ADJUVATORS TO THE PROPAGATION OF MOUSE MAMMARY TUMOR CELLS ON EXPANSES OF SUBCUTANEOUS TISSUE

The cells of a mouse mammary cancer were obtained with enzymes in suspensions which could be filtered to exclude all which were not single and most which were already dead. Heavy suspensions of these individual cells were plated over the dorsal subcutaneous expanses of female weanling mice where they implanted and grew to form coalescent tumors covering the back more or less entirely. Sparser suspensions, similarly plated (a) gave rise to fewer tumors, and (b) gave rise to tumors reaching measurable size later. These two consequences of sparser plating left room for the testing of adjuvators to transplantation. Adjuvator effects were obtained by splitting the subcutaneous expanses beforehand and by injecting liver along with the plated cells. Through 28 plated generations over 4 yr the tumor maintained completely stable, morphological heterogeneity. These findings with a complex tumor indicate strongly that its heterogeneity comes not from repeated cellular mutation late in its development, but from diverse potentiality to give rise to cells of specific and differing character, inherent in its individual cells at the time of its multicellular origin

FURTHER EXPERIMENTS ON THE CAUSE OF SEQUENTIAL NEOPLASTIC CHANGES : THE EFFECTS OF 20-METHYLCHOLANTHRENE ON TRANSPLANTED EPIDERMAL MOUSE PAPILLOMAS AND THE DERIVATIVE CARCINOMAS

When crystalline 20-methylcholanthrene (MC) and the cells of tar-induced mouse papillomas (paps.) are injected together into the thigh muscles of mice the carcinogen exerts a marked promoting and chemotactic influence upon the cells while it is dissolving in the tissue fluid. Under such circumstances it strongly stimulates and attracts them, with result they surround and include the scattered crystals in small cysts that later coalesce to form a larger one from which the MC only very gradually escapes. Because of these findings intramuscular tests were made to learn whether MC would hasten the occurrence or increase the number of cancers that now and again derive from paps.; but the tests were repeatedly marred by the extraordinary behavior of such cancerous cells as happened to be already present in the implanted material. They responded far more actively to MC than did the pap. cells and soon took over the growths. Some carcinomas which failed to grow when transplanted alone, or only gradually formed small, regressing nodules, gave rise rapidly to huge growths of similar sort when exposed to MC. To exclude cancerous cells so far as possible from the later tests small grafts of pap. tissue with MC crystals adhering to them were implanted subcutaneously. The pap. cells promptly lined the graft pockets, encysting the crystals incidentally, and formed tumors that enlarged progressively by keratinizing inwards. While they did this their living layer of pap. tissue was continually bathed in dissolved MC throughout many weeks. Despite these apparently favorable conditions the carcinogen neither hastened the occurrence nor increased the number of visible epidermal cancers deriving from the paps. It also failed to bring about sequential malignant changes in the carcinomas. These negative results accord with those already obtained through long exposure of the benign pulmonary adenomas of mice to urethane or methylcholanthrene, agents which rapidly induce these benign tumors yet which were found to be incapable of furthering the cancerous changes to which such growths are prone. They accord also with another previous finding, namely that MC fails to bring on the malignant changes of discontinuous, sequential sort that mammary mouse carcinomas often undergo "spontaneously." Taken together these facts indicate that the change or changes whereby normal cells are converted into benign tumor cells differ in nature from those taking place when they become cancer cells, as also from those occurring when cancer cells undergo further, step-like, malignant changes. A study has been begun to learn whether the widely various carcinomas deriving from benign papillomas differ from these latter and from one and other in their chromosomal content

THE PLATING OF TUMOR COMPONENTS ON THE SUBCUTANEOUS EXPANSES OF YOUNG MICE : FINDINGS WITH BENIGN AND MALIGNANT EPIDERMAL GROWTHS AND WITH MAMMARY CARCINOMAS

A procedure analogous to the plating of bacteria is described whereby some complex tumors have been taken apart and their components separately propagated. It was the outcome of finding that the forcible injection of Locke's solution followed by air can be used to split the subcutaneous connective tissue of sucklings and weanlings horizontally over the entire expanse of their backs or bellies, without inducing any complicating inflammation. Tumor fragments suspended in Locke's were widely scattered on the surfaces thus exposed. Most of them remained where they had lodged on the body wall, and rapidly becoming fixed in place, formed growths protected by the overlying cutaneous layer—which, throughout many weeks, remained unattached either to the wall or to them. The procedure is more searching in its disclosure of tumor constituents than those currently employed, and it has the advantage that it preserves the neoplastic components that it reveals. It has been used thus far only to rescue for experimental purposes transplantable, benign, epidermal papillomas from the hidden carcinomas deriving from their cells, and to set free and maintain the neoplastic components of complex mammary tumors of milk factor type. Success was obtained with such of the latter as were chosen for separate propagation, though successive platings were sometimes required for their isolation. Incidentally the procedure revealed two components in the mammary growths which could not have been discerned by previous methods of search. Each formed tumors peculiar to itself

Data Quality Assurance for Supersonic Jet Noise Measurements

The noise created by a supersonic aircraft is a primary concern in the design of future high-speed planes. The jet noise reduction technologies required on these aircraft will be developed using scale-models mounted to experimental jet rigs designed to simulate the exhaust gases from a full-scale jet engine. The jet noise data collected in these experiments must accurately predict the noise levels produced by the full-scale hardware in order to be a useful development tool. A methodology has been adopted at the NASA Glenn Research Center s Aero-Acoustic Propulsion Laboratory to insure the quality of the supersonic jet noise data acquired from the facility s High Flow Jet Exit Rig so that it can be used to develop future nozzle technologies that reduce supersonic jet noise. The methodology relies on mitigating extraneous noise sources, examining the impact of measurement location on the acoustic results, and investigating the facility independence of the measurements. The methodology is documented here as a basis for validating future improvements and its limitations are noted so that they do not affect the data analysis. Maintaining a high quality jet noise laboratory is an ongoing process. By carefully examining the data produced and continually following this methodology, data quality can be maintained and improved over time

Phased Array Noise Source Localization Measurements of an F404 Nozzle Plume at Both Full and Model Scale

A 48-microphone planar phased array system was used to acquire jet noise source localization data on both a full-scale F404-GE-F400 engine and on a 1/4th scale model of a F400 series nozzle. The full-scale engine test data show the location of the dominant noise sources in the jet plume as a function of frequency for the engine in both baseline (no chevron) and chevron configurations. Data are presented for the engine operating both with and without afterburners. Based on lessons learned during this test, a set of recommendations are provided regarding how the phased array measurement system could be modified in order to obtain more useful acoustic source localization data on high-performance military engines in the future. The data obtained on the 1/4th scale F400 series nozzle provide useful insights regarding the full-scale engine jet noise source mechanisms, and document some of the differences associated with testing at model-scale versus fullscale

The promise and peril of genomic screening in the general population

Utilization of sequencing to screen the general population for preventable monogenic conditions is receiving substantial attention due to its potential to decrease morbidity and mortality. However, the selection of which variants to return is a serious implementation challenge. Procedures must be investigated to ensure optimal test characteristics and avoidance of harm from false positive test results

Timing storytime to maximize children\u27s ability to retain new vocabulary

\ua9 2021 The AuthorsShared storybook reading is a key aid to vocabulary acquisition during childhood. However, word learning research has tended to use unnaturalistic (explicit) training regimes. Using a storybook paradigm, we examined whether children (particularly those with weaker vocabularies) are more likely to retain new words if they learn them closer to sleep. Parents read their children (5- to 7-year-olds; N = 237) an alien adventure story that contained 12 novel words with illustrations at one of two training times: at bedtime or 3–5 h before bedtime. Using online tasks, parents tested their children\u27s ability to recall the new words (production) and associate them with pictures (comprehension) immediately after hearing the story and again the following morning. As hypothesized, we replicated two findings. First, children showed overnight improvements in their ability to produce and comprehend new words when tested again the next day. Second, children with better existing vocabulary knowledge showed larger overnight gains in new word comprehension. Counter to expectations, overnight gains in comprehension were larger if the story was read 3–5 h before bedtime rather than at bedtime. These ecologically valid findings are consistent with theories that characterize word learning as a prolonged process supported by mechanisms such as consolidation and retrieval practice, with existing vocabulary knowledge acting as an important source of variability in retention. The findings provide preliminary evidence that encountering new words in stories later in the day (but not too close to sleep) may help to harness vocabulary growth and may be more beneficial than leaving shared storybook reading just for bedtime

The influence of temperature on the apparent lipid digestibility in Atlantic salmon (Salmo salar) fed Calanus finmarchicus oil at two dietary levels

Oils extracted from the marine zooplankton, Calanus finmarchicus, have high levels of n-3 highly unsaturated fatty acids (HUFA) and are therefore of interest as an alternative lipid source in aquafeeds. Copepod lipid is composed mainly of wax esters (WE) with high levels of saturated fatty acids and monounsaturated fatty alcohols which are considered hard to digest, especially at low temperatures. This assumption has however not been verified and for this reason the present study examined the digestibility of diets containing high levels of WE and two fat levels in Atlantic salmon reared at 3 and 12 °C. The fish were acclimated for one month to 3 °C (485 g) and 12 °C (599 g) and then fed one of four diets, high fat fish oil (33% lipid, HFFO), high fat Calanus oil (32% lipid, HFCO), low fat fish oil (17% lipid, LFFO) and low fat Calanus oil (19% lipid, LFCO). The fish meal lipid content was lowered by the use of lipid-extracted fish oil (2.3% lipid). This enabled a level of 50% WE in the LFCO and HFCO oils, compared to 0% in the LFFO and HFFO diets. The fish were then allowed to grow to around 100% of initial weight (220 days at 3 °C and 67 days at 12 °C) and then analysed for faecal lipid digestibility, bile volume, bile composition and intestinal lipolytic activity. Differences were observed in all these parameters in relation to temperature, type of dietary oil and the lipid level in the diet. Faecal lipid content and lipid class composition were dependent on rearing temperature and the type of dietary lipid. Highest levels of undigested lipids were observed in the faeces of fish fed CO. Wax ester-derived fatty alcohols, particularly 20:1n-9 and 22:1n-11, were less extensively digested than corresponding fatty acids from FO at both fat levels and temperatures. Fish kept at 12 ºC had a significantly higher bile volume than fish at 3 ºC and higher volumes were found in fish fed CO diets compared to FO. Decreased faecal passage time at lower temperatures, was not sufficient to ensure high digestibility since the lower bile volume and enzyme activities at 3 °C in the present trial exerted a greater effect. Although the compensatory mechanisms of increased bile volume and lipolytic activity are initiated upon feeding WE at a level of 50% of dietary lipid, these are not sufficient to compensate lipid digestibility and growth as in FO diets. Low inclusion of CO in diets during winter has to be considered as saturated fatty acids and monounsaturated fatty alcohols were poorly digested at 3 °C in fish fed CO diets

The Pic Protease of Enteroaggregative \u3cem\u3eEscherichia coli\u3c/em\u3e Promotes Intestinal Colonization and Growth in the Presence of Mucin

Enteroaggregative Escherichia coli (EAEC) is increasingly being recognized as a cause of diarrheal disease in diverse populations. No small animal model is currently available to study this pathogen. We report here that conventional mice orally inoculated with prototype EAEC strain 042 generally became colonized, though the abundance of organisms cultured from their stool varied substantially among individual animals. In contrast, mice whose water contained 5 g/liter streptomycin consistently became colonized at high levels (ca. 108 CFU/g of stool). Neither conventional nor streptomycin-treated mice developed clinical signs or histopathologic abnormalities. Using specific mutants in competition with the wild-type strain, we evaluated the contribution of several putative EAEC virulence factors to colonization of streptomycin-treated mice. Our data suggest that the dispersin surface protein and Pic, a serine protease autotransporter secreted by EAEC and Shigella flexneri, promote colonization of the mouse. In contrast, we found no role for the aggregative adherence fimbriae, the transcriptional activator AggR, or the surface factor termed Air (enteroaggregative immunoglobulin repeat protein). To study Pic further, we constructed a single nucleotide mutation in strain 042 which altered only the Pic catalytic serine (strain 042PicS258A). Fractionation of the tissue at 24 h and 3 days demonstrated an approximate 3-log10 difference between 042 and 042PicS258A in the lumen and mucus layer and adherent to tissue. Strains 042 and 042PicS258A adhered similarly to mouse tissue ex vivo. While no growth differences were observed in a continuous-flow anaerobic intestinal simulator system, the wild-type strain exhibited a growth advantage over 042PicS258A in a culture of cecal mucus and in cecal contents in vitro; this difference was manifest only after 6 h of growth. Moreover, enhanced growth of the wild type was observed in comparison with that of the mutant in minimal medium containing mucin but not in the absence of mucin. The data suggest a novel metabolic role for the Pic mucinase in EAEC colonization