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The effects of long-term preoperative administration of low-dose erythromycin (EM) were experimentally examined in relation to the treatment of reperfusion disorders following pulmonary thermal ischemia. EM was administered at a dose of 100 mg/day for 1 month to adult mongrel dogs with an average weight of about 12 kg (EM group). A control group that did not receive EM was also enrolled. Using a pulmonary autograft model, collapse-thermal ischemia of the lungs was performed on each animal for 60 minutes. In the early stage of reperfusion, the following measurements were assessed: gas-exchange potency in the left lung, hemodynamics, water content, adhesion of neutrophils to vascular endothelium, and concentration of blood eicosanoids. The results for the 2 groups were then compared. In the control group, the blood level of leukotriene B4 (LTB4) increased shortly after reperfusion, neutrophils migrated toward the vascular endothelium and adhered to it, and pulmonary edema developed after 1 hour. However in the EM group, the blood level of thromboxane B2 was significantly suppressed before and after hilar stripping, and the increase in the blood LTB4 level and the migration of neutrophils shortly after reperfusion in thermal ischemia were suppressed. Eventually alleviation of pulmonary edema was indicated and significantly improved gas exchange was maintained. In conclusion, pulmonary injury during detachment of the hilum of the lung, as well as warm ischemia-reperfusion pulmonary injury, may be alleviated by preoperative administration of low-dose EM on a long-term basis.
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PMID:[Effects of long-term preoperative administration of low-dose erythromycin on warm ischemia-reperfusion pulmonary injury]. 991 77

Reperfusion of ischemic myocardium is necessary to salvage tissue from eventual death. However, reperfusion after even brief periods of ischemia is associated with pathologic changes that represent either an acceleration of processes initiated during ischemia per se, or new pathophysiological changes that were initiated after reperfusion. This 'reperfusion injury' shares many characteristics with inflammatory responses in the myocardium. Neutrophils feature prominently in this inflammatory component of postischemic injury. Ischemia-reperfusion prompts a release of oxygen free radicals, cytokines and other proinflammatory mediators that activate both the neutrophils and the coronary vascular endothelium. Activation of these cell types promotes the expression of adhesion molecules on both the neutrophils and endothelium, which recruits neutrophils to the surface of the endothelium and initiate a specific cascade of cell-cell interactions, leading first to adherence of neutrophils to the vascular endothelium, followed later by transendothelial migration and direct interaction with myocytes. This specific series of events is a prerequisite to the phenotypic expression of reperfusion injury, including endothelial dysfunction, microvascular collapse and blood flow defects, myocardial infarction and apoptosis. Pharmacologic therapy can target the various components in this critical series of events. Effective targets for these pharmacologic agents include: (a) inhibiting the release or accumulation of proinflammatory mediators, (b) altering neutrophil or endothelial cell activation and (c) attenuating adhesion molecule expression on endothelium, neutrophils and myocytes. Monoclonal antibodies to adhesion molecules (P-selectin, L-selectin, CD11, CD18), complement fragments and receptors attenuate neutrophil-mediated injury (vascular injury, infarction), but clinical application may encounter limitations due to antigen-antibody reactions with the peptides. Humanized antibodies and non-peptide agents, such as oligosaccharide analogs to sialyl Lewis, may prove effective in this regard. Both nitric oxide and adenosine exhibit broad spectrum effects against neutrophil-mediated events and, therefore, can intervene at several critical points in the ischemic-reperfusion response, and may offer greater benefit than agents that interdict at a single point in the cascade. The understanding of the molecular processes regulating actions of neutrophils in ischemic-reperfusion injury may be applicable to other clinical situations, such as trauma, shock and organ or tissue (i.e. vascular conduits) transplantation.
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PMID:The role of neutrophils in myocardial ischemia-reperfusion injury. 1061 13

Numerous biologic and synthetic materials have been used with limited success as an interposed graft to repair segmental common bile duct (CBD) defects. The authors report here that an autologous vein graft can be successfully used to correct a CBD deficit contingent on accurate microsurgical technique immediate stenting and rapid graft vascularization. Thirty Sprague-Dawley rats underwent laparotomy and the experimental group (n=25) had a 3-mm segment of the CBD excised. The CBD defect was repaired using an interposed femoral vein graft aided by a plastic stent. The control group (n=5) had the CBD cut and repaired by means of primary anastomosis. The experimental group was subdivided into three sub-groups each examined at three different postoperative intervals: 1, 4 and 12 weeks. The results showed that inflammation was apparent in the venous wall following the first postoperative week. A progressive loss of the vascular endothelium and replacement with the columnar epithelium typical of the CBD was seen in the vein graft. Nineteen of the 25 experimental rats (76 percent) of the animals survived without complication from the surgery and there were no abnormalities in the liver biochemical tests of these animals. Any biliary tract obstruction that developed was attributed to dislocation of the stent leading to collapse of the vein graft (experimental group), or constriction of the anastomosis (control group). This study demonstrates that biliary tract reconstruction using an autologous vein graft can be successfully performed in a rat model of CBD repair. The application of this method to the clinical setting is also discussed.
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PMID:Biliary tract reconstruction using an autologous vein graft in rats. 1066 54

Heme oxygenase (HO) catalyzes degradation of heme to biliverdin, iron, and carbon monoxide. It consists of three isoforms: an inducible form (HO-1), a constitutive form (HO-2), and the third isoform (HO-3), with properties similar to HO-2. There is limited evidence to suggest that the induction of HO-1 may have anti-inflammatory effects in an in vivo model of oxidative stress-mediated renal injury. We experienced the first human case of HO-1 deficiency. The patient had persistent proteinuria and hematuria, with biochemical evidence of renal tubular injury. We obtained three consecutive renal specimens: two from renal biopsies at 2 and 5 years of age and the third from autopsy at 6 years of age. The patient had systemic vascular endothelial-cell injury with massive intravascular hemolysis. The serum was loaded with heme and a large amount of heme-conjugated haptoglobin. A high concentration of haptoglobin was also detectable in urine. Mesangial proliferation or change in glomerular capillary-wall thickness was relatively mild to moderate in all specimens. Electron microscopic examination showed widespread endothelial detachment and subendothelial deposits of an unidentifiable material. It was striking that tubulointerstitial injury, with tubular dilatation and/or atrophy, interstitial fibrosis, and inflammatory cell infiltration, advanced progressively. Tubular epithelial cells were injured, and massive deposition of iron and haptoglobin was detectable. Bowman's capsules were dilated significantly, probably secondary to the collapse of atrophic tubuli. This is the first report to show that HO-1 has critical roles in vivo in protecting renal tubuli, in addition to vascular endothelium, from oxidative injury.
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PMID:Tubular injury as a cardinal pathologic feature in human heme oxygenase-1 deficiency. 1079 20

Cellular adherens junctions are formed by cadherins linked to proteins of the catenin family. In endothelial cells, not only vascular endothelial cadherin but also platelet endothelial cell adhesion molecule-1 localizes into junctions and associates with beta-catenin. To explore a putative cooperation of platelet endothelial cell adhesion molecule-1 and vascular endothelial cadherin, we analyzed transfectants expressing either platelet endothelial cell adhesion (CD31 cells) or vascular endothelial cadherin (CD144 cells) or both molecules (CD31/CD144 cells), and, for comparison, human umbilical vein endothelial cells. Basic fibroblast growth factor completely dissociated vascular endothelial cadherin/beta-catenin complexes and robustly moved beta-catenin into the nucleus in CD144 cells, whereas in CD31/CD144 cells as well as in human umbilical vein endothelial cells, fibroblast growth factor only partially dissociated the junctional complex followed by a significantly reduced nuclear translocation of beta-catenin. In contrast, in CD31 cells, the subcellular distribution of beta-catenin remained unaffected by fibroblast growth factor. As a functional consequence, fibroblast growth factor induced a complete collapse of the F-actin network in CD144 cells, a limited rearrangement of F-actin fibers in CD31/CD144 cells and no F-actin rearrangement in CD31 cells. We also analyzed the effect of fibroblast growth factor-induced rearrangement of junctions on junction permeability for leukocytes: in line with our observation that vascular endothelial cadherin was required for cells to respond to fibroblast growth factor, only in CD31/CD144 cells, but not in CD31 cells, leukocyte transmigration was significantly enhanced by fibroblast growth factor. In conclusion platelet endothelial cell adhesion molecule-1 cooperates with vascular endothelial cadherin in a mutual fashion; platelet endothelial cell adhesion molecule-1 reduces and temporarily limits fibroblast growth factor-induced dissociation of vascular endothelial cadherin/beta-catenin complexes, but requires vascular endothelial cadherin to control leukocyte transmigration in dependence of fibroblast growth factor.
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PMID:Platelet endothelial cell adhesion molecule-1 and vascular endothelial cadherin cooperatively regulate fibroblast growth factor-induced modulations of adherens junction functions. 1116 5

Anthrax is a zoonosis which is particularly prevalent in cattle, goats and sheep and is caused by Bacillus anthracis, a Gram-positive spore forming aerobic microorganism. The endospores can survive outside of the body for many decades. The natural form of anthrax has a cutaneous, pulmonary and intestinal form. The pulmonary form can be rapidly fatal but is difficult to recognise due to an initially non-specific, flu-like clinical picture. As a result of spores being inhaled, a mediastinal lymphadenitis arises from which a systemic disease develops with a violent toxaemia, damage to the vascular endothelium, oedema, internal haemorrhages and circulatory collapse. Anthrax is diagnosed by demonstrating the presence of the bacteria in the cutaneous abnormality, in blood or another sterile body component such as cerebrospinal fluid, by means of a direct preparation, immunofluorescence or surface antigens, molecular diagnostics with PCR, or by means of culturing. B. anthracis is sensitive to quinolones, clindamycin and tetracyclines, and often to penicillin. Although naturally acquired cutaneous anthrax can be effectively treated with a short antibiotic cure, it is nevertheless advised in the USA to complete the full 60-day cure and to regard the cutaneous manifestation as a telltale sign of possible respiratory exposure. Anthrax is not transmitted from one person to another.
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PMID:[Anthrax due to deliberate infection]. 1204 52

Deep vein thrombosis (DVT) and pulmonary embolism (PE) are distinct but related aspects of the same dynamic disease process known as venous thromboembolism (VTE). An estimated 200,000 new cases occur in the United States every year, including 94,000 with PE, resulting in an incidence of 23 per 100,000 patients per year-cases. Without treatment, pulmonary embolism is associated with a mortality rate of approximately 30%, causing nearly 50,000 deaths per year. Moreover, based on post-mortem studies, two-thirds of the patients with pulmonary emboli remain undiagnosed. Clinically, PE may present as (1) isolated dyspnea, (2) pleuritic pain and/or hemoptysis, and (3) circulatory collapse. However, clinical history and examination can be notoriously misleading in reaching a diagnosis. A number of acquired etiologic risk factors (predispositions) are associated with a tendency to develop VTE. These include increasing age, immobilization, surgery, trauma, hospital or nursing home confinement, malignancy, neurologic disease with extremity paresis, as well as certain types of oral contraception and hormone replacement therapy. In addition, a variety of genetic risk factors, such as factor V Leiden, protein S or C deficiency have also been identified. However, in at least half of the instances, no predisposing factors can be identified (idiopathic PE). In the majority of cases thromboemboli originate in the deep veins of the calf or pelvis. The pathogenic conditions for VTE comprise a triad of factors and include (1) venous stasis, (2) hypercoagulable states, and (3) vascular endothelium injury. Occlusion of pulmonary arteries has variable and transient clinical and pathophysiologic consequences, involving both mechanical and reflex effects of vascular occlusion with a consecutive perfusion defect as well as the release of vasoactive and other inflammatory mediators. The objectives of this article are to present an overview of the etiologic and pathogenic factors promoting VTE as well as the pathophysiologic and inflammatory processes following PE.
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PMID:Principle mechanisms underlying venous thromboembolism: epidemiology, risk factors, pathophysiology and pathogenesis. 1258 87

The virulence of pathogenic bacteria is critically dependent on their ability to produce toxins that attack eukaryotic target cells. Microbial toxins are either structural components of the bacterial cell wall (endotoxins) or actively secreted proteins (exotoxins). Sepsis and septic shock, which represent major causes of mortality in modern intensive care medicine, are caused by an inadequate inflammatory and immunological host response to bacterial infection. Emerging evidence suggests that the systemic spread of microbial toxins, rather than bacteremia itself, is the crucial event in the pathogenesis of this dramatic dysregulation. The endothelium, with its diversity of physiological functions is a main target of bacterial toxins. The resulting endothelial dysfunction is believed to contribute to the underlying pathomechanisms and the collapse of homeostasis of organ function. In vitro, bacterial toxins induce subtle alterations of endothelial cell function rather than massive cell damage. Furthermore, bacterial toxins targeting endothelial cells severely alter the behavior of extravascular cells and circulating leukocytes via excessive formation of vasoactive mediators and overexpression of adhesion molecules. Research on the effects of microbial toxins on vascular endothelium has broadened our general understanding of microbial strategies to induce organ damage, even in the absence of viable bacteria. Combining antitoxin strategies with antibiotic therapy may prove to be of benefit to patients suffering from bacterial sepsis in the future.
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PMID:Endothelial responses to bacterial toxins in sepsis. 1470 Feb 71

Acute renal failure (ARF) necessitating renal replacement therapy is a common problem associated with high morbidity and mortality in the critically ill. Hypotension, followed by resuscitation, is the most common etiologic factor, mimicked by ischemia/reperfusion (I/R) in animal models. Although knowledge of the pathophysiology of ARF in the course of this condition is increasingly detailed, the intracellular and molecular mechanisms leading to ARF are still incompletely understood. This review aims at describing the role of cellular events and signals, including collapse of the cytoskeleton, mitochondrial and nuclear changes, in mediating cell dysfunction, programmed cell death (apoptosis), necrosis and others. Insight into the molecular pathways in the various elements of the kidney, such as vascular endothelium and smooth muscle and tubular epithelium leading to cell damage upon I/R will, hopefully, open new therapeutic modalities, to mitigate the development of ARF after hypotensive episodes and to promote repair and resumption of renal function once ARF has developed.
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PMID:Molecular mechanisms of acute renal failure following ischemia/reperfusion. 1564 11

Smoking is a significant risk factor for development of atherosclerosis. However, the pathophysiology of smoking-mediated vessel wall damage is not understood. With tools ranging from analytical chemistry to cell biology, we show that cigarette smoke contains metals that catalyze the direct oxidation of cellular proteins by smoke oxidants. Oxidation of cellular proteins causes a loss of microtubule function, culminating in microtubule depolymerization and proteasome-dependent degradation of alpha-tubulin. As a consequence of the microtubule collapse, cytoskeletal structures as well as intermediate filaments break down, leading finally to a contraction of vascular endothelial cells. We observed a smoke extract-induced, calpain-dependent degradation of the intracellular form of platelet-endothelial cell adhesion molecule 1/CD31, as well as a release of P-selectin/CD62P, IL-6, and IL-8 from endothelial cells into the supernatant. Increased levels of soluble CD62P and IL-6 are well known to be associated with smoking in humans. Increased permeability of the vascular endothelium is a crucial event in atherogenesis. This work highlights the compounds and mechanisms by which cigarette smoke induces leakiness of the vascular endothelium.
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PMID:Cigarette smoke metal-catalyzed protein oxidation leads to vascular endothelial cell contraction by depolymerization of microtubules. 1598 33


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