[Effects of Vibrax (Mechanical Vibrations) on the Arterial Blood Gases of Patients in the Intensive Care Unit after Cardiac Surgery]. / Effekte der Vibraxanwendung (mechanische Vibration) auf die Blutgaswerte von Patienten auf der Intensivstation nach einem kardiochirurgischen Eingriff.

OBJECTIVE: Respiratory physiotherapy is an integral part of the care of patients in intensive care units (ICU) after cardiac surgery. One of the most commonly used techniques in ICU to prevent pulmonary complications are mechanical vibrations, which can be applied with a tool called Vibrax.The aim of this study was to investigate the effects of Vibrax (mechanical vibrations) on the arterial blood gases of patients in ICU during the 1. or 2. day after cardiac surgery. METHODS: A randomized controlled pilot study was conducted with 23 patients. The participants of the control group (CG) received a cardiovascular training with mobilization to the edge of the bed and active breathing exercises. On the patients of the intervention group (IG) additionally Vibrax was applied for 5 minutes. As primary outcome parameter the PaO2/FiO2 ratio was measured. RESULTS: In the CG no significant changes over time were observed (p ≥ 0.06). The IG showed a significant (p = 0.009) increase in the PaO2/FiO2 ratio from before the physiotherapy intervention (M = 296.52, SE = 34.94 mmHg) to 60 minutes after completion of the physiotherapy intervention (M = 331.39, SE = 48.14 mmHg). There was no significant difference between the CG and IG at any measuring time (p ≥ 0.09). CONCLUSION: The results of this pilot study indicate that the application of Vibrax has positive effects on the arterial blood gases of patients in ICU on the 1. or 2. day after cardiac surgery. But whether the effects are clinically relevant could not be clarified.

Neoalveolarisation contributes to compensatory lung growth following pneumonectomy in mice.

Regeneration of the gas exchange area by induction of neoalveolarisation would greatly improve therapeutic options in destructive pulmonary diseases. Unilateral pneumonectomy is an established model to remove defined portions of gas exchange area and study mechanisms of compensatory lung growth. The question of whether new alveoli are added to the residual lung after pneumonectomy in mice was addressed. Left-sided pneumonectomy was performed in 11 adult C57BL/6 mice. Alveolar numbers were analysed in lungs fixed at days 6 and 20 after pneumonectomy and in 10 age-matched controls using design-based stereology based on a physical fractionator. Post-fixation lung volume was determined by fluid displacement. Complete restoration of lung volume was observed 20 days after pneumonectomy. Alveolar numbers were significantly increased by 33% in residual right lungs at day 20 in comparison with control right lungs. In control left lungs, an average of 471+/-162 x 10(3) alveoli was estimated, 49% of which were regenerated by residual lungs at day 20. Of the newly formed alveoli seen at day 20, 74% were already present at day 6. The present data demonstrate that, in addition to growth in size of existing alveoli, neoalveolarisation contributes to restoration of the gas exchange area in adult mice and is induced early after pneumonectomy.

Keratinocyte growth factor prevents intra-alveolar oedema in experimental lung isografts.

Primary graft dysfunction, characterised by intra-alveolar oedema, is a major obstacle in pulmonary transplantation. The present study evaluates the potential of keratinocyte growth factor (palmiferin; DeltaN23-KGF) for the prevention of oedema in lung transplants. Intratracheal instillation of 5 mg x kg(-1) DeltaN23-KGF was performed in Lewis rats on days 3 and 2 before explantation. Control animals obtained an equivalent volume of vehicle. Left lungs were isogeneically transplanted and the graft recipients were sacrificed 1 day later for stereological analysis of intra-alveolar oedema and bronchoalveolar lavage. The total protein and phospholipid content, as well as surfactant proteins, were measured. Surfactant activity was analysed with a pulsating bubble surfactometer. In grafts from control treated donors, the fraction of intra-alveolar oedema amounted to 3.4+/-1.1% of the total parenchymal volume. Treatment of donor lungs with DeltaN23-KGF reduced oedema to a fraction of 1.6+/-0.8%. In the lavage fluid of pulmonary grafts from DeltaN23-KGF-treated donors, the total protein content was decreased compared with vehicle-treated lung transplants, whereas phospholipids did not differ. The protein fraction contained increased amounts of surfactant protein-C after DeltaN23-KGF treatment and surfactant function was improved. Treatment of donor lungs with palifermin protects against intra-alveolar oedema formation upon transplantation. This effect appears to be mediated by an improved surfactant homeostasis.

Direct effects of the prostaglandins E2 and f2alpha on progesterone release by the corpus luteum of the marmoset monkey (Callithrix jacchus) studied by in vitro microdialysis.

The effects of the prostaglandins (PG) E2 and F2alpha on progesterone secretion in luteal tissue (32 corpora lutea) explanted from the mid-luteal ovary of the marmoset monkey (n=13) were investigated using an in vitro microdialysis system. Consecutive applications of 1, 10 and 100 microg/ml PGE2 resulted in a significant increase in secretion of progesterone at the maximum dose of 100 microg/ml, which was shown to be the stimulatory dose in both long-period and 20-min pulse (time to collect one fraction) applications. The response varied individually between 1.4- and 3. 4-fold above the baseline concentrations. Application of 500 microg/ml PGF2alpha led to similar hormone responses. In contrast, lower doses of PGF2alpha (0.5, 5 and 50 microg/ml) resulted in significantly increased levels of secretion of progesterone, to approximately 1.4-fold baseline values, only after the application was terminated (echo effect). Responses were less variable when a short pulse of 20 min duration was applied, instead of long applications of 1-2 h. On the basis of the passage rates measured for tritiated PGF2alpha, transfer through the dialysis membrane was assumed to be in the range of 1% for both PGs. Ultrastructurally, luteal cells lying in a sheath of five to seven cell layers around the dialysis tubing appeared intact and were interconnected by gap junctions. Vesiculation of the smooth endoplasmic reticulum was more prominent after PG treatment, indicating a stimulation of cellular synthesis/secretory activities that was in accordance with the stimulatory action of both PGs on progesterone release under these in vitro conditions.

Improvement of pulmonary preservation with Celsior and Perfadex: impact of storage time on early post-ischemic lung function.

BACKGROUND: Optimal preservation of post-ischemic organ function is a continuing challenge in clinical lung transplantation. METHODS: Using an established extracorporeal rat lung screening model, the results after preservation of 8 lungs, each with the extracellular-type preservation solutions Celsior and Perfadex using ischemic periods of 2 and 4 hours were compared to the results obtained after 2 hours of preservation with low-potassium Euro-Collins with prostacyclin. RESULTS: Oxygenation capacity of all Celsior-preserved organs was significantly higher as compared to LPEC lungs (p < 0.01), and after 4 hours of ischemia, lung preservation in terms of post-ischemic oxygenation ability was significantly higher in the Celsior group compared with Perfadex-protected organs (p < 0.01). CONCLUSION: Especially at extended ischemic times Celsior can provide significantly better pulmonary preservation in terms of oxygenation capacity compared to Perfadex solution, which is associated with a post-ischemic lung function only comparable to preservation with modified Euro-Collins solution.

Retrograde flush perfusion with low-potassium solutions for improvement of experimental pulmonary preservation.

BACKGROUND: Optimal preservation of post-ischemic organ function is a continuing challenge in clinical lung transplantation. Retrograde instillation of preservation solutions has the theoretic advantage of achieving homogeneous distribution in the lung because of perfusing both the pulmonary and the bronchial circulation. So far, we have seen no experimental studies that include stereologic analysis of intrapulmonary edema concerning the influence of retrograde preservation on post-ischemic lung function after preservation with Perfadex and Celsior. METHODS: In an extracorporeal rat model, we perfused 8 lungs, each, using either antegrade or retrograde perfusion technique with Celsior (CE(ant)/CE(ret)) and Perfadex (PER(ant)/PER(ret)). Results were compared with low-potassium Euro-Collins. Post-ischemic lungs were reventilated and reperfused mechanically. We continuously monitored relative oxygenation capacity (ROC), pulmonary artery pressure, flush time, and wet/dry ratio. Furthermore, we used stereologic means to evaluate edema formation. Statistics comprised different analysis of variance models. RESULTS: Relative oxygen capacity of CE(ant)-protected lungs was superior to that of PER(ant) preservation (p = 0.05). Use of PER(ret) resulted in significantly higher ROC as compared with PER(ant) (p < 0.001) and was comparable to results obtained with CE-preservation, which was not further improved with retrograde application. CONCLUSIONS: Celsior provides better lung preservation than does Perfadex when administered antegradely. Retrograde application of Perfadex results in significant functional improvement as compared with antegrade perfusion, which reaches the standard of Celsior-protected organs. Additional in vivo experiments in combination with ultrastructural analysis are warranted to further evaluate retrograde delivery of preservation solutions, which could be used in clinical lung transplantation to further optimize current results.

Combined use of prostacyclin and higher perfusate temperatures further enhances the superior lung preservation by Celsior solution in the isolated rat lung.

BACKGROUND: The poor tolerance of the lung to ischemia and reperfusion (IR) still represents one of the limitations in clinically successful lung transplantation. Modified Euro-Collins (EC) is routinely used in lung preservation, but alternative solutions have been developed for improvement of pulmonary preservation. Celsior is an extracellular solution that has significantly reduced the IR-induced pulmonary damage in animal studies. So far, no extensive experimental studies exist concerning the influence of Celsior on pulmonary gas exchange following IR. METHODS: In an extracorporeal rat lung model 10 lungs, each, were preserved with Celsior (CE) and Celsior/prostacyclin (CEPC, 6 microg/100 ml) at 4 degrees and 15 degrees C, each, and compared to low-potassium Euro-Collins (EC-40, 40 mmol/liter potassium). After 2 hours of ischemia lungs were reventilated and reperfused using a roller pump. Oxygenation in terms of oxygen partial tension in the left atrial effluent, pulmonary vascular resistance (PVR), peak inspiratory pressure, and wet/dry ratio were monitored for 50 minutes. Furthermore, edema formation was evaluated by light microscopy. Statistical analysis was performed using ANOVA models. RESULTS: Compared to the EC-40 group, oxygenation was increased and amount of edema was reduced in most Celsior-preserved organs (p<0.032) with exception of the CEPC group at 4 degrees C (p = 0.06). Additional application of prostacyclin did not have any significant effect on oxygenation in the Celsior group. However, after temperature elevation of the CEPC perfusate to 15 degrees C, a superior partial tension of oxygen was observed (p<0.023) in contrast to the 4 degrees C groups CE and CEPC. The lowest PVR was found in the CE 4 degrees C group (p<0.02). CONCLUSIONS: Celsior provides better lung preservation than EC-40 solution. Application of prostacyclin at higher perfusate temperatures results in additional functional improvement. In vivo experiments and ultrastructural analysis are warranted for further evaluation of Celsior in lung preservation.

Nitroglycerin alters alveolar type II cell ultrastructure after ischemia and reperfusion.

BACKGROUND: Although administration of nitric oxide (NO) has been suggested to reduce pulmonary reimplantation response, concerns remain about cytotoxic side effects. METHODS: Using light and electron microscopy, we examined the effects of the NO donor nitroglycerin (NTG) (0.1 mg/ml) as a supplement to the preservation solution Celsior on the structural integrity of rat lungs after extracorporeal ischemia (4 hours at 10 degrees C) and reperfusion (50 minutes) (IR). We performed evaluation in comparison with Celsior alone after IR using either standard antegrade perfusion through the pulmonary artery or retrograde perfusion through the left atrium as an alternative way to improve the preservation quality. Untreated, non-ischemic lungs served as controls (n = 5 per group). We recorded respiratory and hemodynamic parameters during reperfusion. Tissue collection using systematic uniform random sampling was representative for the whole organ and allowed stereologic quantification of structures. RESULTS: After IR, histochemistry revealed no breaks in the alveolo-capillary barrier and we detected no alveolar flooding. Edema formed in the peribronchovascular cuffs, of which the volume fraction was increased (p =.008). Vasoconstriction of the smaller arteries accompanied antegrade flush, which occurred neither after administration of NTG nor after retrograde flush, as shown by immunostaining for alpha-smooth muscle actin. Treatment with NTG was associated with focal disintegration of Type II cells, which displayed edematous swelling of distinct cell compartments and lysis of mitochondria and cells. Nitroglycerin prevented alveolar collapse, which was increased in the other IR groups (p = 0.013). We observed alterations in intra-alveolar surfactant components. CONCLUSION: These findings indicate pathologic effects of NTG treatment on alveolar epithelial integrity. Therefore, we suggest further critical evaluation of NTG/NO for therapeutic use in lung transplantation.

Increase of inactive intra-alveolar surfactant subtypes in lungs of asthmatic Brown Norway rats.

We tested the hypothesis whether allergic airway inflammation in ovalbumin sensitized and challenged Brown Norway rats is associated with intrinsic surfactant alteration and dysfunction. The determination of intra-alveolar surfactant subtypes and alveolar edema within their original microenvironment is only possible using an ultrastructural stereological approach. Therefore both lungs of control and asthmatic rats were fixed by vascular perfusion. The volume fractions of surfactant subtypes and the epithelial surface fraction covered with alveolar edema were determined by point and intersection counting. Furthermore, lung resistance was measured by means of whole-body plethysmography. The surface activity of surfactant from bronchoalveolar lavage was determined as minimum surface tension at minimal bubble size with a pulsating bubble surfactometer. Compared with controls, in asthmatics (1) the fraction of inactive unilamellar forms was significantly increased from 56% to 66%, (2) the fraction of alveolar epithelium covered with alveolar edema visible by light microscopy was significantly increased from 0.7% to 5.0%, (3) the fraction of alveolar epithelium covered with fluid seen by electron microscopy expanded significantly from 5% to 21%, (4) lung resistance was significantly elevated from 14% to 86% and (5) surface tension was enhanced from 6 mN/m to 12 mN/m. Thus, the inflammatory process after allergen challenge of sensitized Brown Norway rats causes intra-alveolar surfactant alterations. These surfactant alterations might contribute to small airway dysfunction.

Parental problem-solving skills, stress, and dietary compliance in phenylketonuria.

Parents of 30 children with phenylketonuria (PKU) who were classified as being in good dietary control (compliant, measured as within the medically acceptable range of blood phenylalanine levels of 2-10 mg) or poor dietary control (noncompliant, measured as either below or above medically acceptable 2-10 mg blood phenylalanine levels) engaged in verbal and written problem-solving situations under conditions of both high and low time-pressure induced stress. Overall, compliant parents gave higher quality verbal and written problem-solving solutions than noncompliant parents. Stress reduced the quality of problem solving in both compliant and noncompliant parents, but even under high stress, compliant parents demonstrated better problem-solving abilities than noncompliant parents. The potential importance of these findings for preventive intervention in PKU families is discussed.

Progress toward understanding follicle development in vitro: appearances are not deceiving.

The interactive factors that influence the developmental progress of a follicle and determine whether it will progress to ovulation or toward atresia, are highly complex. In vitro models are being developed that are intended to provide a simplified environment to facilitate understanding of the dynamics of the processes involved. The purpose of this overview is to evaluate progress to date and to focus attention on issues that need more careful consideration to improve the usefulness of the models. Basically, two approaches exist. One, attached follicle culture, employs either enzyme-digested or mechanically harvested follicles depending on the method but allows attachment of the follicles to the culture surface. This produces a rounded or flattened structure (depending on culture conditions) that is no longer an intact follicle. During this culture, the cells reorganize themselves, some remaining in contact with the oocyte and others attaching to the culture surface and proliferating. The other approach, intact 3-dimensional follicle culture, employs mechanically dissected preantral follicles that are cultured as free-floating intact structures. Intact follicle culture emulates the in vivo developmental pattern of the follicle more closely than a non-intact structure can, and thereby provides a favorable model to investigate the interaction between hormonal and paracrine factors in the development of the follicle in isolation from systemic effects. For example, intact follicle culture has begun to be used to investigate the local effects of several different steroids. In addition, the local effects of inhibin, activin, and follistatin and their interactions with locally produced growth factors and steroids as well as synergy with gonadotrophins are beginning to be investigated. In our laboratory, the focus is on the roles of gonadotrophins at different stages of follicle development, particularly the effect of FSH isoforms in modulating follicle development in vitro. Finally, an important issue that urgently needs to be addressed, for future studies of in vitro follicle development, is the rationalization and standardization of follicle culture conditions.

Assessment of tissue integrity, ultrastructure and steroidogenic activity of corpora lutea of the marmoset monkey, Callithrix jacchus, following in vitro microdialysis.

Microdialysis of marmoset (Callithrix jacchus) corpora lutea in vitro was evaluated regarding morphology, activity of 3 beta-hydroxysteroid-dehydrogenase (3 beta-HSD) and progesterone (P) secretion. Two different dialysis media were used: an unbuffered ringer solution and Krebs-Henseleit buffer gassed with carbogenium. Additionally, the effects of the luteotrophin prostaglandin E2 (PGE2) on P secretion were examined for both media. In general 3 zones of tissue according to the maintenance of cellular integrity could be identified after dialysis. Structurally intact cells were found in close vicinity to the dialysis tubing or the bathing medium after 8 h of perfusion. These 2 zones were separated by a sheet of cells which showed signs of ischemic injury and whose activity of 3-beta-HSD was reduced. During dialysis with ringer solution P release stayed constantly high for a longer period of time than with Krebs buffer. With both media PGE2 stimulated P release but could not prevent the decrease in P production during dialysis with Krebs buffer. In general profiles of baseline secretion, were more stable after treatment than for untreated corpora lutea. There, under dialysis with ringer solution, the ultrastructure of cells close to the dialysis tubing was well preserved exhibiting euchromatic nuclei, tubular sER and numerous mitochondria gathered in the perinuclear region. In contrast, with Krebs buffer heterochromatization of nuclei and vesiculation of smooth endoplasmic reticulum prevailed. After application of PGE2 no histological and ultrastructural differences could be found between tissue dialysed with ringer or Krebs buffer. In these specimens the sER of zone A cells generally appeared vesiculated. Our results indicate (1) a close structure-function relationship of luteal cells in the tested system, (2) the suitability of the system to study intra-luteal regulation and (3) the necessity to control structural integrity of the dialysed tissue.

Involvement of distal airways in a chronic model of experimental asthma.

BACKGROUND: Bronchial asthma is characterized by chronic airway inflammation and airway remodelling which occurs in both proximal and distal airways. These changes are associated with development of airway hyper-responsiveness and airflow limitation. OBJECTIVE: This study was aimed to analyse whether chronic inhalative allergen challenges in mice lead to morphological and physiological changes comparable with this phenotype. METHODS: For this purpose, BALB/c mice were systemically sensitized to ovalbumin (OVA) followed by aerosol allergen challenges on 2 consecutive days per week for 12 weeks. RESULTS: In chronically challenged mice, tissue inflammation in proximal as well as distal airways was observed with a predominance of lymphocytes within the cellular infiltrate. In contrast, inflammation in the airway lumen decreased over time. These changes were associated by a shift in bronchoalveolar lavage-cytokine levels from IL-4, IL-5 and TNF-alpha production (during the acute phase) towards markedly increased levels of TGF-beta during the chronic phase. Goblet cell hyperplasia and subepithelial fibrosis occurred throughout the airway tree. In terms of lung function, chronically challenged mice developed persistent bronchial hyper-responsiveness and progressive airflow limitation. Six weeks after OVA aerosol discontinuation, airway inflammation still persisted although lung function was normalized. CONCLUSION: These data indicate that our model of chronic aerosol allergen challenges leads to a phenotype of experimental asthma with participation of distal airways and persistence of inflammation thereby resembling many morphological and physiological aspects of human bronchial asthma.

Patterns of growth, oestradiol and progesterone released by in vitro cultured mouse ovarian follicles indicate consecutive selective events during follicle development.

This study investigated the relationship between individual follicle growth, steroid release and follicular morphology to provide basic information about critical stages in follicle development. Preantral mouse follicles secreted significant and constant amounts of progesterone that were not related to oestradiol production but did appear to be related to thecal organization. Oestradiol release was variable among follicles of equivalent diameter, but marked increases in oestradiol concentrations were measured in follicles of 300 and 400 microns diameter. Over 4 days of culture, the proportion of follicles growing beyond the threshold diameter of 300 microns was lower in small (140-160 microns) than it was in large preantral follicles (170-210 microns). Retardation of growth below this diameter was associated with significantly decreased steroid concentrations. In follicles growing beyond the threshold diameter, antrum formation progressed, but full Graafian stage was not attained. Among large follicles, variability in oestradiol release could not be associated with obvious histological differences. In contrast, structural disturbances were associated with reduced steroid production and growth abnormalities. Therefore, it is concluded that the preantral follicles selected for culture comprise distinct follicle populations with respect to their developmental potential in vitro, and that follicle development is controlled by endogenous processes involving oestradiol at distinct stages of follicle development.

Keratinocyte growth factor-induced proliferation of rat airway epithelium is restricted to Clara cells in vivo.

Keratinocyte growth factor (KGF) is a potent mitogen of pulmonary bronchial and alveolar epithelial cells. However, it is unclear which type(s) of airway epithelial cells (AEC) proliferate(s) in response to KGF. AEC proliferation was induced in rats by either endobronchial instillation of 5 mg recombinant human (rHu) KGF per kg body weight or by adenoviral transfer of the human KGF gene (Ad5-HuKGF). Alterations in terminal airway AEC were followed for up to 7 days after rHuKGF, and for up to 28 days after Ad5-HuKGF. Cell proliferation, as assessed by immunohistochemistry (IHC) for incorporated 5-bromo-2'-deoxyuridine (BrdU) and quantified by stereology, peaked at days 1-2 and was resolved by day 7 after rHuKGF and by day 21 after Ad5-HuKGF. Double immunofluorescence labelling for BrdU or Ki-67 on the one hand, and for Clara cell specific protein 10 (CC10) and calcitonin-gene related peptide on the other hand, demonstrated that Clara cells, not pulmonary neuroendocrine cells, proliferated in response to human KGF. TUNEL (terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labelling) method in conjunction with IHC for MNF116 failed to detect significant numbers of apoptotic AEC. IHC in conjunction with stereology revealed transient phenotypic alterations with a decrease in CC10, an increase in surfactant protein D and an increase in CD44v6 in AEC. The authors conclude that Clara cells responded to human keratinocyte growth factor in vivo by proliferation as well as by changes in protein expression, whereas no significant response was observed in pulmonary neuroendocrine cells. As Clara cells are intimately involved in airway epithelial repair, ion and fluid transport, and modulate lung inflammation, the potential of human keratinocyte growth factor to protect the lung may in part rely on the response of Clara cells.

Characterisation of post-pneumonectomy lung growth in adult mice.

A model of inducible expansion of the gas exchange area in adult mice would be ideal for the investigation of molecular determinants of airspace regeneration in vivo. Therefore, the post-pneumonectomy (post-PNX) compensatory lung growth in adult C57BL/6 mice was characterised in this study. Mice underwent left-sided PNX. Right lung volume was assessed on days 1, 3, 5, 7, 10 and 21 after PNX, and total DNA and cellular proliferation of the right lung were determined. Lung histology was studied using immunohistochemistry and quantitatively characterised by detailed stereological investigations. Pulmonary function was assessed using a mouse body-plethysmograph. Following PNX, right-lung volume rapidly restored the initial volume of left and right lung. Total DNA increased significantly over 21 days and equalled the total DNA amount of both lungs in the control mice. Septal cell proliferation significantly increased after PNX, and included endothelial cells, epithelial cells, smooth muscle cells and fibroblasts. Stereological investigations of left and right control lungs versus right lungs 21 days after PNX indicated complete restoration of body mass-specific alveolar surface area. Pulmonary function testing showed marked alteration at 3 days and normalisation at 21 days post-PNX. In conclusion, well reproducible reconstitution of alveolar gas-exchange surface based on septal tissue expansion may be provoked by pneumonectomy in adult mice.

Stereological estimation of the volume weighted mean volumes of alveoli and acinar pathways in the rat lung to characterise alterations after ischaemia/reperfusion.

The aim of this study was to characterise pulmonary reimplantation injury in isolated, perfused rat lungs following 2 h of cold ischaemia, and 50 min. of in vitro reperfusion. The effects of 2 differently composed lung preservation solutions (low potassium Euro-Collins and Celsior; each n = 5) were examined in comparison with untreated, nonischaemic control lungs (n = 3). After fixation by vascular perfusion and tissue collection by systematic random sampling, the volume weighted mean volume (Vv) of alveoli and acinar pathways was estimated by light microscopic stereology using the method of point sampled intercepts in plastic embedded, Azan-stained material. Significantly higher Vv of alveoli and acinar paths was found in the Celsior group than in Euro-Collins preserved lungs. However, in the controls the size of acinar pathways was similar to Celsior preserved lungs whereas alveolar size was comparable to preservation with Euro-Collins. The between-animal coefficient of variation of alveoli was very low in controls and Celsior preserved but higher in the Euro-Collins group. Size distribution of alveoli and acinar paths in 15 size classes was largely homogeneous in all groups tested. In the Euro-Collins group the fractions of both class 1-alveoli and class 1-acinar paths significantly exceeded those of the other groups. Widely expanded alveoli (size classes 13-15) only occurred after preservation with Celsior whereas wider acinar paths (size class 15) were found in the Celsior group and in the controls. It is concluded that lung preservation with low-potassium Euro-Collins and Celsior solutions may act differently on distinct spaces in the distal gas-exchange regions of lungs. This may be due to selective effects on pulmonary surfactant activity and on elastic tissue elements in the alveolar ducts, respectively. Additionally, the method of point sampled intercepts is considered to be an efficient tool to evaluate the effects of different preservation solutions on lung parenchyma.

Evaluation of pulmonary edema: stereological versus gravimetrical analysis.

Assessment of lung edema by gravimetrical analysis is a standard method to evaluate the severity of experimentally induced ischemia/reperfusion (IR) injury. The aim of this study was to compare gravimetrical assessment of pulmonary edema with a stereological approach which allows for qualitative and quantitative distinction between intravascular and edematous fluids by light microscopy. Eight experimental groups which differed in mode of preservation, ischemic storage and pharmacological treatments were studied in an extracorporeal rat lung model. Analysis of the pooled data showed that the wet/dry ratio values mainly reflected the amount of intra-alveolar edema (r(s) = 0.442; p = 0.0057) but only stereological assessment of edema formation revealed differences depending on the treatment used. Only stereological data correlated significantly with oxygen tension measured at the end of reperfusion (r(s) = -0.530; p = 0.0009). We conclude that gravimetry is of minor functional importance compared to assessment by stereological methods which prove to be a reliable and efficient tool for the evaluation of IR injury in the different experimental settings.

Improvement of rat lung structure and function after preservation with celsior.

Ischemia/reperfusion-induced increase in pulmonary microvascular permeability was shown to be reduced after preservation with Celsior. We investigated reimplantation-induced lung injury in isolated, reperfused rat lungs after preservation via the pulmonary artery with Celsior, Celsior + prostacyclin, and reduced-potassium (40 mmol) Euro-Collins solution (40 ml/kg/body wt each) followed by 2 h of cold ischemia. Arterial and veneous oxygen tensions were recorded during 50 min of in vitro reperfusion after which the lungs (10 right lungs per experimental group) were fixed by vascular perfusion. The tissue was further processed for microscopy, and histological changes were quantified stereologically. Lung preservation with Celsior resulted in a significantly higher volume of air-filled alveolar space with a large proportion of widely distended alveoli compared with the other groups. In the Euro-Collins group the fraction of atelectatic alveoli exceeded that observed in Celsior-preserved lungs. In accordance, the difference between arterial and venous oxygen tensions was significant among Euro-Collins- and Celsior-protected lungs, with improved oxygenation values in the Celsior group. In contrast, addition of prostacyclin to Celsior treatment resulted in rather variable structural as well as functional data. There were no differences in the volumes of intraalveolar edema among the groups tested. However, the volume of alveolar tissue was increased in the Euro-Collins group. In conclusion, compared with Euro-Collins and Celsior + prostacyclin solutions, preservation with Celsior resulted in improved structural characteristics which in combination with improved oxygenation parameters supports the prospective advantage of Celsior in clinical organ preservation.

Ultrastructural alterations in intraalveolar surfactant subtypes after experimental ischemia and reperfusion.

Ischemia and reperfusion (I/R) result in surfactant dysfunction. Whether the impairment of surfactant is a consequence or a cause of intraalveolar edema formation is still unknown. The cumulative effects of lung perfusion, ischemic storage, and subsequent reperfusion on surfactant ultrastructure and pulmonary function were studied in a rat isolated perfused lung model. The left lungs were fixed for electron microscopy by vascular perfusion either immediately after excision (control; n = 5) or after perfusion with modified Euro-Collins solution (EC), storage for 2 h at 4 degrees C in EC, and reperfusion for 40 min (n = 5). A stereological approach was chosen to discriminate between intraalveolar surfactant subtypes of edematous regions and regions free of edema. Intraalveolar edema seen after I/R in the EC group occupied 36 +/- 6% (mean +/- SEM) of the gas exchange region as compared with control lungs (1 +/- 1%; p = 0.008). Relative intraalveolar surfactant composition showed a decrease in surface active tubular myelin (3 +/- 1 versus 12 +/- 0%; p = 0.008) and an increase in inactive unilamellar forms (83 +/- 2 versus 64 +/- 5%; p = 0.008) in the EC group. These changes occurred both in edematous (tubular myelin, 3 +/- 1%; unilamellar forms, 88 +/- 6%) and in nonedematous regions (tubular myelin, 4 +/- 3%; unilamellar forms, 77 +/- 5%). The ultrastructural changes in surfactant were associated with an increase in peak inspiratory pressure during reperfusion. In conclusion, surfactant alterations seen after I/R are not directly related to the presence of edema fluid in the alveoli. Disturbances in intraalveolar surfactant after I/R are not merely the result of inactivation due to plasma protein leakage but may instead be responsible for an increased permeability of the blood-air barrier, resulting in a vicious cycle of intraalveolar edema formation and progressing surfactant impairment.