Slow Body Research Articles

Oxygen and lung fibrosis.

Young adult rats were continuously exposed to environments containing 9% to 10%, 20% and 80% oxygen for 41 and 84 days. Animals exposed to both extreme oxygen concentrations demonstrated a noticeably slowed body growth, and the weight of the lungs was proportionally lower. Total amount and density of hydroxyproline in the lungs of both groups was markedly higher than in rats exposed to an ambient atmosphere. At both extreme oxygen concentrations, the content of lactate in the lung and total lactate dehydrogenase (LDH) activity were markedly higher, as was the activity of prolyl hydroxylase. The finding of enhanced peroxidizability of lipids in the lungs (examined by determination of malonaldehyde and change in the profile of fatty acids) indicates that both extreme oxygen concentrations represent an injury to lung constituents. We propose that under chronic exposure to low (9% to 10%) or high (80%) oxygen, the lung tissue was damaged (enhanced peroxidizability of lipids). It also developed inflammatory changes (increased lactate and LDH activity) that resulted in the enhancement of fibroplasia (increased activity of prolyl hydroxylase and collagen content). It is also possible that the content of tissue lactate in vivo situations may control the activity of prolyl hydroxylase.

Lactate dehydrogenase isoenzyme pattern and total LDH activity in the lung and liver of rats chronically exposed to low and high oxygen concentrations

Young adult rats were continuously exposed for 44 and 84 days to environments containing 9–11%, 20%, and 80% oxygen. Low and high oxygen atmospheres were achieved by using boxes laminated with silicone rubber membranes which have a differing permeability for oxygen on one side and for carbon dioxide and nitrogen on the other. Animals exposed to both extreme concentrations significantly slowed body growth, and the weight of the lungs was proportionally less. The pattern of LDH isoenzymes in the lung showed the presence of all five characteristically changing isoenzymes in relation to oxygen concentration. A marked increase of M subunits in the LDH in lungs of rats exposed to low oxygen indicated a higher tissue concentration of lactate. Thus, the percentage of M subunits was significantly higher in low oxygen and significantly lower in lungs of rats exposed to high oxygen as compared to controls. Under the same experimental conditions there were no changes in the liver LDH isoenzyme pattern. Total LDH activity in the lungs of rats exposed to either extreme oxygen atmosphere was significantly elevated as compared to controls kept at an ambient atmosphere. It is concluded that chronic exposure of rats to low as well as to high oxygen was injurious to the lung tissue, as evidenced by total LDH activity. Thus, LDH isoenzyme pattern in the lung reflected the actual gas exposure (pO 2), rather than local tissue metabolism.

Maxwell’s equations in the electrodynamics of moving bodies

The electromagnetic field of a point charge moving in free space at velocityu and accelerationa is evaluated on the basis of Maxwell’s equations, and an approximation of this field is made for nonrelativistic velocities. Some differences result between the approximate formulae and the analogous relations that can be found in the literature. Under the hypothesis that the fields of more complex systems can be obtained by means of the superposition of the fields of the various point charges present in these systems, and under other less important hypotheses, the form of the field equations in systems with moving charge carriers is calculated. It results that Maxwell’s equations seem to be valid in an inertial frame for systems in which only «metallic type» conductors carry considerable currents, and when only very slow body motions are involved. If moving bodies, or current in «nonmetallic type» conductors, are involved, other equations must be used, whose form is proposed in this paper. In such equations the extra terms not contained in Maxwell’s equations represent fields depending on the square of the particle velocity, and cannot be obtained by the magnetic field, which produces only linear terms, except for the Lorentz field. Nay, such extra terms can in part be considered as an extension of the Lorentz field. The proposed equations seem to overcome some contradictions present in the literature, regarding the relativistic invariance of the charge and some simple examples of fields with moving bodies. The fields that Maxwell’s equations do not take into account are not negligible with respect to Lorentz fields, which, in similar cases, are commonly considered significant.

Congenital pulmonary stenosis resulting from dysplasia of valve.

A distinctive type of pulmonary valvular stenosis, termed "pulmonary valvular dysplasia," is described from six necropsies and 10 living children. The anatomic features of the stenotic pulmonary valve are unique in that there are three distinct cusps and no commissural fusion. The obstructive mechanism is related to markedly thickened, immobile cusps, characterized by the presence of disorganized myxomatous tissue. Several clinical features tend to distinguish this form of pulmonary stenosis. In each of 16 patients studied, a pulmonary ejection murmur was present, but this was not associated with an ejection click. Other features suggestive of this type of pulmonary stenosis were slow body growth, abnormal facies, and a positive family history of pulmonary stenosis. The electrocardiogram showed a greater degree of right axis deviation than is found in most cases of dome-shaped pulmonary stenosis. Right ventriculography revealed distinctive features of the pulmonary valve which were characterized by lack of typical dome-shaped deformity and by the presence of thick cusps. Experience with simple incision-valvulotomy was associated with a high (38%) operative mortality and significant residual stenosis in survivors. The suggested operative procedures include excision of a valve cusp, placement of a right ventricular outflow patch, or replacement of the pulmonary valve.