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Selected AbstractsUridine adenosine tetraphosphate affects contractility of mouse aorta and decreases blood pressure in conscious rats and miceACTA PHYSIOLOGICA, Issue 2 2010P. B. Hansen Abstract Aim:, In the anaesthetized rat, uridine adenosine tetraphosphate (Up4A) is a circulating, endothelium-derived vasoconstrictor presumably operating as such in un-anaesthetized animals. The present study investigated the in vivo effects of Up4A in conscious mice and rats, and its direct vascular effects in the mouse aorta in vitro. Methods:,In vivo, Up4A was given as step-up infusion at rates of 8,512 nmol min,1 kg,1 for 30 min periods in chronically catheterized rodents. In vitro, the effect of Up4A on rings of mouse aortae mounted in a myograph was tested. Results:, High doses of Up4A (mice: 512 nmol min,1 kg,1; rats: 128 nmol min,1 kg,1) caused hypotension (99 ± 4 to 64 ± 7 mmHg and 114 ± 3 to 108 ± 3 mmHg, respectively, both P < 0.01). In rats, Up4A significantly decreased sodium excretion by >75% and potassium excretion by ,60% without significant changes in urine flow. Exposure of phenylephrine-contracted rings to increasing concentrations of Up4A elicited contraction at 10,7 and 10,6 mol L,1 (18 ± 2% and 76 ± 16% respectively); unexpectedly, 10,5 mol L,1 caused a biphasic response with a contraction (19 ± 6%) followed by a relaxation (,46 ± 6%). No relaxation was observed when the concentration was increased further. Bolus exposure to 10,5 mol L,1 of Up4A caused contraction (+80 ± 2%). Added successively to untreated vessels, increasing concentrations of Up4A (10,7,10,5 mol L,1) induced a biphasic response of contraction followed by relaxation. Conclusion:, Up4A has direct biphasic effects on vascular smooth muscle of the mouse aorta but vasoconstriction dominates at low concentrations. In conscious rodents, step-up infusions of Up4A elicit hypotension and electrolyte retention. [source] Decreased cortisol production in male type 1 diabetic patientsEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 7 2003M. N. Kerstens Abstract Background It is unclear whether cortisol production and the 11,HSD-mediated cortisol to cortisone interconversion are different between type 1 diabetic patients and healthy subjects. Materials and methods Fourteen male, nonobese, normotensive type 1 diabetic patients without severe complications (HbA1c < 8·5%) were studied twice during a daily sodium intake of 50 and 200 mmol, and were then compared with 14 individually matched healthy subjects. Cortisol production was assessed by the sum of urinary cortisol metabolite excretion. Urinary ratios of (tetrahydrocortisol + allo-tetrahydrocortisol)/tetrahydro-cortisone [(THF + allo-THF)/THE] and of free cortisol/free cortisone [UFF/UFE] were determined as parameters of 11,HSD activity. Results Sum of urinary cortisol metabolite excretion during low- and high-salt diet was 7·4 ± 2·5 vs. 7·7 ± 2·3 nmol min,1 m,2 (NS) in diabetic patients and 9·7 ± 2·1 vs. 11·2 ± 4·1 nmol min,1 m,2 (NS) in healthy subjects, respectively (P < 0·05 vs. healthy subjects at both diets). The allo-THF excretion and allo-THF/THF ratios were lower in the diabetic than in the healthy males during both diets (P < 0·05). Urinary (THF + alloTHF)/THE and UFF/UFE were similar in both groups and remained unchanged after salt loading. Conclusions The sum of urinary cortisol metabolite excretion as a measure of cortisol production is lower in nonobese, normotensive type 1 diabetic males with adequate glycaemic control and without severe complications, irrespective of sodium intake. We suggest that this is at least in part as result of diminished 5, reductase activity, resulting in a decreased cortisol metabolic clearance. In type 1 diabetic and in healthy males, the 11,HSD setpoint is not affected by physiological variations in sodium intake. [source] Paraoxonase activity in two healthy populations with differing rates of coronary heart diseaseEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 1 2000Mackness Background The rate of coronary heart disease is over three-fold greater in Belfast than in Toulouse and the excess risk cannot be totally explained by ,classical' risk factors such as total cholesterol, LDL-cholesterol, smoking, etc. Design The effect of the human serum paraoxonase (PON1) 192-genetic polymorphism on plasma lipid and lipoprotein concentrations and on PON1 activity and concentration was investigated in 186 randomly selected healthy subjects from Toulouse and 165 from Belfast. Results The frequency of the R allele of PON1, which has been related to the risk of coronary heart disease, was significantly higher in Belfast (0.33) than in Toulouse (0.24; ,2 = 7.229, P = 0.0072). Subjects from Belfast also had significantly higher serum cholesterol, triglycerides, LDL-cholesterol, and apolipoprotein B, and significantly lower HDL-cholesterol and apolipoprotein A1, but these lipoprotein parameters were independent of the PON1 192-polymorphisms. PON1 activity towards paraoxon was significantly higher in the Belfast population than in Toulouse (median values: 179.7 vs. 129.4 nmol min,1 mL,1 serum, respectively; P < 0.05), which is consistent with our finding of a greater prevalence of the R allele. The median serum concentration of PON1 was 56.3 ,g mL,1 in Belfast, which was significantly lower (P < 0.005) than the level of 71 ,g mL,1 in Toulouse. Conclusions Our results thus provide further support for the hypothesis that populations at increased CHD risk have diminished serum PON1 concentration and an increased prevalence of the R allele of PON1. They are also consistent with reports that the ability of PON1 to hydrolyse paraoxon is inversely related to its capacity to hydrolyse lipid-peroxides, and thus to its antiatherogenic action. [source] Indigo production by Pseudomonas sp.JOURNAL OF BASIC MICROBIOLOGY, Issue 3 2010a marine naphthalene-degrading strain Abstract A technique developed to determine naphthalene dioxygenase (NDO) activity was optimized and used to study the biotransformation of indole to indigo by Pseudomonas sp. J26 whole cells. The maximum production of indigo was achieved at 25 °C using 2.5 mM indole when J26 was grown in the complex medium JPP, while indole concentrations higher than 4 mM proved toxic for cells. The maximum rate of indigo production was 0.56 nmol min,1 mg dry biomass,1, obtaining 75.5 ,M of indigo after 8 h of incubation, while a maximal concentration (138.1 ,M) of indigo was obtained after 20 h. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Indigo production by naphthalene-degrading bacteriaLETTERS IN APPLIED MICROBIOLOGY, Issue 1 2000B. Bhushan A wild-type naphthalene-degrading strain Pseudomonas putida RKJ1 and two recombinant strains each of Ps. putida and Escherichia coli carrying the genes for naphthalene degradation on a recombinant plasmid pRKJ3, produced indigo and indirubin pigments from indole. Naphthalene, salicylate and IPTG induced cells of naphthalene-degrading recombinant bacteria produced up to two times higher indigo compared with the uninduced cells. The maximum rates of indigo formation by Ps. putida RKJ1, Ps. putida RKJ5/pRKJ3, Ps. putida KT2442/pRKJ3, E. coli TB1/pRKJ3 and E. coli AB1157/pRKJ3 were 0·60, 0·80, 0·60, 1·20 and 1·50 nmol min,1 mg dry biomass,1, respectively, using indole as the substrate. The apparent Km values of indigo formation by these same bacteria were 0·22, 0·15, 0·10, 0·21 and 0·20 mmol l,1, respectively, again using indole as the substrate. The present study revealed that E. coli AB1157 was the most efficient of the hosts tested for the expression of the plasmid encoded genes (pRKJ3) from the wild-type strain Ps. putida RKJ1. In addition, both recombinant E. coli strains were capable of producing indigo directly from nutrient medium. [source] Effect of apoE/ATP-containing liposomes on hepatic energy stateLIVER INTERNATIONAL, Issue 5 2003S. Chaïb Abstract: Background/Aims: ATP-containing liposomes partially prevent ATP depletion in the cold-stored liver. As hepatocytes can specifically bind apoE, we investigated whether the addition of apoE to large (200 nm) ATP-containing liposomes increases their uptake by the liver and further improves hepatic energy stores. Methods: Livers from fasted male Hartley guinea-pigs (231±3 g) were perfused for 90 min under our standard conditions (Control, n=6) or after a single bolus addition of plain liposomes (Lip, n=6), ATP (5 ,mol)-containing liposomes (ATP-Lip, n=6) or apoE/ATP-containing liposomes (0.8 or 8 mg apoE/g phospholipids; apoE1-Lip and apoE10-Lip, respectively, n=6 in each group). Liposome uptake and its impact on energy and nitrogen metabolism were studied. Results: At its highest concentration, apoE significantly increased liposome uptake (apoE10-Lip:,9.17±0.69 vs apoE1-Lip:,6.18±0.44 vs ATP-Lip:,6.40±0.88 nmol min,1 g,1; P<0.05). This was associated with a significant increase in intrahepatic ATP (apoE10-Lip: 1033±137 vs apoE1-Lip: 811±98 and ATP-Lip: 648±36 nmol g,1; P<0.05), which was restored to its level in non-perfused livers. Hepatic viability and nitrogen metabolism were not affected. Conclusions: Hepatic ATP content being a key factor in the maintenance of liver graft function, apoE/ATP-containing liposomes should be useful in liver preservation for transplantation. [source] Reversible changes in Ca2+ -activation properties of rat skeletal muscle exposed to elevated physiological temperaturesTHE JOURNAL OF PHYSIOLOGY, Issue 3 2002Chris van der Poel Exposure of relaxed rat extensor digitorum longus (EDL; predominantly fast-twitch) muscle to temperatures in the upper physiological range for mammalian skeletal muscle (43-46 °C) led to reversible alterations of the contractile activation properties. These properties were studied using the mechanically skinned fibre preparation activated in Ca2+ -buffered solutions. The maximum Ca2+ -activated force (maximum force per cross-sectional area) and the steepness of force-pCa (-log10[Ca2+]) curves as measured by the Hill coefficient (nH) reversibly decreased by factors of 8 and 2.5, respectively, when the EDL muscle was treated at 43 °C for 30 min and 5 and 2.8, respectively, with treatment at 46 °C for 5 min. Treatment at 47 °C for 5 min produced an even more marked depression in maximum specific force, which fully recovered after treatment, and in the Hill coefficient, which did not recover after treatment. After all temperature treatments there was no change in the level of [Ca2+] at which 50 % maximum force was generated. The temperature-induced depression in force production and steepness of the force-pCa curves were shown to be associated with superoxide (O2,) production in muscle (apparent rate of O2, production at room temperature, 0.055 ± 0.008 nmol min,1 (g wet weight),1; and following treatment to 46 °C for 5 min, 1.8 ± 0.2 nmol min,1 (g wet weight),1) because 20 mm Tiron, a membrane-permeant O2, scavenger, was able to markedly suppress the net rate of O2, production and prevent any temperature-induced depression of contractile parameters. The temperature-induced depression in force production of the contractile apparatus could be reversed either by allowing the intact muscle to recover for 3-4 h at room temperature or by treatment of the skinned fibre preparation with dithiothreitol (a potent reducing agent) in the relaxing solution. These results demonstrate that mammalian skeletal muscle has the ability to uncouple force production reversibly from the activator Ca2+ as the temperature increases in the upper physiological range through an increase in O2, production. [source] Monoamine oxidase activity in kidney and heart of Piaractus mesopotamicus (Holmberg)JOURNAL OF FISH BIOLOGY, Issue 6 2007C. M. C. Salles The values of Michaelis,Menten constant (KM) and maximum velocity (VMAX) for kidney and heart monoamine oxidase (MAO) from pacu Piaractus mesopotamicus were determined. The mean ±s.e. KM values were 17·28 ± 2·27 ,M for kidney and 15·38 ± 1·86 ,M for heart. MAO activities were 111·60 ± 3·25 and 15·12 ± 0·30 nmols min,1 g,1 of wet tissue for kidney and heart, respectively. In addition, MAO inhibitory studies in these two tissues indicate that this enzyme may be a different isoform of MAO. [source] | |||||||||||||