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Query: UMLS:C0032285 (pneumonia)
 54,520 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An investigation into the pathogenesis of acute pneumonia in 37 young men made it possible to ascertain the role of arachidonic acid metabolites and hormonal regulation in the pathogenesis of the inflammatory reaction in acute bacterial pneumonia. At the initial stage of inflammation, invasion of the infectious agent leads to phagocytosis activation, stimulates the output of immunoglobulins belonging to different classes, which, binding antigens, form immune complexes influencing the output of biologically active substances. This is accompanied by the destruction of pulmonary tissue, release of lipid peroxidation radicals and proteinases, by the enhancement of arachidonic acid degradation under the destructive action on the membranes of phospholipase A2 cells to form prostaglandins participating in the changes in the tone of bronchi, pulmonary vessels and affecting blood coagulation. Activation of the hypophyseo-adrenal system leads to the attenuation of the effects produced by biologically active substances and exerts varying actions in the acute and convalescence periods. The data obtained stress an important role played by metabolic functions of the lungs in the integrative connections of all the systems of the body maintaining homeostasis in pneumonia and the main function of the lungs, namely ventilation.
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PMID:[The metabolism of eicosanoids, glucocorticoids and cyclic nucleotides in young people with acute pneumonia]. 144 Feb 68

The effect of Pneumocystis carinii pneumonia on surfactant phospholipids and lavage phospholipase A2 was investigated. Pneumocystis carinii infection was induced in adult rats by immunosuppression with dexamethasone administered in the drinking water (2 mg/L) for 6 to 8 wk. Surfactant phospholipids were isolated from lung lavage and lung tissue. Dexamethasone administration significantly increased total lung and lavage phospholipids in corticosteroid-treated animals receiving prophylaxis against P. carinii with trimethoprim-sulfamethoxazole (TMP-SMZ) when compared with no treatment control animals. Lavage surfactant phospholipids from P. carinii-infected rats were 25% that of no treatment control rats and less than 10% that of corticosteroid control animals receiving TMP-SMZ. Phospholipid composition of lavage phospholipids was also altered in P. carinii pneumonia, with slight increase in the percentage of sphingomyelin and reduced percentage of total phosphatidylcholine. Postlavage tissue phospholipids of P. carinii-infected rats were 4 times that of no treatment control animals, although only about 50% that of corticosteroid control animals. There was no significant difference in lavage phospholipase A2 activity for the P. carinii-infected and corticosteroid control groups, although the enzyme activity was at least 4 times that of the no treatment control group. The surfactant changes were associated with abnormal excised lung pressure-volume curves and decreased deflation stability in the animals with P. carinii. These results indicate that the corticosteroids used in this model induce an increase in both lung surfactant phospholipids and phospholipase A2. Despite this increase in lavage phospholipids, P. carinii pneumonia in this model causes an alveolar surfactant phospholipid deficiency without significant increase in phospholipase A2 activity.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Surfactant phospholipids and lavage phospholipase A2 in experimental Pneumocystis carinii pneumonia. 348 25

Black-pigmented Gram-negative anaerobic rods are found on mucosal surfaces as indigenous flora. With mucosal damage due to disease, trauma or surgery, these organisms may invade tissues and set up infection. Other important factors determining whether or not infection results include 'inoculum' size, synergy with other organisms and production of virulence factors that include capsules, lipopolysaccharide, attachment factors, proteases, collagenase, neuraminidase, and phospholipase A; also, they may have fibrinolytic and anti-phagocytic activity and may degrade complement and IgG and IgM. Pigmented anaerobes are found in all types of infections including such serious infections as bacteraemia, endocarditis, intracranial abscess, necrotizing pneumonia and necrotizing fasciitis, generally as part of a mixed infecting flora, and they play a key role in experimental mixed infections. They dominate or are prominent in infections involving organisms originating in the oropharynx, such as central nervous system, head and neck, dental and pleuropulmonary infections. Therapy of infections involving pigmented anaerobes includes surgery plus antimicrobial agents; a significant percentage of strains produce beta-lactamase. Much remains to be done to determine the relative importance of the various taxa of black-pigmented Gram-negative anaerobes and of the different virulence factors produced by them.
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PMID:The importance of black-pigmented gram-negative anaerobes in human infections. 851 64

Acute chest syndrome (ACS) is associated with significant morbidity and is the leading cause of death in patients with sickle cell disease (SCD). Recent reports suggest that bone marrow fat embolism can be detected in many cases of severe ACS. Secretory phospholipase A2 (sPLA2) is an important inflammatory mediator and liberates free fatty acids, which are felt to be responsible for the acute lung injury of the fat embolism syndrome. We measured SPLA2 levels in 35 SCD patients during 20 admissions for ACS, 10 admissions for vaso-occlusive crisis, and during 12 clinic visits when patients were at the steady state. Eleven non-SCD patients with pneumonia were also evaluated. To determine if there was a relationship between sPLA2 and the severity of ACS we correlated SPLA2 levels with the clinical course of the patient. In comparison with normal controls (mean = 3.1 +/- 1.1 ng/mL), the non-SCD patients with pneumonia (mean = 68.6 +/- 82.9 ng/mL) and all three SCD patient groups had an elevation of SPLA2 (steady state mean = 10.0 +/- 8.4 ng/mL; vaso-occlusive crisis mean = 23.7 +/- 40.5 ng/mL; ACS mean = 336 +/- 209 ng/mL). In patients with ACS sPLA2 levels were 100-fold greater than normal control values, 35 times greater than values in SCD patients at baseline, and five times greater than non-SCD patients with pneumonia. The degree of SPLA2 elevation in ACS correlated with three different measures of clinical severity and, in patients followed sequentially, the rise in SPLA2 coincided with the onset of ACS. The dramatic elevation of SPLA2 in patients with ACS but not in patients with vaso-occlusive crisis or non-SCD patients with pneumonia and the correlation between levels of SPLA2 and clinical severity suggest a role for SPLA2 in the diagnosis and, perhaps, in the pathophysiology of patients with ACS.
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PMID:Phospholipase A2 levels in acute chest syndrome of sickle cell disease. 863 Apr 25

The purpose of this study was to gather additional evidence in irradiated rat lung on the relationship between annexin I and prostaglandin synthesis. The right hemithorax of the animal was exposed to a single dose of 0 or 30 Gy of X-rays, and the animals were killed 3 months postirradiation. Levels of annexin I and synthesis of prostacyclin (PGI2) were determined in lungs, in cell-free bronchoalveolar lavage (BAL) fluid, and in macrophages lavaged from those lungs. In addition, protein concentration, lactate dehydrogenase (LDH) activity and macrophage count in BAL fluid obtained from irradiated lung were compared with that from sham-irradiated (0 Gy) lung. Levels of annexin I, the putative inhibitor of phospholipase A2, in lung and cell-free BAL fluid were decreased in samples from irradiated animals. By contrast, the level of annexin I in macrophages lavaged from irradiated lung was higher than that in macrophages from sham-irradiated lung. The irradiated lung produced nearly 3.5 times more prostacyclin than did the control lung. However, prostacyclin synthesis by macrophages lavaged from irradiated lung was no different than that of macrophages from sham-irradiated lung. Protein, LDH and macrophage number in BAL fluid from irradiated lungs were significantly higher than in corresponding specimens from sham-irradiated lungs. These data demonstrate that reduced levels of annexin I, as well as increased protein concentration, LDH activity and macrophage numbers in irradiated rat lung are reflected in BAL fluid. Therefore, information obtained from BAL fluid, but not from BAL macrophages, reflects lung status, and may serve as a minimally invasive index of radiation pneumonitis in this model. In irradiated lung, increased PGI2 synthesis coupled with a decreased annexin I level are consistent with the hypothesis of an inhibitory role of annexin I in prostaglandin metabolism. However, this hypothesis is not supported by findings in BAL macrophages, where increased annexin I concentration is not accompanied by a decrease in PGI2 production. In view of the latter findings, and a previous study from our laboratory demonstrating that phospholipase activity in irradiated rat lung is in fact decreased, despite the reduction in annexin I concentration and the hyperproduction of prostanoids, it would seem unlikely that annexin I negatively modulates prostaglandin synthesis via inhibition of phospholipase in this model.
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PMID:Annexin I concentration and prostacyclin production in rat lung and alveolar macrophages following irradiation. 905 17

The inflammation, so conspicuous in cases of respiratory distress, pneumonia, and asthma, is associated with an airway invasion of plasma proteins and a release into the airway lumen of phospholipase A2 (PLA2). This enzyme catalyzes hydrolysis of surfactant phospholipids, the most abundant and important of which is dipalmitoylphosphatidylcholine (DPPC). Its hydrolysis yields equimolar proportions of lysophosphatidylcholine and palmitic acid (LPC/PA). Exact quantification of DPPC hydrolysis is complicated. Consequently, it was decided to simulate hydrolysis whereby DPPC (3 mg/ml) was gradually replaced with LPC/PA (3 mg/ml), yielding seven different grades of simulated hydrolysis: 0, 17, 33, 50, 67, 83, and 100%. Surface properties of the seven mixtures were examined with various concentrations of albumin added. The Bubble Surfactometer was used to study the surfactant film that is given time to develop at a spherical air-liquid interface. A Capillary Surfactometer was used to evaluate surface properties required for airway patency. It was found, using both of these instruments that the surface activity improved as the simulated hydrolysis of DPPC to LPC/PA increased toward 100%, where the activity was maximal. With the Bubble Surfactometer, surface activity of LPC/PA, 3 mg/ml, improved as albumin concentration increased, and when it reached 15 mg/ml, surface tension became 0 mN/m after only 2 min. With the Capillary Surfactometer, requiring a much faster film adsorption, albumin had an opposite effect. LPC/PA alone maintained patency 100% of the time studied, while even a minimal addition of albumin inhibited surfactant function.
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PMID:Surface properties after a simulated PLA2 hydrolysis of pulmonary surfactant's main component, DPPC. 908 5

Aspiration of meconium produces an inflammatory reaction resulting in necrotic changes in lung tissue. To further investigate the mechanisms of the meconium-induced early pulmonary injury, twenty 10-12-d-old piglets were studied for lung tissue ultrastructural and apoptotic changes and phospholipase A2 activity. Twelve piglets received an intratracheal bolus (3 mL/kg) of a 20-mg/mL (thin, n = 6) or 65-mg/mL (thick, n = 6) mixture of human meconium, and control piglets (n = 5) received the same amount of intratracheal saline. Three ventilated piglets with no aspiration were also studied. Pulmonary hemodynamics and systemic oxygenation were followed for 6 h after meconium or saline insufflation. In the control groups, the pulmonary tissue showed open alveolar spaces and intact vascular walls, whereas meconium administration resulted in severe pneumonitis, with alveolar spaces filled with inflammatory exudate. Meconium instillation additionally resulted in edematous changes in the vascular walls and alveolar epithelium, whereas type II pneumocytes were intact. The amount of apoptotic cells was increased, especially in the respiratory epithelium, and the catalytic activity of phospholipase A2 in lung tissue samples was significantly elevated after thick meconium instillation. This activity rise proved to be mainly because of human group I phospholipase A2, introduced by meconium. Our data thus show that aspiration of meconium leads to severe lung tissue inflammation with early ultrastructural changes in the pulmonary alveolar walls and is associated with apoptotic cell death in the epithelium, already during the first hours after the insult. These results further suggest that high phospholipase A2 activity, mainly introduced into the lungs within the meconium, may have an important role in the initiation of these alterations in neonatal lungs.
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PMID:Human meconium has high phospholipase A2 activity and induces cellular injury and apoptosis in piglet lungs. 1054 29

Acute lung injury in Pseudomonas aeruginosa pneumonia depends primarily on ExoU that is delivered directly into the eukaryotic cell via the type III secretion system. Recent studies demonstrated that ExoU has lipase activity, and that the cytotoxicity of ExoU is dependent on its patatin-like phospholipase domain. We investigated the phospholipase A (PLA) activity of ExoU. ExoU, but not non-catalytic ExoU-S142A, preincubated with the BEAS-2B cell lysate showed a weak increase of Ca(2+)-independent PLA(2) activity. When activated ExoU was mixed with secretory type PLA(2), more phospholipase activity was observed, suggesting that ExoU has lysophospholipase A (lysoPLA) activity. A significant increase in lysoPLA activity was also observed. Glycerol enhanced this activity and inhibitors of iPLA(2) suppressed ExoU's lysoPLA activity. Our results suggest that ExoU has a potent lysoPLA activity that requires the presence of the catalytically active site Ser(142) with an unknown eukaryotic cell factor(s) for its activation.
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PMID:Lysophospholipase A activity of Pseudomonas aeruginosa type III secretory toxin ExoU. 1502 Feb 21

We describe 3 cases of neonatal respiratory distress syndrome (RDS) in near-term infants, born from mothers with severe intrahepatic cholestasis of pregnancy. Common pictures of the cases were: good indices of lung maturity in the amniotic fluid; severe RDS requiring mechanical ventilation; high serum bile acid (BA) levels in the early days of life; no meconium aspiration; negative cultures; and absence of indirect laboratory signs of infection. After the first case, we hypothesized that abnormally high BA levels could have reversed the action of phospholipase A2 in the lungs, causing a degradation of phosphatidylcholines to lysophosphatidylcholines and the consequent lack of surfactant activity, leading to the severe respiratory distress. Consequently, in cases 2 and 3, we gave intratracheal surfactant to the infants, which, although administered around the first 24 hours of life, showed to be helpful. Our experience suggests that a high level of attention in the management of newborn infants (even near-term infants) born from women with intrahepatic cholestasis of pregnancy is necessary to detect as soon as possible signs and symptoms of this "unexpected" RDS, which can assume a very severe clinical picture. In such instances, we recommend that the diagnosis of BA pneumonia be kept in mind and that exogenous surfactant be given as soon as possible, even in the presence of indices of normal lung maturity in the amniotic fluid. Finding high levels of BA and lysophosphatidylcholines in the bronchoalveolar lavage of affected infants would aid in support of the diagnosis.
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PMID:Bile acid pneumonia: a "new" form of neonatal respiratory distress syndrome? 1523 44

Although a number of sPLA2 (secretory phospholipase A2) enzymes have been identified in mammals, the localization and functions of individual enzymes in human pathologic tissues still remain obscure. In the present study, we have examined the expression and function of sPLA2s in human lung-derived cells and in human lungs with pneumonia. Group IID, V and X sPLA2s were expressed in cultured human bronchial epithelial cells (BEAS-2B) and normal human pulmonary fibroblasts with distinct requirement for cytokines (interleukin-1b, tumour necrosis factor a and interferon-g). Lentivirus- or adenovirus-mediated transfection of various sPLA2s into BEAS-2B or normal human pulmonary fibroblast cells revealed that group V and X sPLA2s increased arachidonate release and prostaglandin production in both cell types, whereas group IIA and IID sPLA2s failed to do so. Immunohistochemistry of human lungs with pneumonia demonstrated that group V and X sPLA2s were widely expressed in the airway epithelium, interstitium and alveolar macrophages, in which group IID sPLA2 was also positive, whereas group IIA sPLA2 was restricted to the pulmonary arterial smooth muscle layers and bronchial chondrocytes, and group IIE and IIF sPLA2s were minimally detected. These results suggest that group V and X sPLA2s affect lung pathogenesis by facilitating arachidonate metabolism or possibly through other functions.
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PMID:Expression of secretory phospholipase A2 enzymes in lungs of humans with pneumonia and their potential prostaglandin-synthetic function in human lung-derived cells. 1550 93


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