لږ گڼ ليپوپروټين

لږ-گڼ ليپوپروټين يا لږ-گڼ شهمي پروټين (په انگرېزي: Low-density lipoprotein يا په لنډه LDL) د ليپوپروټينو د پينځو سترو ډلو نه يوه ډله شهمي پروټين دي چې د غټې کچې نه تر وړې کچې په دې ترتيب اوډل کېږي، کايلومايکرون، خورا لږ-گڼ ليپوپروټين/شهمي پروټين، منځنی-گڼ ليپوپروټين/شهمي پروټين، لږ-گڼ ليپوپروټين/شهمي پروټين، ډېر-گڼ ليپوپروټين/شهمي پروټين. دا ليپوپروټينونه د ژونکو نه چاپېر اوبلن چاپېريال او د اوبو پر بنسټ د وینې بهير کې د غوړو د گڼ شمېر ماليکولونو، چې په دغو کې کولېسټرول هم راځي، د لېږدېدو چارې برابروي. څېړنيزو زده کړو جوته کړې چې په لوړه کچه د بي-ډول لږ-گڼ ليپوپروټينونه (اې-ډوله لږ-گڼ ليپوپروټينو په خلاف) روغتيايي ستونزې او د زړه او رگونو ناروغيو ته وده ورکوي. دا ډول ليپوپروټينونه اکثراً د بد کولېسټرول په نامه هم پېژندل کېږي او د دغو په خلاف ډېر-گڼ ليپوپروټينونه د ښه کولېسټېرول په نامه پېژندل کېږي.LDL and HDL Cholesterol: What's Bad and What's Good?

د آزمېښتون آزموينې 
په درملگريزو آزمېښتونو کې اکثرا د وينې اخيستنې وروسته په وينه کې د LDL-C کچې راپور وړاندې کېږي، دا هغه معيار دی چې د کولېسټرول لرونکو لږ-گڼ ليپوپروټينو شمېر پرې څرگندېږی. په کلينيکي لحاظ، دا اندازه شوی شمېر ډېر ارزښت لري. د شمېرپوهنې له مخې د LDL-C د کچې شمېر د هغو لږ-گڼ ليپوپروټينو د څومره والي په اټکل کېدو کې کارېږی چې روغ بدن د اتېروسکلېروسېز ناروغۍ په لور بيايي.  

د LDL نېغه مېچنه هم په آزمېښتون کې شونې ده او د پورته ياد شوي آزمېښت په پرتله په ځينو ځاينو کې موثره هم ده. خو دا آزمېښت د ډېر لگښت او په ځانگړو آزمېښتونونو کې د ترسره کېدنې په پار ډېر نه ترسره کېږي. په ۲۰۰۸ ز. کال کې ADA او ACC د NMR په مرسته د LDL ماليکولونو نېغه مېچنه تصويب کړه چې په ځينو روابطو کې تر ټولو ښه او په ځینو وگړو کې د زړه او رگونو د رنځونو د وېرې په اټکلېدو کې کارېږي.John D. Brunzell, MD, FACP, Michael Davidson, MD, FACC, Curt D. Furberg, MD, PhD, Ronald B. Goldberg, MD, Barbara V. Howard, PhD, James H. Stein, MD, FACC, FACP and Joseph L. Witztum, MD Lipoprotein Management in Patients With Cardiometabolic Risk, J Am Coll Cardiol, 2008; 51:1512-1524.  

ژونکيميا
جوړښت
Each native LDL particle contains a single apolipoprotein B-100 molecule (Apo B-100, a protein that has 4536 amino acid residues and a mass of 514 kDa), which circulates the fatty acids, keeping them soluble in the aqueous environment. In addition, LDL has a highly hydrophobic core consisting of polyunsaturated fatty acid known as linoleate and about 1500 esterified cholesterol molecules. This core is surrounded by a shell of phospholipids and unesterified cholesterol, as well as the single copy of Apo B-100. LDL particles are approximately 22 nm (0.00000087 in.) in diameter and have a mass of about 3 million daltons, but since LDL particles contain a changing number of fatty acids, they actually have a distribution of mass and size. Determining the structure of LDL has been a tough task because of its heterogeneous structure. First structure of LDL at human body temperature in native condition has been recently found using cryo-electron microscopy and it has resolution of 16 Angstrom.

د LDL څېرمه ډولونو مخبېگلې
LDL particles vary in size and density, and studies have shown that a pattern that has more small dense LDL particles, called Pattern B, equates to a higher risk factor for coronary heart disease (CHD) than does a pattern with more of the larger and less dense LDL particles (Pattern A).  This is because the smaller particles are more easily able to penetrate the endothelium. Pattern I, for intermediate, indicates that most LDL particles are very close in size to the normal gaps in the endothelium (26 nm).   According to one study, sizes 19.0 to 20.5 nm were
designated as pattern B and LDL sizes 20.6–22 nm were designated as pattern A.http://onlinelibrary.wiley.com/doi/10.1002/clc.4960280510/pdf

Some in the medical community have suggested the correspondence between Pattern B and CHD is stronger than the correspondence between the LDL number measured in the standard lipid profile test.  Tests to measure these LDL subtype patterns have been more expensive and not widely available, so the common lipid profile test is used more commonly. http://www.msnbc.msn.com/id/35058896/ns/health-heart_health/t/bad-cholesterol-its-not-what-you-think/#.T4Gkub_Owrg

There has also been noted a correspondence between higher triglyceride levels and higher levels of smaller, denser LDL particles and alternately lower triglyceride levels and higher levels of the larger, less dense LDL.

With continued research, decreasing cost, greater availability and wider acceptance of other lipoprotein subclass analysis assay methods, including NMR spectroscopy, research studies have continued to show a stronger correlation between human clinically obvious cardiovascular event and quantitatively measured particle concentrations.

ژونکې منځ ته لېږدېدنه
When a cell requires cholesterol, it synthesizes the necessary LDL receptors, and inserts them into the plasma membrane. The LDL receptors diffuse freely until they associate with clathrin-coated pits. LDL particles in the blood stream bind to these extracellular LDL receptors. The clathrin-coated pits then form vesicles that are endocytosed into the cell.

After the clathrin coat is shed, the vesicles deliver the LDL and their receptors to early endosomes, onto late endosomes to lysosomes. Here the cholesterol esters in the LDL are hydrolysed. The LDL receptors are recycled back to the plasma membrane.

 سرچينې