Geochemical changes in sulfidic mine tailings stored under a shallow water cover

The objective of this study was to assess the effectiveness of an engineered shallow water cover in reducing the oxidation of sulfidic mine tailings and thus preventing the development of acid rock drainage. Fresh tailings were submerged under a 0.3-m water cover in experimental field cells. From 1996 to 1998, we followed the chemistry of the interstitial water near the tailings-overlying water interface using in situ dialysis, and determined pH and dissolved oxygen (DO) profiles across the tailing water interface using micro-electrodes. Penetration of DO into the tailings was limited to <7 mm, even in the presence of DO produced by benthic periphyton. Anoxia in the tailings was further demonstrated by the appearance of dissolved sigmaH2S, Fe and Mn in pore water at depths -1.5 cm below the interface. However, there was clear evidence of surface oxidation of the mine tailings at the mm scale (i.e., DO depletion, coupled with localized increases in [H+] and [SO4(2-)]). Mobilization of Cd and Zn from this surface layer was indicated by the presence of sub-surface peaks in the concentrations of these two metals in the tailings interstitial water and by a change in their solid phase partitioning from refractory to more labile fractions. In contrast, mobilization of Cu from tailings was less evident. Unlike previous reports, which suggested that submerged tailings were effectively inert, our results show alteration of the superficial layer over time.

ERCC1 expression as a molecular marker of cisplatin resistance in human cervical tumor cells

Cisplatin is a valuable adjuvant to radiotherapy for the treatment of cervical cancer. Because the advantage of combining cisplatin with radiotherapy is likely to be attributable to additive cell killing by these 2 agents, such protocols should primarily benefit patients who have inherently cisplatin-sensitive tumors. Development of a molecular assay to rapidly evaluate the cisplatin responsiveness of cervical tumors would thus be extremely valuable. We investigated whether high pre-treatment mRNA levels of the ERCC1 nucleotide excision repair gene are predictive of cisplatin resistance in early-passage human cervical cancer cells, as they are in several other tumor types. Expression of the ERCC1 gene at the mRNA and protein levels was established by Northern and Western blotting, respectively, in a panel of single-cell-derived cervical carcinoma cell lines that exhibited a wide range of inherent sensitivity to cisplatin. There was a significant (p </= 0.011) correlation between ERCC1 mRNA levels and cisplatin resistance in these cell lines. However, there was no obvious relationship between ERCC1 protein levels and cisplatin resistance. Thus, the association between high ERCC1 mRNA levels and cisplatin resistance might be an epiphenomenon. Nonetheless, pre-treatment ERCC1 mRNA levels may be a useful molecular marker for identifying cervical tumors likely to be refractory to cisplatin, and further investigation in clinical biopsy material is warranted.

Beneficial effect of proprioceptive physical activities on balance control in elderly human subjects

Age and lack of physical activities may both be responsible for poor balance control. Conversely, physical activities may modulate postural control in elderly individuals. We examined which type of exercise might prove most beneficial to retain or regain proper balance. Nineteen healthy subjects, aged over 60, regularly practicing proprioceptive (group I) or bioenergetic (group II) physical activities and 21 controls only walking on a regular basis, were studied. All were submitted to a dynamic posturographic test and to a test evaluating lower limbs muscular strength. Control individuals displayed the poorest balance and muscular performance. Group I subjects had the best postural control with average muscular strength. In group II, muscular strength was significantly increased, but balance control was of poor quality. Proprioceptive exercise therefore appears to have the best impact on balance control.

The Genexpress Index: a resource for gene discovery and the genic map of the human genome

Detailed analysis of a set of 18,698 sequences derived from both ends of 10,979 human skeletal muscle and brain cDNA clones defined 6676 functional families, characterized by their sequence signatures over 5750 distinct human gene transcripts. About half of these genes have been assigned to specific chromosomes utilizing 2733 eSTS markers, the polymerase chain reaction, and DNA from human-rodent somatic cell hybrids. Sequence and clone clustering and a functional classification together with comprehensive data base searches and annotations made it possible to develop extensive sequence and map cross-indexes, define electronic expression profiles, identify a new set of overlapping genes, and provide numerous new candidate genes for human pathologies.

Selective gene expression during sporulation of Physarum polycephalum

The two-dimensional gel electrophoresis of polypeptides synthesized in vitro from poly(A)+ RNA showed that mRNA populations change during sporulation of Physarum polycephalum. The differential hybridization of a cDNA library prepared from poly(A)+ RNA isolated from sporulating cells revealed that of 846 clones, 64 corresponded to sporulation-specific mRNAs. Further analysis demonstrated that these clones contained seven different sequences: three abundant sequences composing 3.2, 1.8, and 1.2% of the library and four other less abundant sequences. It is probable that all the major mRNAs specifically expressed in early stages of sporulation were identified. The most abundant mRNA from this group coded for a hydrophobic protein that contained a signal peptide. This protein is 47% similar to another Physarum protein, which was encoded by the most abundant plasmodium-specific mRNA. The plasmodial mRNA was degraded during sporulation and was replaced by the sporulation mRNA. These two proteins are thus encoded by members of a gene family whose expression is developmentally regulated.

Zinc Deposition in Acid Lakes: The Role of Diffusion

Steep negative concentration gradients of dissolved zinc are present between the overlying waters and the anoxic pore waters of two acid lakes. In the anoxic pore waters, the low zinc concentrations can be explained as due to the formation of relatively insoluble zinc sulfide minerals. Downward diffusive fluxes of dissolved zinc account for at least 50 to 75 percent of the recent zinc deposition to the sediments of these lakes. This downward diffusion occurs to a depth of 2 to 3 centimeters below the sediment water interface, where pronounced maxima in total zinc are observed. These subsurface peaks in total zinc have been interpreted as an indication of recent lake acidification. The present observations indicate that such subsurface peaks may also result from a diagenetic activity unrelated to recent changes in lake acidity.

Early childhood education: a means to earlier diagnosis of hearing impairment in the multihandicapped

Detection of congenital or infantile hearing loss is often delayed in otherwise normal children, but even greater delays occur in the multihandicapped. Neonatal hearing screening and high risk register techniques have not had universal acceptance. A collaborative project between medical school otology and audiology personnel and a school for multihandicapped children under the age of 3 years in the Department of Special Education in another university has significantly reduced detection time and provided speech, language and other remedial therapy while otologic diagnosis and educational functional assessment proceed. The investigators and staff are bilingual. Parents learn to observe and work with their own child at the school and in the home.

Yeast, rye, and calf histones. Similarities and differences detected by electrophoretic and immunological methods

Yeast histones H2A, H2B, and H3 were purified using the standard histone purification procedures of differential solubility and exclusion chromatography. Yeast histone H4 was isolated by the same methods in a fraction containing one other major protein component. The four yeast core histones were identified by their reactions with antisera against rye and (or) calf histone fractions as well as by their electrophoretic, chromatographic, and solubility properties. The immunological distances between yeast H2B and rye and calf H2B fractions are substantial, as is the rye-calf distance for H2B. The immunological distance between yeast H2A and rye H2A is also large and is similar to the rye H2A - calf H2A distance. On the other hand, the immunological distance between yeast H3 and rye and calf H3 is much greater than that between rye H3 and calf H3. These and other results indicate that yeast H3 differs appreciably from the H3 of higher eucaryotes.

Design and characteristics of a cell for photoacoustic spectroscopy of condensed matter

We describe a photoacoustic cell which is simple to use, easy to construct, and which gives a great sensitivity, expressed as a signal-to-noise ratio of 3000. Calibration of the cell indicates that it can be used with confidence as a general purpose photoacoustic cell.

Amino acid composition of sperm histones in the house cricket Acheta domesticus

Histones were isolated from late spermatids and spermatozoa of the house cricket Acheta domesticus, and the individual histone fractions were separated by electrophoresis on polyacrylamide-urea gels. The stained gels were cut so as to isolate the different histone fractions, and the amino acid compositions were determined using the technique of Houston (Houston, L.L.: Anal. Biochem. 44, 81-88 (1971). Five of the histones had amino acid compositions resembling those for the histones of calf thymus and were thus identified as fractions F1, F3, F2a2, F2b, and F2al. Another protein (SH) located exclusively in the late spermatids and spermatozoa was found to be basic and histone-like. It is a protein containing relatively high amounts of arginine (12.6%) and low amounts of lysine (7.6%), and, as a result, it has a low ratio of lysine-arginine (0.6). Other noteworthy features are its high contents of serine, glutamic acid, and glycine. It is arginine rich histone and in this regard resembles other such proteins, but it does contain unique features which distinguish it from all previously described histones.

Degradation of Phenolic Compounds Downstream from a Petroleum Refinery Complex

Measurements downstream from refinery outfalls in the region of Montreal East have shown that, under favorable temperature conditions, the concentration of phenolic substances in the river water rapidly diminishes with distance from the refineries. Mass balance calculations at different transverse sections show that this decrease in concentration cannot be attributed to dilution only. Laboratory experiments performed on river water samples demonstrate the effects of water temperature and sterilization on the rate of phenol breakdown. Results support the idea that biodegradation is responsible for the self-purification of phenolics in the St. Lawrence River.