Variable tidal volumes improve lung protective ventilation strategies in experimental lung injury

RATIONALE

Noisy ventilation with variable Vt may improve respiratory function in acute lung injury.

OBJECTIVES

To determine the impact of noisy ventilation on respiratory function and its biological effects on lung parenchyma compared with conventional protective mechanical ventilation strategies.

METHODS

In a porcine surfactant depletion model of lung injury, we randomly combined noisy ventilation with the ARDS Network protocol or the open lung approach (n = 9 per group).

MEASUREMENTS AND MAIN RESULTS

Respiratory mechanics, gas exchange, and distribution of pulmonary blood flow were measured at intervals over a 6-hour period. Postmortem, lung tissue was analyzed to determine histological damage, mechanical stress, and inflammation. We found that, at comparable minute ventilation, noisy ventilation (1) improved arterial oxygenation and reduced mean inspiratory peak airway pressure and elastance of the respiratory system compared with the ARDS Network protocol and the open lung approach, (2) redistributed pulmonary blood flow to caudal zones compared with the ARDS Network protocol and to peripheral ones compared with the open lung approach, (3) reduced histological damage in comparison to both protective ventilation strategies, and (4) did not increase lung inflammation or mechanical stress.

CONCLUSIONS

Noisy ventilation with variable Vt and fixed respiratory frequency improves respiratory function and reduces histological damage compared with standard protective ventilation strategies.

Membrane compartments and purinergic signalling: occurrence and function of P2X receptors in lung

P2X receptors are cation-selective ion channels activated by extracellular ATP. They form homo- and heterotrimeric complexes that differ in their functional properties and subcellular localization. These membrane ion channels are also expressed in pulmonary epithelial cells. Recent work indicates that alveolar epithelial type I cells selectively express P2X(4) and P2X(7) receptor subtypes in addition to a large number of other ion channels present in the alveolar epithelium. Up- or downregulation of their expression is associated with several disease states. This minireview analyses the role of P2X receptors and of extracellular ATP and adenosine in lung disease, the relationship of P2X receptors to other ion channels in the alveolar epithelium and their distribution in lipid rafts/caveolae.

Increased expression of glycodelin mRNA and protein in rat lungs during ovalbumin-induced allergic airway inflammation

Asthma is a chronic inflammatory disease accompanied by airway obstruction and hyper-responsiveness. Asthmatic inflammation is characterized by the expression of multiple genes for inflammatory mediators. Glycodelin is a glycoprotein with several functions in cell recognition and differentiation. There is substantial evidence that glycodelin may be a mediator for immunomodulatory and immunosuppressive effects on several human tissues. To determine the potential role of glycodelin in the pulmonary immune response, we examined the distribution of the glycodelin mRNA and protein in an experimental rat model of allergen-induced airway inflammation. The experimental model developed an airway response to inhaled nebulized ovalbumin in adult rats. Two groups of rats (ovalbumin and saline) were challenged for 3 weeks, lungs were fixed and embedded, and sections were studied for expression of glycodelin mRNA by in situ hybridization and protein by immunohistochemistry. Glycodelin is expressed in Clara cells of bronchial epithelium, type II pneumocytes and alveolar macrophages. Densitometric analyses show a significant increase of the glycodelin mRNA and protein expression in rat lungs after ovalbumin challenge. Induced glycodelin amounts in tissue, particularly in Clara cells and alveolar macrophages were found. The altered expression pattern of glycodelin may contribute to the pulmonary immune response in asthmatic inflammation.

The cancer paradigm of severe pulmonary arterial hypertension

The plexiform lesions of severe pulmonary arterial hypertension (PAH) are similar in histologic appearance, whether the disease is idiopathic or secondary. Both forms of the disease show actively proliferating endothelial cells without evidence of apoptosis. Here, we discuss the pathobiology of the atypical, angioproliferative endothelial cells in severe PAH. The concept of the endothelial cell as a "quasi-malignant" cell provides a new framework for antiproliferative, antiangiogenic therapy in severe PAH.

Inactivation of AP1 proteins by a nuclear serine protease precedes the onset of radiation-induced fibrosing alveolitis

Radiation-induced lung damage comprises inflammation (alveolitis) as well as disturbed regulation of cell differentiation and proliferation (fibrosis). The transcriptional regulation of this process is poorly understood. One key transcription factor involved in the regulation of proliferation and differentiation is AP1 (activator protein 1). The present study examined changes in the DNA-binding activity of AP1 after irradiation and defined the underlying molecular mechanisms in an animal model. The right lungs of Fischer rats received a single radiation dose of 20 Gy. Lung tissue was tested for AP1 DNA-binding activity, AP1 mRNA, and levels of AP1 proteins as well as for c-Jun specific proteolytic activity. After an initial increase, the AP1 DNA-binding activity was completely lost starting at 5.5 weeks after irradiation, which is 2.5 weeks before the onset of fibrosing alveolitis. This was not caused by reduction of mRNA levels or size. Instead, a selective nuclear cleavage of c-Jun by a serine protease caused the loss of AP1 activity. Considering the central role of AP1 in cell proliferation and differentiation and the strict timely correlation to the onset of the disease, the complete loss of AP1 function is likely to play a critical role in radiation-induced fibrosing alveolitis.

The adverse cardiopulmonary phenotype of caveolin-1 deficient mice is mediated by a dysfunctional endothelium

Recently generated caveolin-1 deficient mice (cav-1(-/-)) display several physiological alterations such as severe heart failure and lung fibrosis. The molecular mechanisms how the loss of caveolin-1 (cav-1) mediates these alterations are currently under debate. A plethora of studies support a role of cav-1 as a negative regulator of endothelial nitric oxide synthase (eNOS). Accordingly, constitutive eNOS hyperactivation was observed in cav-1(-/-). Given the hyperactivated eNOS enzyme we hypothesized that disturbed eNOS function is involved in the development of the cardiopulmonary pathologies in cav-1(-/-). The present study argues that loss of cav-1 results in enhanced eNOS activity but not in increased vascular tetrahydrobiopterin (BH(4)) levels (which acts as an essential eNOS cofactor) thereby causing a stoichiometric discordance between eNOS activity and BH(4) sufficient to cause dysfunctional eNOS signaling. The resultant oxidative stress is largely responsible for major cardiac and pulmonary defects observed in cav-1(-/-). BH(4) donation to cav-1(-/-) led to a normalized BH(4)/BH(2) ratio, to reduced oxidant stress, to substantial improvements of both systolic and diastolic heart function and to marked amelioration of the impaired lung phenotype. Notably, the antioxidant tetrahydroneopterin which is not essential for eNOS function showed no relevant effect. Taken together these novel findings indicate that dysfunctional eNOS is of central importance in the genesis of the cardiopulmonary phenotype of cav-1(-/-). Additionally, these findings are generally of paramount importance since they underline the deleterious role of an uncoupled eNOS in cardiovascular pathology and they additionally suggest BH(4) as an effective cure.

Characterization of the molecular interaction between caveolin-1 and the P2X receptors 4 and 7 in E10 mouse lung alveolar epithelial cells

P2X(4) and P2X(7) receptors are abundantly expressed in alveolar epithelial cells, and are thought to play a role in regulating fluid haemostasis. Here, we analyzed the expression and localization of the P2X(4)R, and characterized the interaction between Cav-1 and both P2X(4)R and P2X(7)R in the mouse alveolar epithelial cell line E10. Using the biotinylation assay, we found that only glycosylated P2X(4)R is exposed at the cell surface. Triton X-100 solubility experiments and sucrose gradient centrifugation revealed that P2X(4)R was partially localized in Cav-1 rich membrane fractions. Cholesterol depletion with Mbeta-CD displaced Cav-1 and P2X(4)R from the low-density to the high-density fractions. Suppression of Cav-1 protein expression using short hairpin RNAs resulted in a large reduction in P2X(4)R levels. Double immunofluorescence showed that P2X(4)R and Cav-1 partially colocalize in vitro. Using the GST pull-down assay, we showed that Cav-1 interacts in vitro with both P2X(4)R and P2X(7)R. Co-immunoprecipitation experiments confirmed the interaction between P2X(7)R and Cav-1. ATP stimulation increased the level of P2X(4)R in the lipid raft/caveolae fraction, whereas Cav-1 content remained constant. Our results support recent evidence that P2X receptors are present in both raft and non-raft compartments of the plasma membrane and thus exhibit variable ATP sensitivity.

A role for the receptor for advanced glycation end products in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a severely debilitating disease associated with a dismal prognosis. There are currently no effective therapies for IPF, thus the identification of novel therapeutic targets is greatly needed. The receptor for advanced glycation end products (RAGE) is a member of the immunoglobulin superfamily of cell surface receptors whose activation has been linked to various pathologies. In healthy adult animals, RAGE is expressed at the highest levels in the lung compared to other tissues. To investigate the hypothesis that RAGE is involved in IPF pathogenesis, we have examined its expression in two mouse models of pulmonary fibrosis and in human tissue from IPF patients. In each instance we observed a depletion of membrane RAGE and its soluble (decoy) isoform, sRAGE, in fibrotic lungs. In contrast to other diseases in which RAGE signaling promotes pathology, immunohistochemical and hydroxyproline quantification studies on aged RAGE-null mice indicate that these mice spontaneously develop pulmonary fibrosis-like alterations. Furthermore, when subjected to a model of pulmonary fibrosis, RAGE-null mice developed more severe fibrosis, as measured by hydroxyproline assay and histological scoring, than wild-type controls. Combined with data from other studies on mouse models of pulmonary fibrosis and human IPF tissues indicate that loss of RAGE contributes to IPF pathogenesis.

Very long-term self-renewal of small intestine, colon, and hair follicles from cycling Lgr5+ve stem cells

The intestinal epithelium and the hair follicle represent examples of rapidly self-renewing tissue in adult mammals. We have recently identified a novel stem cell gene Lgr5 expressed in multiple adult tissues. At the bottoms of crypts in small intestine and colon as well as in hair follicles, Lgr5 marks cycling cells with stem cell properties (Barker et al. 2007; Jaks et al. 2008). Using an inducible Lgr5-Cre knockin allele in conjunction with the Rosa26-LacZ Cre reporter strain, long-term lineage-tracing experiments were performed in adult mice. The Lgr5(+ve) crypt-based cell generated all epithelial lineages during a 14-month period, implying that it represents the stem cell of the small intestine and colon. Similarly, lineage tracing during a 14-month period revealed that Lgr5(+ve) cells located in the bulge of the hair follicle sustained multiple rounds of hair growth. These observations support the counterintuitive notion that Lgr5(+ve) cells are actively cycling, yet represent long-term stem cells of these adult, self-renewing tissues.

The significance of caveolin-1 expression in parietal epithelial cells of Bowman's capsule

AIMS

To analyse the expression of caveolin-1 in normal human kidney and during diseases leading to nephrotic syndrome in children and to compare its pattern with those observed in control samples, both human and animal.

METHODS AND RESULTS

The study group was composed of 104 children diagnosed with minimal change disease (MCD), focal segmental glomerulosclerosis (FSGS), lupus glomerulonephritis (LGN) and Schönlein-Henoch glomerulopathy (SH). The research protocol employed direct immunohistochemical assay with the use of mono- and polyclonal antibodies against caveolins. Kidney samples of Wistar rats, wild-type mice and caveolin-1-deficient mice were also analysed. In the control human samples, caveolin-1 was most abundant in the muscle layer of blood vessels and parietal epithelial cells (PECs). Its expression in PECs was significantly lower in children diagnosed with FSGS and LGN than in those with MCD, SH or in controls. In the control animal tissues, except for knock-out mice, caveolin-1 was present in distal convoluted tubules, PECs, endothelial cells and muscle.

CONCLUSIONS

Caveolae are extremely stable elements of PECs and can be excluded from their cell membrane only in response to the dramatic cell reconstruction observed in FSGS and LGN.

Caveolin-1 and caveolin-3 form heterooligomeric complexes in atrial cardiac myocytes that are required for doxorubicin-induced apoptosis

Caveolae are 50- to 100-nm invaginations of the plasma membrane. Caveolins are the structural protein components of caveolar membranes. The caveolin gene family is composed of three members: caveolin-1, caveolin-2, and caveolin-3. Caveolin-1 and caveolin-2 are coexpressed in many cell types, including adipocytes, endothelial cells, epithelial cells, and fibroblasts. In contrast, caveolin-3 expression is essentially restricted to skeletal and smooth muscle cells as well as cardiac myocytes. While the interaction between caveolin-1 and caveolin-2 has been documented previously, the reciprocal interaction between endogenous caveolin-1 and caveolin-3 and their functional role in cell types expressing both isoforms have yet to be identified. Here we demonstrate for the first time that caveolin-1 and caveolin-3 are coexpressed in mouse and rat cardiac myocytes of the atria but not ventricles. We also found that caveolin-1 and caveolin-3 can interact and form heterooligomeric complexes in this cell type. Doxorubicin is an effective anticancer agent, but its use is limited by the possible development of cardiotoxicity. Using caveolin-1- and caveolin-3-null mice, we show that both caveolin-1 and caveolin-3 expression are required for doxorubicin-induced apoptosis in the atria through activation of caspase 3. Together, these results bring new insight into the functional role of caveolae and suggest that caveolin-1/caveolin-3 heterooligomeric complexes may play a key role in chemotherapy-induced cardiotoxicity in the atria.

Directed Differentiation of Mouse Embryonic Stem Cells into Pancreatic-Like or Neuronal- and Glial-Like Phenotypes

The derivation of definitive endoderm and in particular endocrine cell types from undifferentiated embryonic stem (ES) cells remains difficult to achieve. In this study, we investigated the potential to regulate the differentiation of ES cells into endodermal derivatives using extracellular factors previously associated with various aspects of pancreatic development. Feeder-free-cultured mouse ESD3 cells were manipulated to form embryoid bodies (EBs) in the presence of retinoic acid (RA). RA-treated EBs were subsequently exposed to sodium butyrate (SB), betacellulin (BTC) or activin A (AA). A comparative analysis was performed on these models of directed differentiation in parallel with a model of spontaneous differentiation. Lineage differentiation was determined by profiling multilineage marker transcript expression (neuronal, myogenic, exocrine and endocrine pancreas, extraembryonic and apoptotic) and subsequent protein expression within ES-derived cultures. Using a two-stage differentiation protocol developed during this study, we successfully demonstrated the derivation of an intermediate multipotential population (RA_EBs) from undifferentiated ES cells that preferentially gives rise to pancreatic endocrine insulin-expressing cell types in the presence of SB, and neuronal- and glial-like cell types in the presence of AA or BTC.

Immunocytochemical and biochemical detection of EMMPRIN in the rat tooth germ: differentiation-dependent co-expression with MMPs and co-localization with caveolin-1 in membrane rafts of dental epithelial cells

In tooth development matrix metalloproteinases (MMPs) are under the control of several regulatory mechanisms including the upregulation of expression by inducers and downregulation by inhibitors. The aim of the present study was to monitor the occurrence and distribution pattern of the extracellular matrix metalloproteinase inducer (EMMPRIN), the metalloproteinases MMP-2 and MT1-MMP and caveolin-1 during the cap and bell stage of rat molar tooth germs by means of immunocytochemistry. Strong EMMPRIN immunoreactivity was detected on the cell membranes of ameloblasts and cells of the stratum intermedium in the bell stage of the enamel organ. Differentiating odontoblasts exhibited intense EMMPRIN immunoreactivity, especially at their distal ends. Caveolin-1 immunoreactivity was evident in cells of the internal enamel epithelium and in ameloblasts. Double immunofluorescence studies revealed a focal co-localization between caveolin-1 and EMMPRIN in ameloblastic cells. Finally, western blotting experiments demonstrated the expression of EMMPRIN and caveolin-1 in dental epithelial cells (HAT-7 cells). A substantial part of EMMPRIN was detected in the detergent-insoluble caveolin-1-containing low-density raft membrane fraction of HAT-7 cells suggesting a partial localization within lipid rafts. The differentiation-dependent co-expression of MMPs with EMMPRIN in the enamel organ and in odontoblasts indicates that EMMPRIN takes part in the induction of proteolytic enzymes in the rat tooth germ. The localization of EMMPRIN in membrane rafts provides a basis for further investigations on the role of caveolin-1 in EMMPRIN-mediated signal transduction cascades in ameloblasts.

Phenotypic alterations in type II alveolar epithelial cells in CD4+ T cell mediated lung inflammation

BACKGROUND

Although the contribution of alveolar type II epithelial cell (AEC II) activities in various aspects of respiratory immune regulation has become increasingly appreciated, our understanding of the contribution of AEC II transcriptosome in immunopathologic lung injury remains poorly understood. We have previously established a mouse model for chronic T cell-mediated pulmonary inflammation in which influenza hemagglutinin (HA) is expressed as a transgene in AEC II, in mice expressing a transgenic T cell receptor specific for a class II-restricted epitope of HA. Pulmonary inflammation in these mice occurs as a result of CD4+ T cell recognition of alveolar antigen. This model was utilized to assess the profile of inflammatory mediators expressed by alveolar epithelial target cells triggered by antigen-specific recognition in CD4+ T cell-mediated lung inflammation.

METHODS

We established a method that allows the flow cytometric negative selection and isolation of primary AEC II of high viability and purity. Genome wide transcriptional profiling was performed on mRNA isolated from AEC II isolated from healthy mice and from mice with acute and chronic CD4+ T cell-mediated pulmonary inflammation.

RESULTS

T cell-mediated inflammation was associated with expression of a broad array of cytokine and chemokine genes by AEC II cell, indicating a potential contribution of epithelial-derived chemoattractants to the inflammatory cell parenchymal infiltration. Morphologically, there was an increase in the size of activated epithelial cells, and on the molecular level, comparative transcriptome analyses of AEC II from inflamed versus normal lungs provide a detailed characterization of the specific inflammatory genes expressed in AEC II induced in the context of CD4+ T cell-mediated pneumonitis.

CONCLUSION

An important contribution of AEC II gene expression to the orchestration and regulation of interstitial pneumonitis is suggested by the panoply of inflammatory genes expressed by this cell population, and this may provide insight into the molecular pathogenesis of pulmonary inflammatory states. CD4+ T cell recognition of antigen presented by AEC II cells appears to be a potent trigger for activation of the alveolar cell inflammatory transcriptosome.

Downregulation of caveolin-1 affects bleomycin-induced growth arrest and cellular senescence in A549 cells

Bleomycin is an anti-cancer drug that induces both apoptosis and senescence, two processes thought to involve caveolin-1. Here we investigate the role of caveolin-1 in bleomycin-induced senescence. We show that bleomycin-treated A549 cells exhibit: senescence-like cell morphology; a senescence-associated increase in SA-beta-galactosidase activity; cell cycle arrest; and upregulation of p53 and p21. As predicted, we find that caveolin-1 amount increases in response to bleomycin-treatment and that modulation of caveolin-1 affects p21 and p53 levels, cell cycling, and senescence (SA-beta-galactosidase activity). Interestingly, senescence-associated cell cycle arrest via p53 and p21 and SA-beta-galactosidase activity is reduced in young A549 cells when short hairpin RNA specific for caveolin-1 was applied before bleomycin-treatment. Our results support the hypothesis that downregulation of caveolin-1 expression affects bleomycin-induced cell cycle arrest and subsequent cellular senescence that is driven by p53 and p21.

Caveolin-1 influences P2X7 receptor expression and localization in mouse lung alveolar epithelial cells

The P2X7 receptor has recently been described as a marker for lung alveolar epithelial type I cells. Here, we demonstrate both the expression of P2X7 protein and its partition into lipid rafts in the mouse lung alveolar epithelial cell line E10. A significant degree of colocalization was observed between P2X7 and the raft marker protein Caveolin-1; also, P2X7 protein was associated with caveolae. A marked reduction in P2X7 immunoreactivity was observed in lung sections prepared from Caveolin-1-knockout mice, indicating that Caveolin-1 expression was required for full expression of P2X7 protein. Indeed, suppression of Caveolin-1 protein expression in E10 cells using short hairpin RNAs resulted in a large reduction in P2X7 protein expression. Our data demonstrate a potential interaction between P2X7 protein and Caveolin-1 in lipid rafts, and provide a basis for further functional and biochemical studies to probe the physiologic significance of this interaction.

Bleomycin induces caveolin-1 and -2 expression in epithelial lung cancer A549 cells

BACKGROUND

Bleomycin induces apoptosis in alveolar epithelial cells. The expression of caveolin-1 and -2 in lung epithelial-derived A549 cells was analysed in terms of apoptosis after exposure to bleomycin.

MATERIALS AND METHODS

Apoptosis was investigated using flow cytometry, ELISA, immunohistochemistry and Western blot analysis. Caveolin-1 and -2 were determined at the protein level (Western blot). Intracellular caveolin-1 distribution was studied with immunofluorescence, as well as sucrose density gradient centrifugation.

RESULTS

Caveolin-1 and -2 were up-regulated 1 h after exposure to bleomycin and preceding the occurrence of caspase-8, and of caspase-3 and caspase-9 cleavage products. Sucrose density gradient centrifugation revealed that bleomycin exposure led to a partial translocation of caveolin-1 from caveolin-rich membrane fractions to non-raft fractions. Successful inhibition of bleomycin-induced apoptosis by the broad-spectrum caspase inhibitor zVAD-fmk did not influence the amount of caveolin-1 and -2.

CONCLUSION

The early up-regulation of caveolin-1 and -2 following bleomycin exposure is a rather apoptosis-independent event related to other unknown mechanisms of bleomycin-mediated cell injury.

Enzymhistochemische Diagnostik gastrointestinaler Motilitätsstörungen

The enzyme histochemical reactions for acetylcholinesterase, lactic dehydrogenase, succinic dehydrogenase and nitroxide synthase are currently the gold standards for the diagnosis of gastrointestinal motility disorders. The acetylcholinesterase staining reaction shows the cholinergic nerve fibre network of the muscularis mucosae and muscularis propria, and correlates with their acetylcholinesterase activity. Lactic dehydrogenase, succinic dehydrogenase and nitroxide synthase selectively demonstrate the nerve cells of the myenteric and submucous plexus. These enzyme histochemical techniques require fresh, native tissue. Consequently, the transport of biopsies from gastroenterology or surgery to pathology must be well organized and feasible without time loss. Alternatively, biopsies may be mailed on dry ice to more distant pathology institutes. The enzyme histochemical laboratory technique has been optimized and refined over four decades. The optimized reactions are highly reliable and reproducible. In particular, a standardized methodology is a prerequisite for the interinstitutional comparability of results. This laboratory manual provides a detailed methodological description of the most important enzyme histochemical reactions for the diagnosis of gastrointestinal motility disorders.

The function of alpha- and beta-adrenoceptors of the saphenous artery in caveolin-1 knockout and wild-type mice

BACKGROUND AND PURPOSE

Adrenoceptors can associate with cardiac caveolae. To investigate the function of vascular caveolae, adrenoceptor-mediated effects were compared in the saphenous artery of caveolin-1 knockout (cav-1KO) and wild-type (WT) mice.

EXPERIMENTAL APPROACH

Electronmicroscopy was used to detect caveolae. Real-Time quantitative PCR was used for adrenoceptor subtypes. Catecholamine-evoked contractions and relaxations were studied in arterial segments.

KEY RESULTS

Caveolae were found in arterial smooth muscle from WT but not from cav-1KO mice. Arterial mRNA levels for the adrenoceptors alpha1A, alpha1B, alpha1D, beta1, beta2 and beta3 were similar in cav-1KO and WT. (-)-Noradrenaline contracted cav-1KO (-log EC50M=7.1) and WT (-log EC50M=7.3) arteries through prazosin-sensitive receptors. Maximum (-)-noradrenaline-evoked contractions were greater in cav-1KO than WT arteries. (-)-Isoprenaline relaxed WT arteries (-log EC50M=7.3) more potently than cav-1KO arteries (-log EC50M=6.8); the effects were antagonized partially and similarly by the beta2-selective antagonist ICI118551 (50 nM). The (-)-isoprenaline-evoked relaxation was partially antagonized by the beta1-adrenoceptor-selective antagonist CGP20712 (300 nM) in WT but not cav-1KO arteries. The beta3-adrenoceptor-selective antagonist L748337 (100 nM) partially antagonized the relaxant effects of (-)-isoprenaline in cav-1KO but not in WT arteries. BRL37344 partially relaxed arteries through beta3-adrenoceptors in cav-1KO but not WT. The relaxant effects of BRL37344 were decreased by the NO synthase inhibitor OmegaL-nitroarginine.

CONCLUSIONS AND IMPLICATIONS

The function of arterial alpha1- and beta2-adrenoceptors is similar in cav-1KO and WT mice. beta1-adrenoceptor-mediated relaxation in WT is lost in cav-1KO and replaced by the appearance of beta3-adrenoceptors.

Effects of vaporized perfluorohexane and partial liquid ventilation on regional distribution of alveolar damage in experimental lung injury

OBJECTIVE

To determine whether the patterns of distribution of histological effects of vaporized perfluorohexane (PFH) and partial liquid ventilation (PLV) differ significantly in acute lung injury.

DESIGN AND SETTING

Experimental study in an animal research laboratory.

SUBJECTS

Eighteen pigs.

INTERVENTIONS

After induction of acute lung injury by means of infusion of oleic acid animals were randomly assigned to PFH, PLV, or gas ventilation (GV) groups. Six hours thereafter animals were killed, and lung tissue samples were taken for analysis.

MEASUREMENTS AND RESULTS

Histopathological analysis revealed less damage with PFH than with GV or PLV in the nondependent and central regions. PFH and PLV showed less injury in the dependent regions than GV. GV and PFH were associated with less histological damage in the nondependent than the dependent regions, whereas PLV presented the opposite pattern. Morphometric analysis showed increased aeration in nondependent than dependent regions with PFH and GV. PLV led to more aeration in the periphery than in central areas.

CONCLUSIONS

PFH was associated with a more homogeneous attenuation of alveolar damage across the lungs, although this therapy had more pronounced effects in nondependent zones. PLV showed the opposite pattern, with more important reduction in alveolar damage in dependent lung regions. Interestingly, reduction in alveolar damage with PFH was as effective as with PLV in dependent zones. Our findings suggest that vaporized perfluorocarbon could be advantageous as adjunctive therapy in the treatment of acute lung injury.

[Advanced glycation end products and pseudoexfoliation--correlation between clinical outcome and histological findings]

BACKGROUND

Pseudoexfoliation syndrome (PXS) as a stress-induced microfibrillopathy often shows a prolonged postoperative course. Formation of advanced glycation end products (AGEs) might be also associated with an increased oxidative stress. This study investigated for the first time immunohistochemically lens capsules of PXS patients for the AGE carboxymethylysine (CML) and correlated the findings with the clinical outcome of the patients.

METHODS

55 patients (22 male, 33 female; mean age 73.9 +/- 14.1 years) with PXS and pseudoexfoliation glaucoma (PXG) after cataract extraction were included. All lens capsules could be investigated immunohistochemically for the AGE CML. Both preoperative biometric data as well as intra- and postoperative courses were included in the investigations, followed by a correlation analysis of the immunohistochemical findings.

RESULTS

29 PXS and 26 PXG patients with a mean axial length of 23.1 +/- 1.1 mm were explored. Both groups showed a postoperative decrease of intraocular pressure and a moderate increase of visual acuity. Intraoperatively, 6 zonulolyses occurred and postoperatively 11 patients showed problems like increases of intraocular pressure. Immunohistochemically, CML could be detected in most of the epithelial cells of the lens capsules but only in a small part of the pseudoexfoliation (PEX) fibrils. A correlation between positive CML immunoreaction and the clinical course was not detectable.

CONCLUSIONS

Cataract extraction in patients with PEX glaucoma shows different specialities and risks. The AGE CML was detectable in human lens capsules. A direct correlation between clinical course and immunohistochemical reaction of the PEX fibrils could not be found. Overall, CML seems not to be a valuable predictive factor for the clinical course in patients with PXS and PXG.