Bacterial cell wall polymers (peptidoglycan-polysaccharide) cause reactivation of arthritis.

Intraperitoneal (i.p.) injection of peptidoglycan-polysaccharide derived from group A streptococci (PG-APS) causes chronic arthritis with spontaneous remissions and exacerbations. We hypothesized that, following i.p. injection, PG-APS released from hepatic stores mediated spontaneous recurrences of arthritis. We tested whether transplanted livers with large amounts of PG-APS were able to reactivate quiescent arthritis. Saline-loaded (group 1) or PG-APS-loaded (group 2) livers were transplanted into rats which had been injected intra-articularly 10 days earlier with PG-APS in one joint and saline in the other. A comparison was made with the arthritis that occurred in rats injected i.p. with PG-APS which did not receive transplants (group 3). Arthritis was monitored by serial measurement of joint diameters. Transplantation of saline-loaded livers (group 1) caused no reactivation of arthritis. However, transplantation of PG-APS-loaded livers (group 2) reactivated arthritis (P < 0.0001). Injection of PG-APS i.p. (group 3) induced the most-severe arthritis. PG-APS levels in plasma decreased with time, and PG-APS accumulated in the spleen in groups 2 and 3. Plasma and hepatic levels of PG-APS in rats injected i.p. with PG-APS were greater than levels in rats transplanted with PG-APS-loaded livers, which in turn were greater than levels in rats with saline-loaded livers. Plasma tumor necrosis factor did not correlate with recurrence of arthritis. Transplantation with PG-APS-loaded livers induced reactivation of arthritis in preinjured joints. The extent of arthritis was proportional to hepatic PG-APS content. Reactivation of arthritis may be mediated by slow release of liver-sequestered PG-APS or cytokines (not tumor necrosis factor) released by the liver

Modulating mitophagy in mitochondrial disease

Mitochondrial diseases may result from mutations in the maternally-inherited mitochondrial DNA (mtDNA) or from mutations in nuclear genes encoding mitochondrial proteins. Their bi-genomic nature makes mitochondrial diseases a very heterogeneous group of disorders that can present at any age and can affect any type of tissue. The autophagic-lysosomal degradation pathway plays an important role in clearing dysfunctional and redundant mitochondria through a specific quality control mechanism termed mitophagy. Mitochondria could be targeted for autophagic degradation for a variety of reasons including basal turnover for recycling, starvation induced degradation, and degradation due to damage. While the core autophagic machinery is highly conserved and common to most pathways, the signaling pathways leading to the selective degradation of damaged mitochondria are still not completely understood. Type 1 mitophagy due to nutrient starvation is dependent on PI3K (phosphoinositide 3-kinase) for autophagosome formation but independent of mitophagy proteins, PINK1 (PTEN-induced putative kinase 1) and Parkin. Whereas type 2 mitophagy that occurs due to damage is dependent on PINK1 and Parkin but does not require PI3K. Autophagy and mitophagy play an important role in human disease and hence could serve as therapeutic targets for the treatment of mitochondrial as well as neurodegenerative disorders. Therefore, we reviewed drugs that are known modulators of autophagy (AICAR and metformin) and may effect this by activating the AMP-activated protein kinase signaling pathways. Furthermore, we reviewed data available on supplements, such as Coenzyme Q and the quinone idebenone, that we assert rescue increased mitophagy in mitochondrial disease by benefiting mitochondrial function

Studies of rat lung viability and adenine nucleotide metabolism after death.

BACKGROUND: Prior studies from our laboratory have supported the use of cadaveric lungs for transplantation. In this study we investigated different preservation strategies for lungs retrieved from cadavers 4 hours after circulatory arrest. METHODS: Seventy-two Sprague-Dawley rats were sacrificed and then ventilated with 100% oxygen for 4 hours. The lungs were then flushed with modified Euro-Collins, University of Wisconsin, or Carolina rinse solution, either alone, with prostaglandin E1, or with prostaglandin E1 plus the free radical scavenger dimethylthiourea. After an additional 4-hour cold storage, the left lung was flushed with trypan blue solution to quantify cell viability, whereas the right lung was used to determine wet-to-dry weight ratios and to measure the levels of the adenine nucleotides adenosine triphosphate, adenosine diphosphate, and adenosine monophosphate by high-performance liquid chromatography. RESULTS: Viability was consistently better in the lungs flushed with Carolina rinse solution; these differences were statistically significant compared with those in the corresponding modified Euro-Collins subgroups (p < 0.005). The addition of prostaglandin E1 to all three preservation solutions improved the total adenine nucleotide levels; this increase was statistically significant for the modified Euro-Collins subgroup (p < 0.005). The total adenine nucleotide levels for the University of Wisconsin subgroups were higher than those for the corresponding modified Euro-Collins subgroups. The highest total adenine nucleotide levels were obtained in lungs flushed with Carolina rinse plus prostaglandin E1. Wet-to-dry weight ratios were always significantly lower in the lungs preserved with University of Wisconsin solution (p < 0.05), with a value similar to that of fresh tissue. CONCLUSIONS: The characteristics of the solution used to flush and to store rat cadaveric lungs have an impact on lung viability and adenine nucleotide metabolism. The ideal preservation strategy may allow for lung retrieval from cadavers for safe transplantation

Lung retrieval from cadaver donors with nonbeating hearts: optimal preservation solution.

BACKGROUND: We have previously studied the time course of pulmonary cell viability, ultrastructural damage, and adenine nucleotide metabolites after circulatory arrest in a rat model to investigate the feasibility of lung retrieval for transplantation from cadavers. This study was designed to investigate the effect of hypothermic flush and subsequent 4-hour storage with either modified Euro-Collins or University of Wisconsin solution on lungs retrieved 4 hours after death. METHODS: Ninety-six Sprague-Dawley rats were sacrificed by intraperitoneal injection of pentobarbital. Control lungs were flushed immediately after sacrifice and stored for 4 hours. Rats in the experimental groups were sacrificed, and then their lungs were either ventilated with 100% oxygen or not ventilated for 4 hours before flushing with either Euro-Collins or University of Wisconsin solution followed by 4-hour hypothermic storage. At the end of the storage period, all right lungs were maintained at -70 degrees C and used to determine wet-to-dry weight ratios and adenine nucleotide levels with high-pressure liquid chromatography. Left lungs were assessed for viability with trypan blue dye exclusion. The effect on viability of flushing with Carolina rinse solution after storage was also assessed. RESULTS: The percentage of viable cells in the control group after 4-hour hypothermic storage was 74% +/- 2% in Euro-Collins solution-flushed lungs and 78% +/- 2% in University of Wisconsin solution-flushed lungs. This result was virtually identical to that of lungs retrieved after 4 hours of in situ oxygen ventilation followed by 4 hours of hypothermic storage. Nonventilated cadaver lungs had substantially less viability. Adenosine triphosphate levels were significantly higher in the control group than in the oxygen-ventilated group, which were higher still than those in the nonventilated group. Adenosine triphosphate levels were consistently higher in University of Wisconsin solution-flushed lungs compared with Euro-Collins solution-flushed lungs in all groups. Total adenine nucleotide levels had a similar pattern. Wet-to-dry ratios were significantly lower in the control group (Euro-Collins = 6.27 +/- 0.46, University of Wisconsin = 4.63 +/- 0.07) compared with the oxygen-ventilated (Euro-Collins = 9.80 +/- 0.44, University of Wisconsin = 10.96 +/- 0.60) and nonventilated (Euro-Collins = 9.44 +/- 0.26, University of Wisconsin = 11.54 +/- 1.16; p < 0.0001) groups. CONCLUSIONS: Four hours of circulatory arrest before 4 hours of hypothermic storage had no additional adverse impact on lung viability compared with lungs subjected to 4 hours of hypothermic storage alone, provided nonperfused lungs were ventilated with 100% oxygen. Adenine nucleotide levels were well maintained in oxygen-ventilated cadaver lungs, more so in University of Wisconsin solution-flushed lungs compared with Euro-Collins solution-flushed lung

When does the lung die? I. Histochemical evidence of pulmonary viability after 'death'

An inadequate number of lung donors for transplantation results in the death of many potential lung recipients awaiting a transplant. Canine experiments in our laboratory have shown effective gas exchange in lungs transplanted from cadaver donors (lungs retrieved after circulatory arrest). The time course of pulmonary cell death after circulatory arrest is unknown. To address this question, we used trypan blue dye exclusion to quantitate lung cell death at postmortem intervals in rats. One hundred ninety Sprague-Dawley rats were killed and separated into four groups: (1) control (n = 10); (2) nonventilated group (n = 60); (3) oxygen-ventilated group (n = 80); and (4) nitrogen-ventilated group (n = 40). At intervals after the animals' deaths, trypan blue was infused into the pulmonary artery followed by fixative, and the left lung was excised. Histologic sections were prepared for each rat lung, and the percentage of nonviable cells was quantified with light microscopy. Control lungs retrieved immediately after death showed little or no uptake of trypan blue dye. In nonventilated rats, 36%, 52%, and 77% of cells were nonviable in lungs retrieved 2, 4, and 12 hours after death, respectively. These results were similar to 34%, 58%, and 71% nonviability at the same intervals in nitrogen-ventilated cadaver rat lungs. Oxygen-ventilated cadaver rats, however, had significantly fewer nonviable lung cells at each time interval: 13%, 10%, and 26%, respectively (p < 0.01). Thus, postmortem mechanical ventilation with oxygen appears to delay lung death in the rat after circulatory arrest. Nonventilated and nitrogen-ventilated cadaver lungs had a similar severity and progression of ischemic injury

Donor lungs from ventiled cadavers: impact of a free radical scavenger.

BACKGROUND: The shortage of donors for lung transplantation may be alleviated with the use of lungs retrieved from cadavers. The purpose of this study was to determine whether a free radical scavenger, dimethylthiourea, would improve the function of lungs retrieved from ventilated cadavers. METHODS: Left lung transplantation was performed in 21 dogs. Donors were sacrificed then ventilated with 100% oxygen. After 2 hours, donor lungs were flushed in a blinded fashion with 2 L of modified Euro-Collins solution, with either dimethylthiourea (n = 10) or saline solution (n = 11) added, then harvested. A donor right lung lobe was perfused with trypan blue vital dye to assess cell viability at harvest and after the transplantation. Percentage of nonviability was similar in the dimethylthiourea and control groups (13 versus 20 at retrieval and 38 versus 41 at graft reperfusion). After transplantation, the right pulmonary artery and bronchus were occluded, rendering the recipient on the pulmonary graft. The recipient's lungs were ventilated for 8 hours, with the inspired oxygen fraction maintained at 0.4. RESULTS: Seven of ten dogs in the dimethylthiourea group survived the 8-hour period, compared with 4 of 11 dogs in the control group. Compared with the control survivors (n = 4) at 8 hours after the operation, the dimethylthiourea survivors (n = 7) had a higher mean arterial oxygen pressure (144 +/- 21 versus 98+/- 12 mm Hg) and cardiac output (2.2 +/- 0.2 versus 1.6 +/- 0.2 L/min) and a lower mean pulmonary vascular resistance (946 +/- 96 versus 1414 +/- 128 dynes.sec-1.cm5, p < 0.05) and extravascular lung water (10.6 +/- 1.2 versus 12.3 +/- 3.2 ml/kg). Differences between groups during the 8-hour period were usually insignificant. CONCLUSIONS: This model imposes a rigorous challenge to the single transplanted lung, and yet cadaver lungs still supported life in half of the recipients. Dimethylthiourea may confer a benefit to recipients of cadaver lungs

When does the lung die? Time course of hight energy phosphate depletion and relationship to lung viability after 'death'.

The shortage of lung donors for clinical transplantation could be significantly alleviated if lungs could be retrieved from cadavers hours after death. However, the time course of loss of lung viability after circulatory arrest and organism death remains unclear. To determine postmortem adenine nucleotide tissue levels in the lung and their relationship to lung viability, Sprague-Dawley rats were sacrificed and then ventilated with 100% oxygen (n = 50, O2) or 100% nitrogen (n = 40, N2) or left nonventilated (n = 50). Lungs from control rats (n = 20) were retrieved immediately after sacrifice. Lungs in the three study groups were retrieved at successive intervals postmortem. Adenine nucleotides (ATP, ADP, and AMP) and hypoxanthine and xanthine metabolites of adenosine were extracted from lung tissue and measured using high-performance liquid chromatography. Pulmonary parenchymal cell viability was quantified by pulmonary artery infusion of trypan blue vital dye in the contralateral lung of each animal. By 4 hr postmortem, viability was 85 +/- 1% in the O2-ventilated cadaver rat lungs, significantly higher than in the N2-ventilated (43 +/- 8%) and in the nonventilated (48 +/- 4%) lungs, where the percentage of viable cells was similar. All of the groups showed a time-dependent decrement in ATP levels and total adenine nucleotide (TAN) levels after death, but this was markedly attenuated in O2-ventilated cadaveric rat lun