The motion of the left ventricle—III

We use the concept of a layered wall, where each separate layer is to be homogeneous, isotropic, and incompressible, to derive stress-strain relations for the middle layer muscle ring at the transverse midsection of the left ventricle; a convenient method of formulation is that based on the elastic potential function. The hoop or circumferential stress in all three layers is found using dimensional and mechanical parameters derived earlier. The various parameters are expressed as Fourier series so that their behavior over a complete ventricular cycle is known analytically. The cases of simple elongation and what we termcurvilinear simple elongation are considered for the middle layer muscle ring strain, and the resulting stress-strain relations are derived. The results are compared with an incompressible rubber-like material known as a Mooney material.     

Contributions to the mathematical theory of epidemics—III. Further studies of the problem of endemicity

(1) The mathematical investigation of the progress of an infectious disease in a community of susceptible individuals has been extended to include the case where members of the community are removed as the result of some general cause of death acting according to constant non-specific death rates, as well as by death from the disease itself. Under the more general conditions here dealt with the main conclusions arrived at in the previous paper remain qualitatively unaltered. The limitations which remain are that the susceptibility and the infective power of the individual are supposed to be independent of his age, and further that specific individual immunity does not exist in the sense that the part of the population which escapes infection is assumed to be just as susceptible as the whole population would have been if it had not been infected. (2) In the general case a unique steady state is found to exist provided that certain relatively simple conditions are satisfied. In the special cases considered a unique steady state in general exists when these conditions continue to be satisfied; but in particular instances, when these conditions are not satisfied, unique steady states will exist provided that certain other requirements are fulfilled. (3) Increase of birth rates, in general, increases both the absolute and the relative prevalence of the disease in its steady state. The effect of increase in the non-specific death rates is less simple, but has been worked out at some length. Decrease in the infectivity of the disease or in the susceptibility of the uninfected results in an increase in the whole population density as well as in an increase in the number of infected. The effect upon the relative incidence of the disease cannot be simply expressed, but it has been worked out in detail in the text. In the absence of immigration, and with the birth rates and also the non-specific death rates equal for virgins and recovered, variation in infectivity or susceptibility will not alter the relative incidence of the disease. The total population, however, will increase with decrease of either of these two factors, whilst the number of diseased will also increase proportionately. (4) Two types of threshold values have been encountered. In the first type the quantity in question must initially exceed the threshold value if the event or process is to occur in the population. Two examples of this type have been found, namely, in Cases (4) and (2'd).(ABSTRACT TRUNCATED AT 400 WORDS)     

Symbiosis of hydra and algae—III. Extracellular products of the algae

• 1.1. Green algae symbiotic with Chlorohyra viridissima when isolated from the host and incubated with NaHC¹⁴O₃ converted 85 per cent of the CP¹⁴ to maltose which was liberated to the medium.
• 2.2. Other C¹⁴ compounds detected in the medium were glucose, glycolic acid, alanine and an oligosaccharide.
• 3.3. It is suggested that the algae provide Chlorohydra viridissima with maltose.

     

Studies on the enzymic browning of apples—III purification of apple phenolase

Phenolase has been extracted from apple peel preparations by the use of Triton X-100, and separated into two fractions on a DEAE-cellulose column. Since each fraction was homogeneous by starch gel electrophoresis and exhibited similar substrate specificities it was considered that they were isozymes.     

Tropolones of cupressaceae—III.

Twenty-two samples of heartwood from various Cupressus species were analyzed by paper chromatography to determine the tropolones present. Nootkatin and β-thujaplicin seem to occur in all species. Pygmaein, α-thujaplicinol, and α-dolabrinol occur only in the three cypresses from the California coast—C. pygmea, C. goveniana, and C. abramsiana. γ-Thujaplicin is found in large amounts in two closely related species, C. forbesii (southern California) and C. guadalupensis (Guadalupe Island, Baja California), as well as in C. lusifanica, a species known in cultivation only; it appears sporadically in C. arizonica and in the related species C. glabra. Hydronootkatinol and β-thujaplicinol are fairly common, usually in small amounts. α-Thujaplicin and β-dolabrin seem to be rare trace constituents.     

The pH Dependence and the Binding Equilibria of the Calcium Indicator — Arsenazo III

The underlying principles of binding equilibria of arsenazo III with Ca²⁺ and Mg²⁺ are presented. Ca²⁺ and Mg²⁺ can bind arsenazo III in several different protonated forms depending on pH. The binding affinities of these different protonated forms of arsenazo III with Ca²⁺ increase in the order of H₄A_4- <H₃A^5- >H₂A^6- and with Mg²⁺, H₄A^4- > H₃A^5- > H₂A^6-. Arsenazo III is not membrane bound. The sensitivity ratio of arsenazo III with Ca²⁺ to arsenazo III with Mg²⁺ is close to two orders of magnitude. Arsenazo III and its complexes are extremely sensitive to pH changes. With 5 μM arsenazo III, the minimum detectable amount of Ca²⁺ can be as low as 0.08 μM. Contrary to current belief, we found that Mg²⁺ can bind to arsenazo III in a slightly acidic medium. Potential applications of arsenazo III to the study of membrane Ca²⁺ transport are also discussed.     

Comparative biochemical studies of milks—III. Immunoelectrophoretic comparisons of milk proteins of the artiodactyla

• 1.1. Milk proteins from nineteen species of artiodactyls and from five other species have been examined immunoelectrophoretically versus rabbit antisera for milk proteins from Bos taurus.
• 2.2. Milks of ruminants gave positive reactions to anti-cow β-lactoglobulin and anti-cow α-lactalbumin sera. Milks from non-ruminant artiodactyls and from perissodactyls, rodents, lagomorphs and primates did not react with these antisera.
• 3.3. Milk proteins from both ruminant and non-ruminant species reacted with anti-cow serum albumin and anti-cow casein sera.

     

Chemical examination of the roots of Terminalia arjuna—the structures of arjunoside III and arjunoside IV,two new triterpenoid glycosides

The non-phenolic fraction of the alcoholic extract of the root bark of Terminalia arjuna yielded two new triterpenoid glycosides, arjunoside III and arjunoside IV in addition to arjunglucoside I and arjunetin. The structure of arjunoside III was established as the 28-β-d(+)-glucuronopyranoside of arjunic acid by a study of its chemical and spectroscopic (¹H and ¹³C NMR) data. Arjunoside IV was shown to be the 3-O-α- l(?)-rhamnoside of arjunic acid. Leucocyanidin, ellagic acid and gallic acid have been isolated from the phenolic part of the root extract.