

You ask a parent for consent, not baby

In canada it is not ethical to pay the parent, so the baby participate in the study. In USA it is ethical

Many studies were done on abandonned babies in 1960s

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37
Q

How do we measure direct oxidation rate

A

Need a blood sample and a breath

Infusing labelled Amino acid into the blood, where it mixes with excisted amino acid pool-> protein is synthesized or catabolized

We can measure CO2 from the bag , every half an hour and taking blood samples to test for AAs

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38
Q

How does the graph of direct oxidation study looks like

A
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39
Q

Why a choice of test AAs for direct oxidation study becomes an issue

A

Only BCAAs, lysine and Phe have their carbons irreversible commited to oxidation. So we can measure only this AAs requirement

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40
Q

What are some restrictions of direct oxidation method

A

Can’t measure 0 intake, because our tracer is an AAs

Restricted choice of test AAs

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41
Q

What is the analytical (measuring) part of direct oxidation method

A

Collecting blood and breath samples

To measure the ratio of labelled compound to unlabelled-> using mass spectrometer (IRMS-isotope ratio MS for CO2 enrichement ,calorimeter for CO2 production)

Blood sample ratio is measured on GCMS (gas chromotograph)

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42
Q

What you need to do with data and need to account in modeling in direct oxidation method

A

Steady snacking= 24 hour/meal feeding- to keep nitrogen balance

need to use statistics to make a nice breakpoint

Breakpoint increase in oxidation with increasing intake

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43
Q

What is the concept of indicator AA oxidation (IAAO)

A

When an indispensable AA is limiting, then all other indispensable AA will be oxidized

Increasing intake of limiting AA will decrease IAAO

For example, if lysing is the test AA. The indicator is Phe (tracer), and the test is the other AA, for example Lysine

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44
Q

How does the graph of IAAO looks like if Phe is an indicator and Lysine is test

A

Look in the notebook

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45
Q
A
46
Q

What is the advantage of IAAO

A

You are changing only one thing at a time

  • Free choice of test AA, can study zero intake
  • Tracer AA pool not perturbed with changing test AA intake
47
Q

What AAs can be used as an indicator in IAAO

A

Phe,Lys, Leu

48
Q

How the results are collected in IAAO

A
  • Breath Collection:
  • IRMS for CO2 enrichment, Calorimeter for CO2 production
  • Blood samples; Urine samples (non‐invasive)
  • GCMS for AA enrichment
49
Q

In Canada it is very hard to get a permission to get a blood sample from a baby, so how can we collect data from this age group

Where the blood is taken from a baby

A

If the baby is having blood taking for clinical reasons, then this blood can be taken for tests

Capillary

We know more of sick premature babies than from healthy babies

50
Q

How to minimize the invasiveness of IAAO model (trace administration and sampling) , which is doen for kids and babies

A

Tracer Administration
• Repeated oral “nibbling”
of tracer solution after
4‐h feeding equilibration( giving tracer every half an hour)

Sampling
• Breath collection for CO2
enrichment
• Urine in place of blood for
plasma AA enrichment, because though 99% of amino acid is tarnsported back in blood, 1 % is exreted and we calculate how much of AA is in the blood

51
Q

Common principle of determining AA requirement for all methods

A

Ethical, compliance, statistical (and modeling- why are we doing eat, to determine a point where the responce changes) and technological (expensive equipment)

52
Q

With the research we can find what data for AA requirement

A

EAR, and then plus 2 SD to have RDA

53
Q

What is Lysine requirement

A

now EAR = 31 mg/kg/d
now ‐RDA = 38 mg/kg/d (EAR + 2 x cv)

54
Q

What was the old and the new essential amino acid requirment and to whom it applies

A

DRI report= 285 mg/g protein

Used to be 2-3 times lower WHO 1985= 111 mg/g protein

Need more qualitive AAs

to adults and children>1 year

55
Q

What are potential limiting indispensable AAs

A

Lysine, threonine,tryptophan,sulphur AAs

56
Q

Thoug Tryptophan requirement is low is it met?

A

Can be an issue for vegans and vegetarians and to people who have low diversity diet

57
Q

So witht he new requirements (DRI 2003) are we meeting AA requirementO

A

issue
• Vegans with lower protein intake and lower protein
quality – limiting AA is significant issue especially
for children

• International – food security and diet diversity –
very important especially for children

58
Q

What can be done to vegans so they get all the requirement

A

Complementary proteins
• Beans and rice
• Legumes and grains

59
Q

How they proved that Histidine is essential

A

It is very difficult to establish its requirement

His free diet for 48 days

Histidine metabolism is not like the other, because adaptation takes more time

Nitrogen balance was still zero, was decreased protein turnover ( slowing of protein metabolism all-together) and decreased oxidation of indicator AA (Phe , done through IAAO method)

Histidine availability from day 0 to day 48 went down

Hematocrit went down substantially by 6 percent

Hemoglobin declined by 22 g/L

Albumin decreased by 6 g/L

That is why balck box does not work, because nitrogen balance remained zero

60
Q

Histidine is very abundant in ___

A

Hemoglobin

61
Q

Histidine deficiency looked like ___ anad why

A

Like iron deficiency anemia, becauses decreased hemoglobin, decreased hematocrit

But in anemia ferritin is going to decline, when in histidine deficiency it decreased and transferrin in iron anemia usually increases, when in histidine it decreased

62
Q

2 stages in adaptation

A

Short-term ( really does not change the function)

Long-term (accommodation, changing function)

63
Q

Do we have problems with DRI requirements in regards to descrimination

A

“Separate requirements could not be determined for
women versus men,
or for older adults and the elderly.”

We know nothing about pregnancy, lactation

Only children based on factorial approach ( adding up components like this much is needed for growth, this much for something else,etc.), but not direct studies

No for infants from studies, but only AI based in breast milk

As well as for endurance training

Functional criteria of adequacy (as the study with Histidine)
• Conditionally indispensable AAs
and special products

64
Q

Why women should have seperate requirements

A

Women have different hormone profile, for example

In the follicular fase (before ovulation) the requirements for protein in mg/kg of BW was lower than requirement for men and in the luteal fase (after ovulation) it was the same as for men

However, when the requirement was recalculated as mg/kg/LBM men and women in follicular fase was the same, but in luteal it was a lot higher

65
Q

What conditions should be tested for AA requirements

A
  • Prematurity
  • Healthy infants!!!
  • Intravenous feeding
  • Inborn errors
  • Metabolic stress
  • Liver disease
  • Exercise
66
Q

What does it mean special products of protein

A

Neurotransmitter, peptides, etc.

67
Q

Is there higher requirement AA/protein in critical illnes

A

0.8 g/kg for everyone

But then Hoffer tested maybe in critical illness 2-2.5 g/kg is needed

68
Q

Can you supply a patient with 2-2.5 g/kg and sometimes 3 g/kg by food

A

No, that is why parental nutrition or through gastric tube

69
Q

Why parental nutrition is good for critical illness

A

Bypass splanchic control ( by-pass the liver and the intestine)

Can supply more

70
Q

Composition of intravenous regimes and problems with it

A

Free AAs

Water soluble nutrients: vitamains, minerals, glucose, AAs. But the bags are clear-> destruction of vitamins

Solubility: The mixture is a lipid emulsion. Lecithin as an emulsifier (soy bean oil emulsion)->proinflammatory eicosinoids

Stability: only lysine has minimum solubiltiy in water, so it is fine in the emulsion, but others will degrade in 7 days

71
Q

Issues with designing an optimal profile of AAs: aromatic AAs

A 
tyrosine insolubility (when F is pretty soluble), transient
hyperphenylalaninemia and hypertyrosinemia
72
Q

How can you overcome hypertyrosinemia

A

Ways of tyrosine synthesize

Add more Phenylalanine and rely of conversion of F to tyr(1)

Add a souble precusroe of tyrosine that is stable (2)- N-acetyltyrosine

3- add a dipeptide of Tyr that can be split and make Tyr available- Glycyl-tyrosine

73
Q

The difference between vamin and vaminolact

A

Vamin - used for adults, AA profile is designed as in egg albumin, has high F

Vaminolact- Aimed for infants (has the Aas profile for breast milk), so here relatively low of F concetration)

74
Q

0 nitrogen balance means ___ nitrogen retention

A

0 nitrogen retention

75
Q

Vaminolact showed lower percent of nitrogen retention in babies than vamin in adults, so can what was done to figure out what is better solution

A

Three different solutions was given:

Vaminolact+F as in vamin

Vaminolact+NAT

and Vaminolact+Glycyl-tyrosine

The first one worked, but excess F in babies is not good

Nat did not work, because converts in adults and rat models, but not in babies and baby pigs, they do not have enzyme and all peed out

Dipeptide worked

76
Q

How can protein defficiency can influence tissues

A

In pigs

Gut (75% of protein is made every day ). When malnourished practically double decrease Gut is very affected by protein deficiency-> compromised absorption of nutrients, barrier function of the gut and immunity by bacteria-> malnourished child is more vulnerable to infections

Liver has like 10 percent decrease on deficient

Skin 10 percent decrease on deficient

Muscle protein synthesize is lower in deficient pigs (like a third reduction)

In human adult 2% of muscle a day

77
Q

Protein is ___ nitrogen

A

16%

78
Q

What is RDA in 2007 from the study

A

EAR 0.91 g/kg

RDA 0.99 k/kg

male: Another 0.93 g/kg, RDA-1.24 g/kg

Elder women: 0.94 g/kg, RDA-1.24 g/kg

The same for elder women and young men

79
Q

What is net Phe balance

A

Dietary phenylalanine-urinary phenylalanine

80
Q

What is the requirement of protein for endurance-trained men

A

2.1 g/kg per day-EAR

RDA- 2.6 g/kg per day

81
Q

What happened to young men who consumed 0.6 g/kg/day, 0.75 and 1 for 7 days

A

On 0.6 and 0.75 g/kg for 7 days

lower of turnover of protein -> protein metabolism was slower

Lower synthesize of glutathione synthesize (tripeptide, majoe cellular antioxidant, if low that increased susceptibility to oxidatove stress)

Decrease in albumin synthesize ( when its lowered, it means the body is stressed)

Increase in fibrinogen (goes up in states of stress and injury)

All the results mean” moderate protein defiiciency results in a minor stress response. Current EAR and RDA are too low

82
Q
A
83
Q

How we measure the weight gain of infants normality

A

Percentiles

84
Q

Little changes in nutrition can cause big changes in ____

A

Function and growth

85
Q

When we have the most rapid growth

A

Average birth weight: 7.5 pounds and doubled to 16 pounds in 5 months-> highest energy and protein requirements out of the whole life span

86
Q

Role of GI in AA metabolism

A

Pepsin in stomach (starts cleavage of peptide bonds) – acid pH(denaturation)
• Proteases from pancreas in small intestine – luminal
digestion (like Trypsin, chemotrypsin, but there are a lot, because R groups are different)
• Peptidases on brush border of intestinal epithelial cells (final celavage of proteins)
• Active transporters (The same as SGLT2/GLUT2 transports , but many because Aas are different)

87
Q

What happens AAs metabolism in fed state

A

By portal vein goes to the liver, where the protein synthesize will be increased and increased (catabolism of AAs

From their blood will go to pancreas. In response to increased AAs, increased insulin secretion

And glut 4 cells, where GLUT4 will be increased, as well as protein synthesize, and AAs transporters on muscle cells

88
Q

What happens in short-term fast

A

No absorption in GI

Lower insulin, more glucagon

Less protein synthesize, relatively higher protein breakdown

89
Q

What is the usual dosage of protein in meal to get the maximum rate of protein synthesize

What else is important for protein synthesize

A

30 grams

Timing is important (skipping breakfast not good)

90
Q

what happens in long term fast to AA metabolism

A

Increase in protein breakdown, especially glycogenic to feed the brain

Then ketogenesis turns on to preserve protein, Ketone synthesize is a good survival ,because it feeds the brain and slows protein break down

91
Q

Difference in liver and muscle protein handling

A
92
Q

Anabolic and catabolic reactions of AAs handling in liver

A

Anabolic
– Constitutive protein
synthesis
– Plasma protein
synthesis (fibrinogen, albumin)
– Gluconeogenesis
– Lipogenesis

Catabolic
– AA catabolism
– Urea cycle

93
Q

What is hypertrophy of muscles and how is it activated

A

Hypertrophy (building muscle mass)
– Growth
– Anabolic (fed state, exercise)
– Activation of PI3K Akt
pathway (responsive to insulin, for example translation and transcription of proteins)

94
Q

Atrophy of muscles : what is it and how is it activated

A

– Wasting
– Catabolic
– Activation of
ubiquitin proteosome
pathway (Misfolded proteins are tagged by ubiquitin and then it goes to protesome when it is going to be lyzed)

Stimulated by cachexia(A range of diseases can cause cachexia, most commonly cancer, congestive heart failure, chronic obstructive pulmonary disease, chronic kidney disease and AIDS)

and catabolic stress

95
Q

How do we figure out if it is the nutrient availability that causes the metabolic change or it is hormone that cause metabolic change

A

Insulin clamp study

96
Q

What is sacropenia

A

degenerative loss of skeletal muscle mass, quality, and strength

Response to one of proteolytic pathways

97
Q

Describe insulin clamp study

A

We clamp insulin at a particular concentration and measure what happens to metabolism

Insulin is infused intraveneously in high doses (hyperinsulinemic)

We also infuse glucose in different concentrations to achieve a particular target. For example, we want to inject enough glucose, so plasma glucose is 5 mmol/L. Done through another pump. You have to measure every 5 minutes to measure glucose concetration and if changes, you infuse more.

We are measuring the achievement of steady state of glucose, we know the input rate. Somebody who is very sensitive to insulin is going to take up a lot of glucose, so if we have high infusion rate-> high sensitivity to insulin. Diabetic is going to have low infusion rate of glucose, because peripheral tissues are not taking up a lot of glucose

98
Q

Insulin clamp and AA infusion

A

Insulin increases protein synthesize, AA transport and decreases protein break down

We observe what happens to plasma AAs (going to cells,decreased protein break down, no new AA coming from the diet, decreasing rate of protein synthesize), thus we can aslo clamp AAs at a rate to stimulate short term fasting (euAAemia) or like after the meal (hyperAAemia), and then we can measure protein synthesize and protein breakdown-> effect on protein synthesize and protein break down

99
Q

why we have have essential and non-essential AAs, probably

A

Essential AAs (9 AAs)
• 59 enzymes total
• Expensive to synthesize
• ?survival advantage to
be able to rely on diet

Non‐Essential AAs (11 AAs)
• 17 enzymes
• Easy to synthesize
• ?survival advantage to
maintain capacity to
synthesize

100
Q

body protein synthesize proportion for different places

A

50% visceral

10 blood cells

10 plasma proteins

30 muscle

101
Q

What will happen to body protein synthesize proportion in infection

A

Blood cells are going to be prioritized, compromising from muscles

102
Q

Special products of AAs

A

ATP, nucleic acids, creatine, taurine, glutathione,nitric oxide, neurotransmitters

103
Q

How much protein we synthesize a day and what proportion are special products

A

300 grams
Minor

104
Q

Usually most special products are made from

A

Non essential AAs

105
Q

Glutathione precursors

A

Glutamate,cysteine, glycine

106
Q

Synthesis of dispensible AAs (rates, proportion of BMR, precursor)

A
  • High flux rates
  • High proportion from de novo synthesis
  • Synthesis accounts for 8% of basal metabolic rate
  • Ultimate precursor is glucose
  • Except for tyrosine
  • For cysteine – only the S is from methionine, the other part is from other places
107
Q

The correlation between intestine and kidney in synthesis of arginine and arginine role

A

Polyamine promotes protein synthesize

Instetinal-kisney access, needs organ cooperation

108
Q

Who can become deficient in arginine and how the problem can be ressolved

A

Patients who are stressed need a lot of arginine ( premature babies)

If not enough arginine->protein synthesize is not changed really, but urea cycle is stuck, ammonia in plasma increase-> vomiting, censures and death

If you are defficient in arginine, but you give citruline, the symptoms will be ressolved

In adults arginine deficiency will cause nothing, because we have this synthesis cycle

109
Q
A
110
Q

What is said about serine in the textbook and how was figured out that it is not 100% true

A

In textbook it says that serine is synthesized in the liver form 3 glycolytic intermediate

Liver is the major site of gluconeogenesis and cori cycle

We give glucose with C13 to test the hypothesis (m+6)

So if it is like that, serine will be M+3, because pyruvate->lactate from peripheral tissues that is labelled

Pyruvate(+3)->lactate and alanine still 3 ->liver->pyruvate->and then TCA cycle mixes all things, so finally you get Serine (+1,+2,+3)

Gluconeogenesis is not a ditect pathway to glucose

111
Q

What is happening in the body in T1DM and T2DM

A

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