|
No treatments are currently available to reverse the structuralheart changes resulting from IUGR. Telomere length provides CVD insights in survivors of LeningradSiege In abstract P190 investigators from the Almazov Federal Heart,Blood and Endocrinology Centre, St Petersburg, Russian Federation,studied the telomere length of survivors from the siege ofLeningrad (1941 to 1944), which was responsible for citizens beingsubjected to some of the most extreme levels of starvation known inhistory . "For workers the bread ration was 250g, which amounted to just 300calories, with around half that for the rest of the population,"said Olga Freylikhman, one of the study investigators. The diet,she added, contained virtually no protein. By the end of the siegeout of a population of 2.9 million, including 0.5 million children,over 630,000 people had died from hunger related causes. Telomeres are the DNA-protein complexes that encase the ends ofchromosomes. Often likened to the plastic caps on shoelaces, theyserve the function of promoting chromosome stability. Consistentlyshortened telomere lengths have been associated with health riskand disease - one study showed that mean telomere lengths (measuredin blood DNA) predicted the 15 year risk of CVD mortality, andothers identified shorter telomeres among subjects who smoked, hadelevated blood pressure, and premature myocardial infarctions(MIs). Identification of survivors for the study was made possible by thefact that after World War II, inhabitants of Leningrad (now StPetersburg) who survived the siege were invited to join specialsupport societies. From these societies, still in existence today,investigators have been able to recruit 40 subjects born during thesiege, and 260 born before the siege who had lived through thedeprivations as children. Survivors were compared to age matchedcontrols born during the same period (1930 to 1943) and now livingin St Petersburg, but who had not been exposed to siege conditions.All subjects were asked to fill in questionnaires regardinglifestyle factors and take part in a range of tests including bloodpressure measurements, fasting lipids and glucose tests, carotidultrasound, arterial stiffness, and cognitive function, as well asmeasurements of their telomere lengths by quantitative PCR. While measurements of telomere length for all subjects are now inprogress, preliminary results (presented in the abstract) comparingthe telomere length of survivors of the siege (n=106), withcontrols (n=27) show that survivors had significantly shortertelomere lengths (p 0.005). Furthermore investigators found ahigher prevalence of current metabolic disorders among siegesurvivors. No difference in telomere length, however, was foundbetween the 20 subjects born during the siege and the 86 bornbefore the siege. "Our results suggest that measuring telomere length mightultimately be used as a way to stratify heart risk in people who'veexperienced both intrauterine starvation and food shortages duringchildhood. Those found to be at high risk could be managed usingaggressive prevention measures," said Freylikhman. One possible explanation for the lack of differences found betweensubjects exposed to intrauterine shortages and those experiencingchildhood starvation, suggested Freylikhman, is that the peoplewith IUGR who have shorter telomere lengths were more likely tohave died immediately following the siege. Further studies are planned to explore differences in telomerelength according to the ages of children at the time of siege, andto explore whether telomere length and metabolic disorders affectthe offspring of survivors of the siege. Spanish team documents IUGR changes to heart muscle architecture In the second study Iratxe Torre and colleagues set out to identifythe changes that occur to the cardiac muscle "architecture"following IUGR . The investigators, from The Hospital Clinic ofBarcelona, Spain, used an animal model of IUGR based on theselective ligature of the uteroplacental vessels in pregnantrabbits that restrict blood flow to the foetus. "Rabbits represent an ideal model for IUGR. They have similarplacenta structure and heart muscle compositions to humans andpossess a two-horned uterus. Ligatures can be applied to one horn,while the other can be left to provide the perfect experimentalcontrol," explained Torre. Using Polarization Second Harmonic Generation Microscopy (PSHGM), atechnique that is highly sensitive to changes in the molecularorganisation of cardiac sarcomeres, the team revealed differencesin the position of myosin proteins between IUGR animals andcontrols. Sarcomeres, representing the basic contractile unit of cardiacmuscle, are composed of the protein actin (which forms the thinfilaments) and the protein myosin (which forms the thick filament).Actin and myosin slide past each other when muscles contract andrelax. The Spanish team found that the distance between the myosinmolecules inside the thick filaments (known as the helical pitchangle) was increased slightly in the IUGR rabbit muscle (by aroundtwo nanometres) immediately following birth in comparison to thenormal controls. The displacement, persisted when young adults wereexamined again 70 days after birth. "Our work suggests the 3D conformation of myosin within the cardiacthick filaments is changed following IUGR," said Torre. In a secondabstract , she added, the team went on to observe that similarchanges occur in the myosin filaments of older rabbits (aged aroundone year). "It appears that growth restricted rabbits are born withprematurely old sarcomeres," said Torre. "Changes to the myosinstructure might provide a direct explanation for the adverse CVoutcomes found in IUGR." Measurements of the helical pitch angle, which documents highlyprecise changes to the structure and orientation of myosin thickfilaments, the investigators suggested, offers a new way to assessthe effectiveness of potential treatments to prevent thecardiovascular complications of IUGR in animal models. "Using sucha precise approach would allow much faster development oftreatments related to both the heart changes occurring in IUGR andcardiomyopathies related to ageing," said Torre. Additional References Citations. We are high quality suppliers, our products such as China Food Process Machinery , Vaccum Dryer Manufacturer for oversee buyer. To know more, please visits Pulveriser Machine.
Related Articles -
China Food Process Machinery, Vaccum Dryer Manufacturer,
|
