Lipid metabolism in the heart —Contribution of BMIPP to the diseased heart—

Lipid contributes greatly in cardiac metabolism to produce high energy ATPs, and is suggested to be related to the progression and deterioration of heart disease. It is fortunate that the I-123-betamethyliodophenylpentadecanoic acid (BMIPP) imaging technique is now available in determining heart condition, but we must be cautious about the interpretation of images obtained with this new tracer. From the uptake of BMIPP into the cell to breakdown and catabolism of it, there exist so many critical enzymatical pathways relating to the modification of BMIPP imaging. In clinical evaluation, the image will be translated as the integral effects of these pathways. In other words, we must be aware of these critical pathways regulating lipid metabolism and modifying factors in order to correctly understand BMIPP imaging. Lipid transport is affected by the albumin/FFA ratio in the blood, and extraction with membrane transporter proteins. Fatty acid binding protein (FABP) in the cytosole will play an important role in regulating lipid flux and following metabolism. Lipid will be utilized either for oxidation, triglyceride or phospholipid formation. For oxidation, carnitine palmitoil transferase is the key enzyme for the entrance of lipid into mitochondria, and oxidative enzymes such as acyl CoA dehydrogenase (MCAD, LCAD, HAD) will determine lipid use for the TCA cycle. ATPs produced in the mitochondria again limit the TG store. It is well known that BMIPP imaging completely changes in the ischemic condition, and is also shown that lipid metabolical regulation completely differs from normal in the very early phase of cardiac hypertrophy. In the process of deteriorating heart failure, metabolical switching of lipid with glucose will take place. In such a different heart disease conditions, it is clear that lipid metabolical regulation, including many lipid enzymes, works differently from in the healthy condition. These lipid enzymes are regulated by nuclear factor peroxisome proliferator-activated receptors (PPAR) just like a conductor of an orchestra. Most of the regulating mechanisms of the PPAR are still unknown, but reduction of this nuclear factor is shown in the process of decompensated heart failure. This review is based by mostly on our fundamental and Japanese clinical data. BMIPP has been used clinically in abundant cases in Japan. In such situations, further correct information on lipid metabolism, including BMIPP, will contribute to the understanding of deteriorating heart disease and its prognosis.     

Optimum predrilled hole size for bone screws used in osteochondral fixation: in vitro biomechanical study and clinical case

Background  

Bone screws have a mechanical advantage over bone pegs for fixation of osteochondral fractures. The purpose of this study was to investigate predrilling methods to facilitate bone screw insertion.     

A simplified radiometabolite analysis procedure for PET radioligands using a solid phase extraction with micellar medium

A solid phase extraction method has been developed for simple and high-speed direct determination of PET radioligands in plasma.MethodsThis methodology makes use of a micellar medium and a solid-phase extraction cartridge for displacement of plasma protein bound radioligand and separation of PET radioligands from their radiometabolites without significant preparation. The plasma samples taken from monkey or human during PET measurements were mixed with a micellar eluent containing an anionic surfactant sodium dodecyl sulphate and loaded onto SPE cartridges. The amount of radioactivity corresponding to parent radioligand (retained on the cartridge) and its radioactive metabolites (eluted with micellar eluent) was measured.ResultsUnder the optimized conditions, excellent separation of target PET radioligands from their radiometabolites was achieved with a single elution and short run-time of 1 min. This method was successfully applied to study the metabolism for ¹¹C-labelled radioligands in human or monkey plasma. The amount of parent PET radioligands estimated by micellar solid phase extraction strongly corresponded with that determined by radio-LC. The improved throughput permitted the analysis of a large number of plasma samples (up to 13 samples per one PET study) for accurate estimation of metabolite-corrected input function during quantitative PET imaging studies.ConclusionSolid phase extraction together with micellar medium is fast, sensitive and easy to use, and therefore it is an attractive alternative method to determine relative composition of PET radioligands in plasma.     

Two Cases of Reversible Left Ventricular Hypertrophy during Recovery from Takotsubo Cardiomyopathy

We report 2 cases of reversible ventricular hypertrophy in patients with takotsubo cardiomyopathy (stress‐induced cardiomyopathy) during recovery of cardiac function. The first case involved a 72‐year‐old woman who presented with cerebral infarction. On admission, an elevated troponin I and decreased apical wall motion were observed with normal myocardial perfusion imaging. The second case involved a 79‐year‐old woman who presented with angina, anxiety resulting from emotional stress, slightly decreased apical wall motion, and normal epicardial arteries. In both cases, apical hypertrophy of the left ventricle was observed at approximately 3 weeks after onset, when the wall motion had improved. The ventricular wall gradually became thinner over time. To our knowledge, this is the first report of reversible ventricular hypertrophy in patients with takotsubo cardiomyopathy. We hypothesize the hypertrophic signaling in the myocardium was stimulated by catecholamines, which are the suggested etiology of takotsubo cardiomyopathy, and the hypertrophied myocardium gradually returned to normal as the syndrome receded.