To further explore the limitations to maximal O(2) consumption (.VO(2 max)) in exercise-trained skeletal muscle, six cyclists performed graded knee-extensor exercise to maximum work rate (WR(max)) in hypoxia (12% O(2)), hyperoxia (100% O(2)), and hyperoxia + femoral arterial infusion of adenosine (ADO) at 80% WR(max). Arterial and venous blood sampling and thermodilution blood flow measurements...

Previous work with 8-chloro-cAMP (8-Cl-cAMP) has raised questions as to whether it works as a cAMP analogue or as a nucleoside analogue after its conversion to 8-chloro-adenosine (8-Cl-Ado). Although degradation of 8-Cl-cAMP to 8-Cl-Ado in culture medium or plasma has been shown, cellular pharmacology data are missing. The purpose of the present study was to identify the cellular metabolism of ...

We argue that the phenomenon of autocatalytic decision overload (ADO) may be a key mechanism contributing to catastrophic collapse of command and control (C2) systems. We introduce the concept of ADO and describe typical scenarios for such a collapse. We then provide a simple nonlinear difference equation model for the dynamics of error propagation in C2 systems which exhibits the ADO phenomena...

1 Department of Biological Sciences, College of Sciences, Afe Babalola University, Ado Ekiti, Nigeria. 2 Department of Botany, University of Ibadan, Nigeria. 3 Department of Physiology, University of Ibadan, Nigeria., 4 Department of Biochemistry, College of Medicine, Afe Babalola University, Ado Ekiti, Nigeria. 5 Department of Anatomy, College of Medicine, Afe Babalola University, Ado Ekiti, N...

The influence of transmembrane flux limitations on cellular metabolism of purine nucleosides was assessed in whole organ studies. Transcapillary transport of the purine nucleosides adenosine (Ado) and inosine (Ino) via paracellular diffusion through interendothelial clefts in parallel with carrier-mediated transendothelial fluxes was studied in isolated, Krebs-Henseleit-perfused rabbit and guin...

8-Chloro-adenosine (8-Cl-Ado) is an adenosine derivative, which inhibits proliferation and induces apoptosis in various tumor cells. Subtoxic concentration of 8-Cl-Ado sensitizes human hepatoma cells to tumor necrosis factor-related apoptosis inducing ligand (TRAIL)-triggered apoptosis. However, the molecular mechanism by which TRAIL cytotoxicity is amplified by 8-Cl-Ado is unknown. In the pres...

Altered postictal cerebral blood flow dilatory responses may contribute to brain injury following neonatal seizures. We developed an initial series of experiments to characterize the effects of seizure activity on cerebral vascular dilatory responses during the immediate postictal period. Significant attenuation of postictal hypoxic cerebral vasodilation was noted. We hypothesize that this dimi...

Adenosine (ADO) is a homeostatic inhibitory autocoid that is released at sites of inflammation and tissue injury, and exerts anti-inflammatory effects via multiple interactions at ADO receptor subtypes. Inhibition of ADO kinase (AK) increases extracellular ADO concentrations and AK inhibitors have demonstrated ADO-mediated anti-inflammatory effects in acute models of inflammation. To evaluate t...

BACKGROUND In the kidney, adenosine (ADO) can induce either vasoconstriction or vasodilatation, mediated by A1 or A2 receptors, respectively. The vasodilator influence may be of special importance in the renal medulla which operates at low tissue pO(2) levels and is susceptible to ischaemic damage. It has not been established if ADO induced vasodilatation is modified by salt intake. METHODS W...

Adenosine (ADO) is a potent bronchoconstrictor in allergic patients and has been shown to increase the release of histamine from human lung tissues. Antagonists of ADO A1 and A2A receptors are not effective in attenuating these effects. Therefore, involvement of ADO A3 receptors in the bronchoconstrictor and/or inflammatory effects have to be considered. Eosinophils also play a pivotal role in ...