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Biomedical subjects

G Kemeny

Publications and source records attributed to G Kemeny.

At least 19 recordsLinked to original sources
PubMed1985

Discrete charge carrier transfer sites on proteins? A D.C. conductivity study on ultrathin protein films.

D.C. electrical conduction in thin protein films (200 mg/cm2; approximately 2 mu in thickness) of bovine serum albumin and its dinitrophenylated derivatives with different stoichiometric composition was investigated at 17, 20 and 23% relative humidities and at room temperature. Statistically significant decrease in conductivity due to derivatization was observed even at protein-2,4-dinitrophenol stoichiometry as low as 1:2. A charge injection mechanism based upon discrete charge carrier transfer sites could account for the observations. Analogous events may operate in cellular signaling and coding.

Animals↗
PubMed1979

Stochastic studies of aging and mortality in multicellular organisms. II. The finite theory.

We extend the development of a quantitative phenomenological theory of aging rooted in order theory. An organism is represented abstractly by a chain with a finite number of links. Each link corresponds to a possible rate-limiting event or process in senescence. A link is said to break when the corresponding event occurs or the corresponding process goes to completion. The chain is said to break, and the organism subsequently to perish, when the first link breaks, whichever link that might be. Two models are introduced to describe the failure of an arbitrary link. The first requires that a link break only after sustaining a fixed amount of deterioration; the second associates a non-zero probability of failure with each level of wear. The net deterioration of an intact chain is taken, crudely, to correspond to the decline in physiological vitality sustained by an organism during senescence. Failure of an arbitrary link is described in both models by a Markov process. The corresponding mortality rate derived in each instance describes aspects of available empirical data which cannot be accounted for by either the Gompertz or power-law relations. The decline in vitality is shown in both cases to be linear over time intervals of practical interest. The influence of temperature on the senescence of poikilotherms is briefly examined. We describe the effect of temperature both on longevity and the decline in vitality; indicate how substantial discrepancies can arise in the calculation of a macroscopic, effective, activation enthalpy; and lend theoretical support to the existence of temperature--memory effects in senescence.

Aging↗
PubMed1976

Charge pair model of bioenergetics: redox enzymes.

A model of electron transfer between redox enzymes is constructed on the assumption that the apoenzyme contains orientable units, which are tentatively identified with flipping amino acids. The model is based on the entatic state hypothesis, and the rate of electron transfer is derived.

Apoenzymes↗
PubMed1975

Physical basis of charge pairing in mitochondria.

The postulate of charge pairing in the mitochondrial inner membrane is justified by applying a formula due to Fuoss to calculate the probability density for the distance between a positive and a negative charge. For dielectric constants 10 or less pairing is absolute, for 20 there is some tendency towards pairing, and at 78 it is nonexistent. Pairing, partner exchange or charge substitution, inhibition, and antiport uncoupling can be rationalized within this framework.

Computers↗
PubMed1974

Charged pair current networks in bioenergetics.

The operation of bioenergetic systems is postulated to be based on charged pair networks. The basic elements of the networks are pairs of opposite charges accompanied by conformational changes of the protein medium. The elementary events are the separation and recombination of charged pairs and partner exchange between two such pairs. The last event makes the construction of networks possible and provides for the flexibility of coupling modes in mitochondria. Bioenergetic systems appear to use electricity in a hitherto unsuspected way. The networks are constructed entirely on electrostatic principles. The possibility of generalization to include mechanical elements is discussed.

Electricity↗
PubMed1974

Energy transfer mechanisms in mitochondria.

The problem of free energy transfer and transduction in mitochondria is reviewed from the point of view of conservative and dissipative mechanisms. Excited states are inherently dissipative and are not considered viable possibilities. If the free energy is already a local minimum and present in the form of potential energy, conservative transfer is possible within a properly designed medium. The design features are compatible with what is known about mitochondria.

Energy Transfer↗