Heart function vitally relies on precisely controlled intracellular Ca homeostasis during each cardiac cycle. Abnormalities in Ca regulation cause contractile dysfunction and arrhythmias under different pathological conditions including heart failure (HF). Playing a particularly important role in heart contraction is the sarcoplasmic reticulum (SR). In adult ventricular myocytes, the SR forms a...

The sarcoplasmic reticulum (SR) is a specialized form of endoplasmic reticulum (ER) in skeletal muscle and is essential for calcium homeostasis. The mechanisms involved in SR remodeling and maintenance of SR subdomains are elusive. In this study, we identified myotubularin (MTM1), a phosphoinositide phosphatase mutated in X-linked centronuclear myopathy (XLCNM, or myotubular myopathy), as a key...

SR-PSOX in Cultured Aortic Smooth Muscle Cells and Umbilical Endothelial Cells To the Editor: In the November issue of Arteriosclerosis, Thrombosis, and Vascular Biology, Minami et al1 demonstrated expression of the novel scavenger receptor for phosphatidylserine and oxidized lipoprotein (SR-PSOX) in lipid-laden macrophages accumulated in the intima of human atherosclerotic lesions. Because SR-...

Infection of hepatocytes by Plasmodium falciparum sporozoites requires the host tetraspanin CD81. CD81 is also predicted to be a coreceptor, along with scavenger receptor BI (SR-BI), for hepatitis C virus. Using SR-BI-knockout, SR-BI-hypomorphic and SR-BI-transgenic primary hepatocytes, as well as specific SR-BI-blocking antibodies, we demonstrate that SR-BI significantly boosts hepatocyte perm...

Protein translocation across and insertion into membranes is a process essential to all life forms. In higher eukaryotes, this process is initiated by targeting the translating ribosome to the endoplasmic reticulum via the signal recognition particle (SRP) and its membrane-associated heterodimeric receptor (SR). This targeting step is regulated by three G proteins, SRP54, SR alpha, and SR beta,...

The scavenger receptor class B type I (SR-BI), which mediates selective cellular cholesterol uptake from high-density lipoproteins (HDLs), plays a key role in reverse cholesterol transport. The orphan nuclear receptor liver receptor homolog 1 (LRH-1) and SR-BI are co-expressed in liver and ovary, suggesting that LRH-1 might control the expression of SR-BI in these tissues. LRH-1 induces human a...

The depth to which seawater and fresh water circulate through modern carbonate platforms may be estimated with Sr/Sr isotope ratios of dissolved Sr that is enriched through carbonate mineral dissolution and recrystallization. In 23 water samples from onshore San Salvador Island and Long Island, Bahamas, carbonate mineral dissolution and aragonite-to-calcite transformations elevate Sr concentrat...

Identifying sources of sampling variation and quantifying their magnitude is critical to the interpretation of ecological field data. Yet, most monitoring programs of reef fish populations based on underwater visual censuses (UVC) consider only a few of the factors that may influence fish counts, such as the diver or census methodology. Recent studies, however, have drawn attention to a broader...

Longitudinal tubules and junctional sarcoplasmic reticulum (SR) were prepared from heart muscle microsomes by Ca2+-phosphate loading followed by sucrose density gradient centrifugation. The longitudinal SR had a high Ca2+ loading rate (0.93 +/- 0.08 mumol.mg-1.min) which was unchanged by addition of ruthenium red. Junctional SR had a low Ca2+ loading rate (0.16 +/- 0.02 mumol.mg-1.min) which wa...

Solving a set of simultaneous linear equations is probably the most important topic in numerical methods. For solving linear equations, iterative methods are preferred over the direct methods specially when the coefficient matrix is sparse. The rate of convergence of iteration method is increased by using Successive Relaxation (SR) technique. But SR technique is very much sensitive to relaxatio...