Search

The nontransforming polyoma virus mutant NG-18, screened originally for its ability to grow in polyoma-transformed cells, has now been shown to grow in a variety of other cell types. Among cells found to be substantially permissive for the growth of NG-18 are: Phenotypic revertants of polyoma-transformed 3T3 cells, C-type RNA virus transformed and/or producing 3T3 cells, 3T3 cells that become transformed upon infection with leukemia virus, primary baby mouse kidney epithelial cells, and primary mouse embryo fibroblasts. Among cells found to be poor hosts for the growth of NG-18 are: Several 3T3 cell lines, SV40-transformed 3T3 cells, spontaneously transformed 3T3 cells, radiation- and chemical carcinogen-transformed 3T3 cells, and late passage mouse embryo fibroblasts. Similar results have been obtained using three other independently isolated host range mutants of the same type as NG-18. The permissive state thus does not require a cell-associated polyoma genome as the basis for complementation of growth for this class of host range mutant. In addition, the results demonstrate that cells can be permissive for the growth of such nontransforming virus mutants without themselves possessing properties commonly associated with transformation: Loss of density-dependent inhibition of growth, low serum requirement for growth, loss of anchorage dependence of growth, and lectin agglutinability. Implications of these findings are discussed in reference to possible mechanisms of action of the NG-18 gene in productive infection and transformation.

BS>The nucleation and crystal growth from solutions of zinc in mercury were studied; the test amalgam formed one pole of a concentration cell whose emf was used as a continuous measure of the concentration. The metastable region in which spontaneous nucleation could not occur extended to 2 deg C below the saturation temperature. Nucleation at temperatures below the metastable region normally produced a crop of fine crystals mainly suspended in the liquid phase, which sometimes subsequently aggregated into a solid cap at the surface or walls. The rate of nucleation varied approximately as exp (--const/ DELTA T/sup 2/). Stirring increased the nucleation rate by only a factor of about 5. The rates observed were immensely greater than those reported by Hollomon and Turnbull for pure metals subdivided into small drops; this would suggest heterogeneous nucleation on foreign particles. If a first crop of crystals were allowed to form and then to be removed from the system, the subsequent rate of nucleation was not signiflcantly reduced by this treatment; this would suggest that the rate cannot depend on the presence of foreign particles. One possible explanation is that nucleation may occur only at the glass wall, and the growing crystallites aremore » subsequently floated into the solution. Another depends on the further observation that if a small number of crystals is added to a solution cooled at such a rate as to keep it within the metastable region (where spontaneous nucleation cannot otherwise occur), an immense crop of nuclei is produced equal in number to that obtained with spontaneous nucleation at temperatures below the metastable region. In other words it would appear that nuclei breed nuclei with a high multiplication factor. The high rates of nucleation of a bulk liquid phase may be due to this breeding of nuclei and not to heterogeneous nucleation. If massive zinc is added to an amalgam that is in equilibrium with a solid phase that has been obtained by cooling a solution from higher temperatures, the massive zinc dissolves and is reprecipitated as very fine crvstals; this is attributed to the metastability of the alpha phase at the temperatures in question. From emf data on 2-phase amalgams, heats of solution were calculated. The solid phase in these experiments could be largely freed from mercury by centrifugation and was found to consist of hexagonal plates and prisms rounded by stirring. (auth)« less

Heats of mixing of methanol and water and of methanol-d and and heavy water were determined at 25 deg in an adiabatic calorimeter. Deviations between the two systems are most pronounced for solutions dilute in alcohol and a Tian-Calvet microcalorimeter was used for additional measurements in this region. The results are consistent with the concept of the strengihening of hydrogen bonding by deuterium substitution. data. Further correlations of k5 and the homogeneous exchange rate are possible via recent theoretical interpretations of Marcus.

Values of three functions E(h,α,τ,), F(h,α,τ), and G(h,α,τ,), denned inequations (1), (2), and (7), have been calculated numerically for h = 600–15,000, α = 3–15, and τ = 150–1950. These results should be of use in certain problems of heat conduction in regions with cylindrical symmetry.

Aqueous solutions of dimethyldodecylphosphine oxide exhibit a lower consolute boundary near 40°C. This boundary is moved to higher temperatures, and the region of immiscibility is decreased, with increasing ethanol concentration. Light scattering data at 30°C. show that increasing ethanol concentration also greatly reduces the micelle molecular weight (MMW) from the very high value in water of 555,000 to values more consistent with spherical micelle configurations. Most of this decrease in MMW occurs from 0% to 20% (v/v) ethanol. The critical micelle concentration (CMC) increases slightly as the solvent is changed from 0 to 20% ethanol and then increases markedly at higher ethanol concentration, being increasingly less well defined. Calorimetric studies confirm these CMC changes and agree with CMC values obtained from surface tension measurements; the light scattering CMC values are consistently 2–3 times higher than those determined by these other techniques, however. Standard molal enthalpies and entropies of micellization, ΔHm0 and ΔSm0, are much reduced over the range 0%–20% ethanol concentration and then remain almost constant at higher concentrations, where micellization increasingly less approximates a phase change. These data are indicative of a reduction of the amount of ordered water released during micellization in the presence of ethanol and represent weakened hydrophobic bonding. The effect of ethanol on the phase diagram, MMW, CMC, and thermodynamic parameters is shown to be self-consistent and to be different above and below ∼20% v/v ethanol.

The sorption of radioactive dimethyldodecylphosphine oxide (DC 12 PO) in various substrates has been studied as a function of both surfactant concentration, and of time. The substrates studied and the equilibrium sorption levels (in milligrams per gram of substrate) observed at room temperature were: Cotton, 2.1; rayon, 7.6; nylon 11.8; polyester, 0.26; carbon black, 8.4; lampblack, 16.9; polyethylene, 1.3; polystyrene, 375; and silica, 176. With cotton, the quantity of DC 12 PO sorbed increased with increasing temperature; with carbon black, no such change was observed. Sorption on the hydrophobic substrates generally occurred below the critical micelle concentration (cmc) attaining the maximum level near the cmc. With the hydrophilic substrates, most of the sorption occurred above the cmc. Monolayer coverage is indicated by the data obtained for carbon black, polyethylene, polystyrene, silica, and polyester fabric. The rate of sorption data obtained for cotton, rayon, and nylon fabrics can be treated as resulting from diffusion processes. Average diffusion coefficients are calculated to be about 5 × 10 −12 cm 2 per see for all fabrics at 27.6°C and resemble data published for the sorption of dyes. Sites for sorption on cotton appear to be heterogeneous, and rather high solubility of DC 12 PO occurs in rayon and nylon. The sorption properties for DC 12 PO are similar to those reported for alkylpolyoxyethyleneglycol monoethers.

“Two Ss, isolated from each other, were provided with two push buttons by means of which each could give the other a shock or score. The Ss were divided into a Weak Shock and a Strong Shock group. All Ss were merely told that they could press the two buttons in any manner that they pleased (no infor

SUMMARY The feasibility of renal function studies as viability assays during isolated in vitro perfusion at 25 C has already been described. The present study demonstrates the applicability of this assay system to currently improved perfusion protocols at lower temperatures. Carefully isolated canine kidneys were perfused for 2 hr at 5 C with homologous pooled plasma exposed to 95% 02/5% CO2 in a membrane oxygenator. One-half-hour samples of urine and plasma were collected for urine: plasma (U:P) ratios and clearance determinations. Temperatures were then returned to 25 C for 1 hr to allow comparison between retained function and previously established base line values. Randomly chosen kidneys were autografted to nephrectomized donors as a final test of functional capacity. Although decreases in mean perfusion pressure and renal plasma flow (RPF) of 20 mm Hg and 50% were respectively noted, a 66% increase in renal resistance occurred at 5 C. A 75% drop in renal oxygen consumption was accompanied by low U:PPAE, U:PNa, and U:PK values, indicative of diffuse suppression of activity throughout the nephron. Marked decreases in creatinine and para-aminohippuric acid (PAH) clearance effected a falloff in mean urine flow. This metabolic and physiological inhibition was completely reversible at 25 C, and autografted kidneys functioned normally after minimal elevations of blood urea nitrogen and creatinine occurred during the 1st postoperative week. While 5 C temperatures appear to preclude most studies of nephron physiology, values are still obtainable to permit in vitro preoperative assessment of functional integrity.

1. 1. A fatal case of convulsions associated with general anesthesia is reported. One hundred sixty-eight cases have previously been published. 2. 2. The etiology of convulsions under general anesthesia is not established and the treatment is not standardized. The recommendations made by Lundy in 1937 are of interest. They are: “1. Convulsions can probably be controlled by the use of barbiturates intravenously. 2. The most dangerous cases are those in which there is profound toxemia and therefore in selecting the anesthetic for such cases it might be better to use spinal, infiltration, or block anesthesia or avertin to produce basal anesthesia, than to use an inhalation anesthetic only.”

A thermal titration calorimeter, suited to rapid and accurate measurement of heats of micellization of surfactants, is described. The critical micelle concentration (CMC) and standard heat of micellization ( ΔH m o ) for dimethyldecylamine oxide are determined in solutions of urea, guanidinium salts, and alcohols of varying concentrations. The entropy and enthalpy of micellization are reduced in all solutions, relative to water, with the exception of 1-butanol solutions. The results can be interpreted as a reduction of the amount of ordered water released during micellization of the surfactant—an effect associated with the involvement of hydrophobic bonding in the process. Urea and guanidinium salts weaken these hydrophobic bonding contributions to micellization. Alcohols appear to play a dual role of weakening the surfactant's hydrophobic contributions while favoring micelle formation at high enough alcohol chain length owing to probable incorporation in the micelle. This is inferred from the increase in ΔH m o values in 1-butanol solutions and at high concentrations of methanol, ethanol, and 1-propanol. With ethanol at high concentration, the CMC is not sharp.

The transfer of heat in a Tian–Calvet microcalorimeter is treated theoretically. Although quantitative agreement between predicted behavior and experimental observation is not obtained, the qualitative features brought out by the considerations should be helpful in the design and use of this type of calorimeter.