Cholesterol - HDL & LDL

This post is from an old email that was written by dear Balaji on February 24th the Tuesday, 2004 @ 7:16:53 PM as a follow up to a discussion about cholesterol in phone...
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Guys,

This is what I have understood from the information I have collected.

What is a cholesterol?
cholesterol is a white, powdery fatty substance being produced by animal cells (not plants). In human beings, most of it is produced in the liver cells. It is also synthesized in other parts of the body but, not in a significant amount. So, liver cells are the manufacturing site of cholesterol for all practical purposes.

What is its function?

• Repairing cell membranes
• Aids manufacturing Vitamin D on the skin's surface
• Production of important hormones like estrogen and testosterone
• (possibly) helping cell connections that are important for memory and learning.

Then, what the heck are HDL, LDL, VLDL?
In order for the cholesterol to do the above mentioned functions, it needs to be transported to various parts of the body. Wonder who could be the transporter? It is none other than our blood.... But, cholesterol and blood are like "kerosene and water" they do not mix with each other which brings us to the point that we need somebody who can act like an agent to transport cholesterol.

Lipoproteins
The agents are nothing but the lipoproteins. Note here that lipoproteins are not meant to transport cholestrol, but also other fatty substances (lipids) like triglycerides too. But, lets see the cholesterol lipoproteins first... The core of the lipoprotein molecule contains the fatty substance (cholesterol, triglycerides) with the outer core of proteins called "apolipoprotein".

Types of Cholesterol carrying Lipoproteins
These lipoproteins are of various types based on the thickness of cholesterol core.

• Very Low density Lipoproteins (VLDL):

The inner core contains 10-15% of total cholesterol and some triglycerides. As the VHDL molecule circulates in the blood, it deposits triglycerides on the bidy tissue and eventually becomes low density lipoprotein (just the cholesterol core with negligible triglycerides).

• Low density Lipoproteins (LDL):

LDL are formed from VLDLs. (smaller in size tha VLDLs)

• High density lipoprotein (HDL):

HDL much smaller in size than LDL. Remember density = mass / volume. Lower the volume, higher the density for the same mass.

Why LDL is the villain and HDL is not?
Most of the cholesterol (75%) synthesized in the liver is carried by the LDLs rather than HDL. LDL in its natural form a harmless soul. But, it is very vulnerable to transform itself into a "villain". The transformation is the "oxidation process". Before going to oxidation, lets see what LDL and HDL actually do ?

Since LDL carries the major amount of cholesterol, abundance of LDL increases the amount of cholesterol floating in the blood. HDL actually does the cleaning process like a "good" boy. It transports the cholesterol from various organs and tissues back to the liver for "recycling". Actually the cholesterol transported back to liver by HDL are transformed into bile juices some of which are excreted via faecal matter and some of which are used for other vital functions (sort of recycling operation). so, having a low HDL and high LDL means "abundance of cholesterol" floating on the blood. Lets "turn" back to the "oxidation".

Sidebar: Oxidation: what is that??
Oxidants are unstable "oxygen-free" radicals. The onset of a chemical reaction with an oxidant is called oxidation.

LDL - villainy
The LDL molecule is prone to oxidation because of its chemical composition. The excess cholesterol (due to LDL) tend to deposit inside the arterial walls (blood vessel) which triggers the release of oxidants by the cell walls. The LDL gets modified and thus the villain is "born".

In reponse to the formation of oxidized LDL, the body releases various immune factors aimed at protecting the damaged arterial walls. Unfortunately, these immune factors are release in excess which causes inflammation and promote further injury. Also, an enzyme produced by the arterial cell wall called "phospholipase A2" binds to oxidized LDL which causes "plaque" on areterial walls. another danger is this "oxidized LDL" reduced levels of nitric oxide that helps relax the blood vessels allowing blood to flow freely.

Remember the good guy HDL - in addition to clean up, he prevents the oxidation of LDL. HDL have anti-oxidant properties of its own.

So, HDL - way to go... LDL - becomes a bad bad bad guy if he is in excess...

HDL, LDL values - what do they mean ?

• HDL - Ideal 60 mg/dL. Less than 40 mg/dL is not a good sign

• LDL - Less than 100 mg/dL is good. Above 100 - 120 mg/dL means borderline risk and above 120 mg/dL is BIG trouble.
  

Tidbits:
Our body gets cholesterol also from the food that we eat (particularly from the meat products). But, only 40% of it actually enters the blood stream. The major culprits are "saturated and transfats". some theory suggests that (not sure, but saw in many web sites) that saturated fats stimulates an increased synthesis of cholesterol thereby contributing indirectly to more LDL. transfats are believed to raise LDL as well as reduce HDL (much bigger culprit). Lets move on to triglycerides.

Triglycerides - What are they?
Triglycerides are other form of fatty substances that are derived from our food. They are used to meet the body's energy needs. Calories ingested in our meal that are not used immediately by our body are transported to tissues to be stored for later use. The transportation again occurs through the blood. The lipoproteins that are used to transport the triglycerides are chylomicrons.

Chylomicrons
Since the digestion takes place in our intestine, these chylomicrons (another type of lipoproteins) transport these triglycerides to the liver, muscle cells and the adipose tissue. The core of chylomicron contains 80% triglycerides and rest are "phospholipids".

Why high triglyceride level is harmful?
It seems that triglycerides interact with HDL in such a way that HDL level reduces in the blood which is not a good sign... Also, regardless of cholesterol levels, they are responsible for blood clots that form and block the arteries. High levels are associated with "overactive immune" system that can cause considerble damage to cells and tissues, including the arteries. Optimal level is 150 mg/dL of blood.

THE END.

Sources:
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1. http://www.healthandage.com/Home/
2. http://cholesterol.about.com/cs/cholesteroltypes/a/lipotypes.htm
3. http://www.americanheart.org/presenter.jhtml?identifier=4778
4. http://www.google.com

-Balaji.

P.S: What a long-mail.
--
"Two roads diverged in a wood and I took the one less traveled by and,
that has made all the difference" -- Robert Frost

Balaji Krithikaivasan (PhD Student),
[Co]mputer [N]etworking [Re]search [L]ab (CoNReL)

Antioxidants - some bare facts

As the low carb diet fad is wearing away, there is a new word that is becoming popular in the food world - Antioxidants... A search in google news might fetch a long list of studies and articles suggesting that intake of antioxidants can slow down aging, prevent or slow down cancer, prevent macular degeneration, prevent atherosclerosis and blah, blah, and blah...?!

So, what are these antioxidants ? And how true are these claims that it can prevent anything from aging to cancer to heart diseases ? and if so, what are the easiest ways to add these miracle components to our daily diet ?

What are Antioxidants ?
To understand Antioxidants, we need to first know about free radicals. Free radicals are the unstable atoms produced in our body as a result of the metabolic processes (during exercise, respiration where oxygen is "burnt" for energy) as well as due to exposure to tobacco smoke, some herbicides, radiation, sunlight(!) etc., These free radicals are highly reactive in nature, and so, they try to steal electrons from the neighboring atoms to become stable.

Sounds harmless ? Nope... Whenever these free radicals steal electrons from other atoms that are already stable, they will cause that atom to become a free radical and so this starts a chain reaction. And this is where antioxidants work their magic... they can donate electrons to the free radicals to stabilize them and still remain stable, thereby putting an end to the chain reaction - which otherwise can lead to damage in the cells, and the DNA...

(But then we have to also remember that, free radicals are all not totally villainous! Our body does use free radical damage for some beneficial purposes too - like for killing bacteria and digesting dead tissue or for removing harmful chemicals by the liver.)

What are the health benefits of Antioxidants ?
The best knowledge that we have now is that, higher intake of antioxidants corresponds to lower risk of cancer and heart diseases. But what is more interesting is that, there are also studies concluding that taking antioxidant supplementation can actually be detrimental to health and still, there is a controversy in using antioxidants as supplements for prevention or cure of specific diseases. Here are some of the conclusions from various studies:

• No study has found that increased intake of antioxidants through food, can be detrimental to health.
• Several studies investigating the antioxidant properties of red wine, have indicated that red wine does decrease the risk of heart diseases significantly even in cases of high fat intake!
• A meta-analysis done by cleveland clinic, concluded that vitamin E which is an antioxidant did not reduce the risk of a cardiovascular disease.
• Another study found that beta carotene supplementation for lung cancer patients actually increased the mortality rate, after which the study was discontinued.
• According to the National Cancer Institute, cancer prevention properties of antioxidants are not clear in people trials while lab and animal trials do indicate that they can prevent or slow down cancer.
• Studies on Lycopene (an antioxidant found in red fruits and vegetables like tomato), indicate that intake of lycopene in the form of tomatoes, reduced risk of cardio vascular diseases, cancer and macular degeneration. But still it is not conclusive enough to tell that whether Lycopene was the sole contributor or it might be due to other antioxidants in tomato like Vitamin C & Folate.
• Several studies investigating the antioxidant effects of Green Tea have indicated that increased intake of green tea can prevent cancer, can cure ulcer in rats, can help increase HDL etc.,
  

So my feeling is that though there are a lot of disagreeing studies regarding the effect of (mostly, individual) antioxidants on various diseases, one thing still remains unchallenged - that is, people with high intake of antioxidant rich food seem to be having a reduced risk of cancer and heart diseases.

How much Antioxidants do we need ?
Unfortunately, there seems to be no conclusive recommendation on the total amount of antioxidants that a person needs, to prevent or slow down diseases, and i think this is primarily because there are a number of antioxidants that can be utilized by our body, studies, so far seem to focus only on particular antioxidants...

But there are several studies recommending specific amounts of some antioxidant rich food like, 6 to 8 cups of green tea a day might help reduce the risk of cancer, or 2 to 3 drinks of red wine per week might reduce the risk of heart disease or 5 servings of antioxidant rich fruits and vegetables might be sufficient to reap the benefits of antioxidants etc.,

How can we add Antioxidants to our daily diet ?
Antioxidant content of foods is measured by ORAC units. In general, prunes, pomegranates and berries top the list of the best sources of antioxidants, though of late, a new type of berry from Asia called Wolfberry or Goji berry is gaining popularity (in spite of some doubts) and these berries are claimed to contain as much as ten times more antioxidants (25300 ORAC units) than blueberries (2400)!

And finally, here are some antioxidant rich food that we can easily add to our diet along with their ORAC levels...

• Eat purple or blue colored fruits and berries (mainly due to their Anthocyanins content) - they contain as much as 5 to 10 times more antioxidants than many other fruits and vegetables! Examples are blueberries (2400) , blackberries (2036), raspberries (1220), strawberries (1540), plums (949), red cabbage, purple egg plant (aka aubergine or brinjal), black currant, pomegranate(3307)), red grapes (739) and red wine...

• Eat foods rich in Vitamin C and E, both of which are antioxidants. (though supplementing vitamin E is not recommended by the UC Berkeley's wellness letter for lack of conclusive studies. A tidbit - Vitamin E was discovered here in UCB!

• Eat yellow, orange or red colored fruits and vegetables and green leafy vegetables that are rich in carotenoids like Beta Carotenes and Lycopene. Examples are the carrots (200), beets (1840), cantaloupes (250), mangoes, papaya, sweet potatoes (295), pumpkins, apricots, nectarines that are rich in beta carotenes, and spinach (1260), romaine lettuce, kale and broccoli (890), and lycopene rich fruits like tomatoes, watermelons (100), grapefruit and guava.

• Drink Green Tea - which has powerful antioxidants called polyphenols that are suggested to prevent cancer based on many population based studies.

And finally, a good news for those chocoholics! Cocoa and Dark Chocolates (13120!!) are found to have much much more antioxidants called flavanoids, than the blueberries (2400), green tea or red wine!!

Looking at the list above, you might realize that many of these fruits and vegetables are not only good sources of antioxidants but they might also be good sources of other vitamins, minerals and phytonutrients... So, as the doctors always say, there is no diet better than a well rounded diet consisting of different varieties of fruits and vegetables, that might just help us to,

"Live Long and Prosper"!

Borat in SNL!

Watched BORAT over the weekend. very funny movie and lot of funny comments... like "Kazhakstan has lot of problems - social, economic and J3w"... felt like watching it again!!

I think a few scenes might be gross for some folks and i am sure they will be censored in some countries, in case the movie is not banned!

here is the saturday night live opening by Borat - it has quite some jokes from the movie!

Speed of Light using Marshmallows!!

A few days back, I was warming up my food in the microwave and it was unevenly warm and so i was thinking of trying out some experiment to see if there was some pattern of areas that got heated up quickly and areas that dont... and for this experiment, i thought we should use small cups containing the liquid that is used in the microwaveable cold/heating packs which turn blue when cold and hot when red... but then it needs quite some work done ?

so, i decided to just learn if somebody had tried in the internet and voila!

Uneven heating in the microwave can be attributed to factors like: A fixed pattern of destructive interference of the reflected microwaves, Position of the food (never place at the center?), Composition of the food and the time to cook...

Here are two interesting experiments that i am planning to do this week:

1. Find the pattern in which microwaves interfere in your microwave.
   
2. Find the speed of microwave which is also the Speed of Light by measuring the wavelength of the microwaves by heating a layer of marshmallows!

Ah, the simple pleasures of microwaving... ;-)

Feynman and the Manhole covers...

A week before, i would not have imagined that soon, i might be blogging about something as trivial (or is it?) as the shape of the Manhole Covers!!

i was posed with this question by a friend this week, and my immediate answer was, "is it because its easier to dig circular holes ?" Supposedly, Microsoft and IBM (since the 60s ?!) have been asking this question in their interviews to test lateral thinking ability and the expected answer is that "manhole covers are round because round is the only shape that can never fall into the manhole..."

Though given the popularity of this question and this answer, if i were an interviewer, and if someone gives this politically correct answer, i might doubt that the person is not thinking laterally to explore other answers besides this cliched one ;-) And there are also other complex shapes fitting this requirement of having a constant diameter like the Reuleaux triangles and similar shapes drawn using any odd sized polygon...

Though the expected answer is a very creative one, here's a more realistic reason on how the circular shape has, indeed become the universal standard: "circle seems to be a default (and natural too ?) shape for underground drains and pipes, probably due to reasons like their ability to withstand pressure better, and it has been the case since the roman empire!! and hence the covers were made to fit the circular holes :-) also, i have not seen any evidence yet that, there were some other shapes in use, before the circular ones, and we then moved to circular covers due to their advantage..."

and here's some manhole trivia from the net...

* Nashua, a town in New Hampshire, US has triangular manhole covers, which is being phased out in favor of circular ones (not because triangular covers are falling inside the manholes)

* India is the world leader in manufacturing manhole covers

* China faces the problem of manhole cover thefts and its govt has taken steps to reduce manhole cover thefts in Beijing from 24,000 in 2004 to 4000 in 2005

and how would somebody as clever and mischievous as Richard Feynman answer this question ? below is the snippet of this entertaining imagination from this interestng site about Microsoft Interview experiences:

Interviewer: Now comes the part of the interview where we ask a question to test your creative thinking ability. Don't think too hard about it, just apply everyday common sense, and describe your reasoning process.

Here's the question: Why are manhole covers round?

Feynman: They're not. Some manhole covers are square. It's true that there are SOME round ones, but I've seen square ones, and rectangular ones.

Interviewer: But just considering the round ones, why are they round?

Feynman: If we are just considering the round ones, then they are round by definition. That statement is a tautology.

Interviewer: I mean, why are there round ones at all? Is there some particular value to having round ones?

Feynman: Yes. Round covers are used when the hole they are covering up is also round. It's simplest to cover a round hole with a round cover.

Interviewer: Can you think of a property of round covers that gives them an advantage over square ones?

Feynman: We have to look at what is under the cover to answer that question. The hole below the cover is round because a cylinder is the strongest shape against the compression of the earth around it. Also, the term "manhole" implies a passage big enough for a man, and a human being climbing down a ladder is roughly circular in cross-section. So a cylindrical pipe is the natural shape for manholes. The covers are simply the shape needed to cover up a cylinder.

Interviewer: Do you believe there is a safety issue? I mean, couldn't square covers fall into the hole and hurt someone?

Feynman: Not likely. Square covers are sometimes used on prefabricated vaults where the access passage is also square. The cover is larger than the passage, and sits on a ledge that supports it along the entire perimeter. The covers are usually made of solid metal and are very heavy. Let's assume a two-foot square opening and a ledge width of 1-1/2 inches. In order to get it to fall in, you would have to lift one side of the cover, then rotate it 30 degrees so that the cover would clear the ledge, and then tilt the cover up nearly 45 degrees from horizontal before the center of gravity would shift enough for it to fall in. Yes, it's possible, but very unlikely. The people authorized to open manhole covers could easily be trained to do it safely. Applying common engineering sense, the shape of a manhole cover is entirely determined by the shape of the opening it is intended to cover.

Interviewer (troubled): Excuse me a moment; I have to discuss something with my management team. (Leaves room.)

(Interviewer returns after 10 minutes)

Interviewer: We are going to recommend you for immediate hiring into the marketing department.