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Biomedical subjects

J Sampson

Publications and source records attributed to J Sampson.

88 records · Page 5Linked to original sources
PubMed1977

Developmentally regulated cyclic AMP-dependent protein kinases in Dictyostelium discoideum.

Two apparently distinct species of cyclic AMP-dependent protein kinase appear during the first 1-2 hr of development in Dictyostelium discoideum; no such activity can be detected in vegetative cell extracts. These two kinases are similar in properties to the type I and II cyclic AMP-dependent protein kinases found in a number of mammalian tissues. Their time of appearance supports the idea that one or both mediate the effects of cyclic AMP on gene expression early in Dictyostelium development.

Cell Extracts↗
PubMed1976

Cell patterning in migrating slugs of Dictyostelium discoideum.

When front quarters of migrating slugs of Dictyostelium discoideum are isolated by surgery and induced to friut immediately they produce fruiting bodies with disproportionately large stalks (Raper, 1940). The data in this communication show that the 'stalky' character of fruits derived from front quarters persists even if the cells of the front quarter are disaggregated and hence to reaggregate before fruiting. The data also demonstrate that friuts derived from rear quarters of slugs have disproportionately large spore heads, and that this effect becomes more pronounced with increasing age of the slugs. These observations support the view that the cells of the front and rear of migrating slugs are to some extent committed to different fates.

Cell Differentiation↗
PubMed1975

Effects of nitrous oxide on decision-strategy and sustained attention.

Effects of 10,20, and 30% N2O on decision-making strategy, reaction-times, sustained attention, the Digit Symbol Subsititution Test (DSST), short-term memory and the Clyde Mood Scale were assessed in 12 test subjects. Decision-making strategy, as measured by 2-choice probability-learning, was unaffected by 30% N2O once a strategy had been formulated, but reaction-times were increased. Sustained attention was significantly affected in 33% of our subjects, whereas performance on the DSST and on the short-term memory task was impaired in virtually all subjects. Changes were noted in several mood-scale factors with 30% N2O. No residual drug effects were found.

Adolescent↗
PubMed1975

The control of protein synthesis during the stimulation of lymphocytes by phytohaemagglutinin. III. Poly(U) translation and the rate of polypeptide chain elongation.

1. Cell-free systems from phytohaemagglutinin-stimulated pig lymphocytes are much more active in both endogenous protein synthesis and the translation of poly(U) than those from unstimulated lymphocytes. 2. Addition of tRNA stimulates the translation of poly(U) and greatly reduces the difference between systems from stimulated and unstimulated lymphocytes. Endogenous protein synthesis is not increased by added tRNA. 3. Systems from stimulated lymphocytes have an increased capacity to form aminoacyl-tRNA with several different amino acids. This reaction is limited by the amount of tRNA present in the cell-free system. 4. The rate of polypeptide elongation is not affected by lymphocyte stimulation. The increased rate of protein synthesis must therefore be due to an increase in the frequency of initiation of the synthesis of protein molecules.

Amino Acyl-tRNA Synthetases↗
PubMed1970

Laboratory studies with a selective Enterococcus medium.

Lancefield group D streptococci are involved with appreciable frequency in a variety of infectious processes. The presumptive recognition of these bacteria on initial culturing of clinical specimens is an objective not attained readily by selective media available in the clinical laboratory. Selective Enterococcus agar was evaluated with emphasis on its ability to sequester enterococci from specimens with many microbial components. In addition, the sensitivity of this new agar was compared with Trypticase Soy agar containing sheep blood and Mitis Salivarius agar. All enterococci isolated from clinical material were classified in accordance with accepted biochemical and immunochemical criteria. The enterococci grew on the new medium as distinctive colonies surrounded by a black zone. Only Listeria monocytogenes presented similar colonial morphology after 48 hr. Most other bacteria did not grow at all or appeared markedly different. The sensitivity of the new agar was of the same order of magnitude as on blood or Mitis-Salivarius agars, but its selectivity was superior.

Agar↗
PubMedDate not supplied

Addressing cultural orientations in fear appeals: promoting AIDS-protective behaviors among Mexican immigrant and African American adolescents and American and Taiwanese college students.

Fear appeals threatening the individual have been shown to be powerful persuasive devices in the cultures where they have been studied. However, most fear appeal research has been conducted with members of individualist cultures. Individualist cultures place self-needs above group concerns, while collectivist cultures place group needs above self-concerns. Little is known about the effectiveness of fear appeals (or other persuasive strategies) in collectivist cultures. Two studies assessed the effectiveness of AIDS-prevention fear appeals threatening the self versus fear appeals threatening the group (i.e., family) on members of individualist and collectivist cultures. The first study focuses on African American and Mexican immigrant junior high school youth. The second study focuses on U.S. and Taiwanese college undergraduates. The results indicated that fear appeals should address cultural orientation (i.e., individualist versus collectivist orientation) to achieve maximum effectiveness. The results also indicate that one cannot assume cultural orientation based on ethnicity.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

Widespread arsenic contamination of soils in residential areas and public spaces: an emerging regulatory or medical crisis?

A critical review finds government agencies allow, permit, license, or ignore arsenic releases to surface soils. Release rates are controlled or evaluated using risk-based soil contaminant numerical limits employing standardized risk algorithms, chemical-specific and default input values. United States arsenic residential soil limits, approximately 0.4- approximately 40 ppm, generally correspond to a one-in-one-million to a one-in-ten-thousand incremental cancer risk range via ingestion of or direct contact with contaminated residential soils. Background arsenic surface soil levels often exceed applicable limits. Arsenic releases to surface soils (via, e.g., air emissions, waste recycling, soil amendments, direct pesticide application, and chromated copper arsenic (CCA)-treated wood) can result in greatly elevated arsenic levels, sometimes one to two orders of magnitude greater than applicable numerical limits. CCA-treated wood, a heavily used infrastructure material at residences and public spaces, can release sufficient arsenic to result in surface soil concentrations that exceed numerical limits by one or two orders of magnitude. Although significant exceedence of arsenic surface soil numerical limits would normally result in regulatory actions at industrial or hazardous waste sites, no such pattern is seen at residential and public spaces. Given the current risk assessment paradigm, measured or expected elevated surface soil arsenic levels at residential and public spaces suggest that a regulatory health crisis of sizeable magnitude is imminent. In contrast, available literature and a survey of government agencies conducted for this paper finds no verified cases of human morbidity or mortality resulting from exposure to elevated levels of arsenic in surface soils. This concomitance of an emerging regulatory health crisis in the absence of a medical crisis is arguably partly attributable to inadequate government and private party attention to the issue.

Animals↗
PubMedDate not supplied

Utility of canine microsatellites in revealing the relationships of pure bred dogs.

The variability of 19 canine microsatellite loci was examined within and between three pure breeds of dog. Their phylogenetic relationships were estimated by microsatellite and conventional genetic distances which indicated that greyhounds and German shepherds had longer diverse evolutionary histories, whereas Labrador retrievers were established much later. Our three breeds differ mainly in the relative frequencies of alleles at a locus and in distribution of alleles across loci. As a consequence of sampling strategy, greyhounds express significantly lower polymorphism than the other two breeds. However, some highly polymorphic microsatellite loci were common to all three breeds. High exclusion power of such loci made them valuable for parentage testing. Although the exclusion probability at a single locus is relatively low, it increases by every added microsatellite. The six most polymorphic ones sufficed to reach the exclusion probability of 99% in all three breeds tested here. As the majority of pedigree dogs have similar population structures, the data presented can be used to estimate the probability of biological paternity for any dog breed, despite the absence of appropriate population data. Polymorphic canine microsatellites proved to be valuable descriptors of population structure, and evolutionary and filial relationships.

Alleles↗
PubMedDate not supplied

Use of cosmid-derived and chromosome-specific canine microsatellites.

The majority of microsatellite markers being used to generate the emerging genetic linkage maps of the dog are derived from small-insert, random clones. While such markers are easy to generate, they have the disadvantage that they cannot easily be physically mapped by fluorescence in situ hybridization (FISH), making it difficult to assess the extent of genome coverage represented by such maps. In contrast, microsatellite markers from large-insert libraries enable the linkage groups within which they fall to be physically anchored to specific chromosomes. One aim of our work is to identify at least one microsatellite-containing cosmid clone for each canine chromosome, to ensure that linkage groups exist for all chromosomes. This is particularly important for a species with as complex a karyotype as the dog. Locating two cosmids on each chromosome would allow the orientation of the linkage groups to be established. Chromosomal locations of cosmid clones containing microsatellites have been determined by FISH and confirmed using canine chromosome-specific paints. Microsatellite sequences have been genotyped on the DogMap reference family. Microsatellites derived from flow-sorted, chromosome-specific libraries represent another source of useful markers. Initial studies have been carried out on the canine X chromosome, on which markers were underrepresented in our initial studies.

Animals↗
PubMedDate not supplied

Burkholderia pseudomallei traced to water treatment plant in Australia.

Burkholderia pseudomallei was isolated from environmental specimens 1 year after an outbreak of acute melioidosis in a remote coastal community in northwestern Australia. B. pseudomallei was isolated from a water storage tank and from spray formed in a pH-raising aerator unit. Pulsed-field gel electrophoresis confirmed the aerator and storage tank isolates were identical to the outbreak strain, WKo97.

Australia↗