Ultrasound backscatter microscope analysis of mouse melanoma progression

The incidence and mortality rate of cutaneous melanoma continue to increase throughout the world, making the study of melanoma biology an important area of current research. While recent breakthroughs in transgenic mouse technology have led to promising mouse skin models of melanoma, there is presently no technique available for quantitatively studying subsurface melanoma progression, in vivo. We demonstrate the first application of an imaging method called ultrasound backscatter microscopy (UBM) for imaging early murine melanomas with spatial resolution of 30 microns axial and 60 microns lateral. Murine B16 F10 melanomas have been imaged from their earliest detection, over several days, until they are 2 to 5 mm in diameter. Melanoma dimensions measured by UBM were found to be in excellent agreement with those determined histopathologically on the excised tumours. The relative rms errors in UBM-determined melanoma height and width were found to be 8.7% and 4.2%, respectively. The mean rate of increase in tumour height of early murine melanoma was found to be 0.37 +/- 0.06 mm/day. Computer-generated volumetric renderings of melanomas have been produced from three-dimensional image data, allowing quantitative comparisons of tumour volumes to be made. Using a priori assumptions of ellipsoid tumour shape, the relative error in UBM-determined volume was shown to be less than 17%. These results should be of considerable interest to investigators studying melanoma biology using mouse skin models, and have implications in the use of high frequency ultrasound imaging for the clinical assessment of cutaneous melanoma.     

Physiological response of Lactobacillus plantarum to salt and nonelectrolyte stress

In this report, we compared the effects on the growth of Lactobacillus plantarum of raising the medium molarity by high concentrations of KCl or NaCl and iso-osmotic concentrations of nonionic compounds. Analysis of cellular extracts for organic constituents by nuclear magnetic resonance spectroscopy showed that salt-stressed cells do not contain detectable amounts of organic osmolytes, whereas sugar-stressed cells contain sugar (and some sugar-derived) compounds. The cytoplasmic concentrations of lactose and sucrose in growing cells are always similar to the concentrations in the medium. By using the activity of the glycine betaine transport system as a measure of hyperosmotic conditions, we show that, in contrast to KCl and NaCl, high concentrations of sugars (lactose or sucrose) impose only a transient osmotic stress because external and internal sugars equilibrate after some time. Analysis of lactose (and sucrose) uptake also indicates that the corresponding transport systems are neither significantly induced nor activated directly by hyperosmotic conditions. The systems operate by facilitated diffusion and have very high apparent affinity constants for transport (>50 mM for lactose), which explains why low sugar concentrations do not protect against hyperosmotic conditions. We conclude that the more severe growth inhibition by salt stress than by equiosmolal concentrations of sugars reflects the inability of the cells to accumulate K+ (or Na+) to levels high enough to restore turgor as well as deleterious effects of the electrolytes intracellularly.     

The effect of (2'-5') and (3'-5') phosphodiester linkages on conformational and stacking properties of cytidylyl-cytidine in aqueous solution

Conformational properties of (2'-5') and (3'-5') CpC have been determined by proton magnetic resonance spectroscopy at 220 MHz. The ribose ring structures are predominantly 3E with the exception of the ring from the 2'-phosphate fragment of C(2'-5')pC which exhibits an 2E pucker. Bases are oriented anti with respect to the ribose and the conformations about C4'-C5', C5'-O5', C3'-O3' (C2'-O2') are gg, g'g', and g+ in equilibrium g-, respectively. The dimers exist as mixtures of stacked (g+g+ and g-g- about the P-O(C) bonds) and unstacked species at 20 degrees C. Stacking is estimated to be 35% in both dimers.     

Reproductive efficiency as a social indicator

An index of reproductive effiency (RE) is proposed as a social indicator that will meet the need to consider various forms of pregnancy wastage, to compare their relative costs, and to guide reproductive health policy accordingly. This article discusses conceptual and measurement aspects of RE. Conversion of wanted to unwanted pregnancies and the reverse, interpretation of abortion in relation to other pregnancy outcomes, defining the end point for the reproductive process and criteria for the events to be included as significant outcomes are conceptual issues. Measurement problems include: whether aggregation is justified, prospective and retrospective tracking of outcomes, record limitations, duplication of adversities in a single pregnancy, and selection of optimal rate for comparison. A measurement of RE for the entire United States based on the National Natality Survey of 1964-1966 is presented, showing 74.5 percent of pregnancies resulting in healthy liveborn infants. For those years, data on abortions could not be included. Within the group of reported pregnancy losses, the importance of congenital abnormalities and low-birth-weight babies is enhanced by application of economic weights based on associated medical care costs. Changing opportunities for birth timing, prenatal and infant care, and control of family size are social means of reducing adverse outcomes associated with teenage pregnancy and high-parity births, often found together with poverty. Successive increments in RE may be progressively more expensive to achieve, and cost effectiveness comparison will be necessary.