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Biomedical subjects

A Tessier

Publications and source records attributed to A Tessier.

18 recordsLinked to original sources
PubMed2003

Improved muscle strength and power in elderly exercising regularly.

Since the number of elderly people with a sedentary lifestyle is considerable and still growing, regular exercise could be an extra stimulant to compensate for the decrease in functional capacities. The potential positive effects of physical and sporting activities (PSA) on muscular function in relation to the period of practice were studied. Muscular strength and power were evaluated by dynamometric knee and ankle tests on 40 healthy subjects aged over 60 years old, split into four groups according to the period of practice. Higher muscular performance was obtained in subjects who had always practised PSA, whereas subjects who had always been inactive displayed the worst muscular performances. Subjects who had begun PSA practice lately had good muscular strength and power, close to those of the AA group, whereas the subjects who had stopped the practice at an early age did not perform as well. Life-long PSA attenuates the age-related loss of muscle function, and initiation at old age improves it. This, and the absence of any beneficial effects of PSA stopped when young, indicates that the actual activity level is an important determinant of skeletal muscle function at old age. Practicing PSA increases muscular strength and power and thus improves daily living activities in elderly people.

Adaptation, Physiological↗
PubMed2001

Influence of current velocity on cadmium accumulation by an aquatic moss and the consequences for its use as a biomonitor.

Aquatic mosses are widely used as biomonitors of contaminant concentrations in running waters. The results of several previous studies suggest that metal concentrations in mosses are influenced by current velocity and that this variable should be taken into account when mosses are used as metal biomonitors. However, in these studies, the purported influence of water velocity was confounded by other uncontrolled variables. We conducted our study to test the influence of current velocity on Cd accumulation by the riverine moss Fontinalis dalecarlica. We found no difference in Cd accumulation over 2 weeks by moss exposed in the laboratory to a constant Cd concentration over a wide range of current velocities (0.01-0.70 m s-1) that occur in the field. Similarly, the results of a field experiment, in which we exposed F. dalecarlica in a Cd-contaminated creek to four current velocities (0.05-0.50 m s-1), confirmed that in nature Cd accumulation by this moss is not influenced by current velocity. We show that a bioaccumulation model that ignores current velocity describes Cd accumulation by F. dalecarlica very well. Our results suggest that current velocity does not have to be considered when using aquatic mosses as metal biomonitors.

Biological Availability↗
PubMed2001

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.

Geologic Sediments↗
PubMed2001

Cadmium accumulation by invertebrates living at the sediment-water interface.

Benthic animals can take up trace metals both from the sediment compartment in which they burrow and from the water column compartment above their burrows (we define both compartments as containing water and particles). If criteria for the protection of benthic animals are based on metal concentrations in one of these two compartments, then it should first be demonstrated that the majority of the metal taken up by these animals comes from the given compartment. To determine whether benthic animals take up the majority of their cadmium (Cd) from the sediment compartment, we created a Cd gradient in lake sediment and compared Cd accumulation by the invertebrates colonizing these sediments with Cd concentrations in the sediment compartment. On the basis of this relationship and using a bioaccumulation model, we estimate that indigenous benthic invertebrates take up the majority of their Cd from the water column compartment. The results of our experiment are similar to those from a previous study conducted on a different benthic community in a larger lake. Taxa common to both lakes obtained similar proportions of their Cd from the water column compartment, suggesting that Cd accumulation by the same species will be constant across lakes of differing size and chemistry. Our results strengthen the argument that the protection of benthic communities from metal pollution should consider metal in both the water column and sediment compartments. In this regard, the AVS model, which considers only sedimentary metals, was more effective in predicting Cd concentrations in pore waters than those in most animal taxa. We suggest that measurements of vertical chemical heterogeneity in sediments and of animal behavior would aid in predicting the bioaccumulation and effects of sedimentary pollutants.

Animals↗
PubMed2000

Big houses, big cars, superfleas and the costs of reproduction.

The assumption of costs of reproduction were a logical necessity for much of the early development of life history theory. An unfortunate property of 'logical necessities' is that it is easy to also assume that they must be true. What if this does not turn out to be the case? The existence and universality of costs of reproduction were initially challenged with empirical data of questionable value, but later with increasingly strong theoretical and empirical results. Here, we discuss Ken Spitze's 'superfleas', which represent what we consider to be the strongest empirical challenge to the universality of costs, then offer a possible explanation for their existence.

Journal Article↗
PubMed2000

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.

Antineoplastic Agents↗
PubMed1999

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.

Aged↗
PubMed1995

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.

Amino Acid Sequence↗
PubMed1988

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.

Amino Acid Sequence↗
PubMed1983

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.

Child, Preschool↗
PubMed1980

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.

Animals↗
PubMed1976

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.

Amino Acids↗