Hemodynamic and ventilatory responses to fentanyl, fentanyl-droperidol, and nitrous oxide in patients with acquired valvular heart disease.
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Fentanyl (10 mug/kh) or fentanyl (10 mug/kg) plus droperidol (100 mug/kg) administered intravenously during 20 minutes to adult patients with acquired valvular heart disease produced minimal circulatory changes. The trend during drug infusion was for mean arterial pressure and systemic vascular resistance to decrease, and for cardiac index and stroke volume index to increase without change in heart rate. Central venous pressure increased during drug infusion (P less than 0.05) but decreased to awake levels following controlled ventilation and skeletal-muscle paralysis, probably reflecting thoracoabdominal-muscle rigidity rather than a circulatory response. Hypoventilation during drug infusion necessitated assisted or controlled ventilation, with or without skeletal muscle paralysis, in 14 of 16 patients. Addition of 60 per cent nitrous oxide following fentanyl or fentanyl-droperidol infusion significantly decreased mean arterial pressure, heart rate, and cardiac index. All circulatory changes were similar in direction and extent to those previously found during morphine-nitrous oxide anesthesia. (Key words: Anesthetics, intravenous, fentanyl; Anesthetics, gases, nitrous oxide; Heart, effect of fentanyl, dorperidol, and nitrous oxide.). (+info)
Tissue engineering in the twenty-first century.
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In the 20th century, free tissue transfers have been successfully introduced using microvascular anastomosis techniques. Transplants not only include whole organs such as the kidney, liver and lung, but also bone, muscle and skin. However, there are a limited number of organs available for transplantation. This leads to the patient not only suffering from the malfunctioning tissue or organ, but also from the psychological trauma of an indefinite waiting period. The rapidly evolving field of tissue engineering is beginning to have an impact on free tissue transfers including organ. Small biopsy specimens can be grown into a large number of cells. These cultured cells can then be seeded onto biodegradable polymers, which serve several purposes. Firstly, the polymers function as a cell delivery system that enables the transplantation of a large numbers of cells into an organism. Secondly, they create a three-dimensional space for cell growth and serve as a template, thereby providing a structure for the extracellular matrix. These approaches have been demonstrated as practical strategies for the reconstruction of many tissues such as the liver, intestines, heart valve leaflets, bone and cartilage. (+info)
Sulbactam efficacy in experimental models caused by susceptible and intermediate Acinetobacter baumannii strains.
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Sulbactam and imipenem were compared in an experimental pneumonia model in immunocompetent mice, using a susceptible strain of Acinetobacter baumannii, and in an experimental endocarditis model in rabbits, using an intermediately susceptible strain. In the former, sulbactam was as efficacious as imipenem in terms of survival, sterility of lungs and in the bacterial clearance from lungs and blood, provided that the t > MIC for sulbactam (1.84 h) was similar to that for imipenem (2.01 h). In the endocarditis model, imipenem (t > MIC, 2.12 h) was more efficacious than sulbactam (t > MIC, 1.17 h) in bacterial clearance from vegetations. These results show the efficacy of sulbactam in infections caused by susceptible strains of A. baumannii, with an MIC up to 4 mg/L, provided that doses reach a t > MIC similar to that of imipenem. The activity of sulbactam was time dependent. (+info)
A novel role for VEGF in endocardial cushion formation and its potential contribution to congenital heart defects.
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Normal cardiovascular development is exquisitely dependent on the correct dosage of the angiogenic growth factor and vascular morphogen vascular endothelial growth factor (VEGF). However, cardiac expression of VEGF is also robustly augmented during hypoxic insults, potentially mediating the well-established teratogenic effects of hypoxia on heart development. We report that during normal heart morphogenesis VEGF is specifically upregulated in the atrioventricular (AV) field of the heart tube soon after the onset of endocardial cushion formation (i.e. the endocardium-derived structures that build the heart septa and valves). To model hypoxia-dependent induction of VEGF in vivo, we conditionally induced VEGF expression in the myocardium using a tetracycline-regulated transgenic system. Premature induction of myocardial VEGF in E9.5 embryos to levels comparable with those induced by hypoxia prevented formation of endocardial cushions. When added to explanted embryonic AV tissue, VEGF fully inhibited endocardial-to-mesenchymal transformation. Transformation was also abrogated in AV explants subjected to experimental hypoxia but fully restored in the presence of an inhibitory soluble VEGF receptor 1 chimeric protein. Together, these results suggest a novel developmental role for VEGF as a negative regulator of endocardial-to-mesenchymal transformation that underlies the formation of endocardial cushions. Moreover, ischemia-induced VEGF may be the molecular link between hypoxia and congenital defects in heart septation. (+info)
Sequestration of aggregated LDL by macrophages studied with freeze-etch electron microscopy.
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The detailed morphology of macrophages involved in the uptake and intracellular processing of low density lipoprotein (LDL) and, ultimately, formation of macrophage-derived foam cells of atherosclerotic lesions has long fascinated investigators. This study examined localization of LDL in subcellular compartments of macrophage-derived intimal foam cells in cardiac valves isolated from rabbits by diet-induced hypercholesterolemia and, as an in vitro model of formation of foam cells, in cultured human monocyte-macrophages incubated for 2;-120 h with aggregated LDL produced by vortexing or phospholipase C lipolysis. The quasi-three-dimensional morphology of macrophages involved in endocytosis was preserved by ultrarapid freezing and freeze-etch microscopy in conjunction with thin-section electron microscopy. This approach produced unique images of subcellular compartments in human monocyte-macrophages involved in the uptake and processing of aggregated LDL with a clarity not previously reported. Three-dimensional ultrastructural analyses revealed a complex network of coated and uncoated vesicles, surface-connected saclike compartments, and endosomal/lysosomal compartments including the labyrinth of vesicular/tubular lysosomes all enmeshed in the microtubular, microfilament cytoskeletal network. These dynamic views of subcellular structures at the high resolution of the electron microscope provide an additional framework to better understand how lipoprotein particles are transported into, and processed within, macrophages during foam cell formation in atherogenesis. (+info)
In situ morphometric analysis of left and right ventricles in fetal rats: changes in ventricular volume, mass, wall thickness, and valvular size.
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We studied morphological changes in the left and right ventricles of fetal rats in late-gestation using rapid whole-body freezing technique. Pregnant Wistar rats (term, 21.5 day) were immediately frozen in liquid nitrogen on 17-, 18-, 19-, 20-, and 21-day of gestation. The frozen fetal hearts were serially sectioned with a sliding microtome and photographed. The ventricular volume, mass, wall thickness, and area of valvular orifice were measured on the photographs. During the study period, the left and right ventricular volumes increased very rapidly (9.9-fold and 7.6-fold, respectively) compared with the increase in the body weight (4.0-fold); the volumes divided by body weight increased linearly. Left and right ventricular masses also rapidly increased (5.9-fold and 5.0-fold, respectively). Mass/volume ratios for the two ventricles rapidly decreased. The wall thicknesses divided by body weights rapidly decreased with the progression of the gestational age. The left and right ventricles at 17 day of gestation have relative hypertrophy and relatively large valvular orifices as compared with those in terminal gestation. The improvement of the relative hypertrophy of the ventricles may indicate the morphological and functional maturation of the fetal heart. (+info)
The pitfalls of transthoracic echocardiography. A case of eustachian valve endocarditis.
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A case of infective endocarditis involving the vestigial eustachian valve is presented and the available English medical literature is reviewed. Only 5 prior cases have been reported: 4 of those required transesophageal echocardiography for diagnosis, and the other was found at autopsy. This clinical entity is routinely missed on transthoracic echocardiography. Injection drug use is a common predisposing factor, and Staphylococcus aureus is the most commonly identified organism. This report broadens the differential diagnosis of endovascular infections in injection drug users and highlights the importance of transesophageal echocardiography for diagnosis in selected patients. (+info)
Periostin (an osteoblast-specific factor) is expressed within the embryonic mouse heart during valve formation.
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Periostin was originally isolated as a osteoblast-specific factor that functions as a cell adhesion molecule for preosteoblasts and is thought to be involved in osteoblast recruitment, attachment and spreading. Additionally, periostin expression has previously been shown to be significantly increased by both transforming growth factor beta-1(TGFbeta1) and bone morphogenetic protein (BMP)-2. Likewise the endocardial cushions that form within embryonic heart tube (embryonic day (E)10-13) are formed by the recruitment, attachment and spreading of endocardial cells into the overlying extracellular matrix, in response to secreted growth factors of the TGFbeta and BMP families. In order to determine whether periostin is similarly involved in heart morphogenesis, in situ hybridization and reverse transcription-polymerase chain reaction were used to detect periostin mRNA expression in the developing mouse heart. We show for the first time that periostin mRNA is expressed in the developing mouse embryonic and fetal heart, and that it is localized to the endocardial cushions that ultimately divide the primitive heart tube into a four-chambered heart. (+info)