Isolevuglandin-protein adducts in humans: products of free radical-induced lipid oxidation through the isoprostane pathway

A family of extremely reactive electrophiles, isolevuglandins (isoLGs), is generated in vivo by free radical-induced lipid oxidation and rearrangement of endoperoxide intermediates of the isoprostane pathway. Protein adducts of two different oxidized lipids, isoLGE(2) and iso[4]LGE(2), and the corresponding autoantibodies are present in human blood. Western blot analysis of a polyacrylamide gel electrophoresis gel detects several immunoreactive plasma proteins. Only a minor fraction of the isoLG-protein modifications is associated with low density lipoprotein since mean levels were decreased only 20-22% by immunoprecipitation of apolipoprotein B (apoB). Mean levels of both isoLGE(2) and iso[4]LGE(2)-protein adducts in plasma from patients with atherosclerosis (AS) (n=16) or end-stage renal disease (RD) (n=8) are about twice those in healthy individuals (n=25). These elevated levels are not related to variations in age, total cholesterol or apoB. A linear correlation (r=0.79) between plasma isoLGE(2) and iso[4]LGE(2)-protein adduct levels in all 49 individuals is consistent with a common free radical-induced mechanism for the production of both oxidized lipids in vivo. The correlation is even stronger (r=0.86) for patients with AS or RD. That isoLG-protein adduct levels are more strongly correlated with disease than are total cholesterol or apoB suggests an independent defect that results in an abnormally high level of oxidative injury associated with AS and RD.     

Protein adducts of iso[4]levuglandin E2, a product of the isoprostane pathway, in oxidized low density lipoprotein.

Levuglandin (LG) E2, a cytotoxic seco prostanoic acid co-generated with prostaglandins by nonenzymatic rearrangements of the cyclooxygenase-derived endoperoxide, prostaglandin H2, avidly binds to proteins. That LGE2-protein adducts can also be generated nonenzymatically is demonstrated by their production during free radical-induced oxidation of low density lipoprotein (LDL). Like oxidized LDL, LGE2-LDL, but not native LDL, undergoes receptor-mediated uptake and impaired processing by macrophage cells. Since radical-induced lipid oxidation produces isomers of prostaglandins, isoprostanes (isoPs), via endoperoxide intermediates, we postulated previously that a similar family of LG isomers, isoLGs, is cogenerated with isoPs. Now iso[4]LGE2-protein epitopes produced by radical-induced oxidation of arachidonic acid in the presence of protein were detected with an enzyme-linked immunosorbent assay. Iso[4]LGE2-protein epitopes are also generated during free radical-induced oxidation of LDL. All of the LGE2 isomers generated upon oxidation of LDL are efficiently sequestered by covalent adduction with LDL-based amino groups. The potent electrophilic reactivity of iso-LGs can be anticipated to have biological consequences beyond their obvious potential as markers for specific arachidonate-derived protein modifications that may be of value for the quantitative assessment of oxidative injury.     

Distinguishing levuglandins produced through the cyclooxygenase and isoprostane pathways

The cyclooxygenase (COX) pathway generates enantiomerically pure levuglandin (LG) E(2) by a rearrangement of the prostaglandin (PG) endoperoxide PGH(2). The isoprostane pathway generates racemic LGE(2) together with stereoisomers, designated collectively as isoLGE(2), through free radical-induced lipid oxidation. Within seconds, both LGs and isoLGs are rapidly sequestered by protein adduction. In theory, the diastereomeric purity of LGE(2)-protein adduct-derived lysyl lactams can reveal the relative contributions of the COX and isoprostane pathways to LGE(2) stereoisomer production in vivo. Notably, however, the detection of LGE(2)-protein adducts does not provide a basis for inferring their formation through the isoprostane pathway in vivo unless the COX pathway can be rigorously excluded. In contrast, LGE(2)structural isomers, designated collectively as iso[n]LGE(2)s, are produced exclusively through the isoprostane pathway. Immunoassays that selectively recognize iso[n]LGE(2)-protein adducts are the only tools available to unambiguously detect and quantify the production of isolevuglandins in vivo through free radical-induced oxidation of arachidonates.     

Isolevuglandins and mitochondrial enzymes in the retina: mass spectrometry detection of post-translational modification of sterol-metabolizing CYP27A1

We report the first peptide mapping and sequencing of an in vivo isolevuglandin-modified protein. Mitochondrial cytochrome P450 27A1 (CYP27A1) is a ubiquitous multifunctional sterol C27-hydroxylase that eliminates cholesterol and likely 7-ketocholesterol from the retina and many other tissues. We investigated the post-translational modification of this protein with isolevuglandins, arachidonate oxidation products. Treatment of purified recombinant CYP27A1 with authentic iso[4]levuglandin E(2) (iso[4]LGE(2)) in vitro diminished enzyme activity in a time- and phospholipid-dependent manner. A multiple reaction monitoring protocol was then developed to identify the sites and extent of iso[4]LGE(2) adduction. CYP27A1 exhibited only three Lys residues, Lys(134), Lys(358), and Lys(476), that readily interact with iso[4]LGE(2) in vitro. Such selective modification enabled the generation of an internal standard, (15)N-labeled CYP27A1 modified with iso[4]LGE(2), for the subsequent analysis of a human retinal sample. Two multiple reaction monitoring transitions arising from the peptide AVLK(358)(-C(20)H(26)O(3))ETLR in the retinal sample were observed that co-eluted with the corresponding two (15)N transitions from the supplemented standard. These data demonstrate that modified CYP27A1 is present in the retina. We suggest that such protein modification impairs sterol elimination and likely has other pathological sequelae. We also propose that the post-translational modifications identified in CYP27A1 exemplify a general mechanism whereby oxidative stress and inflammation deleteriously affect protein function, contributing, for example, to cholesterol-rich lesions associated with age-related macular degeneration and cardiovascular disease. The proteomic protocols developed in this study are generally applicable to characterization of lipid-derived oxidative protein modifications occurring in vivo, including proteins bound to membranes.     

Proteomics reveal Cochlin deposits associated with glaucomatous trabecular meshwork

The etiology of primary open angle glaucoma, a leading cause of age-related blindness, remains poorly defined, although elevated intraocular pressure (IOP) contributes to the disease progression. To better understand the mechanisms causing elevated IOP from aqueous humor circulation, we pursued proteomic analyses of trabecular meshwork (TM) from glaucoma and age-matched control donors. These analyses demonstrated that Cochlin, a protein associated with deafness disorder DFNA9, is present in glaucomatous but absent in normal TM. Cochlin was also detected in TM from the glaucomatous DBA/2J mouse preceding elevated IOP but found to be absent in three other mouse lines that do not develop elevated IOP. Histochemical analyses revealed co-deposits of Cochlin and mucopolysaccharide in human TM around Schlemm's canal, similar to that observed in the cochlea in DFNA9 deafness. Purified Cochlin was found to aggregate after sheer stress and to induce the aggregation of TM cells in vitro. Age-dependent in vivo increases in Cochlin were observed in glaucomatous TM, concomitant with a decrease in type II collagen, suggesting that Cochlin may disrupt the TM architecture and render components like collagen more susceptible to degradation and collapse. Overall, these observations suggest that Cochlin contributes to elevated IOP in primary open angle glaucoma through altered interactions within the TM extracellular matrix, resulting in cell aggregation, mucopolysaccharide deposition, and significant obstruction of the aqueous humor circulation.     

PRDX6 attenuates oxidative stress- and TGFβ-induced abnormalities of human trabecular meshwork cells

Oxidative stress and TGFβ-induced disturbance of cells and tissues are implicated in initiation and progression of pathophysiology of cells/tissues. Using primary human Trabecular Meshwork (TM) cells from normal and glaucomatous subjects, this study demonstrated that peroxiredoxin (PRDX) 6, an antioxidant, offsets the deleterious effects of oxidative stress on TM cells by optimizing ROS and TGFβ levels. An analysis of glaucomatous TM cells revealed a reduced expression of PRDX6 mRNA and protein. Biochemical assays disclosed enhanced levels of ROS, as well as high levels of TGFβs and these cells expressed elevated extracellular matrix (ECM) and Tsp1 proteins with reduced MMP2; conditions implicated in the pathophysiology of glaucoma. Non-glaucomatous TM cells exposed to TGFβs/ROS showed similar features as in glaucomatous cells. The abnormalities induced were reversed by delivery of PRDX6. The data provide evidence that oxidative stress-induced abnormality in TM may be related to reduced PRDX6 expression and provide a foundation for antioxidant-based therapeutics for treating glaucoma.     

Intracellular Cl regulates Na-K-Cl cotransport activity in human trabecular meshwork cells

The trabecular meshwork (TM) of the eye plays a central role inmodulating intraocular pressure by regulating aqueous humor outflow,although the mechanisms are largely unknown. We and others have shownpreviously that aqueous humor outflow facility is modulated byconditions that alter TM cell volume. We have also shown that theNa-K-Cl cotransport system is a primary regulator of TM cell volume andthat its activity appears to be coordinated with net efflux pathways tomaintain steady-state volume. However, the cellular mechanisms thatregulate cotransport activity and cell volume in TM cells have yet tobe elucidated. The present study was conducted to investigate thehypothesis that intracellular Cl concentration([Cl]_i) acts toregulate TM cell Na-K-Cl cotransport activity, as has been shownpreviously for some other cell types. We demonstrate here that thehuman TM cell Na-K-Cl cotransporter is highly sensitive to changes in[Cl]_i. Our findingsreveal a marked stimulation of Na-K-Cl cotransport activity, assessedas ouabain-insensitive, bumetanide-sensitive K influx, in TM cells following preincubation of cells with Cl-free medium as a means ofreducing [Cl]_i. Incontrast, preincubation of cells with media containing elevated Kconcentrations as a means of increasing [Cl]_i results ininhibition of Na-K-Cl cotransport activity. The effects of reducing[Cl]_i, as well aselevating [Cl]_i, onNa-K-Cl cotransport activity are concentration dependent. Furthermore, the stimulatory effect of reduced[Cl]_i is additive withcell-shrinkage-induced stimulation of the cotransporter. Our studiesalso show that TM cell Na-K-Cl cotransport activity is altered by avariety of Cl channel modulators, presumably through changes in[Cl]_i. These findingssupport the hypothesis that regulation of Na-K-Cl cotransport activity,and thus cell volume, by[Cl]_i may participatein modulating outflow facility across the TM.

     

The role of oxidative stress in glaucoma

DNA damage is related to a variety of degenerative diseases such as cancer, atherosclerosis and neurodegenerative diseases, depending on the tissue affected. Increasing evidence indicates that reactive oxygen species (ROS) play a key role in the pathogenesis of primary open angle glaucoma (POAG), the main cause of irreversible blindness worldwide. Oxidative DNA damage is significantly increased in the ocular epithelium regulating aqueous humor outflow, i.e., the trabecular meshwork (TM), of glaucomatous patients compared to controls. The pathogenic role of ROS in glaucoma is supported by various experimental findings, including (a) resistance to aqueous humor outflow is increased by hydrogen peroxide by inducing TM degeneration; (b) TM possesses remarkable antioxidant activities, mainly related to superoxide dismutase-catalase and glutathione pathways that are altered in glaucoma patients; and (c) intraocular-pressure increase and severity of visual-field defects in glaucoma patients parallel the amount of oxidative DNA damage affecting TM. Vascular alterations, which are often associated with glaucoma, could contribute to the generation of oxidative damage. Oxidative stress, occurring not only in TM but also in retinal cells, appears to be involved in the neuronal cell death affecting the optic nerve in POAG. The highlighting of the pathogenic role of ROS in POAG has implications for the prevention of this disease as indicated by the growing number of studies using genetic analyses to identify susceptible individuals and of clinical trials testing the efficacy of antioxidant drugs for POAG management.     

Mechanisms of ATP release, the enabling step in purinergic dynamics

The only effective intervention to slow onset and progression of glaucomatous blindness is to lower intraocular pressure (IOP). Among other modulators, adenosine receptors (ARs) exert complex regulation of IOP. Agonists of A(3)ARs in the ciliary epithelium activate Cl(-) channels, favoring increased formation of aqueous humor and elevated IOP. In contrast, stimulating A(1)ARs in the trabecular outflow pathway enhances release of matrix metalloproteinases (MMPs) from trabecular meshwork (TM) cells, reducing resistance to outflow of aqueous humor to lower IOP. These opposing actions are thought to be initiated by cellular release of ATP and its ectoenzymatic conversion to adenosine. This view is now supported by our identification of six ectoATPases in trabecular meshwork (TM) cells and by our observation that external ATP enhances TM-cell secretion of MMPs through ectoenzymatic formation of adenosine. ATP release is enhanced by cell swelling and stretch. Also, enhanced ATP release and downstream MMP secretion is one mediator of the action of actin depolymerization to reduce outflow resistance. Inflow and outflow cells share pannexin-1 and connexin hemichannel pathways for ATP release. However, vesicular release and P2X(7) release pathways were functionally limited to inflow and outflow cells, respectively, suggesting that blocking exocytosis might selectively inhibit inflow, lowering IOP.     

Mapping Molecular Differences and Extracellular Matrix Gene Expression in Segmental Outflow Pathways of the Human Ocular Trabecular Meshwork

Elevated intraocular pressure (IOP) is the primary risk factor for glaucoma, and lowering IOP remains the only effective treatment for glaucoma. The trabecular meshwork (TM) in the anterior chamber of the eye regulates IOP by generating resistance to aqueous humor outflow. Aqueous humor outflow is segmental, but molecular differences between high and low outflow regions of the TM are poorly understood. In this study, flow regions of the TM were characterized using fluorescent tracers and PCR arrays. Anterior segments from human donor eyes were perfused at physiological pressure in an ex vivo organ culture system. Fluorescently-labeled microspheres of various sizes were perfused into anterior segments to label flow regions. Actively perfused microspheres were segmentally distributed, whereas microspheres soaked passively into anterior segments uniformly labeled the TM and surrounding tissues with no apparent segmentation. Cell-tracker quantum dots (20 nm) were localized to the outer uveal and corneoscleral TM, whereas larger, modified microspheres (200 nm) localized throughout the TM layers and Schlemm’s canal. Distribution of fluorescent tracers demonstrated a variable labeling pattern on both a macro- and micro-scale. Quantitative PCR arrays allowed identification of a variety of extracellular matrix genes differentially expressed in high and low flow regions of the TM. Several collagen genes (COL16A1, COL4A2, COL6A1 and 2) and MMPs (1, 2, 3) were enriched in high, whereas COL15A1, and MMP16 were enriched in low flow regions. Matrix metalloproteinase activity was similar in high and low regions using a quantitative FRET peptide assay, whereas protein levels in tissues showed modest regional differences. These gene and protein differences across regions of the TM provide further evidence for a molecular basis of segmental flow routes within the aqueous outflow pathway. New insight into the molecular mechanisms of segmental aqueous outflow may aid in the design and delivery of improved treatments for glaucoma patients.     

Oxidative stress and potential applications of free radical scavengers in glaucoma

Abstract

Glaucoma is the leading cause of irreversible blindness in industrialized countries and comprises a group of diseases characterized by progressive optic nerve degeneration. Glaucoma is commonly associated with elevated intraocular pressure due to impaired outflow of aqueous humor resulting from abnormalities within the drainage system of the anterior chamber angle (open-angle glaucoma) or impaired access of aqueous humor to the drainage system (angle-closure glaucoma). Oxidative injury and altered antioxidant defense mechanisms in glaucoma appear to play a role in the pathophysiology of glaucomatous neurodegeneration that is characterized by death of retinal ganglion cells. Oxidative protein modifications occurring in glaucoma serve as immunostimulatory signals and alter neurosupportive and immunoregulatory functions of glial cells. Initiation of the apoptotic cascade observed in glaucomatous retinopathy can involve oxidant mechanisms and different agents have been shown to be neuroprotective. This review focuses on the molecular mechanisms of oxidant injury and summarizes studies that have investigated novel free radical scavengers in the treatment of glaucomatous neurodegeneration.     

Senescent phenotype of trabecular meshwork cells displays biomarkers in primary open-angle glaucoma

Glaucoma is a major cause of irreversible blindness, affecting more than 70 million individuals worldwide. Elevated intraocular pressure (IOP) is a major risk factor in the development of glaucoma and in the progression of glaucomatous damage. High IOP usually occurs as a result of an increase in aqueous humor outflow resistance in trabecular meshwork (TM). Primary open angle glaucoma (POAG) is characterized by quantifiable parameters including the IOP, the aqueous outflow facility, and geometric measurements of the optic disc and visual defects. Morphological and biochemical analyses of the TM of POAG patients revealed loss of cells, increased accumulation of extracellular matrix (ECM), changes in the cytoskeleton, cellular senescence and the process of subclinical inflammation. Various biochemical and molecular biology biomarkers of TM cells senescence are considered in the article. Oxidative stress is becoming an important factor more likely to be involved in the pathogenesis of POAG. Treatment of TM cells with oxidative stress induced POAG-typical changes like ECM accumulation, cell death, disarrangement of the cytoskeleton, advanced senescence and the release of inflammatory markers. Oxidative stress is able to induce characteristic glaucomatous TM changes and these oxidative stress-induced TM changes can be minimized by the use of antioxidants, such as carnosine-related analogues and IOP-lowering substances. There is evidence demonstrating that carnosine related analogues may have antioxidative capacities, can prevent cellular senescence and the attrition of telomeres during the action of oxidative stress. Prevention of oxidative stress exposure to the TM with N-acetylcarnosine ophthalmic prodrug of carnosine and oral formulation of non-hydrolized carnosine may help to reduce the progression of POAG. The previous work has demonstrated that carnosine is able to reach the TM directly via the transcorneal and systemic pathways of administration with N-acetylcarnosine ophthalmic prodrug and oral formulation of non-hydrolized carnosine. We suggest in this article that dual therapy with N-acetylcarnosine lubricant eye drops, oral formulation of non-hydrolized carnosine combined with anti-glaucoma adrenergic drug may become the first-line therapy in glaucoma due to their efficiency in reducing IOP, prevention and reversal of oxidative stress-induced damages in TM and the low rate of severe side effects during combined treatment.     

Role of the autotaxin-lysophosphatidic acid axis in glaucoma,aqueous humor drainage and fibrogenic activity

Ocular hypertension due to impaired aqueous humor (AH) drainage through the trabecular meshwork (TM) is a major risk factor for glaucoma, a leading cause of irreversible blindness. However, the etiology of ocular hypertension remains unclear. Although autotaxin, a secreted lysophospholipase D and its catalytic product lysophosphatidic acid (LPA) have been shown to modulate AH drainage through TM, we do not have a complete understanding of their role and regulation in glaucoma patients, TM and AH outflow. This study reports a significant increase in the levels of autotaxin, lysophosphatidylcholine (LPC), LPA and connective tissue growth factor (CTGF) in the AH of Caucasian and African American open angle glaucoma patients relative to age-matched non-glaucoma patients. Treatment of human TM cells with dexamethasone, tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) increased the levels of autotaxin protein, a response that was mitigated by inhibitors of glucocorticoid receptor, NF-kB and SMAD3. Dexamethasone, TNF-α, IL-1β and LPC treatment of TM cells also led to an increase in the levels of CTGF, fibronectin and collagen type 1 in an autotaxin dependent manner. Additionally, in perfused enucleated mouse eyes, autotaxin and LPC were noted to decrease, while inhibition of autotaxin was increased aqueous outflow through the TM. Taken together, these results provide additional evidence for dysregulation of the autotaxin-LPA axis in the AH of glaucoma patients, reveal molecular insights into the regulation of autotaxin expression in TM cells and the consequences of autotaxin inhibitors in suppressing the fibrogenic response and resistance to AH outflow through the TM.     

Proteasome inhibition by chronic oxidative stress in human trabecular meshwork cells

The pathophysiologic mechanisms leading to the malfunction of the trabecular meshwork (TM)-Schlemm's canal (SC) outflow pathway in glaucoma are still unclear. We hypothesize that chronic oxidative stress may contribute to the malfunction of the outflow pathway by impairing the intracellular proteasome system of the cells, decreasing the ability of the tissue to modulate outflow resistance. To study the effects of chronic oxidative stress on proteasome function, primary cultures of human TM cells were incubated under 40% oxygen and proteasome activity was analyzed by measuring the accumulation of enhanced green fluorescent protein fused to a PEST motif. Changes in proteasome content, cellular senescence, and cell viability were also monitored. After 10 days of exposure to chronic oxidative stress, TM cells showed a marked decline in proteasome activity that was associated with premature senescence and decreased cell viability. These results suggest that proteasome failure may be involved in glaucoma pathophysiology.     

Potential role of lysosomal dysfunction in the pathogenesis of primary open angle glaucoma

Primary open angle glaucoma (POAG) is a late onset disease usually accompanied by elevated intraocular pressure (IOP) that results from the failure of the trabecular meshwork (TM) to maintain normal levels of aqueous humor outflow resistance. Cells in the TM are subjected to chronic oxidative stress through reactive oxygen species (ROS) present in the aqueous humor (AH) and generated by normal metabolism. Exposure to ROS is thought to contribute to the morphological and physiological alterations of the outflow pathway in aging and POAG. Our results indicate that chronic exposure of TM cells to oxidative stress causes the accumulation of nondegradable material within the lysosomal compartment leading to diminished lysosomal activity and increased SA-β-Gal expression. Because the lysosomal compartment is responsible for maintaining general cellular turnover, such impaired activity may lead to a progressive cellular decline in the TM cell function and thus contribute to the progression of POAG.     

A promising drug candidate for the treatment of glaucoma based on a P2Y6-receptor agonist

Extracellular nucleotides can regulate the production/drainage of the aqueous humor via activation of P2 receptors, thus affecting the intraocular pressure (IOP). We evaluated 5-OMe-UDP(α-B), 1A, a potent P2Y6-receptor agonist, for reducing IOP and treating glaucoma. Cell viability in the presence of 1A was measured using [3-(4, 5-dimethyl-thiazol-2-yl) 2, 5-diphenyl-tetrazolium bromide] (MTT) assay in rabbit NPE ciliary non-pigmented and corneal epithelial cells, human retinoblastoma, and liver Huh7 cells. The effect of 1A on IOP was determined in acute glaucomatous rabbit hyaluronate model and phenol-induced chronic glaucomatous rabbit model. The origin of activity of 1A was investigated by generation of a homology model of hP2Y6-R and docking studies. 1A did not exert cytotoxic effects up to 100 mM vs. trusopt and timolol in MTT assay in ocular and liver cells. In normotensive rabbits, 100 μM 1A vs. xalatan, trusopt, and pilocarpine reduced IOP by 45 vs. 20–30%, respectively. In the phenol animal model, 1A (100 μM) showed reduction of IOP by 40 and 20%, following early and late administration, respectively. Docking results suggest that the high activity and selectivity of 1A is due to intramolecular interaction between Pα-BH³ and C5-OMe which positions 1A in a most favorable site inside the receptor. P2Y6-receptor agonist 1A effectively and safely reduces IOP in normotense, acute, and chronic glaucomatous rabbits, and hence may be suggested as a novel approach for the treatment of glaucoma.     

In Hypertrophic Cardiomyopathy Reduction of Relative Resting Myocardial Blood Flow Is Related to Late Enhancement, T2-Signal and LV Wall Thickness

Objectives

To quantify resting myocardial blood flow (MBF) in the left ventricular (LV) wall of HCM patients and to determine the relationship to important parameters of disease: LV wall thickness, late gadolinium enhancement (LGE), T2-signal abnormalities (dark and bright signal), LV outflow tract obstruction and age.

Materials and Methods

Seventy patients with proven HCM underwent cardiac MRI. Absolute and relative resting MBF were calculated from cardiac perfusion MRI by using the Fermi function model. The relationship between relative MBF and LV wall thickness, T2-signal abnormalities (T2 dark and T2 bright signal), LGE, age and LV outflow gradient as determined by echocardiography was determined using simple and multiple linear regression analysis. Categories of reduced and elevated perfusion in relation to non- or mildly affected reference segments were defined, and T2-signal characteristics and extent as well as pattern of LGE were examined. Statistical testing included linear and logistic regression analysis, unpaired t-test, odds ratios, and Fisher’s exact test.

Results

804 segments in 70 patients were included in the analysis. In a simple linear regression model LV wall thickness (p<0.001), extent of LGE (p<0.001), presence of edema, defined as focal T2 bright signal (p<0.001), T2 dark signal (p<0.001) and age (p = 0.032) correlated inversely with relative resting MBF. The LV outflow gradient did not show any effect on resting perfusion (p = 0.901). Multiple linear regression analysis revealed that LGE (p<0.001), edema (p = 0.026) and T2 dark signal (p = 0.019) were independent predictors of relative resting MBF. Segments with reduced resting perfusion demonstrated different LGE patterns compared to segments with elevated resting perfusion.

Conclusion

In HCM resting MBF is significantly reduced depending on LV wall thickness, extent of LGE, focal T2 signal abnormalities and age. Furthermore, different patterns of perfusion in HCM patients have been defined, which may represent different stages of disease.