Immunolocalization of collagen types I, III and IV, elastin and fibronectin within the heart of normal and copper-deficient rats

Mesh-like vascular changes in copper deficiency-induced rat cardiomyopathy

The pathological effects of copper deficiency (COD) are well known. However, the pathogenesis of cardiomyopathy resulting from COD remains unclear. In this study, aimed to elucidate the pathogenesis of COD-induced cardiomyopathy by examining the morphology of the cardiovascular system in copper-deficient rats using histopathology, immunohistochemistry, and scanning and transmission electron microscopy. Changes detected in the myocardium and interstitium were consistent with those reported for COD. Morphological changes included mesh-like changes in the capillary endothelial cells that appear to be a novel finding in COD-induced cardiomyopathy. These changes are hypothesized to result from abnormal vascular remodeling following damage to the basement membrane and due to the mechanical effects of myocardial contractions. Although cardiomyopathy may be associated with microcirculatory disorders arising from these lesions, further investigations are necessary to demonstrate a causal relationship between the pathogenesis of cardiomyopathy and the contribution of these lesions to disease progression.

Biochemical and Morphological Alterations in Hearts of Copper-Deficient Bovines

Copper deficiency is an important disease of cattle that produces several clinical signs and lesions, due to alterations in copper-dependent enzymes. One of the organs affected by this deficiency is the heart (falling disease), but nevertheless, these cardiac lesions have not been extensively studied in bovines. The aim of this work was to propose a possible pathogenic mechanism for cardiac lesions in cattle affected by copper deficiency. Because of the possible existence of oxidative distress caused by low levels of copper-zinc-superoxide dismutase and cytochrome oxidase, ultrastructural and histological lesions have been evaluated in the heart of bovines in which a Cu deficiency had been induced using high molybdenum and sulfur levels in the diet. Our results indicated that copper deficiency produces significant damage in myocardium with high levels of lipid oxidation and a significant reduction in copper-zinc-superoxide dismutase activity leading to an oxidative distress situation. However, cytochrome oxidase activity was not significantly reduced. Histological observation revealed a significant increase in the amount of connective tissue, enlarged basement membranes of myocytes, and numerous Anichkov cells, in the hearts of deficient animals. Ultrastructural observation showed a significant enhancement in the mitochondrial volume density, with presence of lesions such as swelling and cristae disruption. We conclude that copper deficiency in bovines causes morphological lesions in the heart due to an oxidative damage produced by copper-dependent enzyme alterations.

Copper-induced reduction in myocardial fibrosis is associated with increased matrix metalloproteins in a rat model of cardiac hypertrophy

AAC induces Cu loss from the heart and depressed MMP-2 in combination with increased TIMPs, leading to increased collagen deposition. TETA replenishes Cu in the heart, increases MMP-2, and decreases TIMP-1 and -2, collectively resulting in reduction in cardiac fibrosis.

Dietary Copper Restriction-Induced Changes in Myocardial Gene Expression and the Effect of Copper Repletion

Dietary copper (Cu) restriction leads to cardiac hypertrophy and failure in mice, and Cu repletion (CuR) reverses the hypertrophy and prevents the transition to heart failure. The present study was undertaken to determine changes in myocardial gene expression involved in Cu deficient (CuD) cardiomyopathy and its reversal by CuR. Analysis was performed on three groups of mice: 4-week-old CuD mice that exhibited signs of cardiac failure, their age-matched copper-adequate (CuA) controls, and the CuD mice that were re-fed adequate Cu for 2 weeks. Total RNA was isolated from hearts and subjected to cDNA microarray and real-time reverse transcription-polymerase chain reaction analysis. Dietary CuD caused a decrease in cardiac mRNA of β-MHC, L-type Ca2+ channel, K-dependent NCX, MMP-2, -8, and -13, NF-κB, and VEGF. The mRNA levels of ET-1, TGF-β, TNF-α, and procollagen-l-α1 and III-α1 were increased in the CuD cardiac tissue. Copper repletion resulted in cardiac mRNA levels of most of the genes examined returning to control levels, although the K-dependent NCX and MMP-2 values did not reach those of the CuA control. In addition, CuR caused an increase in β-MHC, L-type Ca2+channel, MMP-13 to levels surpassing those of CuA control, and a decrease in ET-1, and TNF-at mRNA levels. In summary, changes in gene expression of elements involved in contractility, Ca2+ cycling, and inflammation and fibrosis may account for the altered cardiac function found in CuD mice. The return to normal cardiac function by CuR may be a result of the favorable regression in gene expression of these critical components in myocardial tissue.

Two-photon microscopy of deep intravital tissues and its merits in clinical research

Multiphoton excitation laser scanning microscopy, relying on the simultaneous absorption of two or more photons by a molecule, is one of the most exciting recent developments in biomedical imaging. Thanks to its superior imaging capability of deeper tissue penetration and efficient light detection, this system becomes more and more an inspiring tool for intravital bulk tissue imaging. Two-photon excitation microscopy including 2-photon fluorescence and second harmonic generated signal microscopy is the most common multiphoton microscopic application. In the present review we take diverse ocular tissues as intravital samples to demonstrate the advantages of this approach. Experiments with registration of intracellular 2-photon fluorescence and extracellular collagen second harmonic generated signal microscopy in native ocular tissues are focused. Data show that the in-tandem combination of 2-photon fluorescence and second harmonic generated signal microscopy as two-modality microscopy allows for in situ co-localization imaging of various microstructural components in the whole-mount deep intravital tissues. New applications and recent developments of this high technology in clinical studies such as 2-photon-controlled drug release, in vivo drug screening and administration in skin and kidney, as well as its uses in tumourous tissues such as melanoma and glioma, in diseased lung, brain and heart are additionally reviewed. Intrinsic emission two-modal 2-photon microscopy/tomography, acting as an efficient and sensitive non-injurious imaging approach featured by high contrast and subcellular spatial resolution, has been proved to be a promising tool for intravital deep tissue imaging and clinical studies. Given the level of its performance, we believe that the non-linear optical imaging technique has tremendous potentials to find more applications in biomedical fundamental and clinical research in the near future.

Influence of copper on early development: prenatal and postnatal considerations

Copper (Cu) is an essential nutrient whose requirement is increased during pregnancy and lactation. These represent times of critical growth and development, and the fetus and neonate are particularly vulnerable to deficiencies of this nutrient. Genetic mutations that predispose the offspring to inadequate stores of Cu can be life threatening as is observed in children with Menkes disease. During the last decade, severe Cu deficiency, once thought to be a rare condition, has been reported in the literature at an increasing frequency. Secondary Cu deficiencies can be induced by a variety of ways such as excessive zinc or iron intake, certain drugs, and bariatric surgery. Premature and low birth weight infants can be born with low Cu stores. A number of mechanisms can contribute to the teratogenicity of Cu including decreased activity of select cuproenzymes, increased oxidative stress, decreased nitric oxide availability, altered iron metabolism, abnormal extracellular matrix protein crosslinking, decreased angiogenesis and altered cell signaling among others. The brain, heart, and vessels as well as tissues such as lung, skin and hair, and systems including the skeletal, immune, and blood systems, are negatively affected by suboptimal Cu during development. Additionally, persistent structural, biochemical, and functional adverse effects in the offspring are noted even when Cu supplementation is initiated after birth, supporting the concept that adequate Cu nutriture during pregnancy and lactation is critical for normal development. Although Cu-containing IUDs are an effective method for increasing intrauterine Cu concentrations and for reducing the risk of pregnancy, high amounts of dietary Cu are not thought to represent a direct developmental risk.

Immunohistochemical characterization of the extracellular matrix in normal mitral valves and in chronic valve disease (endocardiosis) in dogs

This study aimed to characterize the composition and distribution of the extracellular matrix (ECM) components in normal canine mitral valves (MV) and in chronic heart valve disease (CVD). MV of 50 dogs (normal (n=9), mild (n=13), moderate (n=17), severe (n=11) CVD) were investigated macroscopically, histologically (H.-E., picrosirius red) and immunohistochemically (collagen I, III, IV, V, VI, elastin, laminin, fibronectin, heparan sulphate). In normal MV, ECM components were expressed in a typical layered pattern. In mild CVD, basement membrane components (laminin, collagen IV, fibronectin) were increased. Advanced CVD was characterized by myxomatous nodular lesions displaying a marginal and a central region comprised mainly of collagen I, VI and fibronectin in the former and collagen I and III in the latter. Collagen IV and laminin appeared multifocally in marked CVD. In conclusion, not only an accumulation of proteoglycans, but also a distinctly altered expression of basement membrane components, and collagens characterizes CVD.

Iron, copper and fetal development

Pregnancy is a period of rapid growth and cell differentiation for both the mother and fetus. Consequently, it is a period when both are vulnerable to changes in dietary supply, especially of those nutrients that are marginal under normal circumstances. In developed countries this vulnerability applies mainly to micronutrients. Even now, Fe deficiency is a common disorder, especially in pregnancy. Similarly, Cu intake in the UK population is rarely above adequate levels, which is a matter of some concern, both in terms of public health and possible clinical consequences. In early studies it was shown that lambs born to mothers on Cu-deficient pastures develop ‘swayback,’ with neurological and muscular symptoms that cannot be reversed by postnatal supplementation. More recently, rat studies have shown that responses such as the ‘startle’ response are lost in offspring of Cu-deficient mothers. Data have shown that prenatal Fe deficiency results in increased postnatal blood pressure, even though the offspring have normal dietary Fe levels from birth. These observations emphasise the importance of Fe and Cu in growth and development. In the present review the importance of these metals and the consequences, both short term and long term, of deficiency will be discussed and some possible mechanisms whereby these effects may be generated will be considered.

Isolated ventricular myocytes from copper-deficient rat hearts exhibit enhanced contractile function

Dietary copper deficiency leads to cardiac hypertrophy, cardiac fibrosis, derangement of myofibrils, and impaired cardiac contractile and electrophysiological function. The purpose of this study was to determine whether impaired cardiac function from copper deficiency is due to depressed contractile function at the single myocyte level. Male Sprague-Dawley rats were fed diets that were either copper adequate (5.59-6.05 microg copper/g body wt; n = 11) or copper deficient (0.29-0.34 microg copper/g body wt; n = 11) for 5 wk. Ventricular myocytes were dispersed and mechanical properties were evaluated using the SoftEdge video-based edge-detection system. Intracellular Ca2+ transients were examined using fura 2-acetoxymethyl ester. Myocytes were electrically stimulated to contract at 0.5 Hz. Properties evaluated included peak shortening (PS), time to peak shortening (TPS), time to 90% relengthening (TR90), and maximal velocities of shortening and relengthening (+/-dL/dt). Myocytes from the copper-deficient rat hearts exhibited significantly enhanced PS values associated with shortened TR90 measurements compared with those from copper-adequate rat hearts. The +/-dL/dt values were enhanced and the intracellular Ca2+ transient decay rate was depressed in myocytes from copper-deficient rats. These data indicate that impaired cardiac contractile function that is seen in copper-deficient whole hearts might not be due to depressed cardiac contractile function at the single cell level but rather to other mechanisms such as cardiac fibrosis.

Immunolocalization of elastin, collagen type I and type III, fibronectin, and vitronectin in extracellular matrix components of normal and myxomatous mitral heart valve chordae tendineae

The identification, distribution, and localization of matrix proteins and the proteins associated with normal and degenerated elastic fibers and collagen fibrils of myxomatous chordae tendineae were studied with immunoelectron microscopy. Ultrathin sections of L R White-embedded tissue were processed by indirect immunogold cytochemistry using primary antibodies against human alpha elastin, collagen types I and III, fibronectin, and vitronectin. In normal chordae tendineae, alpha elastin antibody heavily labeled the elastic fibers in spongiosa and fibrosa, but microfibrils around them were not labeled. Antibodies to collagen type I, collagen type III, and fibronectin all labeled the collagen fibers and microfibrils in the spongiosa. Fibronectin antibody labeling was higher than collagen type III, whereas labeling by anticollagen type I was lower. Intense labeling by vitronectin was observed on the microfibrils in the spongiosa and on electron-dense material around elastic fibers in the spongiosa and fibrosa. In myxomatous chordae tendineae, alpha elastin antibody heavily labeled degenerated elastic fibers, previously unidentified reticulated structures, and other moderately electron-dense material, both in the spongiosa and in the fibrosa, but not the electron-dense fibrous material around them. Antibodies to collagen types I, III, and fibronectin heavy labeled electron-dense aggregates of fibrous material. Vitronectin labeling was observed on electron-dense longitudinally running microfibrils and on the electron-dense microfibrils around degenerated elastic fibers.

Cardiovascular effects of dietary copper deficiency

Dietary copper deficiency may impair cardiovascular health by contributing to high blood pressure, enhancement of inflammation, anemia, reduced blood clotting and arteriosclerosis. The purpose of this review is to compile information on the numerous changes of the heart, blood and blood vessels that may contribute to these cardiovascular defects. These alterations include weakened structural integrity of the heart and blood vessels, impairment of the use of energy by the heart, reduced ability of the heart to contract, altered ability of blood vessels to control their diameter and to grow, and altered structure and function of circulating blood cells. The fundamental causes of these changes rest largely on reduced effectiveness of enzymes that depend on copper for their activity.

Submaximal, aerobic exercise training exacerbates the cardiomyopathy of postweanling Cu-depleted rats

To determine the dual effect of exercise training and copper depletion on myocardial function and ultrastructure, postweanling rats were either trained or sedentary while fed copper-adequate or copper-deficient diets for 8 wk. Rats developed characteristic myocardial subcellular degeneration and increased cardiac mitochondrial volume density when copper depleted, despite lack of overt cardiac hypertrophy, hypertension, or anemia. Training combined with copper depletion induced mild left ventricular hypertrophy. Basal laminae appeared fractionated in areas at capillary-myocyte interface, with focal pericapillary and interstitial collagen accumulation, whereas overt fibrosis was absent or minimal. Electrocardiograms revealed increased QRS wave and QT duration and notching of QRS complex with copper depletion, consistent with intraventricular conductance disturbances. The oxidative capacity of soleus muscle increased with training in copper-adequate rats, but was reduced with progressive copper depletion. These data suggest that copper depletion and training are synergistic in effecting focal accumulation of collagen, with deleterious effect on exercise capacity.

Hyperbaric hyperoxia exaggerates respiratory membrane defects in the copper-deficient rat lung

Scanning (SEM) and transmission electron microscopy (TEM) were used to examine the effect of dietary copper deficiency and hyperbaric hyperoxia, alone and in combination, on lung structure. Male, weanling Sprague-Dawley rats were fed a copper-deficient (CuD, 0.2 microgram/g) or copper-adequate diet (CuA, 5.1 micrograms/g). After 35-41 d on their respective diets, rats from each group were placed inside a pressure vessel kept at 27 degrees C under one of two pressure protocols. Air controls were maintained at 1 atm for 75 min. Rats exposed to oxygen were maintained at 1 atm of air plus 3 atm of oxygen for 1 h and then decompressed for 15 min. Under SEM, none of the treated lungs (CuD, CuA-O2 exposed, or CuD-O2 exposed) showed abnormal lung morphology from the conducting bronchioles down to the alveoli. Copper-deficient red blood cells were abnormally shaped. Under TEM, CuA-O2-exposed lungs showed thicker respiratory membranes, especially basement membranes and endothelial cells, and alveolar Type II cells having more than the usual number of surfactant vacuoles. CuD lungs also showed thicker endothelial and basement membrane components of the respiratory membrane, but normal looking Type II cells. CuD-O2-exposed lungs showed greatly thickened respiratory membranes and severe disruption of both endothelium and basement membrane and, judging by the increased number of nuclei per field, an increase in the number of both Type I and Type II cells. We conclude that copper deficiency enhances the damage caused by O2 toxicity, an effect that may be caused by reduced antioxidant status.