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Biomedical subjects

R A Taylor

Publications and source records attributed to R A Taylor.

At least 19 recordsLinked to original sources
PubMed2003

Nanoscale solid-state quantum computing.

Most experts agree that it is too early to say how quantum computers will eventually be built, and several nanoscale solid-state schemes are being implemented in a range of materials. Nanofabricated quantum dots can be made in designer configurations, with established technology for controlling interactions and for reading out results. Epitaxial quantum dots can be grown in vertical arrays in semiconductors, and ultrafast optical techniques are available for controlling and measuring their excitations. Single-walled carbon nanotubes can be used for molecular self-assembly of endohedral fullerenes, which can embody quantum information in the electron spin. The challenges of individual addressing in such tiny structures could rapidly become intractable with increasing numbers of qubits, but these schemes are amenable to global addressing methods for computation.

Journal Article↗
PubMed2002

A case of anaemia in a neonatal warthog (Phacochoerus aethiopicus) and evaluation of serum-soluble iron in warthogs.

A 38-day-old male warthog (Phacochoerus aethiopicus) with marked anaemia (haematocrit = 14 %) presented to the Denver Zoological Gardens hospital with ataxia, tachypnoea, suspected stunted growth and cardiomegaly. The piglet demonstrated some features consistent with both iron deficiency anaemia and autoimmune haemolytic anaemia. Serum-soluble iron was below the level of detection (< 8.96 micromol/l). Iron deficiency anaemia is a well recognised entity in domestic swine reared on concrete and denied access to soil. Fifteen captive warthogs were subsequently evaluated for serum soluble iron content (mean = 21.62 +/- 4.36 micromol/l as well as 5 neonatal warthog piglets that required hand-rearing. Only 1 of 5 neonatal warthog piglets had measurable serum soluble iron (9.50 micromol/l). These data suggest that warthogs are similar to domestic swine and are born with low iron stores. Some form of iron supplementation should be considered for captive neonatal warthog piglets, especially if they are reared on concrete.

Anemia↗
PubMed2001

KANADI regulates organ polarity in Arabidopsis.

Leaves and floral organs are polarized along their adaxial-abaxial (dorsal-ventral) axis. In Arabidopsis, this difference is particularly obvious in the first two rosette leaves, which possess trichomes (leaf hairs) on their adaxial surface but not their abaxial surface. Mutant alleles of KANADI (KAN) were identified in a screen for mutants that produce abaxial trichomes on these first two leaves. kan mutations were originally identified as enhancers of the mutant floral phenotype of crabs claw (crc), a gene that specifies abaxial identity in carpels. Here we show that KAN is required for abaxial identity in both leaves and carpels, and encodes a nuclear-localized protein in the GARP family of putative transcription factors. The expression pattern of KAN messenger RNA and the effect of ectopically expressing KAN under the regulation of the cauliflower mosaic virus (CAMV) 35S promoter indicate that KAN may also specify peripheral identity in the developing embryo.

Amino Acid Sequence↗
PubMed2000

Mutational analysis of metallo-beta-lactamase CcrA from Bacteroides fragilis.

In an effort to evaluate the roles of Lys184, Asn193, and Asp103 in the binding and catalysis of metallo-beta-lactamase CcrA from Bacteroides fragilis, site-directed mutants of CcrA were generated and characterized using metal analyses, CD spectroscopy, and kinetic studies. Three Lys184 mutants were generated where the lysine was replaced with alanine, leucine, and glutamate, and the analysis of these mutants indicates that Lys184 is not greatly involved in binding of cephalosporins to CcrA; however, this residue does have a significant role in binding of penicillin G. Three Asn193 mutants were generated where the asparagine was replaced with alanine, leucine, and aspartate, and these mutants exhibited <4-fold decrease in k(cat), suggesting that Asn193 does not play a large role in catalysis. However, stopped-flow visible kinetic studies showed that the Asn193 mutants exhibit a slower substrate decay rate and no change in the product formation rate as compared with wild-type CcrA. These results support the proposed role of Asn193 in interacting with and activating substrate during catalysis. Two Asp103 mutants were generated where the aspartate was replaced with serine and cysteine. The D103C and D103S mutants bind the same amount of Zn(II) as wild-type CcrA and exhibited a 10(2)-fold and 10(5)-fold decrease in activity, respectively. Results from solvent isotope, proton inventory, and rapid-scanning visible studies suggest that Asp103 plays a role in generating the enzyme intermediate but does not donate a proton to the enzyme intermediate during the rate-limiting step of the catalytic mechanism.

Amino Acid Substitution↗
PubMed1998

Symptomatic pulmonary hyalinizing granuloma.

An otherwise healthy 37-year-old man came to the emergency room with left-sided dull chest pain of 4 weeks' duration. Physical examination, laboratory studies, and electrocardiogram were all unremarkable. A chest x-ray film revealed calcified pulmonary nodules. Computed tomography of the chest confirmed bilateral parenchymal cavitary lesions. Via limited thoracotomy, a tan nodule measuring 2.5 to 3.0 cm in diameter was excised from the left upper lobe. Histopathologic examination revealed a well circumscribed lesion and extensive lamellar hyalinization. A few foci of finely granular calcification were present within the hyalinizing areas. After surgery and short-term use of nonnarcotic analgesics, the chest pain resolved. Although pulmonary hyalinizing granuloma (PHG) is known to produce cavitating lesions, calcification at multiple sites is also consistent with this diagnosis. Clinicians should remember to include PHG in the differential diagnosis of multiple pulmonary nodules.

Adult↗
PubMed1998

Knee position error detection in closed and open kinetic chain tasks during concurrent cognitive distraction.

It is important to establish whether presumed differences among varieties of motor responses are manifested in related differences in performance. In order to determine possible functional distinctions between closed and open kinetic chain tasks, participants' performance in the presence or absence of cognitive distraction on an error-detection task was assessed. Individual testing of participants consisted of knee extension and flexion movements to experimenter-defined positions, approximating the 25th, 50th, and 75th percentile of the participants' range of motion on the apparatus. Performance under conditions of distraction was significantly worse than in the absence of distraction. Performance using longer movements was significantly more accurate. No substantial differences were found between closed and open kinetic chain movements. Limitations of this research for the distinction between open and closed chain tasks are addressed, and clinical implications of the effects of distraction are presented.

Adult↗
PubMed1989

Flight behavior of Musca domestica and Stomoxys calcitrans (Diptera: Muscidae) in a Kansas dairy barn.

Aerial density, flight thresholds, and periodicity were estimated for the house fly, Musca domestica L., and the stable fly, Stomoxys calcitrans (L.), from data collected by suction traps located in a dairy barn in Kansas between 1 July and 31 October 1970. M. domestica catches increased from July to August, declining to near zero by the end of October. S. calcitrans catches peaked in July and September with a major decline in August. Both species exhibited a diel periodicity in flight with maximal activity during the early afternoon. Secondary peaks were detected in the late afternoon or early evening. M. domestica activity peaked about two hours after S. calcitrans. Male and female S. calcitrans flight activity patterns were slightly different, but peaked at the same time. Both species flew at temperatures between 20 and 38 degrees C. At temperatures over 33 degrees C, stable fly activity decreased rapidly. No upper threshold for flight by M. domestica was detected. The median temperature-flight thresholds of male and female S. calcitrans were significantly different, with females flying at lower temperatures than males. The threshold for M. domestica flight was lower than for S. calcitrans. The shape of the temperature-flight relationship indicated that the flight threshold was determined by heat accumulation.

Animals↗
PubMed1982

The transition from maternal to embryonic control in the 2-cell mouse embryo.

The development of the early 2-cell mouse embryo to the late 2-cell stage is marked by the appearance between 23 and 26 h post-insemination of a complex of polypeptides of mol. wt. approximately 67 K. Addition of alpha-amanitin between 18 and 21 h post-insemination prevents or reduces the subsequent appearance of these polypeptides. Addition of alpha-amanitin after 21 h does not obviously affect the appearance of the approximately 67 K polypeptides. A major change in synthetic profile occurs between 29 and 32 h post-insemination involving many polypeptides. Addition of alpha-amanitin to 2-cell embryos prior to 29 h post-insemination prevents the appearance of the new polypeptides observed during this major change but does not prevent the disappearance of the old polypeptides. In contrast, addition of alpha-amanitin after this time does not affect the appearance of the new polypeptides. This result, together with other evidence presented, suggests that during the 2-cell stage the embryonic genome shows transcriptional activity in two phases at 18-21 and 26-29 h post-insemination, that these transcripts are utilized soon after their synthesis, and that most maternal transcripts used before the second phase of embryonic transcription become ineffective soon afterwards.

Amanitins↗
PubMed1981

Mesothelioma: current perspectives.

Thirty patients with the diagnosis of mesothelioma were admitted to the Swedish Hospital Medical Center, Seattle, from 1975 to 1979. Of these, 26 had pleural and 4 had peritoneal mesothelioma. In 20 of the patients with pleural mesothelioma, the diagnosis had been made by open thoractomy and in only one by needle biopsy of the pleura. The average survival of the patients with pleural tumors from time of diagnosis was 15 months, and two are alive at three and eight months, respectively, one of whom had an apparent solitary benign mesothelioma. The average survival of those with peritoneal mesothelioma was ten months, although one has survived six years. There were 17 patients with a known history of exposure to asbestos, 14 while working in shipyards. Because of the relatively high incidence of this previously rare tumor in the Puget Sound, Washington, area, and the generally dismal results of therapy, better methods of diagnosis including thoracoscopy and a more systematic approach to treatment are recommended.

Asbestos↗
PubMed1978

Estrogens in food: the almond mystery.

Studies were made of 36 different nuts, grains, fruits and vegetables commonly used as human foods; each of these was fed to a group of ovariectomized rats for 10 days as a sole diet. The estrogenic activities of the foods were estimated by comparing the uterine weights, uterine fluid volumes and the vaginal cornification indices of each group of rats with those of groups fed other foods. Almonds, cashew nuts, peanuts, oats, corn, wheat and apples all showed estrogenic activity. The original sample of almonds showed the greatest estrogenic activity (p less than 0.01) which was confirmed by repetition of the experiment (p less than 0.01), but subsequent studies of other samples of almonds showed no estrogenic activity. Possible reasons for the disparity of the results with different lots of almonds are discussed.

Animals↗
PubMed1978

Linkage and gene localization of hereditary spherocytosis (HS).

Fifteen kindreds with dominant hereditary spherocytosis (HS) were studied. Expansion of the data from a family with an 8/12 translocation provided further evidence that at least one locus for HS is located near the breakpoint of the translocation. Linkage analysis of all families showed a lack of linkage with all marker loci studied except for Gm (IgG). Linkage between Gm and HS was shown to be significant with a maximum lod score of 3.42 at a recombination fraction of 22%. No heterogeneity of the recombination fraction was observed either between sexes or between families. These results are compatible with the hypothesis that HS is not a heterogeneous disorder.

Female↗
PubMed1977

Aggregation, migration and population mechanics.

A concept is developed for the regulation of populations by density-dependent movement, rather than by overt competition alone. Fitness is seen as maximising the reproductive advantage of a balance between migratory and congregatory behaviours. Population density is shown to be spatially, as well as temporally dynamic and a mechanism is proposed that accounts for observed spatial behaviour.

Animals↗