Morphological and cytoskeletal changes caused by non-membrane damaging cytotoxin of Vibrio cholerae on Int 407 and HeLa cells

End-group mediated conjugation of bacterial polysaccharides (PSs) to carrier proteins containing T-helper cell epitopes renders such polysaccharides immunogenic also in young infants. Optimal construction of such conjugate vaccines requires fragmentation of the PS prior to the coupling reaction. In the present study a general simple and inexpensive method for the fragmentation of PSs is presented. It is based on the irradiation of isolated PSs in an electron beam accelerator. Exposure of isolated pneumococcal capsular polysaccharides (PnPSs) to ionizing radiation resulted in their partial depolymerization in a radiation dose-dependent manner. Radiation, unlike sonication, generated PnPS fragments of molecular size lower than 50 kDa and as small as 1.5 kDa when high radiation doses were used. These PnPS fragments have terminal reducing groups that can be easily used for chemical activation and subsequent coupling to any chosen carrier protein. The radiation-produced PnPS fragments retained their antigenic epitopes, when compared to native, full-size PnPSs as determined by enzyme-linked immunoassay.     

Role of arginase in sciatectomized muscle

Substrate kinetics of arginase were investigated in normal and sciatectomized gastrocnemius muscle of frog. Sciatectomized muscle arginase showed 47% elevation in V while Km showed no change. Sciatectomic activation of muscle arginase accounted for the stepped up urea levels which may be of significant use in combating ammonia toxicity and maintaining chemohomeostasis.     

Distribution of Clostridium perfringens and Fecal Sterols in a Benthic Coastal Marine Environment Influenced by the Sewage Outfall from McMurdo Station, Antarctica

The spatial distribution, movement, and impact of the untreated wastewater outfall from McMurdo Station, Antarctica, were investigated under early austral summer conditions. The benthic environment was examined to determine the distribution of Clostridium perfringens in sediment cores and the intestinal contents of native invertebrates and fish along a transect of stations. These stations extended ca. 411 m south of the outfall. The findings revealed that the concentration of C. perfringens decreased with depth in the sediment and distance from the outfall. High percentages of tunicates and sea urchins were colonized with this bacterium along the transect. Coprostanol concentrations were also measured in sediment samples taken from each of the transect stations, and a similar trend was observed. These results are in agreement with the findings of previous studies performed with the water column and collectively provide evidence that the disposal of domestic wastes deserves special consideration in polar marine environments.     

Ethnic differentials in early childhood mortality in Nepal

This paper investigates the association of early childhood mortality (between birth and second birthday) with ethnicity in Nepal, based on data from the 1976 Nepal Fertility Survey, which was part of the World Fertility Survey. The approach is through a series of hazard models, which incorporate ethnicity, year of birth, mother's illiteracy, father's illiteracy, rural-urban residence, region, sex, maternal age, survival of previous birth, previous birth interval, and breast-feeding as covariates. Ethnic differentials in early childhood mortality are not explained by the other socioeconomic and demographic covariates, except for a modest effect of illiteracy, but the remaining covariates explain a great deal of variability in early childhood mortality itself. Analysis using an improved specification of breast-feeding as an age-varying covariate indicates, on average, that breast-feeding, relative to not breast-feeding, reduces age-specific mortality risks during the first 2 years of life by 76%, a very large effect.     

STEM ANATOMY OF PARTHENIUM ARGENTATUM,P. INCANUM AND THEIR NATURAL HYBRIDS

Guayule (Parthenium argentatum Gray) contains rubber in the parenchymatous cells of stems and roots. Stem anatomy of P. argentatum is described along with that of P. incanum H.B.K. (mariola). Anatomy of these species differs significantly. Phloem rays in both species increase in width by cell division and expansion; however, the increase observed in mariola is less as compared to that in guayule. Axial xylem parenchyma in guayule is generally a two-cell strand as compared to the fusiform axial xylem parenchyma observed in mariola. Vascular ray cells and cells of the pith region of guayule are parenchymatous, whereas those of mariola are sclerenchymatous. As a result of introgression between guayule and mariola, three forms of guayule exist in the native stands of Mexico. Morphological differences between these guayule plants have been described previously. The stem anatomy of these three groups of plants differ importantly. Group I guayule plants, least introgressed by mariola, have taller rays with the cells of pith region and vascular rays parenchymatous. Group III plants, highly introgressed by mariola, have a few to many cells of vascular rays and pith with lignified secondary walls and shorter rays. Many of the anatomical characteristics of group II plants, somewhat introgressed by mariola, are intermediate between group I and III plants.