A phenomenological calculus of Wiener description space.

The phenomenological calculus is a categorical example of Robert Rosen's modeling relation. This paper is an alligation of the phenomenological calculus and generalized harmonic analysis, another categorical example. Our epistemological exploration continues into the realm of Wiener description space, in which constitutive parameters are extended from vectors to vector-valued functions of a real variable. Inherent in the phenomenology are fundamental representations of time and nearness to equilibrium.

Characterization of mutant forms of the quinoprotein methanol dehydrogenase lacking an essential calcium ion.

Methanol dehydrogenase (MDH) from Methylobacterium extorquens, Methylophilus methylotrophus, Paracoccus denitrificans and Hyphomicrobium X all contained a single atom of Ca2+ per alpha 2 beta 2 tetramer. The role of Ca2+ was investigated using the MDH from Methylobacterium extorquens. This was shown to be similar to the MDH from Hyphomicrobium X in having 2 mol of prosthetic group (pyrroloquinoline quinine; PQQ) per mol of tetramer, the PQQ being predominantly in the semiquinone form. MDH isolated from the methanol oxidation mutants MoxA-, K- and L- contained no Ca2+. They were identical with the enzyme isolated from wild-type bacteria with respect to molecular size, subunit configuration, pI, N-terminal amino acid sequence and stability under denaturing conditions (low pH, high urea and high guanidinium chloride) and in the nature and content of the prosthetic group (2 mol of PQQ per mol of MDH). They differed in their lack of Ca2+, the oxidation state of the extracted PQQ (fully oxidized), absence of the semiquinone form of PQQ in the enzyme, reactivity with the suicide inhibitor cyclopropanol and absorption spectrum, which indicated that PQQ is bound differently from that in normal MDH. Incubation of MDH from the mutants in calcium salts led to irreversible time-dependent reconstitution of full activity concomitant with restoration of a spectrum corresponding to that of fully reduced normal MDH. It is concluded that Ca2+ in MDH is directly or indirectly involved in binding PQQ in the active site. The MoxA, K and L proteins may be involved in maintaining a high Ca2+ concentration in the periplasm. It is more likely, however, that they fill a 'chaperone' function, stabilizing a configuration of MDH which permits incorporation of low concentrations of Ca2+ into the protein.

Seat belt aorta: acute dissection and thrombosis of the abdominal aorta.

Aortic trauma mainly involves the thoracic aorta (95%), while the abdominal aorta is infrequently involved (5%). Of growing interest is the role of seat belts in abdominal aortic injuries. Although seat belts are known to cause injuries to the abdominal viscera, they rarely produce aortic trauma. We report here an acute dissection with thrombosis of the abdominal aorta leading to complete peripheral occlusion as a result of lap-type seat belt injury. The two previously reported cases of similar injuries which resulted in incomplete occlusion are reviewed. A hypothesis for the causal mechanism of these injuries is described. The authors also stress careful follow-up of all patients with seat belt injuries since other intra-abdominal vascular injuries may be present.

The release of labelled acetylcholine and choline from cerebral cortical slices stimulated electrically.

1 In order to establish the origin of the increased efflux of radioactivity caused by electrical stimulation of cerebral cortical slices which had been incubated with [(3)H]-choline, labelled choline and acetylcholine (ACh) collected by superfusion were separated by gold precipitation.2 In the presence of physostigmine electrical stimulation (1 Hz, 10 min) increased the release of only [(3)H]-ACh which was greatly enhanced by the addition of atropine.3 Continuous stimulation in the presence of physostigmine resulted in an evoked release of [(3)H]-ACh which declined asymptotically. This evoked release appeared to follow first-order kinetics with a rate constant which remained stable over the course of prolonged stimulation.4 The rate constant for the evoked release of [(3)H]-ACh with 1 Hz stimulation was three times greater in the presence of physostigmine and atropine than in the presence of physostigmine alone, while the size of the store from which [(3)H]-ACh was released was nearly identical under these two conditions.5 In the absence of physostigmine and atropine, stimulation caused the appearance of only [(3)H]-choline in the samples.6 Reduction of [(3)H]-ACh stores before the application of physostigmine resulted in a reduced evoked release of total radioactivity, both in the absence or presence of physostigmine and atropine, and decreased the evoked release of [(3)H]-ACh without affecting the release of [(3)H]-choline.7 Results suggest that electrical stimulation of cortical slices which had been incubated with [(3)H]-choline causes the release of only [(3)H]-ACh, both in the presence or absence of an anticholinesterase. The evoked increase in the efflux of total radioactivity is therefore a good measure of the release of [(3)H]-ACh.

Ionic flows through a single homogeneous membrane : A thermodynamic analysis.

The Kedem-Katchalsky equation for the flow of a mono-monovalent salt through a highly charged permselective membrane is given as a first order expansion of a single integral of the Kirkwood-Bearman-Spiegler equations. The integration is performed under the assumption that the partial frictional coefficientsζ ij are concentration independent. Conditions for the validity of the expansion are presented. A close relationship to the Goldman equation is demonstrated. If impermeable salts are present in the bathing solutions, the Kedem-Katchalskypractical parameters ω, σ, and τ1 may be ill-defined. Nevertheless, an ionic flow equation of similar form, but of significant difference, can be derived for this situation. The Kedem-Katchalsky equation for salt flow is a special case of this more general equation.