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Computer Communication Networks↗
Biomedical subjects
J W Ballard
Publications and source records attributed to J W Ballard.
Unraveling selection in the mitochondrial genome of Drosophila.
We examine mitochondrial DNA variation at the cytochrome b locus within and between three species of Drosophila to determine whether patterns of variation conform to the predictions of neutral molecular evolution. The entire 1137-bp cytochrome b locus was sequenced in 16 lines of Drosophila melanogaster, 18 lines of Drosophila simulans and 13 lines of Drosophila yakuba. Patterns of variation depart from neutrality by several test criteria. Analysis of the evolutionary clock hypothesis shows unequal rates of change along D. simulans lineages. A comparison within and between species of the ratio of amino acid replacement change to synonymous change reveals a relative excess of amino acid replacement polymorphism compared to the neutral prediction, suggestive of slightly deleterious or diversifying selection. There is evidence for excess homozygosity in our world wide sample of D. melanogaster and D. simulans alleles, as well as a reduction in the number of segregating sites in D. simulans, indicative of selective sweeps. Furthermore, a test of neutrality for codon usage shows the direction of mutations at third positions differs among different topological regions of the gene tree. The analyses indicate that molecular variation and evolution of mtDNA are governed by many of the same selective forces that have been shown to govern nuclear genome evolution and suggest caution be taken in the use of mtDNA as a "neutral" molecular marker.
Animals↗
Evidence from 12S ribosomal RNA sequences that onychophorans are modified arthropods.
The evolutionary relationships of the onychophorans (velvet worms) and the monophyly of the arthropods have generated considerable debate. Cladistic analyses of 12S ribosomal RNA sequences indicate that arthropods are monophyletic and include the onychophorans. Maximum parsimony analyses and monophyly testing within arthropods indicate that myriapods (millipedes and centipedes) form a sister group to all other assemblages, whereas crustaceans (shrimps and lobsters) plus hexapods (insects and allied groups) form a well-supported monophyletic group. Parsimony analysis further suggests that onychophorans form a sister group to chelicerates (spiders and scorpions) and crustaceans plus hexapods, but this relationship is not well supported by monophyly testing. These relationships conflict with current hypotheses of evolutionary pathways within arthropods.
Animals↗
A simple technique for sexing blackfly larvae of the taxon Austrosimulium bancrofti.
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Animals↗
Feeding strategies of the horseflies Hybomitra expollicata and Tabanus bromius in southern France.
Blood-feeding success of female horseflies, Hybomitra expollicata Pandellé and Tabanus bromius L. (Diptera: Tabanidae), was studied. Bloodmeal weights of flies permitted different periods of residence on a horse's belly were estimated, and related to subsequent ovarian development and the number of mature eggs produced. Fitness gain per visit to a host (as estimated by the number of mature eggs produced) increased more rapidly with residence time on the host for H.expollicata than for T.bromius. H.expollicata inhibed blood more rapidly and, above a threshold bloodmeal size, produced a consistently higher number of eggs per unit weight of blood ingested. The feeding strategies of the two species are compared.
Animals↗
Factors influencing silhouette trap captures of the blackfly Austrosimulium bancrofti in Queensland, Australia.
Three silhouette traps of novel design were used to investigate the trap finding ability of female Austrosimulium bancrofti (Taylor) (Diptera: Simuliidae) in southeast Queensland. The traps were 'upright', 'elongate' or 'square' in shape. Five highly significant factors: hour after sunrise, temperature, relative humidity, trap shape and distance between traps, were included in a model which generated fitted estimates of flies captured under defined conditions. The rate of increase and the level of maximum capture rate indicated that the elongate trap captured the highest numbers of blackflies. An interaction between hour after sunrise and temperature suggests a strong endogenous modification of trap finding activity. Numbers captured increased with increasing distance between traps and decreasing relative humidity. The importance of these results in understanding behaviour of A. bancrofti is discussed.
Animals↗
Evaluation of lopamidol and diatrizoate in excretory urography: a double-blind clinical study.
Image opacification, patients' tolerance, and clinical and laboratory findings were evaluated in patients having excretory urography at three centers. In a double-blind, parallel study, iopamidol was compared with diatrizoate (50-ml dose), and in an open-label trial, the administration of a 100-ml dose of iopamidol was evaluated. In the double-blind study, a total of 84 patients received 50 ml of either iopamidol or diatrizoate. In the open-label study, another 42 patients received a 100-ml dose of iopamidol. Image opacification scores after the administration of the 50-ml doses showed better opacification with iopamidol than with diatrizoate in the renal calices (p less than .05) and in the composite kidney (p less than .05). Opacification scores were higher for 100-ml doses of iopamidol than for 50-ml doses in all anatomic regions as well as in the composite kidney (p = .0001). Patients' tolerance to iopamidol was significantly better than their tolerance to diatrizoate (p less than .025). Investigators observed adverse drug reactions in a total of 10 patients. In the double-blind study, one of 43 patients had transient bradycardia after the administration of iopamidol. In the same study, four of 41 patients who received diatrizoate had five minor adverse drug reactions. With 100-ml doses of iopamidol, five of 42 patients had adverse reactions. No adverse side effects required therapy in either study. There were no significant changes in vital signs or laboratory values after drug administration. The results of this study show that iopamidol is a suitable agent for excretory urography at doses of 50 and 100 ml. Patients report fewer unpleasant side effects with iopamidol than with diatrizoate. Overall image quality was better with iopamidol than with diatrizoate. Overall evaluation of drug performance was better with iopamidol than with diatrizoate.
Adolescent↗
An investigation of the potential of Aedes camptorhynchus (Thom.) as a vector of Ross River virus.
Aedes camptorhynchus (Thom.) collected on the mid-south coast of New South Wales during the winter of 1982 were highly susceptible to infection (ID50 = 10(2.4) VERO pfu/mosquito) when fed on rat tail skins containing blood and serial dilutions of the T48 strain of Ross River (RR) virus. After 2 d, when no virus was detectable, rapid proliferation allowed transmission from 5 d post ingestion. A maximum transmission rate occurred 9 d post-feeding when 4 of 4 infected mosquitoes transmitted virus. The susceptibility of Ae camptorhynchus to RR virus infection was compared with that of a laboratory colony of Ae aegypti (L.) (ID50 = 10(3.8) VERO pfu/mosquito).
Aedes↗
Transluminal angioplasty in a community hospital: a surgeon's viewpoint.
We have found transluminal angioplasty to be a safe and effective procedure for the relief of arterial obstruction. In a community hospital over a 20-month period, we did 100 consecutive dilatation procedures, many involving multiple dilatations, with no morbidity or mortality. Iliac lesions were dilated successfully (74/80) more often than femoral lesions (15/20). Several patients had relief of impotence. Transluminal angioplasty was used successfully as an adjunct to operation both as staged and combined procedures to dilate the donor artery for a femoral-femoral bypass graft or femoral-popliteal graft, or to dilate the outflow of a new or existing graft.
Angioplasty, Balloon↗
Percutaneous removal of flexible foreign body from the heart.
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Catheterization↗