Branched isomeric 1,2,3-triazolium-based ionic liquids: new insight into structure-property relationships.

A series of four isomeric 1,2,3-triazolium-based ionic liquids (ILs) with vary degree of branching were synthesized and characterized to investigate the effect of ion branching on thermal and physical properties of the resulting IL. It was found that increased branching led to a higher ionicity and higher viscosity. The thermal properties were also altered significantly and spectral changes in the near edge X-ray absorption fine structure (NEXAFS) spectra show that branching affects intermolecular interaction. While the ionicity and viscosity varying linearly with branching, the MDSC and NEXAFS measurements show that the cation shape has a stronger influence on the melting temperature and absorptive properties than the number of branched alkyl substituents.

The impact of the Fundamental Critical Course on knowledge acquisition in Rwanda.

Background: Emerging critical care systems have gained little attention in low- and middle-income countries. In sub-Saharan Africa, only 4% of the healthcare workforce is trained in critical care, and mortality rates are unacceptably high in this patient population. Objectives: We sought to retrospectively describe the knowledge acquisition and confidence improvement of practitioners who attend the Fundamental Critical Care Support (FCCS) course in Rwanda. Methods: We conducted a retrospective study in which we assessed survey data and multiple-choice question data that were collected before and after course delivery. The purpose of these assessments at the time of delivery was to evaluate participants' perception and acquisition of critical care knowledge. Results: Thirty-six interprofessional clinicians completed the training. Performance on the multiple-choice questions improved overall after the course (mean score pre-course of 56.5% to mean score post-course of 65.8%, p-value <0.001) and improved in all content areas with the exception of diagnosis and management of acute coronary syndrome and acute respiratory failure/mechanical ventilation. Both physicians and nurses improved their scores significantly (68.9% to 75.6%, p-value = 0.031 and 52.0% to 63.5%, p-value <0.001, respectively). Self-reported confidence in level of knowledge also increased in all areas. Survey respondents indicated on open-answer questions that they would like the course offerings at least annually, and that further dissemination of the course in Rwanda was warranted. Conclusion: Deploying the established FCCS course improved Rwandan healthcare provider knowledge and confidence across most critical care content areas. Therefore, this course represents a good first step in bridging the gaps noted in emerging critical care systems. Contributions of the study: Critical care education in sub-Saharan Africa is limited and few staff have formal training. The aim of the study was to determine whether a focused course delivered in Rwanda on critical care management improved knowledge in key areas. Our retrospective study on results from a multiple choice question test and survey indicate that short courses may improve knowledge of critical care management.

Regulation of clustered gene expression by cofactor of BRCA1 (COBRA1) in breast cancer cells.

Eucaryotic genes that are coordinately expressed tend to be clustered. Furthermore, gene clusters across chromosomal regions are often upregulated in various tumors. However, relatively little is known about how gene clusters are coordinately expressed in physiological or pathological conditions. Cofactor of BRCA1 (COBRA1), a subunit of the human negative elongation factor, has been shown to repress estrogen-stimulated transcription of trefoil factor 1 (TFF1 or pS2) by stalling RNA polymerase II. Here, we carried out a genome-wide study to identify additional physiological target genes of COBRA1 in breast cancer cells. The study identified a total of 134 genes that were either activated or repressed upon small hairpin RNA-mediated reduction of COBRA1. Interestingly, many COBRA1-regulated genes reside as clusters on the chromosomes and have been previously implicated in cancer development. Detailed examination of two such clusters on chromosome 21 (21q22) and chromosome X (Xp11) reveals that COBRA1 is physically associated with a subset of its regulated genes in each cluster. In addition, COBRA1 was shown to regulate both estrogen-dependent and -independent transcription of the gene cluster at 21q22, which encompasses the previously identified COBRA1-regulated TFF1 (pS2) locus. Thus, COBRA1 plays a critical role in the regulation of clustered gene expression at preferred chromosomal domains in breast cancer cells.

Nucleotide sequence and derived amino acid sequence of a cDNA encoding human muscle carbonic anhydrase.

We report the nucleotide (nt) sequence of a full length cDNA clone, pCA15, which encodes the human muscle-specific carbonic anhydrase, CAIII. pCA15 identifies a 1.7-kb mRNA, which is present at high levels in skeletal muscle, at much lower levels in cardiac and smooth muscle and which appears to be developmentally regulated. The CAIII mRNA is distinguished by a 887-nt long 3'-untranslated region, containing two AAUAAA signal sequences and is longer than either of the mRNAs encoding the erythrocyte CAs, CAI and CAII, which each have relatively shorter 3'-untranslated regions, 360 and 670 nt long, respectively. The derived amino acid (aa) sequence for human CAIII shows 85% homology with ox CAIII, 62% homology with human CAII and 54% with human CAI when simple pairwise aa comparisons are made. We describe an allelic variation at a TaqI restriction site for CAIII which occurs at high frequency in the European population.

24-hour lung preservation: simplified versus conventional University of Wisconsin solution in a porcine model.

BACKGROUND: Experimentally, the University of Wisconsin solution (UW) has been shown to be superior to the EuroCollins solution (EC) for lung graft preservation. We showed previously that the inclusion of the trisaccharide raffinose as an impermeant in the UW is largely responsible for this superiority. In this study, we used a new porcine model of isolated lung reperfusion to evaluate the use of a simple solution of phosphate-buffered raffinose (PBr) for lung preservation. METHODS: Lungs were stored for 24 hr at 4 degrees C after a single pulmonary artery flush with either UW (n = 5) or PBr (n = 5) solution. Left lungs were ventilated with room air and reperfused for 4 hr by venovenous extracorporeal circulation from a support animal. Controls (n = 5) were flushed with UW and reperfused without storage. RESULTS: Control lungs performed better than those stored in either solution in terms of oxygenation (P = 0.034) and airway pressure (P = 0.032). There were no significant differences between the two stored groups for any parameters. Data for stored lungs after 4 hr of reperfusion (means with 95% confidence intervals) include oxygenation (mm Hg): control 101.6 (14.5), UW 85.2 (14.5), PBr 75.0 (14.5); blood flow (ml/ min): control 572 (90), UW 466 (90), PBr 468 (90); peak airway pressure (mm Hg): control 15.9 (3.0), UW 21.0 (3.0), PBr 22.6 (3.0); pulmonary artery pressure (mm Hg): control 17.5 (3.2), UW 22.3 (2.9), PBr 24.5 (2.9). Graft edema (percentage tissue water): control 86.4 (0.8), UW 89.9 (1.8), PBr 89.3 (1.0). CONCLUSION: PBr is a far simpler and less expensive alternative to UW, and appears to provide a similar level of lung graft protection.

Lung graft preservation. Comparison of phosphate-buffered sucrose, modified EuroCollins, and University of Wisconsin solutions.

Phosphate-buffered sucrose (PBS) has been shown to be highly effective for renal graft storage. It may, therefore, be useful for lung graft storage. Recent studies have suggested a possible role for University of Wisconsin (UW) solution in lung preservation. The object of this study was to evaluate these two solutions in comparison with EuroCollins (EC) solution for lung graft preservation in an isolated rat lung model. Lungs were stored for 6 hr at 4 degrees C after a single pulmonary artery flush with either PBS with prostacyclin (n = 10), EC with prostacyclin (n = 5), or UW (n = 5) solution. Reperfusion of the isolated lung was carried out for 1 hr using a venovenous extracorporeal circulation from a ventilated support rat. The support animals and isolated lungs were ventilated with room air. Control values were obtained from lungs reperfused immediately after harvesting (n = 5). At 1 hr, PBS provided a similar level of protection to EC: pO2, 45 +/- 10 mmHg and 54 +/- 6 mmHg; graft blood flow, 4.1 +/- 1.2 ml/min and 3.5 +/- 0.42 ml/min; peak airway pressure, 32 +/- 2.5 mmHg and 36 +/- 3.6 mmHg; weight gain, 4.1 +/- 0.6 g and 4.2 +/- 0.6 g, respectively (P = NS). However, the UW group provided superior function, which was similar to the control group: pO2, 128 +/- 2.7 mmHg and 126 +/- 5 mmHg; graft blood flow, 9.9 +/- 0.4 ml/min and 10.2 +/- 0.8 ml/min; peak airway pressure, 17.6 +/- 0.4 mmHg and 16.5 +/- 0.6 mmHg; weight gain, 0.12 +/- 0.1 g and 0.19 +/- 0.13 g, respectively (P = NS). UW was superior in all parameters to PBS and EC (P < 0.001). This suggests that the renal solutions PBS and EC are inappropriate for lung graft preservation, and that the requirements of the lung during hypothermic storage differ from those of the kidney.

Modulation of lung reperfusion injury by nitric oxide: impact of inspired oxygen fraction.

BACKGROUND: Attempts to attenuate lung reperfusion injury by administration of inhaled nitric oxide have yielded conflicting results. We hypothesized that the inspired oxygen fraction may play an important role in determining the outcome of nitric oxide therapy. METHODS: Rat lungs were reperfused in a circuit incorporating a support animal either immediately after flushing (group A) or after 24-hr hypothermic storage (groups B-D). During the first 10 min of reperfusion, grafts were ventilated with 95% oxygen in groups A and B, 95% oxygen and 20 ppm nitric oxide in group C, and 20% oxygen and 20 ppm nitric oxide in group D. Ventilation during the subsequent 50 min of reperfusion was with 100% oxygen only, in all groups. RESULTS: Graft function in group B was poor compared to group A in terms of blood flow and pulmonary artery and peak airway pressures. In group C, although 5 out of 10 grafts functioned at control levels, the remainder performed poorly. Function in group D, on the other hand, was uniformly good. CONCLUSIONS: Inhaled nitric oxide can prevent lung reperfusion injury, but this effect may be compromised by concurrent ventilation with high oxygen concentrations.

Comparison of saccharides as osmotic impermeants during hypothermic lung graft preservation.

We have previously shown that the trisaccharide raffinose is largely responsible for the superior lung graft performance seen after storage in University of Wisconsin solution. To investigate the use of osmotic agents in perfusates for hypothermic lung graft storage, we compared saccharides of various molecular weights in an isolated rat lung model. Grafts were flushed with 1 of 6 preservation solutions (n=5 each group) containing either a monosaccharide (glucose [G] or fructose [F]), disaccharide (trehalose [T] or sucrose [S]), or trisaccharide (raffinose [R] or melezitose [M]. Grafts were stored for 6 hours at 4 degrees C, reperfused by a veno-venous circuit from an anesthetized support animal for 60 min, and ventilated with room air. The best graft function was seen when trisaccharides were used (PO2; R 126 +/- 3 mm Hg, M 129 +/- 3 mm Hg, blood flows: R 10.2 +/- 0.42 ml/min, M 10.3 +/- 0.22 ml/min). Disaccharides produced similar oxygenation (T 133 +/- 3 mm Hg, S 129 +/- 3 mm Hg) and flows (T 10.3 +/- 0.29 ml/min, S 9.7 +/- 0.4 ml/min) at 60 min, but initial flows were reduced. Monosaccharides produced the least satisfactory graft function, with impaired oxygenation (F 110 +/- 14 mm Hg, P<0.05; G 69 +/- 10 mm Hg, P<0.01) and blood flows (G 6.5 +/- 0.6 ml/min, F 9.1 +/- 0.6 ml/min, P<0.01 each). Only glucose-stored lungs demonstrated a significant decrease in compliance (P<0.01) and weight gain (P<0.01). The worst results were seen with glucose, which is the osmotic agent most commonly used for clinical lung storage. A solution containing a trisaccharide or disaccharide may be more appropriate for this purpose.

ABO genotyping of complete hydatidiform moles.

It has been suggested that the ABO blood group of a patient and her partner influence the clinical outcome for patients having a pregnancy with a complete hydatidiform mole (CHM). Since CHM lack red blood cells, it has not previously been possible to type CHM serologically and investigate the relationship between the blood group of the CHM and that of the patient. In the present study we have demonstrated the feasibility of using molecular genotyping to determine the ABO genotype of CHM, the ABO genotype being consistent with the androgenetic origin of CHM in all cases. In the series of 48 cases of CHM, the requirement for chemotherapy was not significantly different in those patients with a CHM of like blood group compared with those with a CHM of unlike blood group.

Raffinose improves the function of rat pulmonary grafts stored for twenty-four hours in low-potassium dextran solution.

OBJECTIVES: The perfect strategy for pulmonary graft preservation remains elusive. Experimental work supports the use of perfusates, such as Euro-Collins, University of Wisconsin, and low-potassium dextran solutions. We use low-potassium dextran solution in our clinical program, but we aim for continued improvement. The trisaccharide raffinose has been shown to be responsible for the efficacy of University of Wisconsin perfusate in lung preservation. Raffinose is superior to a variety of other saccharides for this purpose. We tested the hypothesis that the addition of raffinose to low-potassium dextran solution might further improve graft function. METHODS: In a randomized blinded study with a rat left lung transplant model, donor lungs were flushed with either standard low-potassium dextran solution or low-potassium dextran solution modified by the addition of 30 mmol/L raffinose (n = 5 for each group). Alprostadil (prostaglandin E(1), 500 microg/L) was added to the perfusates in accordance with our clinical practice. Grafts were stored inflated at 4 degrees C for 24 hours. After transplantation, recipients were ventilated with a fraction of inspired oxygen of 1 and a positive end-expiratory pressure of 2 cm H(2)O. Graft function was evaluated by measuring oxygenation at 2 hours after graft reperfusion, peak airway pressure throughout the reperfusion period, and the wet/dry lung weight ratio. RESULTS: The group receiving low-potassium dextran solution with raffinose demonstrated significantly higher oxygenation (oxygen tension, 370 +/- 45 mm Hg vs 150 +/- 64 mm Hg; P =.0025), lower peak airway pressures at 2 hours after lung reperfusion (11 +/- 2.7 mm Hg vs 16 +/- 2.4 mm Hg; P <.001), and a lower wet/dry weight ratio (4.7 +/- 1.26 vs 11 +/- 5. 0; P =.017). CONCLUSION: Modification of low-potassium dextran solution with the trisaccharide raffinose resulted in a significant improvement in graft function in this model and merits further evaluation with respect to the mechanisms involved.

Attenuation of lung graft reperfusion injury by a nitric oxide donor.

OBJECTIVE: One of the primary features of ischemia-reperfusion injury is reduced production of protective autocoids, such as nitric oxide, by dysfunctional endothelium. Administration of a nitric oxide donor during reperfusion of lung grafts may therefore be beneficial through modulation of vascular tone and leukocyte and platelet function. METHODS: Rat lung grafts were flushed with University of Wisconsin solution and reperfused for 1 hour in an ex vivo model incorporating a support animal. Group I grafts (n = 6) were reperfused immediately after explantation, group II (n = 6) and III (n = 5) grafts after 24 hours of storage at 4 degrees C. In group III, glyceryl trinitrate, a nitric oxide donor, was administered during the first 10 minutes of reperfusion at a rate of 200 micrograms/min. In an additional group (n = 5), 200 micrograms/min hydralazine was administered instead, to assess the effect of vasodilation alone. RESULTS: Graft function in group II deteriorated compared with that in group I, with significant reduction of graft effluent oxygen tension and blood flow and elevation of pulmonary artery pressure, peak airway pressure, and wet/dry weight ratio. In contrast, in group III, glyceryl trinitrate treatment improved graft function to baseline levels in all these parameters. Administration of hydralazine, meanwhile, produced mixed results with only two out of five grafts functioning at control levels. CONCLUSIONS: In this model, administration of glyceryl trinitrate to supplement the nitric oxide pathway in the early phase of reperfusion has a sustained beneficial effect on lung graft function after 24-hour hypothermic storage, probably through mechanisms beyond vasodilation alone.

Pulmonary graft preservation: a worldwide survey of current clinical practice.

BACKGROUND: Flush perfusion of pulmonary grafts with cold modified EuroCollins solution supplemented by prostaglandin treatment was introduced clinically 10 years ago. Primary graft failure remains a major cause of morbidity and death after lung transplantation. During the last decade, much experimental work has led to reports of alternative storage solutions, differing storage conditions, and pharmacologic interventions that improve pulmonary graft performance. It is unclear how these findings have influenced current clinical practice. METHODS: A worldwide survey of the 125 centers performing lung transplantation was conducted by questionnaire. RESULTS: One hundred twelve replies were received (90%). Most centers (n = 86) continue to use EuroCollins solution (77%), of whom 69% include prostaglandin therapy and 32% donor steroid treatment. University of Wisconsin solution (UW) is used by 15 centers (13.5%), of which 10 (67%) use prostaglandin and seven (47%) use donor steroids. Nine centers use Papworth solution and one uses donor core cooling. The volume of flush used varied widely, from 20 to 120 ml/kg, with median volumes of 60, 60, and 30 ml/kg in centers using EuroCollins, UW, and Papworth solutions, respectively. Two thirds of centers using EuroCollins solution store grafts at 0 degrees to 5 degrees C, and one third at 5 degrees to 10 degrees C. One center that uses EuroCollins solution stores grafts at 10 degrees to 15 degrees C. Centers using UW solution are evenly split at 0 degrees to 5 degrees C and 5 degrees to 10 degrees C. Most centers that use Papworth solution store grafts at 5 degrees to 10 degrees C. Only six centers use superoxide radical scavengers. The maximum ischemic period accepted by centers varies from 4 to 12 hours, with median periods of 8, 7, 6, and 6 hours for the UW, EuroCollins, Papworth, and donor core cooling centers, respectively. All but one of the UW centers (93%) expressed satisfaction with the quality of graft preservation achieved by UW solution. Only 58 of the 86 centers using EuroCollins solution (67%) were satisfied. Six of nine centers using Papworth solution were satisfied. CONCLUSIONS: There has been a trend toward the use of UW solution and a slightly warmer storage temperature. However, for most centers, graft storage techniques have changed little over the last decade.

University of Wisconsin solution for lung graft preservation: which components are important?

Rat lung grafts were perfused with either Euro-Collins solution, University of Wisconsin solution, or one of six modified University of Wisconsin solutions that had been sequentially depleted of specific components (n = 5 each group). After storage at 4 degrees C for 6 hours, the isolated, ventilated pulmonary graft was reperfused for 1 hour with recirculating venous blood from a support animal. In a further group, lungs were reperfused immediately after explanation to provide control values. Grafts flushed with University of Wisconsin solution functioned at control levels with regard to oxygen tension: University of Wisconsin solution 128 +/- 2.7 mm Hg, control 126 +/- 5 mm Hg; graft blood flow: University of Wisconsin solution 9.9 +/- 0.4 ml/min, control 10.2 +/- 0.8 ml/min; peak airway pressure: University of Wisconsin solution 17 +/- 0.5 mm Hg, control 16.5 +/- 0.6 mm Hg; and weight gain: University of Wisconsin solution 0.12 +2- 0.1 gm, control 0.19 +/- 0.13 gm. In contrast, lungs treated with Euro-Collins solution functioned less well: oxygen tension 54 +/- 6 mm Hg, graft blood flow 3.5 +/- 0.42 ml/min, peak airway pressure 35 +/- 4 mm Hg, and weight gain 4.15 +/- 0.5 gm (p < 0.0001 all parameters). Sequential removal of hydroxyethyl starch, magnesium, allopurinol, adenosine, glutathione, and lactobionate from University of Wisconsin solution did not impair the efficacy of the solution.(ABSTRACT TRUNCATED AT 250 WORDS)

Controlled pressure reperfusion of rat pulmonary grafts yields improved function after twenty-four-hours' cold storage in University of Wisconsin solution.

BACKGROUND: Pulmonary graft recipients commonly have a degree of pulmonary hypertension. Immediate reperfusion of stored pulmonary grafts at supraphysiologic or even physiologic pressures may be detrimental to subsequent function. We wished to test the hypothesis that initial reperfusion of pulmonary grafts at low pressures may be beneficial. METHODS: We used an isolated, ventilated rat lung model, perfused by an extracorporeal veno-venous circuit from a support animal. Three groups of donor lungs (n = 5 each) were flushed with cold University of Wisconsin solution. Group I was reperfused immediately at physiologic pressure to provide control values. Group II grafts were stored at 4 degrees C for 24 hours and reperfused at physiologic pressure. Group III grafts were also stored at 4 degrees C for 24 hours but reperfused according to a protocol of reduced pressure initially, with increments every 15 minutes up to physiologic levels by 60 minutes. Grafts and support animals were ventilated with room air. Graft function was assessed over a 2-hour period with regard to oxygenation, vascular resistance, peak airway pressure, and the wet/dry weight ratio. RESULTS: Grafts in group II functioned poorly at 2 hours compared with control values: group II: oxygen tension 68 +/- 4 mm Hg; pulmonary vascular resistance 2488 +/- 675 x 10(3) dyne.sec/cm5; peak airway pressure 32 +/- 1 mm Hg wet/dry wright ratio 9.1 +/- Group I: oxygen tension 136 +/- 2 mm Hg; pulmonary vascular resistance 120 +/- 3 x 10(3) dyne.sec/cm5; peak airway pressure 13 +/- 1 mm Hg and wet/dry weight ratio 3.6 +/- 0.3; p < 0.001 all parameters except pulmonary vascular resistance: p < 0.05. In contrast, grafts undergoing controlled pressure reperfusion (group III) achieved function comparable with baseline values at 2 hours: oxygen tension 137 +/- 3 mm Hg; pulmonary vascular resistance 132 +/- 7 x 10(3) dyne. sec/cm5; peak airway pressure 13 +/- 1 mm Hg; wet/dry weight ratio 4.1 +/- 0.3 (p = Not significant). CONCLUSIONS: The pressure at which pulmonary grafts are initially reperfused appears to be critical to their subsequent integrity. A protocol of controlled reperfusion may reduce reperfusion injury and improve graft function in clinical practice.

Critical importance of the first 10 minutes of lung graft reperfusion after hypothermic storage.

BACKGROUND: We have shown previously that lung graft function can be improved by achieving reperfusion with stepwise increments of perfusion pressure over 60 minutes. This study aimed to establish whether similar benefit could be achieved with a shorter, simpler protocol and different storage conditions. METHODS: Rat lungs were flushed with University of Wisconsin or modified Euro-Collins solution and reperfused for 1 hour with blood from a support animal. Grafts were reperfused immediately or after storage at 4 degrees C for 24 hours (University of Wisconsin solution) or 6 hours (Euro-Collins solution). Stored-graft reperfusion was initiated with a 0-, 5-, or 10-minute period during which reperfusion pressure was reduced by 50%. RESULTS: Stored grafts receiving 0 to 5 minutes of initial low-pressure reperfusion performed poorly, with reduced oxygenation and blood flow and elevated pulmonary artery pressure, airway pressure, and wet/dry weight ratio. In contrast, 10 minutes of initial 50%-pressure reperfusion yielded function comparable with that in controls with both storage conditions. CONCLUSIONS: An initial 10-minute period of 50%-pressure reperfusion improves the function of stored rat lung grafts, whereas 5 minutes is insufficient.

Relative importance of prostaglandin/cyclic adenosine monophosphate and nitric oxide/cyclic guanosine monophosphate pathways in lung preservation.

BACKGROUND: Modulation of vascular tone and platelet and neutrophil function through the prostaglandin/cyclic adenosine monophosphate or nitric oxide/cyclic guanosine monophosphate pathway can benefit lung graft function. The relative importance of these pathways is unclear. METHODS: Rat lung grafts (5 per group) were studied in an ex vivo reperfusion model. Group I grafts were pretreated with prostacyclin (20 ng.kg-1.min-1), flushed with cold Euro-Collins solution containing prostacyclin (200 micrograms/L), and reperfused immediately for 1 hour. Group II grafts were similarly procured but were stored at 4 degrees C for 6 hours before reperfusion. In group III, no prostacyclin therapy was used; instead, the nitric oxide donor glyceryl trinitrate (0.1 mg/mL) was added to the flush/storage solution, and the grafts were stored for 6 hours. RESULTS: Group II grafts performed poorly compared with those in group I, with substantial deterioration of oxygenation and blood flow and elevation of pulmonary artery pressure, peak airway pressure, and wet to dry weight ratio. In contrast, graft function in group III was similar to that in controls. CONCLUSIONS: Lung graft integrity after storage in Euro-Collins solution was better preserved by glyceryl trinitrate than by prostacyclin in this model.

Raffinose improves 24-hour lung preservation in low potassium dextran glucose solution: a histologic and ultrastructural analysis.

BACKGROUND: We have previously shown that the addition of raffinose to low potassium dextran (LPD) preservation solution improves transplanted rat lung function after 24 hours of storage. The mechanisms by which raffinose acts are unclear. The aim of this study was to examine the histologic and ultrastructural correlates of this enhanced pulmonary function after preservation with raffinose. METHODS: In a randomized, blinded study, rat lungs were flushed with LPD, or LPD containing 30 mmol/L of raffinose, and stored for 24 hours at 4 degrees C. Control lungs were flushed with LPD but not stored (n = 5 each group). Changes in postpreservation edema were determined. In addition, lungs were flushed with a trypan blue solution to quantify cell death, and examined using both light and electron microscopy. RESULTS: The LPD lungs gained significantly more weight (25.5%+/-5.5%) compared with raffinose-LPD lungs (5.2%+/-5.3%; p < 0.0001). There were higher percentages of dead cells in the LPD lungs (29%+/-0.3% of total cells) compared with raffinose-LPD lungs (14%+/-1.4%; p < 0.001) and control lungs (0.2%+/-5%; p < 0.001). Control lungs maintained normal ultrastructure, whereas LPD lungs showed a decreased number of intact type II pneumocytes and significant cellular necrosis. Interstitial and alveolar edema with interstitial macrophage infiltration was also observed. Alveolar capillaries were collapsed. In contrast, raffinose-LPD lungs showed only mild alterations such as minimal interstitial edematous expansion, fewer damaged cells, and minimal capillary injury. CONCLUSIONS: Raffinose exerts a cytoprotective effect on pulmonary grafts during preservation, which explains the previously documented improved function. This simple modification of LPD with raffinose may provide clinical benefit in extended pulmonary preservation.

Controlled reperfusion protects lung grafts during a transient early increase in permeability.

BACKGROUND: We have previously shown that an initial 10-minute period of low-pressure reperfusion prevents the lung graft dysfunction that follows physiologic-pressure reperfusion. Possible mechanisms were investigated in this study. METHODS: Rat lungs were reperfused ex vivo using a parabiotic animal after 0-hour (groups A through C) or 24-hour (groups D through G) storage. Reperfusion pressure was either physiologic (groups A through D) or reduced by 50% for a specified time (groups E through G). The duration of reperfusion was 5 minutes (groups A, D, and E), 10 minutes (groups B and F), or 30 minutes (groups C and G), at which time endothelial permeability was measured through iodine 125-labeled albumin leakage and neutrophil sequestration through tissue myeloperoxidase activity. RESULTS: Graft function in group D deteriorated rapidly, whereas groups E through G performed at control levels. Albumin leakage was significantly elevated in group D; with controlled reperfusion, it was elevated after 5 minutes (group E) but had returned to baseline at 10 minutes (group F) and 30 minutes (group G). Myeloperoxidase levels were not significantly different between groups. CONCLUSIONS: Endothelial permeability is transiently elevated in the early phase of lung graft reperfusion. Initial low-pressure reperfusion may be protective by preventing irreversible edema formation during this period.

Low-dose nitric oxide inhalation during initial reperfusion enhances rat lung graft function.

BACKGROUND: In ischemia-reperfusion injury, the production of nitric oxide by dysfunctional endothelium falls rapidly within minutes of the onset of reperfusion. Replenishment during this critical early period using inhaled nitric oxide may benefit lung grafts through modulation of vascular tone, endothelial permeability, neutrophil and platelet function, and availability of reactive oxygen species. METHODS: Rat lung grafts were flushed with 60 mL/kg cold University of Wisconsin solution and were reperfused either immediately (group I, n = 5) or after 24-hour 4 degrees C storage (groups II and III, n = 5 each), for 60 minutes in an ex vivo model incorporating a support animal. Graft ventilation was with room air. In group III, 20 parts per million inhaled nitric oxide was added during the initial 10 minutes of reperfusion, whereas in groups I and II, equivalent flows of nitrogen were added to standardize oxygen concentration. RESULTS: Compared with group I, graft function in group II was poor, with reductions in oxygenation and blood flow and elevations of mean pulmonary artery pressure, peak airway pressure, and wet to dry weight ratio. In contrast, during nitric oxide inhalation in group III, graft function improved to control levels. This improvement was subsequently sustained throughout the reperfusion period. CONCLUSIONS: Low-dose inhaled nitric oxide administration in the early phase of reperfusion of stored lung grafts can yield sustained improvement in function. There may be a role for inhaled nitric oxide in the prevention of reperfusion injury in transplanted lungs.