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Biomedical subjects

A McDougall

Publications and source records attributed to A McDougall.

6 recordsLinked to original sources
PubMed1992

Sperm-induced currents at fertilization in sea urchin eggs injected with EGTA and neomycin.

Membrane currents were measured in single voltage-clamped sea urchin eggs (Lytechinus pictus and Lytechinus variegatus) that were injected with either EGTA or neomycin and inseminated. Although egg activation and the fertilization calcium wave were prevented by injection of either of these compounds, sperm attached and still elicited inward currents. Sperm-induced currents in EGTA-injected eggs had an abrupt onset, quickly reached a maximum, and then slowly declined in amplitude. Sperm incorporation occurred readily in EGTA-injected eggs. Similar results were obtained with another calcium chelator, BAPTA. In neomycin-injected eggs, sperm-induced currents generally had an abrupt onset and, in contrast to EGTA-injected eggs, the currents usually cut off rapidly. Sperm failed to enter the neomycin-injected eggs and the duration of sperm-induced currents in neomycin-injected eggs was markedly dependent upon the voltage-clamp holding potential, with shorter duration currents occurring at -70 than at -20 mV. The lability of the initial interaction between sperm and egg at negative holding potentials may explain why activation often fails when the egg membrane is voltage clamped at these potentials (Lynn et al., Dev. Biol. 128, 305-323, 1988).

Animals↗
PubMed1992

Internal calcium release and activation of sea urchin eggs by cGMP are independent of the phosphoinositide signaling pathway.

We show that microinjecting cyclic GMP (cGMP) into unfertilized sea urchin eggs activates them by stimulating a rise in the intracellular free calcium ion concentration ([Ca2+]i). The increase in [Ca2+]i is similar in both magnitude and duration to the transient that activates the egg at fertilization. It is due to mobilization of calcium from intracellular stores but is not prevented by the inositol trisphosphate (InsP3) antagonist heparin. Furthermore, cGMP does not stimulate the eggs Na+/H+ antiport when the [Ca2+]i transient is blocked by the calcium chelator bis-(O-aminophenoxy)-N,N,N',N'-tetraacetic acid (BAPTA), suggesting that cGMP does not activate eggs by interacting with the their phosphoinositide signaling pathway. However, the [Ca2+]i increase and activation are prevented in eggs in which the InsP3-sensitive calcium stores have been emptied by the prior microinjection of the InsP3 analogue inositol 1,4,5-trisphosphorothioate. These data indicate that cGMP activates eggs by stimulating the release of calcium from an InsP3-sensitive calcium store via a novel, though unidentified, route independent of the InsP3 receptor.

Animals↗
PubMed1991

Risks and benefits of paracetamol antipyresis in young children with fever of presumed viral origin.

To examine whether antipyretic therapy in young children is associated with potential risks (interference with enhanced host defences at febrile temperatures) or benefits (improved comfort and behaviour), a randomised, double-blind, placebo-controlled trial of paracetamol was conducted among 225 children 6 months to 6 years of age who presented with acute (less than or equal to 4 days) fever (greater than or equal to 38 degrees C per rectum) without evident bacterial focus of infection. Parents were asked to give paracetamol liquid 10-15 mg/kg or placebo every 4 h as needed for fever and to avoid bathing, sponging, or other pharmacological agents. Parents kept temperature and symptom diaries and recorded changes in child comfort and behaviour according to a pretested, 5-category Likert-type questionnaire 1-2 h after every dose. There were no significant differences between treated and placebo groups in mean duration of subsequent fever (34.7 vs 36.1 h) or other symptoms (72.9 vs 71.7 h). Paracetamol-treated children were more likely to be rated by their parents as having at least a 1-category improvement in activity (38 vs 11%; p = 0.005) and alertness (33 vs 12%; p = 0.036) but no significant differences were noted in mood, comfort, appetite, or fluid intake. That overall improvement in behaviour and comfort with paracetamol was not impressive is underscored by the inaccuracy of parents' "guess" at the end of the trial as to which agent their child had received-45% correct guesses for paracetamol and 52% for placebo. The data suggest that the clinically relevant hazards and benefits of paracetamol antipyresis have been exaggerated.

Acetaminophen↗
PubMed1979

Extra-abdominal desmoid tumours.

Desmoid tumours are not common but have a distinct resemblance to fibrosarcomata. Their clinical appearance and progress should be recognised since failure to distinguish them from sarcomata could result in extensive and unnecessarily mutilating operations. Three cases of extra-abdominal desmoid tumours are reported. Two of the patients had tumours arising from multicentric foci in the same limb. The disappearance of the tumours in two patients after the menopause, and the variation in the tumours during the menstrual cycle in the third patient, add weight to the theories about endocrine control.

Adolescent↗
PubMed1977

The preformed socket and modular assembly for primary amputees.

A method is described by which an artificial limb can be fitted as soon as an above-knee or below-knee amputation wound is healed, by using preformed sockets which enable the prosthetist to fit the limb within the hour. The method has been found safe, and better than other methods previously described to facilitate the early mobilisation and rehabilitation of the amputee.

Amputation, Surgical↗