Nutrition Flashcards
Describe what happens in T1DM on cellular level and in general
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
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
What was the design of the study in 1950s
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
Why there are difficulties in designing protein studies
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
Why subjects are asked to go on the diet before the study as well
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
What are 3 stages in study modelling
Clinical/Metabolic
Analytical
Modelling
What is clinical/metabolic part of the study
analytical
Clinical/Metabolic
• COMPLETE intake and collections
• Adaptation of urea pool
Analytical (easy peasy)
• Routine analysis of total Nitrogen
What moments should be remembered in modelling stage of the study
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
In what conditions Arginine becomes indispensable
Infants and under severe health conditions
They are making it , but not enough
Name indispensible, conditionally indispensable and dispensible AAs
Phe and Tyr, as well as meth and cysteine are considered together
Because Tyr is synthesized from Phe
Methionine and cysteine are sulphur AAs, cysteine is synthesized from methionine
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
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
What is flow of the tracer
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
Tracer dilution principles of data experiment : what assumptions are made
- 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
- Homogenety of pool
- Massless tracer
- No tracer recycling ( so if you label AAs, it does not get resynthesized)
what do we know here when giving the tracer AA in the diet
We know diet intake, we can meaure AA oxidation, thus we can calculate
What are naturally occuring isotopes of C, H,N,O,S
Carbon 13,Hydrogen 2 (deuterium),nitrogen 15,oxygen 18,sulphur 34
what is the advantage of isotope
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
How does Gas Chromatograph Mass Spectrometer works
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
What is nutritional indispensable
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.
What is metabolically essential amino acids
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
What AAs are strictly metabolically indispensible
Lysine, Threoine and tryptophan
Others we can synthesize from ketoacids, if they would be available ( 6 other nutritional essential, are not metabolically essential )
What is a cofactor for transaminase
Pyridoxine - vitamin b6
What is the chicken that laid the golden egg study
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
What we can see from the graph
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
What is GLX and why it is important
Glutamine and Glutamate- fuel for the gut , nout glucose unlike other tissues
what can we conclude from this graph
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
Why would a food company invest in research about utilization of glutamate
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
How can we measure AA requirement
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
Every subject should be studies at ___ test AA intake levels above and below requirement, to test for
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
All methods should give ___
The same answer
Why plasma concentrations is not accepted as a measure of AA change
Endpoint should show clear response to change in test AA intake, plasma do not change much, wont see the end
For how long CO2 should be measured
CO2 if carbon is labelled ( hours to a couple of days)
Why men are willing to participate in the studies
Do not need to shop, to cook, free
Female- does not like the taste, the smell
Where it is better to take blood sample for analysis
Better from the artery, because mixed blood and does not reflect the metabolized
But not ethical
Why subjects get little money for the study
You can pay for the expenses, but usually not paid , because there is not enough money to become a motive
Ethics of doing research in babies
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
How do we measure direct oxidation rate
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
How does the graph of direct oxidation study looks like
Why a choice of test AAs for direct oxidation study becomes an issue
Only BCAAs, lysine and Phe have their carbons irreversible commited to oxidation. So we can measure only this AAs requirement
What are some restrictions of direct oxidation method
Can’t measure 0 intake, because our tracer is an AAs
Restricted choice of test AAs
What is the analytical (measuring) part of direct oxidation method
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)
What you need to do with data and need to account in modeling in direct oxidation method
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
What is the concept of indicator AA oxidation (IAAO)
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
How does the graph of IAAO looks like if Phe is an indicator and Lysine is test
Look in the notebook
What is the advantage of IAAO
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
What AAs can be used as an indicator in IAAO
Phe,Lys, Leu
How the results are collected in IAAO
- Breath Collection:
- IRMS for CO2 enrichment, Calorimeter for CO2 production
- Blood samples; Urine samples (non‐invasive)
- GCMS for AA enrichment
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
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
How to minimize the invasiveness of IAAO model (trace administration and sampling) , which is doen for kids and babies
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
Common principle of determining AA requirement for all methods
Ethical, compliance, statistical (and modeling- why are we doing eat, to determine a point where the responce changes) and technological (expensive equipment)
With the research we can find what data for AA requirement
EAR, and then plus 2 SD to have RDA
What is Lysine requirement
now EAR = 31 mg/kg/d
now ‐RDA = 38 mg/kg/d (EAR + 2 x cv)
What was the old and the new essential amino acid requirment and to whom it applies
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
What are potential limiting indispensable AAs
Lysine, threonine,tryptophan,sulphur AAs
Thoug Tryptophan requirement is low is it met?
Can be an issue for vegans and vegetarians and to people who have low diversity diet
So witht he new requirements (DRI 2003) are we meeting AA requirementO
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
What can be done to vegans so they get all the requirement
Complementary proteins
• Beans and rice
• Legumes and grains
How they proved that Histidine is essential
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
Histidine is very abundant in ___
Hemoglobin
Histidine deficiency looked like ___ anad why
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
2 stages in adaptation
Short-term ( really does not change the function)
Long-term (accommodation, changing function)
Do we have problems with DRI requirements in regards to descrimination
“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
Why women should have seperate requirements
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
What conditions should be tested for AA requirements
- Prematurity
- Healthy infants!!!
- Intravenous feeding
- Inborn errors
- Metabolic stress
- Liver disease
- Exercise
What does it mean special products of protein
Neurotransmitter, peptides, etc.
Is there higher requirement AA/protein in critical illnes
0.8 g/kg for everyone
But then Hoffer tested maybe in critical illness 2-2.5 g/kg is needed
Can you supply a patient with 2-2.5 g/kg and sometimes 3 g/kg by food
No, that is why parental nutrition or through gastric tube
Why parental nutrition is good for critical illness
Bypass splanchic control ( by-pass the liver and the intestine)
Can supply more
Composition of intravenous regimes and problems with it
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
Issues with designing an optimal profile of AAs: aromatic AAs
tyrosine insolubility (when F is pretty soluble), transient hyperphenylalaninemia and hypertyrosinemia
How can you overcome hypertyrosinemia
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
The difference between vamin and vaminolact
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)
0 nitrogen balance means ___ nitrogen retention
0 nitrogen retention
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
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
How can protein defficiency can influence tissues
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
Protein is ___ nitrogen
16%
What is RDA in 2007 from the study
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
What is net Phe balance
Dietary phenylalanine-urinary phenylalanine
What is the requirement of protein for endurance-trained men
2.1 g/kg per day-EAR
RDA- 2.6 g/kg per day
What happened to young men who consumed 0.6 g/kg/day, 0.75 and 1 for 7 days
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
How we measure the weight gain of infants normality
Percentiles
Little changes in nutrition can cause big changes in ____
Function and growth
When we have the most rapid growth
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
Role of GI in AA metabolism
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)
What happens AAs metabolism in fed state
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
What happens in short-term fast
No absorption in GI
Lower insulin, more glucagon
Less protein synthesize, relatively higher protein breakdown
What is the usual dosage of protein in meal to get the maximum rate of protein synthesize
What else is important for protein synthesize
30 grams
Timing is important (skipping breakfast not good)
what happens in long term fast to AA metabolism
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
Difference in liver and muscle protein handling
Anabolic and catabolic reactions of AAs handling in liver
Anabolic
– Constitutive protein
synthesis
– Plasma protein
synthesis (fibrinogen, albumin)
– Gluconeogenesis
– Lipogenesis
Catabolic
– AA catabolism
– Urea cycle
What is hypertrophy of muscles and how is it activated
Hypertrophy (building muscle mass)
– Growth
– Anabolic (fed state, exercise)
– Activation of PI3K Akt
pathway (responsive to insulin, for example translation and transcription of proteins)
Atrophy of muscles : what is it and how is it activated
– 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
How do we figure out if it is the nutrient availability that causes the metabolic change or it is hormone that cause metabolic change
Insulin clamp study
What is sacropenia
degenerative loss of skeletal muscle mass, quality, and strength
Response to one of proteolytic pathways
Describe insulin clamp study
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
Insulin clamp and AA infusion
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
why we have have essential and non-essential AAs, probably
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
body protein synthesize proportion for different places
50% visceral
10 blood cells
10 plasma proteins
30 muscle
What will happen to body protein synthesize proportion in infection
Blood cells are going to be prioritized, compromising from muscles
Special products of AAs
ATP, nucleic acids, creatine, taurine, glutathione,nitric oxide, neurotransmitters
How much protein we synthesize a day and what proportion are special products
300 grams
Minor
Usually most special products are made from
Non essential AAs
Glutathione precursors
Glutamate,cysteine, glycine
Synthesis of dispensible AAs (rates, proportion of BMR, precursor)
- 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
The correlation between intestine and kidney in synthesis of arginine and arginine role
Polyamine promotes protein synthesize
Instetinal-kisney access, needs organ cooperation
Who can become deficient in arginine and how the problem can be ressolved
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
What is said about serine in the textbook and how was figured out that it is not 100% true
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
What is happening in the body in T1DM and T2DM
