The medical concept of prognosis is analysed into its basic constituents: patient data, medical intervention, outcome, utilities and probabilities; and sources of utility and probability values are discussed. Prognosis cannot be divorced from contemplated medical action, nor from action to be taken by the patient in response to prognostication. Regrettably, the usual decision-theoretic approach ignores this latter aspect. Elicitation of utilities, decision contemplation and prognostic counselling interweave, diagnostics playing a subsidiary role in decision-oriented clinical practice. At times the doctor has (...) grounds for withholding information. As this is known to the patient, prognostic counselling becomes a conflict-prone and rationality-thwarting activity. The meaning of standard phrases such as prognosis of a disease, the prognosis of this patient, the prognosis is unknown, is examined. (shrink)

Substrate cycles are ubiquitous structures of the cellular metabolism (e.g. Krebs cycle, fatty acids -oxydation cycles, etc... ). Moiety-conserved cycles (e.g. adenine nucleotides and NADH/NAD, etc...) are also important.The role played by such cycles in the metabolism and its regulation is not clearly understood so far. However, it was shown that these cycles can generate multistationarity (bistability), irreversible transitions, enhancement of sensitivity, temporal oscillations and chaotic motions (Hervagault & Canu, 1987; Hervagault & Cimino, 1989; Reich & Sel'kov, 1981; Ricard & (...) Soulié, 1982). Fig. 1: Scheme of the open binary substrate cycle under study. The substrate S is converted into P with a net rate v2. Substrate P is converted in turn into S with a net rate v3. Step v2 is inhibited by excess of the substrate, S. In addition, the cycle operates under open conditions, that is zero-order input of S at rates \ga0(v1) and first order outputs of S and P at rates \gaS and \gaP(v4), respectively. (shrink)