Administration of fructose 1,6-diphosphate during early reperfusion significantly improves recovery of contractile function in the postischemic heart

The Preoperative Inflammatory Status Affects the Clinical Outcome in Cardiac Surgery

AIMS

There are many reasons for the increase in post-operative mortality and morbidity in patients undergoing surgery. In fact, an activated inflammatory state before cardiac surgery, can potentially worsen the patient's prognosis and the effects of this preoperative inflammatory state in the medium-term remains unknown.

METHODS

There were 470 consecutive patients who underwent cardiac surgery, and were divided in three groups according to the median values of preoperative C-reactive protein (CRP) and fibrinogen (FBG): The first group was the low inflammatory status group (LIS) with 161 patients (CRP < 0.39 mg/dL and FBG < 366 mg/dL); the second was the medium inflammatory status group (MIS) with 150 patients (CRP < 0.39 mg/dL and FBG ≥ 366 mg/dL or CRP ≥ 0.39 mg/dL and FBG < 366 mg/dL,); and the third was the high inflammatory status group (HIS) with 159 patients (CRP ≥ 0.39 mg/dL and FBG ≥ 366 mg/dL,).

RESULTS

The parameters to be considered for the patients before surgery were similar between the three groups except, however, for age, left ventricular ejection fraction (LVEF) and the presence of arterial hypertension. The operative mortality was not significantly different between the groups (LIS = 2.5%, MIS = 6%, HIS = 6.9%, p = 0.16) while mortality for sepsis was significantly different (LIS = 0%, MIS = 1.3%, HIS = 3.7%, p = 0.03). The infections were more frequent in the HIS group (p = 0.0002). The HIS group resulted in an independent risk factor for infections (relative risk (RR) = 3.1, confidence interval (CI) = 1.2-7.9, p = 0.02). During the 48-months follow-up, survival was lower for the HIS patients. This HIS group (RR = 2.39, CI = 1.03-5.53, p = 0.05) and LVEF (RR = 0.96, CI = 0.92-0.99, p = 0.04) resulted in independent risk factors for mortality during the follow-up.

CONCLUSIONS

The patients undergoing cardiac surgery with a preoperative highly activated inflammatory status are at a higher risk of post-operative infections. Furthermore, during the intermediate follow-up, the preoperative highly activated inflammatory status and LVEF resulted in independent risk factors for mortality.

Current Issues and Perspectives in Patients with Possible Sepsis at Emergency Departments

In the area of Emergency Room (ER), many patients present criteria compatible with a SIRS, but only some of them have an associated infection. The new definition of sepsis by the European Society of Intensive Care Medicine and the Society of Critical Care Medicine (2016), revolutionizes precedent criteria, overcoming the concept of SIRS and clearly distinguishing the infection with the patient's physiological response from the symptoms of sepsis. Another fundamental change concerns the recognition method: The use of SOFA (Sequential-Sepsis Related-Organ Failure Assessment Score) as reference score for organ damage assessment. Also, the use of the qSOFA is based on the use of three objective parameters: Altered level of consciousness (GCS <15 or AVPU), systolic blood pressure ≤ 100 mmHg, and respiratory rate ≥ 22/min. If patients have at least two of these altered parameters in association with an infection, then there is the suspicion of sepsis. In these patients the risk of death is higher, and it is necessary to implement the appropriate management protocols, indeed the hospital mortality rate of these patients exceeds 40%. Patients with septic shock can be identified by the association of the clinical symptoms of sepsis with persistent hypotension, which requires vasopressors to maintain a MAP of 65 mmHg, and serum lactate levels >18 mg/dL in despite of an adequate volume resuscitation. Then, patient first management is mainly based on: (1) Recognition of the potentially septic patient (sepsis protocol-qSOFA); (2) Laboratory investigations; (3) Empirical antibiotic therapy in patients with sepsis and septic shock. With this in mind, the authors discuss the most important aspects of the sepsis in both adults and infants, and also consider the possible treatment according current guidelines. In addition, the possible role of some nutraceuticals as supportive therapy in septic patient is also discussed.

Current Issues and Perspectives in Patients with Possible Sepsis at Emergency Departments

In the area of Emergency Room (ER), many patients present criteria compatible with a SIRS, but only some of them have an associated infection. The new definition of sepsis by the European Society of Intensive Care Medicine and the Society of Critical Care Medicine (2016), revolutionizes precedent criteria, overcoming the concept of SIRS and clearly distinguishing the infection with the patient’s physiological response from the symptoms of sepsis. Another fundamental change concerns the recognition method: The use of SOFA (Sequential-Sepsis Related-Organ Failure Assessment Score) as reference score for organ damage assessment. Also, the use of the qSOFA is based on the use of three objective parameters: Altered level of consciousness (GCS <15 or AVPU), systolic blood pressure ≤ 100 mmHg, and respiratory rate ≥ 22/min. If patients have at least two of these altered parameters in association with an infection, then there is the suspicion of sepsis. In these patients the risk of death is higher, and it is necessary to implement the appropriate management protocols, indeed the hospital mortality rate of these patients exceeds 40%. Patients with septic shock can be identified by the association of the clinical symptoms of sepsis with persistent hypotension, which requires vasopressors to maintain a MAP of 65 mmHg, and serum lactate levels >18 mg/dL in despite of an adequate volume resuscitation. Then, patient first management is mainly based on: (1) Recognition of the potentially septic patient (sepsis protocol-qSOFA); (2) Laboratory investigations; (3) Empirical antibiotic therapy in patients with sepsis and septic shock. With this in mind, the authors discuss the most important aspects of the sepsis in both adults and infants, and also consider the possible treatment according current guidelines. In addition, the possible role of some nutraceuticals as supportive therapy in septic patient is also discussed.

Fructose-1,6-bisphosphate preserves glucose metabolism integrity and reduces reactive oxygen species in the brain during experimental sepsis

Sepsis is one of the main causes of hospitalization and mortality in Intensive Care Units. One of the first manifestations of sepsis is encephalopathy, reported in up to 70% of patients, being associated with higher mortality and morbidity. The factors that cause sepsis-associated encephalopathy (SAE) are still not well known, and may be multifactorial, as perfusion changes, neuroinflammation, oxidative stress and glycolytic metabolism alterations. Fructose-1,6-bisphosphate (FBP), a metabolite of the glycolytic route, has been reported as neuroprotective agent. The present study used an experimental sepsis model in C57BL/6 mice. We used in vivo brain imaging to evaluate glycolytic metabolism through microPET scans and the radiopharmaceutical ¹⁸F-fluoro-2-deoxy-D-glucose (¹⁸F-FDG). Brain images were obtained before and 12 h after the induction of sepsis in animals with and without FBP treatment. We also evaluated the treatment effects in the brain oxidative stress by measuring the production of reactive oxygen species (ROS), the activity of catalase (CAT) and glutathione peroxidase (GPx), and the levels of fluorescent marker 2'7'-dichlorofluorescein diacetate (DCF). There was a significant decrease in brain glucose metabolism due to experimental sepsis. A significant protective effect of FBP treatment was observed in the cerebral metabolic outcomes. FBP also modulated the production of ROS, evidenced by reduced CAT activity and lower levels of DCF. Our results suggest that FBP may be a possible candidate in the treatment of SAE.

Characterization of the high-affinity uptake of fructose-1,6-bisphosphate by cardiac myocytes

Previously, we reported that fructose-1,6-bisphosphate (FBP) was taken up by rat cardiac myocytes by two processes: a component that was saturable at micromolar levels and a nonsaturable component that dominated at millimolar levels. Here, we continued to characterize the saturable high-affinity component, with the aim of identifying the physiological substrate and role for this activity. ATP, ADP, and AMP inhibited the uptake of FBP with apparent affinities of 0.2-0.5 mM. Fumarate and succinate were very weak inhibitors. Several phosphorylated sugars (ribulose-1,5-phosphate, fructose-1-phosphate, ribose-5-phosphate, and inositol-2-phosphate) inhibited FBP uptake with apparent affinities of 40-500 μM. As in our previous study, no tested compound appeared to bind as well as FBP. The data suggest that the best ligands have two phosphoryl groups separated by at least 8 Å. The rates of FBP uptake were measured from 3° to 37°. The calculated activation energy was 15-50 kJ/mol, similar to other membrane transport processes. Uptake of FBP was tested in several types of cells other than cardiac myocytes, and compared to the uptake of 2-deoxyglucose and L: -glucose. While FBP uptake in excess of that of L: -glucose was observed in some cells, in no case was the uptake as high as in cardiac myocytes. The physiological substrate and role for the high-affinity FBP uptake activity remain unknown.

Fructose-1,6-bisphosphate inhibits in vitro and ex vivo platelet aggregation induced by ADP and ameliorates coagulation alterations in experimental sepsis in rats

Sepsis is a systemic response to an infection that leads to a generalized inflammatory reaction. There is an intimate relationship between procoagulant and proinflammatory activities, and coagulation abnormalities are common in septic patients. Pharmaceutical studies have focused to the development of substances that act on coagulation abnormalities and on the link between coagulation and inflammation. Fructose-1,6-bisphosphate (FBP) is a high-energy glycolitic metabolite that in the past two decades has been shown therapeutic effects in great number of pathological situations, including sepsis. The aims of this study were to assess the effects of FBP on platelet aggregation in vitro and ex vivo in healthy and septic rats and evaluate the use of FBP as a treatment for thrombocytopenia and coagulation abnormalities in abdominal sepsis in rat. FBP inhibited platelet aggregation (P < 0.001) in vitro in healthy rats from the smallest dose tested, 2.5 mM, in a dose-dependent manner. The mean effective dose calculated was 10.6 mM. The highest dose tested, 40 mM, completely inhibited platelet aggregation (P < 0.001) induced by ADP. Platelet aggregation in plasma from septic rats was inhibited only with higher doses of FBP, starting from 20 mM (P < 0.001). The calculated mean effective dose was 19.3 mM. Ex vivo platelet aggregation in septic rats was significantly lower (P < 0.05) than healthy rats and the treatment with FBP, at the dose of 2 g/kg, diminished the platelet aggregation at the extension of 27% (P < 0.001), suggesting that FBP is a potent platelet aggregation inhibitor in vivo. Moreover, treatment with FBP 2 g/kg prevented thrombocytopenia (P < 0.001), prolongation of prothrombin and partial thromboplastin time (P < 0.001), but not fibrinogen, in septic rats. The most important findings in this study are that FBP is a potent platelet aggregation inhibitor, in vitro and ex vivo. It presents protective effects on coagulation abnormalities, which can represent a treatment against DIC. The mechanisms for these effects remain under investigation.

Cardioprotection by metabolic shut-down and gradual wake-up

Mitochondria play a critical role in cardiac function, and are also increasingly recognized as end effectors for various cardioprotective signaling pathways. Mitochondria use oxygen as a substrate, so by default their respiration is inhibited during hypoxia/ischemia. However, at reperfusion a surge of oxygen and metabolic substrates into the cell is thought to lead to rapid reestablishment of respiration, a burst of reactive oxygen species (ROS) generation and mitochondrial Ca(2+) overload. Subsequently these events precipitate opening of the mitochondrial permeability transition (PT) pore, which leads to myocardial cell death and dysfunction. Given that mitochondrial respiration is already inhibited during hypoxia/ischemia, it is somewhat surprising that many respiratory inhibitors can improve recovery from ischemia-reperfusion (IR) injury. In addition ischemic preconditioning (IPC), in which short non-lethal cycles of IR can protect against subsequent prolonged IR injury, is known to lead to endogenous inhibition of several respiratory complexes and glycolysis. This has led to a hypothesis that the wash-out of inhibitors or reversal of endogenous inhibition at reperfusion may afford protection by facilitating a more gradual wake-up of mitochondrial function, thereby avoiding a burst of ROS and Ca(2+) overload. This paper will review the evidence in support of this hypothesis, with a focus on inhibition of each of the mitochondrial respiratory complexes.

Fructose-1,6-diphosphate attenuates acute lung injury induced by lipopolysaccharide in mice

Fructose-1,6-diphosphate (FDP), a high-energy glycolytic pathway intermediate, is reported to have a salutary effect in endotoxic shock and sepsis, but its underlying mechanism of action in inflammation is incompletely understood. In this study, our aim was to examine the function of FDP on acute lung injury (ALI) induced by lipopolysaccharide (LPS). We found that in vitro pretreatment with FDP remarkably repressed the production of TNF-alpha and IL-6 in murine alveolar macrophages MH-S exposed to LPS. In the mouse model of LPS-induced inflammatory lung injury, intravenous precondition of a single 400 mg/kg dose of FDP resulted in a significant reduction in LPS-mediated extravasation of Evans blue dye albumin, bronchoalveolar lavage leucocyte content, and lung tissue myeloperoxidase activity (reflecting phagocyte infiltration). Furthermore, histopathologic examination indicated that alveolitis with inflammatory cells infiltration and alveolar hemorrhage in the alveolar space was less severe in the FDP-treated mice than in the mice treated by LPS alone at 24 h. Additionally, pretreatment with FDP markedly decreased the transcription of TNF-alpha, IL-6 and inducible NO synthase (iNOS), and suppressed the nuclear translocation of NF-kappaB in lung tissues in response to LPS challenge. These results thus suggested that FDP plays an anti-inflammatory role in LPS-mediated acute lung injury, possibly through abrogation of NF-kappaB activation.

Fructose 1,6-Diphosphate Alleviates UV-Induced Oxidative Skin Damage in Hairless Mice

Reactive oxygen species (ROS) are involved in the deleterious effects of UV light on skin. The antioxidant defense system is considered to be crucial for protecting skin from ROS. Recently, we showed that fructose 1,6-diphosphate (FDP), a glycolytic metabolite, reduced oxidative stress in UVB-irradiated keratinocytes. This study set out to determine whether topically applied FDP could exert protective effects against UV-induced skin damage in hairless mice. An in vitro skin permeation study using Franz-type diffusion cells showed that the amount of [14C]-FDP that diffused through the skin increased in a time-dependent manner, and about 3.5% of the applied FDP penetrated the skin after 24 h. Topical application of FDP (1%) preserved the endogenous antioxidant capacity of skin such as catalase and glutathione, which were significantly reduced after UVB irradiation without FDP. FDP also reversed the loss of catalase protein and prevented the accumulation of carbonylated proteins induced by UVB irradiation. These results provide evidence that topically administered FDP could penetrate into the skin and attenuate UVB-induced oxidative skin damage in hairless mice.

Permeability of fructose-1,6-bisphosphate in liposomes and cardiac myocytes

Fructose-1,6-bisphosphate (FBP) helps preserve heart and other organs under ischemic conditions. Previous studies indicated that it can be taken up by various cell types. Here we extended observations from our group that FBP could penetrate artificial lipid bilayers and be taken up by cardiac myocytes, comparing the uptake of FBP to that of L-glucose. Using liposomes prepared by the freeze-thaw method, FBP entered about 200-fold slower than L-glucose. For liposomes of either soybean or egg lipids, 50 mM FBP enhanced the permeability of FBP itself, with little effect on general permeability (measured by uptake of L-glucose). In experiments with isolated cardiac myocytes at 21 degrees C, FBP uptake exceeded the uptake of L-glucose by several fold and appeared to equilibrate by 60 min. There was both a saturable component at micromolar levels and a nonsaturable component which dominated at millimolar levels. The saturable component was inhibited by Pi and by other phosphorylated sugars, though with lower affinity than FBP. Both saturable and nonsaturable uptakes were also observed at 3 degrees C. The results indicate that FBP enters myocytes not by simple penetration through the lipid bilayer, but via at least two distinct protein-dependent processes. The uptake could lead to intracellular effects important in hypothermic heart preservation.

Myocardial protection using fructose-1,6-diphosphate during coronary artery bypass graft surgery: a randomized, placebo-controlled clinical trial

In vitro and in vivo studies suggest that fructose-1,6-diphosphate (FDP), an intermediary glycolytic pathway metabolite, ameliorates ischemic tissue injury through increased high-energy phosphate levels and may therefore have cardioprotective properties in patients undergoing coronary artery bypass graft (CABG) surgery. We designed a randomized, placebo-controlled, double-blinded, sequential-cohort, dose-ranging safety study to test 5 FDP dosage regimens in patients (n = 120; 60 FDP, 60 control) undergoing CABG surgery. Of these dosage regimens, 3 produced no benefit, 1 produced improved cardiac function, and 1 required adjustment as a result of metabolic acidosis. This suggests that we achieved the intended effect of a dose-ranging study. The expected response was observed in patients treated with 250 mg/kg FDP IV before surgery and 2.5 mM FDP as a cardioplegic additive (n = 15). These patients had lower serum creatine kinase-MB levels 2, 4, and 6 h after reperfusion (P < 0.05), fewer perioperative myocardial infarctions (P < 0.05), and improved postoperative cardiac function, as evidenced by higher left ventricular stroke work index (LVSWI) 6, 12, and 16 h (P < 0.01) and cardiac index (CI) at 12 and 16 h (P < 0.05) after reperfusion. Overall efficacy of FDP was tested across all regimens that included IV FDP (n = 88; 44 FDP, 44 control) using 2 (FDP versus placebo) x 3 (dose size) factorial analyses. Area-under-curve (AUC) analysis demonstrated a significant increase in CI (AUC-16h, P = 0.013) and LVSWI (AUC-16h, P = 0.003) and reduction in CK-MB levels (AUC-16h, P < 0.05) in FDP-treated patients. The internal consistency of this dataset suggests that FDP may provide myocardial protection in CABG surgery and supports previous laboratory and clinical studies of FDP in ischemic heart disease.

IMPLICATIONS

Fructose-1,6-diphosphate (FDP) may increase high-energy phosphate levels under anaerobic conditions and therefore ameliorate ischemic injury. A dose-ranging safety study for FDP was conducted in patients undergoing coronary artery surgery. Preischemic provision of FDP significantly improved cardiac function and reduced perioperative ischemic injury. These myocardial protective effects may improve patient outcome after cardiac surgery.

Effects of n-3 fatty acid, fructose-1, 6-diphosphate and glutamine on mucosal cell proliferation and apoptosis of small bowel graft after transplantation in rats

AIM: To evaluate the effects of n-3 fatty acids (n-3FA), fructose-1, 6-diphosphate (FDP) and glutamine (GLN) on mucosal cell proliferation and apoptosis of small bowel graft.

METHODS: One hundred and ninety-six inbred strain Wistar rats were grouped as donors and recipients, and underwent heterotopic small bowel transplantation (SBT). n-3FA, FDP and GLN were administered via gastric tube as well as venous infusion for 10 d before and after surgery, respectively. The proliferation and apoptosis of mucosal cells were analyzed with flow cytometry and in situ cell death detection kits.

RESULTS: Apparent apoptosis and minor proliferation of mucosal cells of small bowel graft after transplantation were observed. A higher mucosal cell proliferative index and lower apoptotic index were found in all small bowel grafts after supplying with n-3FA, FDP and GLN.

CONCLUSION: Nutritional support with n-3FA, FDP and GLN promotes mucosal cell proliferation significantly, and prevents mucosal cell from undergoing apoptosis with different degrees. These regulatory effects on the apoptosis alter the structure and absorption function of transplanted small bowel favorably.

Fructose-1,6-bisphosphate for improved outcome after hypothermic circulatory arrest in pigs

OBJECTIVE

Fructose-1,6-bisphosphate is a high-energy intermediate in the anaerobic metabolism. It enhances glycolysis, preserves cellular adenosine triphosphate, and prevents the increase of intracellular calcium during ischemia. The potential neuroprotective effect of fructose-1,6-bisphosphate during hypothermic circulatory arrest was evaluated in a surviving porcine model.

METHODS

Twenty-four pigs were randomly assigned to receive two intravenous infusions of either fructose-1,6-bisphosphate (500 mg/kg) or saline solution. The first infusion was given immediately before a 75-minute period of hypothermic circulatory arrest and the second was given immediately after hypothermic circulatory arrest.

RESULTS

The 7-day survivals were 83.3% in the fructose-1,6-bisphosphate group and 41.7% in the control group (P =.09). The treated animals had significantly better postoperative behavioral scores. The administration of fructose-1,6-bisphosphate was associated with higher venous phosphate and sodium levels, lower venous ionized calcium levels, higher blood osmolarity, and a better fluid balance. Intracranial pressure and venous creatine kinase isoenzyme MB were significantly lower in the fructose-1,6-bisphosphate group during rewarming (P =.01 and P =.001, respectively). Among the treated animals, brain glucose, pyruvate and lactate levels tended to be higher, brain glycerol levels tended to be lower, and the histopathologic score of the brain was significantly lower (P =.04).

CONCLUSIONS

Intravenous administration of fructose-1,6-bisphosphate at 500 mg/kg before and after hypothermic circulatory arrest in a surviving porcine model was associated with better survival, behavioral outcome, and histopathologic score. The observed lower blood creatine kinase isoenzyme MB and brain glycerol levels and the higher brain glucose, pyruvate, and lactate levels in the fructose-1,6-bisphosphate group suggest that this drug has supportive effects on myocardial and brain metabolisms.

An assessment of fructose-1,6-bisphosphate as an antimicrobial and anti-inflammatory agent in sepsis

Tissue lesion mechanisms provoked by sepsis include the infectious process, inflammation, and cellular energy deficit. We chose to test fructose-1,6-bisphosphate (FBP) because of its possible anti-inflammatory and antimicrobial actions. Wistar rats were used and divided into three experimental groups: a control group (n=10), in which a capsule was introduced into the peritoneum of the animals; a septic group (n=10), in which a capsule containing non-sterile fecal matter was introduced together with Escherichia coli (1.5 x 10(9)CFU); and a septic group treated with FBP 500 mg/kg (n=10). The blood cell tests revealed that levels of leukocytes increased significantly in the septic group when compared to both the septic group treated with FBP and the control group. The blood cultures were 100% positive in both the septic group and the septic group treated with bisphosphorylated sugar. The antibiogram only revealed an inhibitory halo in the case of the antibiotic ampicillin, there was no such indication for FBP. The anti-inflammatory power of FBP remained at 60% for 5 h in the rats that received the carrageenan injection. What is more, the sugar reduced the levels of ionic calcium in relation to the control group. This data proves the validity of using FBP in the treatment of sepsis, possibly due to its anti-inflammatory rather than antimicrobial action.

Fructose-1,6-diphosphate alone and in combination with cyclosporine potentiates rat cardiac allograft survival and inhibits lymphocyte proliferation and interleukin-2 expression

BACKGROUND

Fructose-1,6-diphosphate (FDP) reduces postischemic reperfusion injury and is used alone and in combination with cyclosporine A (CsA) as an immunosuppressant.

METHODS

Wistar-Furth rat hearts were grafted to Lewis rats. Activated T-cell proliferation, viability, and interleukin-2 expression were determined.

RESULTS

Mean survival in days were: saline 7.12+/-0.64, FDP 350 mg/kg perioperatively 13.5+/-1.4, FDP 350 mg/kg twice daily 11.4+/-0.75, CsA 2.5 mg/kg daily 12+/-0.81, CsA 5.0 mg/kg daily 12.4+/-0.81, CsA 2.5 mg/kg + FDP 350 mg/kg twice daily 17.6+/-0.4, and CsA 5 mg/kg + FDP 350 mg/kg twice daily 28.2+/-0.97. FDP maximally inhibits T-cell proliferation and concomitantly increases cell viability at 5,000 to 500 microg/mL, whereas CsA inhibits at 500 ng/mL. FDP completely inhibited interleukin-2 expression at 5,000 to 500 microg/mL, whereas CsA partially inhibited at 50 to 500 ng/mL.

CONCLUSION

FDP + CsA prolongs cardiac survival and FDP inhibits T-cell proliferation.

Fructose-1,6-diphosphate attenuates prostaglandin E2 production and cyclo-oxygenase-2 expression in UVB-irradiated HaCaT keratinocytes

1. Fructose-1,6-diphosphate (FDP), a glycolytic metabolite, is reported to ameliorate inflammation and inhibit the nitric oxide production in murine macrophages stimulated with endotoxin. It is also reported that FDP has cytoprotective effects against hypoxia or ischaemia/reperfusion injury in brain and heart. However, underlying mechanisms of its various biological activities are not completely understood. 2. In this study, we examined the effects of FDP on UVB-induced prostaglandin production in HaCaT keratinocytes. 3. Ultraviolet B (UVB, 280-320 nm) irradiation (30 mJ cm(-2)) increased prostaglandin E(2)(PGE(2)) production, which was significantly decreased by FDP in a concentration dependent manner. NS-398, a cyclo-oxygenase-2 (COX-2) selective inhibitor completely inhibited UVB-induced PGE(2) production showing that COX-2 activity is responsible for the increase in PGE(2) production under our experimental conditions. 4. UVB irradiation increased total COX activity and COX-2 mRNA in HaCaT keratinocytes, which were significantly blocked by FDP in a concentration dependent manner. 5. N-acetylcysteine (NAC) significantly attenuated UVB-induced PGE(2) production, COX activity and COX-2 mRNA expression indicating oxidative components might contribute to these events. 6. FDP reduced UVB-induced increase in cellular reactive oxygen species (ROS) level although it did not show direct radical scavenging effect in the experiment using 1,1-diphenyl-2picrylhydrazil (DPPH). FDP preserved the cellular antioxidant capacity including catalase activity and GSH content after irradiation. 7. Our data obtained hitherto suggest that FDP may have a protective role in UVB-injured keratinocyte by attenuating PGE(2) production and COX-2 expression, which are possibly through blocking intracellular ROS accumulation.

Storage solution containing fructose-1,6-bisphosphate inhibits the excess activation of Kupffer cells in cold liver preservation

BACKGROUND

In liver transplantation, the activation of Kupffer cells at the time of cold preservation and reperfusion is considered to play an important role. In the present study, the usefulness of cold storage solution containing fructose-1,6-bisphosphate (FBP) was compared with University of Wisconsin (UW) solution in the function of Kupffer cells.

METHODS

Kupffer cells were separated from rat liver stored at 4 degrees C in each storage solution. Four kinds of storage solutions were used: UW, simplified UW without FBP (0-FBP), and solutions with 10 or 20 mM FBP (10-FBP, 20-FBP). Lipopolysaccharide (LPS) labeled by fluorescein was loaded after 12 or 24 hr of cold preservation in each solution. The rates of cells uptaking LPS as phagocytic ability were measured using flow cytometry. Tumor necrosis factor-alpha, cytokine-induced neutrophil chemoattractant, and nitric oxide (NO) were measured in the supernatant.

RESULTS

Tumor necrosis factor-alpha values in the 20-FBP group were significantly lower than those in the UW group. Cytokine-induced neutrophil chemoattractant values at 60 min after loading LPS were significantly lower in the 20-FBP group than in the UW group. NO values at 24 hr after loading LPS were significantly lower in the 20-FBP group compared with the UW group. The 20-FBP group was highest in the rates of cells uptaking LPS after 24-hr cold preservation.

CONCLUSIONS

The storage solution containing FBP controlled the secretion of cytokines and NO from Kupffer cells and maintained phagocytic ability. This solution was considered to be more useful than UW solution for Kupffer cell protection.

Destabilizing effects of fructose-1,6-bisphosphate on membrane bilayers

Fructose-1,6-bisphosphate (FBP) is a high-energy glycolytic intermediate that decreases the effects of ischemia; it has been used successfully in organ perfusion and preservation. How the cells utilize external FBP to increase energy production and the mechanism by which the molecule crosses the membrane bilayer are unclear. This study examined the effects ofFBP on membrane bilayer permeability, membrane fluidity, phospholipid packing, and membrane potential to determine how FBP crosses the membrane bilayer. Large unilamellar vesicles composed of egg phosphatidylcholine (Egg PC) were made and incubated with 50 mM FBP spiked with 14C-FBP at 30 degrees C. Uptake of FBP was significant (P < 0.05) and dependent on the lipid concentration, suggesting that FBP affects membrane bilayer permeability. With added calcium (10 mM), FBP uptake by lipid vesicles decreased significantly (P < 0.05). Addition of either 5 or 50 mM FBP led to a significant increase (P < 0.05) in Egg PC carboxyfluorescein leakage. We hypothesized that the membrane-permeabilizing effects of FBP may be due to a destabilization of the membrane bilayer. Small unilamellar vesicles composed of dipalmitoyl pC (DPPC) were made containing either diphenyl-1,3,5-hexatriene (DPH) or trimethylammmonia-DPH (TMA-DPH) and the effects of FBP on the fluorescence anisotropy (FA) of the fluorescent labels examined. FBP caused a significant decrease in the FA of DPH in the liquid crystalline state of DPPC (P < 0.05), had no effect on FA of TMA-DPH in the liquid crystalline state of DPPC, but increased the FA of TMA-DPH in the gel state of DPPC. From phase transition measurements with DPPC/DPH or TMA-DPH, we calculated the slope of the phase transition as an indicator of the cooperativity of the DPPC molecules. FBP significantly decreased the slope, suggesting a decrease in fatty acyl chain interaction (P< 0.05). The addition of 50 mM FBP caused a significant decrease (P< 0.05) in the liquid crystalline/gel state fluorescence ratio of merocyanine 540, indicating increased head-group packing. To determine what effects these changes would have on cellular membranes, we labeled human endothelial cells with the membrane potential probe 3,3'-dipropylthiacarbocyanine iodide (DiSC3) and then added FBP. FBP caused a significant, dose-dependent decrease in DiSC3 fluorescence, indicating membrane depolarization. We suggest that FBP destabilizes membrane bilayers by decreasing fatty acyl chain interaction, leading to significant increases in membrane permeability that allow FBP to diffuse into the cell where it can be used as a glycolytic intermediate.

Physiopathological studies in septic rats and the use of fructose 1,6-bisphosphate as cellular protection

OBJECTIVE

The aim of this research project was to test the ability of fructose 1,6-bisphosphate (FBP), which has anti-inflammatory effects and maintains cellular energy levels, to inhibit the septic process in an experimental model in rats.

DESIGN

Prospective, controlled animal trial.

SETTING

Research laboratory.

SUBJECTS

Fed male Wistar rats.

INTERVENTIONS

Three experimental groups were formed for the test: control group, untreated septic group, and septic group treated with FBP (500 mg/kg).

MEASUREMENTS AND MAIN RESULTS

In the control group, there were no deaths; in the untreated septic group, the mortality rate was 100% within 15 hrs; in the septic group treated with FBP, the mortality rate reached 20% within 15 hrs. The blood cell tests revealed that concentrations of hematocrit, leukocytes, monocytes, and immature cells increased significantly in the untreated septic group compared with both the FBP-treated septic group and the control group. The histologic lesions verified in the heart, lungs, liver, and kidneys of septic animals were smaller and even absent in those treated with FBP.

CONCLUSION

FBP reduced the mortality rate provoked by experimental sepsis and ameliorated hematologic and histologic alterations.

Fructose- 1,6-bisphosphate did not affect hippocampal neuronal damage caused by 10 min of complete umbilical cord occlusion in fetal sheep

Fructose-1, 6-bisphosphate (FBP) has a neuroprotective effect in neonatal and adult rats. The purpose of this study was to examine the effects of FBP on hippocampal neuronal damage in fetal sheep asphyxiated by 10 min of complete umbilical cord occlusion. Thirteen fetal sheep at 124 days of gestation were surgically instrumented with catheters. Cardiorespiratory parameters were monitored, and biochemical analyses were performed with the blood samples. During the insult seven fetuses were given FBP (500 mg/kg) and six were given iso-osmotic saline, and hippocampal neuronal damage was examined histologically and scored. Cardiorespiratory changes were the same in both groups, and there was no neuroprotective effect of FBP in this study. However the decrease of serum total Ca level implied the Ca- chelating effect of FBP.

Effect of fructose-1, 6-diphosphate versus diphenhydramine on mortality in compound 48/80-induced shock

Fructose-1,6-diphosphate (FDP) has a salutary effect on hemorrhagic, traumatic and endotoxic shock. The role of FDP on compound 48/80-induced shock was therefore investigated. Sprague Dawley aged male rats (448+/-7.4 gm body weight) were randomly assigned into three groups and treated intraperitoneally with diphenhydramine (DPHM) 15 mg/kg (n=11), 12.5 ml of 10% FDP (n=10) and 12.5 ml saline (n=10). The rats were injected with compound 48/80 (5 mg/kg) 30 min later, and monitored every 10 min for 60 min. Arterial pressure was higher in FDP rats than in DPHM (P<0.01) or saline (P<0.005) groups. Plasma potassium (K(+)) was lower in the FDP group (P<0.01). Arterial pO2 and pCO2 were within physiological range in all groups. A profound decrease in arterial pH and bicarbonate (HCO3(-)) was also observed in all groups. Mortality at 48 h in the saline group was 100%, in the DPHM group 91%, and in the FDP group 20% (P<0.001 and P<0.005, respectively). FDP improved survival significantly in this study.

The uptake and metabolism of fructose-1,6-diphosphate in rat cardiomyocytes

Fructose-1,6-diphosphate (FDP) is a glycolytic intermediate which has been theorized to increase the metabolic activity of ischemic tissues. Here we examine the effects of externally applied FDP on cardiomyocyte uptake and metabolism. Adult rat cardiomyocytes were isolated and exposed to varying concentrations (0, 5, 25 and 50 mM) of FDP for either 1, 16 or 24 h of hypoxia (95% N2/5% CO2), each time period followed by a 1 h reoxygenation (95% air/5% CO2). The uptake of FDP by rat cardiomyocytes was more concentration-dependent than time-dependent. Furthermore, the uptake of FDP by the cardiomyocytes was similar in the hypoxia and normoxia treated cells. Alamar Blue, a redox indicator that is sensitive to metabolic activity, was used to monitor the effects of the FDP on cardiomyocyte metabolism. In the 1 h hypoxia or normoxia group, the 5, 10 and 25 mM FDP showed a significant increase in metabolism compared to the control cells. When the length of hypoxia was extended to 16 h, all doses of FDP were greater than control. And at the 24 h hypoxia or normoxia time period, only the 10, 25 and 50 mM FDP groups were greater than control. The results indicate a non-linear trend between the external concentration of FDP and the changes noted in metabolism. The findings from this study indicate that a narrow concentration range between 5-10 mM augments cardiomyocyte metabolism, but higher or lower doses may have little additional affect.

Fructose-1,6-diphosphate and a glucose-free solution enhances functional recovery in hypothermic heart preservation

BACKGROUND

Fructose-1,6-diphosphate (FDP) has been shown to protect tissue during hypoxia under various ischemic conditions, including isolated heart perfusion. We tested the hypothesis that adding FDP to St. Thomas solution can extend hypothermic heart preservation time.

METHODS

Sixteen adult Sprague-Dawley rats were used. Under general anesthesia, the hearts were removed and preserved at 4 degrees C in St. Thomas solution (30 ml/kg) for 12 hours. FDP (5 mM) was added to the St. Thomas solution in the study group (n = 8), whereas no FDP was used in the control group (n = 10). The hearts were reperfused after 12 hours of preservation using a working heart model.

RESULTS

In the study group, cardiac output ranged from 13.00 +/- 2.34 to 17.66 +/- 1.71 ml/min, maximum aortic flow was 3.40 +/- 1.99 to 9.26 +/- 1.72 ml/min, left ventricular stroke volume ranged from 0.074 +/- 0.014 to 0.092 +/- 0.009 ml, left ventricular stroke work ranged from 6.22 +/- 0.39 to 7.95 +/- 0.44 ml/mmHg, and maximum left ventricular generated power was 14.38 +/- 2.94 to 20.16 +/- 2.49 Joules/min. All of these parameters were higher than those in the control group (p < 0.001). Coronary vascular resistance and myocardial tissue wet/dry weight ratio were lower in the study group than in the control group (p < 0.05).

CONCLUSIONS

Heart function was better preserved when FDP was added to St. Thomas solution during hypothermic rat heart preservation. The mechanism is not totally clear, but enhancement of high-energy phosphate production during ischemia is possible. Key words: heart, procurement, hypothermia, fructose-1,6-diphosphate.

The role of fructose-1,6-diphosphate in cell migration and proliferation in an in vitro xenograft blood vessel model of vascular wound healing

Both smooth muscle cells and endothelial cells play an important role in vascular wound healing. To elucidate the role of fructose-1,6-diphosphate, cell proliferation and cell migration studies were performed with human endothelial cells and rat smooth muscle cells. To mimic blood vessels, endothelial and smooth muscle cells were used in 1:10, 1:5, and 1:1 concentrations, respectively, mimicking large-, mid-, and capillary-sized blood vessels. Cell migration was studied with fetal bovine serum-starved cells. For cell proliferation assay, cells were plated at 30-50% confluency and then starved. The cells were incubated for 48 h with fructose-1,6-diphosphate at (per ml) 10 mg, 1 mg, 500 microg, 250 microg, 100 microg, and 10 microg, pulsed with tritiated-thymidine and incubated with 1 N NaOH for 30 min at room temperature, harvested, and counted. For migration assay, confluent cells were starved, wounded, and incubated for 24 h with same concentrations of fructose-1,6-diphosphate as in proliferation assay. The cells were fixed and counted. Smooth muscle cell proliferation was inhibited by fructose-1,6-diphosphate at 10 mg/ml. In the xenograft models of 1:10, 1:5, and 1:1 fructose-1,6-diphosphate inhibited proliferation at 10 mg/ml. In migration studies 10 mg fructose-1,6-diphosphate per ml was inhibitory to both cell types. In large-, mid-, and capillary-sized blood vessels, fructose-1,6-diphosphate inhibited proliferation of both cell types at 10 mg/ml. At the individual cell level, fructose-1,6-diphosphate is nonstimulatory to proliferation of endothelial cells while inhibiting migration, and it acts on smooth muscle cells by inhibiting both proliferation and migration.

Enhancement of hypothermic heart preservation with fructose 1, 6-diphosphate

BACKGROUND

We hypothesized that the addition of fructose 1, 6-diphosphate (FDP) to a hypothermic heart preservation solution could improve metabolic recovery because it has several beneficial effects.

MATERIALS AND METHODS

Twenty adult Sprague-Dawley rats were used to study hypothermic heart preservation. The hearts were removed under general anesthesia and preserved at 4 degrees C in Euro-Collins solution (30 ml/kg) for 8 h. In the study group (N = 10), FDP (5 mM) was added to the Euro-Collins solution. In the control group (N = 10), no FDP was added. Heart function was studied after preservation using a working heart model. The ability of various concentrations of fructose 1,6-phosphate to passively diffuse through an egg phosphatidylcholine multilamellar vesicle (MLV) membrane bilayer was examined.

RESULTS

Cardiac output ranged from 17.0 +/- 1.9 to 24.9 +/- 1.6 ml/min in the study group vs 2.0 +/- 1.0-12.3 +/- 1.7 ml/min for controls, average aortic flow was 10. 8 +/- 1.4 ml/min in the study group vs -1.3 +/- 1.6 ml/min for controls, and maximum LV generated power was 22.8 +/- 1.7 J/min vs 10.1 +/- 1.6 J/min for controls. Coronary flow, left ventricular stroke volume and stroke work, and myocardial oxygen consumption were much higher in the study group than in the control group. Coronary vascular resistance was lower in the study group than in the control group. Electron microscopic study indicated that many myocytes displayed patches of swollen mitochondria in the control group, but was rarely observed in the study group. The addition of 50 mM FDP caused substantial changes in MLV permeability. No dose of sucrose buffers outside the vesicles resulted in a significant changes of MLV permeability.

CONCLUSIONS

Our results indicate that the addition of FDP to Euro-Collins solution significantly improves hypothermic rat heart preservation, and FDP appeared to cross the membrane bilayer.