Gene and cell therapy for heart disease

Heart disease is the most common cause of morbidity and mortality in Western society and the incidence is projected to increase significantly over the next few decades as our population ages. Heart failure occurs when the heart is unable to pump blood at a rate to commensurate with tissue metabolic requirements and represents the end stage of a variety of pathological conditions. Causes of heart failure include ischemia, hypertension, coronary artery disease, and idiopathic dilated cardiomyopathy. Hypertension and ischemia both cause infarction with loss of function and a consequent contractile deficit that promotes ventricular remodeling. Remodeling results in dramatic alterations in the size, shape, and composition of the walls and chambers of the heart and can have both positive and negative effects on function. In 30-40% of patients with heart failure, left ventricular systolic function is relatively unaffected while diastolic dysfunction predominates. Recent progress in our understanding of the molecular and cellular bases of heart disease has provided new therapeutic targets and led to novel approaches including the delivery of proteins, genes, and cells to replace defective or deficient components and restore function to the diseased heart. This review focuses on three such strategies that are currently under development: (a) gene transfer to modulate contractility, (b) therapeutic angiogenesis for the treatment of ischemia, and (c) embryonic and adult stem cell transfer to replace damaged myocardium.     

Left and right contributions to the<Emphasis Type="Italic"> Xenopus</Emphasis> heart: implications for asymmetric morphogenesis

The left-right asymmetry of the vertebrate heart is evident in the topology of the heart loop, and in the dissimilar morphology of the left and right chambers. How left-right asymmetric gene expression patterns influence the development of these features is not understood, since the individual roles of the left and right sides of the embryo in heart looping or chamber morphogenesis have not been specifically defined. To this end, we have constructed a bilateral heart-specific fate map of the left and right contributions to the developing heart in the Xenopus embryo. Both the left and right sides contribute to the conoventricular segment of the heart loop; however, the left side contributes to the inner curvature and ventral face of the loop while the right side contributes to the outer curvature and dorsal aspect. In contrast, the left atrium is derived mainly from the original left side of the embryo, while the right atrium is derived primarily from the right side. A comparison of our fate map with the domain of expression of the left-right gene, Pitx2, in the left lateral plate mesoderm, reveals that this Pitx2-expressing region is fated to form the inner curvature of the heart loop, the left atrioventricular canal, and the dorsal aspect of the left atrium. We discuss the implications of these results for the role of left-right asymmetric gene expression in heart looping and chamber morphogenesis.     

Relationship between blood pressure,sleep K-complexes,and muscle sympathetic nerve activity in humans

Stage 2 sleep is characterized by the EEG appearance of "K-complexes" and blood pressure oscillations. K-complexes may be directly related to blood pressure changes or they may reflect central sympathetic activation. We analyzed the temporal relationship among K-complexes, heart rate (HR), blood pressure (BP), and muscle sympathetic nerve activity (MSNA) during sleep in eight healthy volunteers (3 men and 5 women, age 22-41 yr). Most K-complexes presented as single large complexes (56 +/- 20%), followed by single small complexes (15 +/- 14%) and as couplets or triplets (13 +/- 6%). Single large K-complexes were preceded by a baroreflex-mediated increase of MSNA in approximately one-half (55%) of the cases. Detailed analysis of HR, BP, and MSNA was possible in 63 (45%) large single K-complexes not disturbed by preceding baroreflex-related changes. Systolic and diastolic BP and MSNA increased significantly after single events (22.5 +/- 13, 5.2 +/- 2.1, and 6.5 +/- 3.0%). Mean sympathetic baroreflex latency was similar after the single large K-complexes compared with the mean value during stage 2 sleep (1,290 +/- 126 vs. 1,279 +/- 61 ms). The area under the burst was significantly increased after single large K-complexes (median 3.9 vs. 9.0 arbitrary units, P < 0.03). The results support the hypothesis that K-complexes express cortical activation leading to temporary facilitation of sympathetic outflow in a graded fashion. Their functional effects appear to be independent of baroreflex modulation of MSNA in approximately 50% of the cases.     

The residue mass of L-pyrrolysine in three distinct methylamine methyltransferases

Single in-frame amber (UAG) codons are found in the genes encoding MtmB, MtbB, or MttB, the methyltransferases initiating methane formation from monomethylamine, dimethylamine, or trimethylamine, respectively, in certain Archaea. The crystal structure of MtmB demonstrated that the amber codon codes for pyrrolysine, the 22nd genetically encoded amino acid found in nature. Previous attempts to visualize the amber-encoded residue by mass spectrometry identified only lysine, leaving information on the existence and structure of pyrrolysine resting entirely on crystallography of a single protein. Here we report successful mass spectral characterization of naturally occurring pyrrolysine and the first demonstration of the amber-encoded residue in proteins other than MtmB. The sequencing of chymotryptic fragments from acetonitrile-denatured proteins by tandem mass spectrometry revealed the mass of the amber-encoded residue in MtmB, MtbB, and MttB as 237.2 +/- 0.2 Da. Fourier transform ion cyclotron resonance mass spectrometry produced an accurate measurement for the pyrrolysyl-residue as 237.1456 Da, within error limits of the predicted mass based on the empirical formula C(12)H(19)N(3)O(2). These measurements support the structure of pyrrolysine in MtmB as 4-methylpyrroline-5-carboxylate in amide linkage with the (epsilon)N of lysine but not the alternative structure in which the 4-substituent of the pyrroline ring is an amine group. The presence of pyrrolysine with statistically identical mass in all three methyltransferases is in keeping with the proposed direct incorporation of pyrrolysine into protein during translation of the UAG codon and suggests that MtbB and MttB may exploit the unusual electrophilicity of pyrrolysine during catalysis.     

Nitric oxide and promotion of cardiac myocyte apoptosis

The removal of damaged, superfluous or energy-starved cells is essential for biological homeostasis, and occurs in every tissue type. Programmed cell death occurs through several closely regulated signal pathways, including apoptosis, in which cell components are broken down and packaged into small membrane-bound fragments that are then removed by neighbouring cells or phagocytes. This process is activated in the cardiac myocyte in response to a variety of stresses, including oxidative and nitrosative stress, and involves mitochondria-derived signals. Loss of cardiac myocytes through apoptosis has been shown to induce cardiomyopathy in a variety of gene-targeted animal models. Because cardiac myocytes have strictly limited ability to regenerate, sustained programmed cell death is likely to contribute to the development and progression of heart failure in a variety of myocardial diseases. At the same time, the cardiac myocyte possesses a number of mechanisms for defence against short-term haemodynamic and oxidative stresses. Our laboratory has recently examined the role of nitric oxide (NO) as a regulator of the programmed death of cardiac myocytes, and the potential contribution of NO and NO-dependent signalling to the loss of myocytes in heart failure. We will review the role of c-Jun N-terminal kinase in response to oxidative and nitrosative stress, and summarise evidence for its role as a cytoprotective mechanism. We will also review evidence implicating NO in the pathophysiology of heart failure, in the context of the extensive and sometimes contradictory body of research on NO and cell survival.     

Differential effects of inhaled nitric oxide and hyperoxia on pulmonary dysfunction in newborn guinea pigs

This study tested the hypothesis that inhaled nitric oxide (NO) and combined NO and hyperoxia will result in less pulmonary dysfunction and delay onset of respiratory signs compared with hyperoxia-exposed newborn guinea pigs (GPs). GPs were exposed to room air (n = 14), 95% O(2) (n = 36), 20 parts per million (ppm) NO (n = 14), or combined 20 ppm NO and 95% O(2) (NO/O(2), n = 13) for up to 5 days. Data evaluated included latency interval for onset of respiratory distress, pressure volume curves, lung histology, and bronchoalveolar lavage (BAL) polymorphonuclear cells (PMNs), proteolytic activity, and total protein. NO-exposed GPs did not develop respiratory distress and had no evidence of pulmonary dysfunction. O(2)-exposed GPs developed respiratory distress after 1-5 days (median 4.0) vs. 3-5 days (median 5.0) for NO/O(2) exposure (P < 0.05). BAL from O(2)-exposed GPs showed increased PMNs compared with NO/O(2)-exposed GPs. O(2)- and NO/O(2)-exposed GPs had comparable reduced lung volumes, lung histology, and increased BAL proteinase activity and total protein. In summary 1) O(2) exposure resulted in multiple measures of pulmonary dysfunction in newborn GPs, 2) 5-day exposure to NO produced no noticeable respiratory effects and pulmonary dysfunction, and 3) short-term exposure (相似文献   

Post-cardiac injury syndrome in acute myocardial infarction patients undergoing PCI: a case report and literature review

Background

In the era of primary percutaneous coronary intervention (PPCI), the incidence of post-cardiac injury syndrome (PCIS) in patients with acute myocardial infarction (AMI) following PPCI has become less common. However, the intrinsic pathogenesis of this medical condition remains largely uncertain. Unlike the prior reports, the present paper provides new mechanistic clues concerning the pathogenesis of PCI-related PCIS.

Case presentation

A 45-year-old male with AMI had developed an early onset of PCIS at 3?h after PPCI. A significantly slower TIMI flow (grade ≤?2) for the culprit arteries was observed through follow-up coronary angiography (CAG); no stent thrombosis or any significant evidence of iatrogenic trauma due the intervention procedures was found. Nevertheless, the the serum level of HsCRP showed similar variation trend as the neutrophil count and troponin T in continuous blood monitoring, which suggested a potential association between PPCI-related coronary microvascular dysfunction (CMD) and pathogenesis of PCIS.

Conclusions

The reported case had excessive inflammatory reaction and CMD resulting from cardiac ischemia-reperfusion injury in an AMI patient with risk factors of endothelial dysfunction. There exists a potential reciprocal causation between PCIS and performance of PPCI in the AMI patient who was susceptible to endothelial damage.

     

Behavioural responses of diverse insect groups to electric stimuli

Anecdotal evidence suggests that cockroaches respond to electrical appliances or outlets. Our objectives were to determine the effect of field‐inducing sources and field attributes on attraction of German cockroaches, Blattella germanica (L.) (Blattodea: Blattellidae), and to test those parameters found effective for attraction of B. germanica for attraction of other groups of insects. In two‐choice, large‐arena experiments, significantly more female, but not nymphal, B. germanica settled in or near electrified coils with static or fluctuating electromagnetic fields produced by low‐level direct current (DC) or alternating current (AC) sources than in control coils without current. Electromagnetic fields with the magnetic, but not the electric, component of the field nulled still attracted B. germanica, suggesting that the electric component of the field may contribute to the attraction or arrestment response of B. germanica. DC‐powered coils with static electromagnetic fields also attracted/arrested brown‐banded cockroaches, Supella longipalpa (Fabricius) (Blattodea: Blattellidae), common silverfish, Lepisma saccharina (L.), firebrats, Thermobia domestica (Packard) (both Thysanura: Lepismatidae), and European earwigs, Forficula auricularia (L.) (Dermaptera: Forficulidae), but they repelled American cockroaches, Periplaneta americana (L.) (Blattodea: Blattidae). If proven in field experiments, electrified coils as trap baits may offer non‐toxic alternatives to pesticides for selective insect control in urban environments.     

Collagen abundance in mechanically stimulated osteoblast cultures using near infrared microscopy

Collagen abundance in osteoblast cell cultures was determined using near infrared microscopy with chemical imaging (NIR-CI) with and without mechanical stimulation of the the cells. MC3T3-E1 mouse osteoblast cells seeded on a polycarbonate substrate were mechanically stimulated using static loads of 13.5 N, 27 N and 40 N applied to the substrates during 2, 4, 6 and 8 days of incubation. Results show that the cells increased their collagen production with 13.5 N and 27 N loads when compared to the control sample with a 27 N load resulting in a noteworthy increase (109%) in collagen production. The 40 N load on the other hand, resulted in an initial decrease in the collagen expression in the extracellular matrix, possibly as a result of cell death or inhibition of the protein secretion process followed by an increase in collagen after cell recovery and proliferation. Qualitative confirmation of these results was performed using confocal microscopy.     

Virus dynamics in a large epishelf lake (Beaver Lake,Antarctica)

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