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Biomedical subjects

A S Wu

Publications and source records attributed to A S Wu.

At least 19 recordsLinked to original sources
PubMed1998

Putting more genetics into genetic algorithms.

The majority of current genetic algorithms (GAs), while inspired by natural evolutionary systems, are seldom viewed as biologically plausible models. This is not a criticism of GAs, but rather a reflection of choices made regarding the level of abstraction at which biological mechanisms are modeled, and a reflection of the more engineering-oriented goals of the evolutionary computation community. Understanding better and reducing this gap between GAs and genetics has been a central issue in an interdisciplinary project whose goal is to build GA-based computational models of viral evolution. The result is a system called Virtual Virus (VIV). VIV incorporates a number of more biologically plausible mechanisms, including a more flexible genotype-to-phenotype mapping. In VIV the genes are independent of position, and genomes can vary in length and may contain noncoding regions, as well as duplicative or competing genes. Initial computational studies with VIV have already revealed several emergent phenomena of both biological and computational interest. In the absence of any penalty based on genome length, VIV develops individuals with long genomes and also performs more poorly (from a problem-solving viewpoint) than when a length penalty is used. With a fixed linear length penalty, genome length tends to increase dramatically in the early phases of evolution and then decrease to a level based on the mutation rate. The plateau genome length (i.e., the average length of individuals in the final population) generally increases in response to an increase in the base mutation rate. When VIV converges, there tend to be many copies of good alternative genes within the individuals. We observed many instances of switching between active and inactive genes during the entire evolutionary process. These observations support the conclusion that noncoding regions serve as scratch space in which VIV can explore alternative gene values. These results represent a positive step in understanding how GAs might exploit more of the power and flexibility of biological evolution while simultaneously providing better tools for understanding evolving biological systems.

Algorithms↗
PubMed1997

Neuronal intestinal dysplasia presenting as an abdominal mass: report of a case.

An unusual clinical presentation of a patient with neuronal intestinal dysplasia is presented. A 46-year-old male noted a palpable mass in the right lower quadrant of his abdomen for two months. A computed axial tomographic scan showed a thickened wall of the cecum with a tumor-like appearance. The excised specimen consisted of a mass caused by the thickened, edematous wall of the dilated cecum and appendix. The wall of the cecum and appendix measured up to 2.5 and 0.8 cm, respectively, in thickness. Microscopic studies showed extensive hyperplasia and hypertrophy of the ganglia and nerve plexuses and hypertrophy of the muscularis propria, consistent with neuronal intestinal dysplasia.

Appendix↗
PubMed1985

Interactive effects of organic and inorganic selenium with cadmium and mercury on spermatozoal oxygen consumption and motility in vitro.

The effects of cadmium (Cd), mercury (Hg), and three different chemical forms of selenium (Se) (selenite, selenocystine, and selenomethionine) on ram spermatozoal motility and oxygen consumption in vitro were studied over a 4-mo period. Concentrations of 10(-6) to 10(-2) M Cd and Hg were injurious to spermatozoa as indicated by depressed motility and reduced oxygen uptake. Equimolar concentrations of Se as selenite, selenocystine, or selenomethionine counteracted the toxicity of Cd and Hg at low concentrations (10(-5) and 10(-6) M) but not at higher concentrations (10(-4) to 10(-2) M). Gel filtration (Sephadex G-75) of seminal plasma and solubilized sperm prepared from semen incubated with Cd or Hg with or without the Se compounds revealed that Cd or Hg eluted with the void volume proteins in all treatments. Incubation of ram spermatozoa with any of the three chemical forms of Se ranging from 10(-6) to 2.5 X 10(-5) M significantly improved sperm motility and oxygen consumption.

Animals↗
PubMed1983

Incorporation of selenium-75 into semen and reproductive tissues of bulls and rams.

After intramuscular injections of 500 muCi 75Se, semen was collected periodically over a 63-day period from a selenium-deficient and a selenium-injected ram which were then killed for collection of the reproductive organs for the gel filtration studies. Testes, accessory glands and semen were also obtained from a bull injected intravenously with 75Se. Gel filtration (Sephadex G 150) of ram testis cytosol resulted in 4 75Se peaks (Ve/Vo ratios of 1 X 1, 1 X 5, 2 X 3, 2 X 9). In the selenium-injected ram the glutathione peroxidase (GSH-Px) peak (Ve/Vo 1 X 5) predominated, but in the selenium-deficient ram, radioactivity of the GSH-Px peak was less than that of the higher molecular weight peak (Ve/Vo 1 X 1). Gel filtration chromatograms of bull testis cytosol yielded 5 75Se peaks (Ve/Vo 1 X 1, 1 X 5, 1 X 9, 2 X 4, 2 X 8). In chromatograms of ram seminal plasma on Sephacryl S-200 there were 2 major (Ve/Vo 1 X 4, 1 X 1) and 2 minor peaks (Ve/Vo 1 X 7, 2 X 4). 75Se increased with time up to 49 days after injection in all peaks. 75Se-labelled bull seminal plasma yielded 2 75Se peaks (Ve/Vo 1 X 1, 1 X 4) which corresponded to the major peaks of ram seminal plasma. Bull and ram seminal plasma GSH-Px activities per mg protein were comparable (28 and 29 nmol NADPHox/min, respectively), but when expressed per ml seminal plasma, activity of the bull was more than 7 times the highest activity of ram seminal plasma (2908 and 385 nmol NADPHox/min, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1975

Ultrastructural demonstration of cilia and ciliary rootlets in mammalian uterine tube epithelium in different functional states.

Tissue from the infundibulum region of the uterine tube (oviduct) of guinea pigs, cattle, sheep, and swine was examined by electron microscopy. In all specimens, cilia and ciliary rootlets were present in variable numbers in the ciliated cells during both the follicular and the luteal phases of the estrous cycle. True degeneration of cilia was not evident during luteal phase or pregnancy. The ciliary rootlets in ruminant and nonruminant species had structural similarities to those described in people and rhesus monkeys. These organelles measured approximately 1 mum long in most species studied, but in the cow, the rootlets, extending downward into the cytoplasm from the proximal end of the basal body, reached a length of 2 mum. The rootlets had a cross-striation of thick and thin bands, the period measuring 40 to 60 nm. Mitochondria were closely associated with the rootlets. The rootlets usually formed a small angle to the axis of the cilium. These organelles probably function as anchoring or stabilizing structures for the motile cilia. Results indicated that the rootlets are more widely distributed in mammalian uterine tube cilia than previously postulated. Polyribosomes, microfilaments, microtubules, and electron-opaque fibrous granules were frequently seen in the cytoplasm of the ciliated cells. The presence of fibrous granules in close association with the basal bodies indicate that these granules have a role in the development of cilia and rootlets. Cilia and precursor fibrous granules were also seen in porcine fetal uterine tube epithelial cells.

Animals↗
PubMedDate not supplied

The oral health status and treatment needs of adults aged 65+ living independently in Ottawa-Carleton.

We report the findings from a dental survey of a random sample of 299 senior citizens living in Ottawa-Carleton. Those examined were younger, less likely to have a regular dentist, and more likely to have oro-facial pain, difficulty chewing, and to perceive a need to visit a dentist compared with those responding to the enrollment phone interview. Among the 65% of seniors who were dentate, 37% had dental decay; men and seniors with low incomes had more decay (p less than 0.05). Periodontal disease was worse among older seniors, men and poor seniors (p less than 0.05). One third of all seniors reported recent oro-facial pain, 50% had difficulty chewing foods and 30% reported some social impact resulting from their oral health. The resources required to treat the prevalent disorders were considerable and differences between dentate and edentulous people were negligible. Senior citizens expressed attitudes which indicate that they value dental health and would like help to achieve it.

Aged↗