Clinical effects of Ganglioside and fructose-1, 6-diphosphate on neonatal heart and brain injuries after Asphyxia

Objective: To study the clinical effect of ganglioside [GM] and fructose-1, 6-diphosphate [FDP] on neonatal heart and brain injuries after asphyxia

Methods: Ninety-one neonates with asphyxia neonatal heart and brain injuries were randomly divided into an observation group and a control group. Both groups were given symptomatic treatment as soon as possible. On this basis, the observation group was given 200 ml of 5% glucose injection and 20 mg of GM and 250 mg/kg-d FDP by intravenous infusion. The above two drugs were given once a day for 14 days. The control group was given 20 ml of 5% glucose injection, 2 ml of cerebrolysin and 250 mg/kg-d FDP by intravenous infusion, once a day for 14 days. Both groups were administered on the first day after admission, and the course of treatment was 14 days. The treatment outcomes of the two groups were compared by detecting the levels of glycogen phosphorylase isoenzyme BB [GPBB], cTn-l and CK-MB, MRI results and Neonatal Behavioral Neurological Assessment [NBNA] scores before and after treatment

Results: The levels of GPBB, cTn-l and CK-MB in the observation group were significantly higher than those of normal neonates. After treatment, the levels of cTn-l and CK-MB in the observation group were closer to those of normal neonates compared with the control group, with significant differences [P<0.05]. There was a significant difference in the brain MRI examination between the two groups [P<0.05]. The NBNA scores of the two groups were significantly different before and after treatment [P<0.05]. The total effective rate of the observation group was significantly higher than that of the control group [P<0.05]. Conclusion: Neonatal heart and brain injuries after asphyxia can be well treated by combining GM with FDP

Structural insight into mechanisms for dynamic regulation of PKM2

Pyruvate kinase isoform M2 (PKM2) converts phosphoenolpyruvate (PEP) to pyruvate and plays an important role in cancer metabolism. Here, we show that post-translational modifications and a patient-derived mutation regulate pyruvate kinase activity of PKM2 through modulating the conformation of the PKM2 tetramer. We determined crystal structures of human PKM2 mutants and proposed a "seesaw" model to illustrate conformational changes between an inactive T-state and an active R-state tetramers of PKM2. Biochemical and structural analyses demonstrate that PKM2(Y105E) (phosphorylation mimic of Y105) decreases pyruvate kinase activity by inhibiting FBP (fructose 1,6-bisphosphate)-induced R-state formation, and PKM2(K305Q) (acetylation mimic of K305) abolishes the activity by hindering tetramer formation. K422R, a patient-derived mutation of PKM2, favors a stable, inactive T-state tetramer because of strong intermolecular interactions. Our study reveals the mechanism for dynamic regulation of PKM2 by post-translational modifications and a patient-derived mutation and provides a structural basis for further investigation of other modifications and mutations of PKM2 yet to be discovered.

Strontium fructose 1,6-diphosphate (FDP-Sr) alleviates oligozoospermia induced by multiglycosides of tripterygium wilfordii in rats / 中华男科学杂志

<p><b>OBJECTIVE</b>To investigate the effects of strontium fructose 1,6-diphosphate (FDP-Sr) on the multiglycosides of tripterygium wilfordii Hook. f. (GTW)-induced oligozoospermia in male rats.</p><p><b>METHODS</b>Forty SD male rats were randomly divided into 3 groups: model (n=10), FDP-Sr (n=10), and control (n=10). The model rats received intragastric administration of GTW at 30 mg/(kg x d) for 40 days to induce oligozoospermia, the rats of the FDP-Sr group orally administered FDP-Sr at 200 mg/(kg x d) for 30 days after GTW induction, while the control rats given but distilled water. Then we obtained the gonad indexes involving the testis, epididymis, preputial gland and seminal vesicle, and determined the count and motility of epididymal sperm, testicular pathomorphology, serum testosterone level and activities of succinodehydrogenase (SDH), lactate dehydrogenase (LDH) and acid phosphatase (ACP) in the testis.</p><p><b>RESULTS</b>The indexes of the testis and seminal vesicle in the control, model and FDP-Sr groups were (0.71 +/- 0.04) and (0.29 +/- 0.04)%, (0.37 +/- 0.04) and (0.25 +/- 0.05)%, and (0.45 +/- 0.07) and (0.31 +/- 0.06)%, respectively; the epididymal sperm counts were (59.87 +/- 11.28), (11.06 +/- 2.53) and (20.95 +/- 4.98) x 10(6)/ml; the serum testosterone levels were (85.31 +/- 7.41), (65.33 +/- 2.90) and (75.32 +/- 5.34) ng/L; and the activities of ACP, LDH and SDH were (95.64 +/- 19.27), (9574.73 +/- 3 578.06) and (6.39 +/- 1.93) U/g prot, (58.42 +/- 12.38), (4820.77 +/- 1 535.22) and (3.48 +/- 0.91) U/gprot, and (83.74 +/- 21.30), (7649.01 +/- 3 123.02) and (5.59 +/- 1.75) U/g prot. All the parameters above were significantly increased in the FDP-Sr group as compared with the GTW models (P < 0.05). Besides, FDP-Sr treatment significantly alleviated the injury of the testicular seminiferous epithelium.</p><p><b>CONCLUSION</b>FDP-Sr can alleviate GTW-induced oligozoospermia, which is closely related with its improvement of testicular function.</p>

Viral hepatitis infection and insulin resistance: a review of the pathophysiological mechanisms / Hepatitis virales y resistencia a la insulina: revisión de los mecanismos fisiopatológicos

Viral hepatitis is a common cause of morbidity in Mexico. Insulin resistance (IR) is related to the liver damage caused by some viral infections, especially chronic infections. Chronic viral infection is an important risk factor for the development of type 2 diabetes mellitus, disease that is currently among the 10 main causes of morbidity and the most common cause of mortality. Although several studies have reported an association between IR and hepatitis B virus or hepatitis C virus (HCV) infection, the pathophysiology has been studied thoroughly only for the association between IR and HCV infection. It is thought that HCV infection causes direct damage through the action of the core proteins, which induces an inflammatory state characterized by secretion of proinflammatory cytokines that interfere with normal insulin signaling and disturb glucose, lipid and protein metabolism. This review summarizes the mechanisms by which viral infection is thought to induce IR.

Las hepatitis virales son una causa común de morbilidad en México. La resistencia a la insulina (RI) ha sido relacionada con el daño hepático causado por infecciones virales crónicas, haciendo de ellas un factor de riesgo para el desarrollo de diabetes mellitus tipo 2, problema de salud que se encuentra entre las primeras 10 causas de morbilidad y es la primera de mortalidad. Aunque varios estudios han reportado una asociación entre la RI y la infección con virus de la hepatitis B y virus de la hepatitis C, sólo con el último se ha estudiado su fisiopatología. Se ha sugerido que produce daño directo a través de proteínas de su núcleo e induce un estado inflamatorio que interfiere con la señalización normal de insulina, resultando en una alteración del metabolismo de glucosa, lípidos y proteínas. Esta revisión resume los mecanismos por los que se sugiere que estas infecciones inducen RI.

Recent advance in the discovery of allosteric inhibitors binding to the AMP site of fructose-1,6-bisphosphatase / 药学学报

Fructose-1, 6-bisphosphatase (FBPase), a rate-limiting enzyme involved in the pathway of gluconeogenesis, can catalyze the hydrolysis of fructose-1, 6-bisphosphate to fructose-6-phosphate. Upon inhibiting the activity of FBPase, the production of endogenous glucose can be decreased and the level of blood glucose lowered. Therefore, inhibitors of FBPase are expected to be novel potential therapeutics for the treatment of type II diabetes. Recent research efforts were reviewed in the field of developing allosteric inhibitors interacting with the AMP binding site of FBPase.

Aging and its impact onthe quality of grafts: an experimental study in rats livers / O impacto do envelhecimento na qualidade do enxerto: estudo experimental em fígados de ratos

CONTEXT: There are consistent clues of worse results with grafts from older donors, especially in hepatitis C. University of Wisconsin (UW) solution is adopted for liver preservation, but other solutions are being studied, as fructose-1,6-bisphosphate (FBP). OBJECTIVE: To determinate the impact of aging of the donor on the cold ischemia injury in rat livers and compare UW and FBP. METHODS: Twenty male Wistar rats were studied - 10, aging 20 weeks: 5 to preservation with UW (C-UW) and 5, FBP (C-FBP); and other 10, aging 50 weeks: 5 to UW (E-UW) and 5 to FBP (E-FBP). Rats were anesthesized, submitted to hepatectomy, and graft was kept under 2-4ºC for 8 hours. Liquid samples were taken at 2, 4, 6, and 8 hours, to determine AST and LDH. At the end, in the liver tissue thiobarbituric acid reactive substances and catalase were determined. RESULTS: Average liver weight was similar between controls and the others (12.5 g ± 1.8 and 13.4 g ± 2.0). AST and LDH levels were higher in C-UW group (P<0.05). In the older group, there was a difference between UW and FBP preserved livers related to LDH, but not to AST. Thiobarbituric acid reactive substances were superior in control group than in the older one (P = 0.001). Catalase activity was similar between these groups (P = 0.11), but it was superior in UW preserved animals (P = 0.02). CONCLUSION: Livers from older rats were similar to the controls regarding cold ischemia injury in FBP group. Surprisingly, with UW solution there was less cold ischemia injury in the elderly group. When comparing both solutions, FBP provided significantly more protection than UW in the controls. There was a trend to FBP to being better than UW in the elderly group. Further studies with liver from older donors and ischemia and reperfusion are needed.

CONTEXTO: Dados da literatura atual sugerem piores resultados quando os transplantes hepáticos são realizados com enxertos provenientes de doadores idosos. O uso da solução Universidade de Wisconsin (UW) é universal; entretanto alternativas como a fructose-1,6-bisfosfato (FBP) vêm sendo estudadas. OBJETIVOS: Determinar o impacto do envelhecimento do doador no dano de isquemia a frio em fígados de ratos, comparando as soluções de FBP e UW. MÉTODOS: Vinte ratos Wistar foram estudados - 10 com 20 semanas: 5 preservados com UW (C-UW) e 5 com FBP (C-FBP); e outros 10, com 50 semanas: 5 com UW (E-UW) e 5 com FBP (E-FBP). A preservação durou 8 horas. Foram dosadas AST e LDH nas alíquotas do líquido de preservação a cada 2 horas. RESULTADOS: Os níveis de AST e LDH foram superiores no grupo (C-UW) (P<0.05). Quando comparadas UW x FBP no grupo de idosos houve diferença quanto à LDH, mas não com a AST. CONCLUSÃO: A preservação dos fígados de ratos idosos foi similar aos dos controles, quando preservados com FBP. Quando utilizada UW, a lesão de preservação foi menor no grupo de ratos idosos. A FBP minimizou a isquemia a frio nos controles, quando comparada a UW. Houve tendência de a FBP ser superior a UW no grupo idosos.

Role of HO/CO in IL-beta induced pancreatic islets apoptosis and the effect of fructose-1, 6-disphosphate / 中国应用生理学杂志

<p><b>AIM</b>To investigate the protective role of HO/CO systems in IL-1beta induced islest apoptosis and to explore the mechanisms of the protective effect of fructose-1, 6-disphosphate (FDP).</p><p><b>METHODS</b>The pancreases of the rats were removed to collect islets cells. The cells were incubated with IL-1beta with/or FDP. Cell activity, insulin secretion, HO-1 activity, CO content and apoptotic percentage were detected.</p><p><b>RESULTS</b>HO-1 activity and CO content of the normal control group were low. IL-1beta induced a significant decrease of cell activity and insulin release, flow cytometry analysis showed that apoptotic percentage of islet cells remarkably increased following the addition of IL-1beta, FDP obviously improved the islets cellular activity damaged by IL-1beta, and basic amount of insulin secretion and stimulated by high glucose were improved (P < 0.01). Content of CO and activity of HO-1 were higher in the IL-1beta group than the normal control group (P < 0.05), and there were significant differences between the FDP groups and IL-1beta group. FDP decreased cell apoptotic percentage. Activities of HO-1 and content of CO were higher than that in the IL-1beta group (P < 0.01).</p><p><b>CONCLUSION</b>FDP can attenuate the IL-1beta induced apoptosis of cultured beta cells, the mechanism of which may be improved HO-1 activity and CO content.</p>

Effect of fructose-1,6-diphosphete on myocardial preservation during pulmonary operations / 中南大学学报(医学版)

OBJECTIVE@#To investigate the effect of fructose-1,6-diphosphete(FDP) on myocardial preservation in pulmonary operations.@*METHODS@#One hundred and six patients undergoing selective pulmonary lobectomy or segmentectomy were randomly divided into 2 groups with 53 patients each. FDP 200 mg/kg was infused intravenously before anesthesia in the FDP group, while 5% glucose with the same volume was given instead of FDP in the control group. ECGs were monitored from before the anesthesia to 72 h after the operation;the time and type of arrhythmia were recorded. Blood samples were taken before the operation (T0), immediately after the operation(T1), at 24 h(T2),48 h(T3)and 72 h(T(4)) after the operation to determine plasma creatine kinase isoenzyme MB(CK-MB) and cardiac troponin I(cTnI) concentrations.@*RESULTS@#The incidence of arrhythmia in FDP group (35 times) was significantly lower than that in the control group(67 times). The incidence of all types of arrhythmia in the FDP group was also significantly lower than that in the control group. The concentrations of CK-MB and cTnI in the FDP group were significantly lower than those in the control group at T1, T2, T3, and T4.@*CONCLUSION@#FDP is effective for myocardial preservation in pulmonary operations.

Protective effect of fructose-1,6-diphosphate against ultrastructural damage in the hippocampus of rats with repeated febrile seizures / 中国当代儿科杂志

<p><b>OBJECTIVE</b>Fructose-1, 6-diphosphate (FDP), serving as a cellular energy substance, has shown its roles in the treatment of hypoxic-ischemic encephalopathy and myocardial damage. The present study aimed at exploring the potentiality of the protective effect of FDP against ultrastructural damage of the hippocampus caused by febrile seizures (FS) in rats.</p><p><b>METHODS</b>Thirty-six 21-day-old male Sprague-Dawley rats were randomly divided into three groups: untreated FS (control), high-dose FDP-treated FS and low-dose FDP-treated FS. FS were induced by hyperthermal bath. Thirty minutes before FS induction, rats in the high-dose and low-dose FDP-treated groups received a peritoneal injection of FDP at a dosage of 50 and 25 mg per 100 g of body weight respectively, whereas the same volume of 0.9% sodium chloride solution were injected to the rats in the control group. Transmission electron microscopy was used to examine the ultrastructural pathologic changes of neurons and organelles as well as the features of synaptic morphological parameters in the hippocampal CA1 area.</p><p><b>RESULTS</b>Neuronal degeneration and necrosis, mitochondria swelling, polyribosomes disaggregation from endoplasmic reticula, and golgiosomes dilation in the hippocampal CA1 area in the two FDP intervention groups were less severe compared with the control group. FDP treatment resulted in significant increases in postsynaptic density thickness (F=12.47, P<0.01), synaptic active zone length (F=14.75, P<0.01) and synaptic interface curvature (F=3.77, P<0.05), as well as a shorter interspace of neural synapses (F=7.29, P<0.01) when compared with the control group. There were no significant differences in the ultrastructural changes between the two FDP treatment groups.</p><p><b>CONCLUSIONS</b>FDP can ameliorate ultrastructural damage in the hippocampus caused by FS in rats. However, further research is warranted for a reasonable and effective dosage of FDP.</p>

Effects of fructose-1,6-diphosphate on concentration of calcium and activities of sarcoplosnic Ca2+-ATPase in cardiomyocytes of Adriamycin-treated rats / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

<p><b>OBJECTIVE</b>To observe the effects of fructose-1,6-diphosphate (FDP) on serum levels of cardiac troponin I (cTnI) and creatine kinase-MB (CK-MB), as well as the concentration of calcium in cardiomyocytes (Myo[Ca(2+)]) and activity of sarcoplosnic Ca(2+)-ATPase (SRCa(2+)-ATPase) in Adriamycin (ADR)-treated rats.</p><p><b>METHODS</b>Rats were intraperitoneally injected with ADR (2.5 mg/kg every other day for 6 times) and then with different dosages of FDP (every other day for twenty-one times). Bi-antibodies sandwich Enzyme linked immune absorption assay (ELISA) was performed to detect serum level of cTnI. CK-MB was detected by monoclonal antibody, Myo[Ca(2+)] was detected by fluorescent spectrophotometry and the activity of SRCa(2+)-ATPase was detected by inorganic phosphate method.</p><p><b>RESULTS</b>FDP (300, 600, 1200 mg/kg) significantly reduced the serum levels of cTnI and CK-MB, while at the same time decreased calcium concentration and increased SRCa(2+)-ATPase activity in cardiomyocytes of ADR-treated rats (P<0.01).</p><p><b>CONCLUSIONS</b>FDP might alleviate the cardiotoxic effects induced by ADR through decreasing calcium level as well as increasing SRCa(2+)-ATPase activity in cardiomyocytes.</p>

Protective effects of fructose-1,6-diphosphate on brain damage caused by febrile seizures in rats / 中华儿科杂志

<p><b>OBJECTIVE</b>Febrile seizure (FS) is a pediatric emergency. The reiterative attacks of FS may result in brain damage to various extents. Fructose-1,6-diphosphate, serving as a cellular energy substance, has been applied to clinical practice for many years and has shown its importance in adjuvant treatment of diseases with myocardial damage. This study aimed to explore the potentiality of protecting rats' brain damage caused by febrile seizure with fructose-1,6-diphosphate (FDP).</p><p><b>METHODS</b>Thirty 21-day-old male Sprague-Dawley (SD) rats were randomly divided into febrile seizure group (FS), sodium chloride solution (NS) control group and FDP intervention group (FD). Febrile seizure was induced by hyperthermal bath at 45 degrees C in the present study. No intervention treatment was given to rats in FS group before febrile seizure. Thirty minutes before febrile seizures, rats in FD group were given peritoneal injection of FDP at a dose of 25 mg per 100 g of body weight, whereas the same volume of 0.9% sodium chloride solution was injected into peritoneum of rats in NS group. Manifestations of seizure and differences in seizure latency, duration of seizure and seizure severity were observed in all the 3 groups. Samples of rat brain were prepared for electron microscopy in order to understand the characteristics of the ultrastructural changes in mitochondria, interspace of neuronal synapses and neurons of hippocampal region CA(1).</p><p><b>RESULTS</b>Data collected from this study indicated that peritoneal injection of FDP at 25 mg per 100 grams of body weight 30 minutes before febrile seizures could result in improvement of the clinical manifestation of the rats caused by febrile seizures. Specifically speaking, the seizure latency was prolonged, the duration of seizures was shortened and severity of seizure was reduced. Analysis of variance and q-test on the data collected from the 3 groups revealed that there were significant differences between FD group and the other two groups (P < 0.05), yet no significant difference was found between FS group and NS group (P > 0.05). Electron microscopic observations on brain specimens revealed that FDP could relieve mitochondrial degeneration and edema. FDP could also reduce neuronal degeneration and necrosis in hippocampal region CA(1) (the percentages of neuronal degeneration and necrosis in the 3 groups were respectively 13% for FD group, 28% for FS group and 30% for NS group). There was a significant difference between FD group and the other two groups (P < 0.05), FDP treatment could prevent interspace of neuronal synapses from enlarging (the mean interspace was 6.47 +/- 0.37 micro m for FD group, 7.60 +/- 0.36 micro m for FS group and 7.53 +/- 0.40 micro m for NS group. The difference between FD group and the other two groups was significant (P < 0.01).</p><p><b>CONCLUSION</b>FDP could lead to prolonged seizure latency, shorter duration of seizures and mitigation of seizures severity. FDP could also reduce neuronal degeneration and necrosis and prevent the interspace of neuronal synapses from enlarging in hippocampal region CA(1). The present study suggests that FDP can protect brain of rat from damages caused by febrile seizures.</p>

Effects of nimodipine and fructose-1,6-diphosphate on cerebral damage in carbon monoxide poisoning mice / 中华医学杂志(英文版)

<p><b>OBJECTIVE</b>To study the dose- and time-dependent protective effects and the synergistic effects of nimodipine (NMDP) and fructose-1,6-diphosphate (FDP) against cerebral damage induced by acute carbon monoxide (CO) poisoning in mice.</p><p><b>METHODS</b>Male mice were exposed to CO 170 mL/kg, i.p. After CO intraperitonealy exposure, mortality of mice, change in memory function estimated by passive avoidance test, the pathomorphologic observation of brain tissue slices, as well as changes of activities of monoamine oxidase (MAO)-B and Ca(2+)-Mg(2+)-ATPase in cerebral tissue were studied. In dose-dependent protective effect study, NMDP (10.6, 5.3, 2.7 mg/kg) and FDP (2.6, 1.3, 0.67 g/kg) was injected ip, respectively 15 min after CO exposure. To study the time-effect relationship of drugs, NMDP (5.3 mg/kg) and FDP (1.3 g/kg) were administered ip respectively 15 minutes, 45 minutes and 120 minutes after CO exposure. The combination of NMDP (2.7 mg/kg) and FDP (0.67 g/kg) was administered ip15 minutes, 45 min and 120 minutes after CO exposure to study the synergism of the two drugs.</p><p><b>RESULTS</b>Either NMDP (10.6, 5.3 mg/kg) or FDP (2.6, 1.3 g/kg) administered ip within 15 minutes after CO exposure significantly decreased the impairment of memory function and mortality rate induced by CO, inhibited the decrease of Ca(2+)-Mg(2+)-ATPase activity, blunted the rising of MAO-B activity and prevented the delayed hippocampal neuronal death in poisoning mice. To our surprise, the combined use of NMDP (2.7 mg/kg) and FDP (0.67 g/kg) within 15 minutes after CO exposure had similar effects to that in NMDP (10.6, 5.3 mg/kg) and FDP (2.6, 1.3 g/kg).</p><p><b>CONCLUSIONS</b>These results suggest that the impairment of CO on brain can be attenuated if NMDP or FDP are administered sufficiently and quickly as soon as possible after CO exposure and there exists a synergism of FDP and NMDP against CO poisoning damage.</p>

Effects of sodium magnesium fructose diphosphate on free calcium concentration and nitric oxide synthase activity of ischemic synaptosome / 药学学报

<p><b>AIM</b>To study the effects of sodium magnesium fructose diphosphate (SMFD) on free calcium concentration and nitric oxide synthase activity of ischemic synaptosome, so as to explore the protective mechanisms of SMFD on cerebral ischemia.</p><p><b>METHODS</b>The synaptosomes from normal rat brain were prepared by phase partition and cultured with oxygen-glucose deprivation to establish ischemic synaptosome model. The intrasynaptosomal free calcium concentration and nitric oxide synthase activity were detected separately after the synaptosomes were co-incubated with SMFD (1.3 mmol.L-1) or fructose-1, 6-diphosphate (FDP, 4.0 mmol.L-1) for 60 min.</p><p><b>RESULTS</b>SMFD decreased the free calcium concentration and reduced the activity of nitric oxide synthase (NOS) of ischemic synaptosomes. Its effects were more powerful than those of FDP.</p><p><b>CONCLUSION</b>SMFD may protect neurons from ischemic injury by preventing intracellular Ca2+ overload and inhibiting the activity of nitric oxide synthase.</p>

Effect of neuroprotectant agent combined with cocktail on expression of anti-apoptotic protein bcl-2 in rats after focal cerebral ischemia / 中华预防医学杂志

<p><b>OBJECTIVE</b>To investigate whether the protective effect of therapy with different combined neuroprotectant agents was better than that of single agent on focal cerebral ischemia.</p><p><b>METHODS</b>The right middle cerebral artery in the rats was occluded with suture occlusion technique. The rats were divided into five groups treated with FDP (50 mg/kg, n = 10), MK-801 (1 mg/kg, n = 10) and NAC (150 mg/kg, n = 10) singly, or in combination, respectively, by intraperitoneal infusion 30 minutes after vessel occlusion. The rats were weighed and assessed neurologically, based on a 5-point scale, six and 24 hours after focal cerebral ischemia. The expression of anti-apoptotic protein bcl-2 was observed with SDS-PAGE protein electrophoresis and Western blot technique.</p><p><b>RESULT</b>The optical density of bcl-2 increased more distinctly in the rats treated with combined neuroprotective agents than that with any single agent six and 24 hours after cerebral ischemia, with a statistically significant difference (P < 0.05).</p><p><b>CONCLUSIONS</b>Treatment with combined neuroprotectant agents could un-regulate the anti-apoptotic protein bcl-2 more distinctly than that with any single agents. Combined use of neuroprotectants might be more effective than that of single agent in protecting rats' brain from ischemia.</p>

Fructose, 1,6-diphosphate mitigates CCl4 suppressed nitric oxide synthase activity in rats.

Effect of fructose 1,6-diphosphate (FDP) and carbon tetrachloride (CCl4) were studied individually and in combination on rat endothelial (ET) and smooth muscle cell (SMC) nitric oxide synthase (NOS) activities in vivo, inhibition of ET and SMC NOS activity in CCl4 treated rats was reversed in FDP + CCl4 treated animals. Cellular based NOS activity was significantly increased in FDP treated group of rats when compared to non treated controls. The results suggest a significant increase in NOS in rats treated with a combination of FDP + CCl4 thus overcoming the suppression of NOS exposed to CCl4 alone.

Aggregation of banana pyrophosphate fructose 6-phosphate 1-phosphotransferase by glycerol.

Addition of glycerol during purification of banana (Musaceae, Musa cavendishii) pyrophosphate fructose 6-phosphate 1-phosphotransferase [(PFP), EC 2.7.1.90] initiated molecular aggregation of the enzyme. The aggregation process was dependent on the glycerol concentration. The native enzyme (66 kDa molecular mass) showed enhanced activity at 3% (V/V) or less of glycerol concentration. Glycerol concentration between 4 and 5% (V/V) affected a gradual and sequential aggregation of native form of the enzyme. These aggregated forms had molecular masses of 135, 200 and 270 kDa. The 135 and 200 kDa forms were stable for about 72 hrs and prolonged storage over 2 weeks resulted in the formation of the 270 kDa form. Concentration over 5% could reduce the time required for aggregation. Fru2.6 bis P activated the enzyme over ten fold, but did not help in the aggregation process. Studies on the role of glycerol on PFP specific activity suggested a difference in the activation process compared to that by Fru2.6bis P. Replacement of Hepes buffer by Tris increased the Fru2.6 bis P requirement for maximum activation by around 10 fold. Removal of glycerol from the buffer media resulted in almost complete inactivation of the enzyme.

Fructose 2, 6 bisphosphate promotes the monomer-tetramer conservation of Leishmania mexicana amazonensis pyruvate kinase type two

The enzyme pyruvate kinase of Leishmania mexicana amazonensis presents two forms with different kinetic properties and behavior for the heterotrophic activator fructose 2,6 bisphosphate. Pyruvate kinase 1, which is isolated as a tetramer, is inhibited by this metabolite. The second activity, Pyruvate kinase 2, is activated by fructose 2,6 bisphosphate, which promotes the monomer-tetramer conversion of this enzyme

Comparative study of phosphofructokinase from rat small intestine and liver. Control by fructose-2,6-bisphosphate and other effectors

As compared to the liver, intestinal mucosa shows a high rate of aerobic glycolysis. This difference has been attributed to the higher activity of the intestinal phosphofructokinase (PFK) isoenzyme. The regulatory properties of rat small intestine and liver PFK were investigated. At pH 8, where PFK activity can be evaluated free of allosteric influences, the specific activity of the liver isoenzyme was 25%higher that of the intestinal one, At pH 7, the mucosal PFK was activated to 80%of its maximal activity at pH 8, while the liver enzyme showed only a 40%activation. The apparent Kms for Fructose-6-P were 0.47 and 1.03 mM for the mucosal and hepatic isoenzymes, respectively. At 2 mM Fructose-6-P, the optimal ATP concentration for both isoenzymes was 1 mM Hogher ATP concentrations strongly anhibited both enzymes, but below 3 mM, PFK activity was larger in the mucosal homogenate. In addition, the intestinal PFK was more sensitive to activation by Fructose-2,6-bisphosphate and 6-phosphogluconate, particulary at low Fructose-6-p concentrations, and by AMP below 0.3 mM. These studies suggest that, under physiological conditions, the intestinal isoenzyme is more active than its liver counterpart. This may acccunt for the high rate of aerobic glycolysis observed in the intestinal mucosa

Fructose 2,6-bisphosphate and trehalose metabolism in Saccharomyces cerevisiae

1. A regulatory mutant of Sccharomyces (fdp) unable to activate fructose 1,6-bisphosphatase present a normal response to the glucose and fructose signals as measured by trehalase activation, indicating that the inability of the strain to grow on these sugars is caused by a defect located beyond membrane interactions. 2. In vivo experiments with a mutant strain bearing a phosphoglucoisomerase gene (pgil-delta) deletion showed that activation of trehalase and deactivation of the tehalose-6-phosphate synthase complex occurred to the same extent whether glucose or fructose was used as signal. 3. These results suggest that fructose-2,6-bisphosphate is not involved in the interconversion of forms of the enzymes of trehalose metabolism. Furthermore, when fructose-2,6-bisphosphate was assayed on trehalose synthesizing activity using cell-free extracts and partially purified preparations of the complex, no effect was observed. 4. We conclude that regulation by cAMP fulfills the requirements for control of trehalose levels in Saccharomyces