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Biomedical subjects

P S Rutledge

Publications and source records attributed to P S Rutledge.

8 recordsLinked to original sources
PubMed2001

Hamigerin A and a hamigerin D decomposition product.

The sponge Hamigera tarangaensis has yielded eight new compounds and we report here the structure of one of these compounds, hamigeran A, C(20)H(25)BrO(5), or methyl 7-bromo-4beta,6-dihydroxy-1beta-isopropyl-3aalpha,8-dimethyl-5-oxo-1a,3a,4,5-tetrahydrocyclopenta[a]naphthalene-4-carboxylate, and the decomposition product of hamigeran D, C(21)H(28)BrNO(4), namely 2-(8-bromo-2beta,7-dimethyl-4-oxo-1,3alpha-benzoxazan-5-yl)-3-isopropylcyclopentylacetic acid.

Animals↗
PubMed2000

Chemistry of sponges. 19. Novel bioactive metabolites from Hamigera tarangaensis.

Seven new compounds (1-6 and 10) with a unique carbon skeleton have been isolated from the sponge Hamigera tarangaensis, and the structure of a previously reported metabolite has been revised from 12 to 8. The structures have been assigned from extensive NMR examination. Compounds 3-6 showed moderate in-vitro cytotoxicity against P-388, while 3 showed 100% in-vitro virus inhibition against both the Herpes and Polio viruses, with only slight cytotoxicity.

Animals↗
PubMed1987

Heat shock protein induction and induced thermal tolerance are independent in adult salamanders.

Ectothermic vertebrates become thermally tolerant (heat hardened) after exposure to heat shock. Eukaryotic cells show a similar response. Cellular thermal tolerance is correlated with the induction of heat shock proteins (hsps). We have investigated the relationship between heat hardening in salamanders and the induction of hsps in the tissues of these organisms. Although the synthesis of hsps can be induced in these animals by sublethal heat shocks, conditions required for hsp induction and heat hardening often do not coincide. We conclude that induced thermal tolerance in adult salamanders is independent of hsp induction in their tissues.

Acclimatization↗
PubMed1981

Scope for activity in the crayfish Pacifastacus leniusculus.

The scope for activity of the crayfish Pacifastacus leniusculus was determined between 5 and 30 degrees C (incipient lethal of 33 degrees C). Standard oxygen consumption rate (VO2) ws low (e.g., 17 ml x kg-1 x h-1 at 20 degrees C); and it increased with temperature over the entire range (Q10 = 2.09 for 5-25 degrees C). Active VO2 increased with temperature (Q10 = 1.76) to a maximum at 20 degrees C (VO2 = 176 ml x kg-1 x h-1), and then decreased. Scope for activity likewise showed a maximum at 20 degrees C (VO2 - 158 ml x kg-1 x h-1) and decreased at higher temperatures. Comparison with fish studies indicates these values represent a relatively well-developed oxygen uptake ability in this decapod crustacean. At 20 degrees C crayfish active VO2 is a significant fraction of that shown by highly active VO2 is a significant fraction of that shown by highly active species such as sockeye (29%), and moderately active species such as goldfish (57%), bullhead (62%), and bass (78%); and it is much greater than active VO2 for sluggish species such as gobiids (> 300%). Also, crayfish scope for activity between 5 and 20 degrees C is virtually identical to scopes for bullhead and bass because crayfish have lower standard VO2 than either of these fish.

Animals↗
PubMed1981

Effects of temperature acclimation on crayfish hemocyanin oxygen binding.

Crayfish, Pacifastacus leniusculus, were acclimated to 10, 20, and 25 degrees C for 1 mo. Hemocyanin from animals at these three acclimation temperatures showed distinctly different oxygen binding patterns. At any particular set of test temperature and pH, hemocyanin from 10 degrees C-acclimated animals had the lowest oxygen affinity and the greatest cooperativity, whereas hemocyanin from 25 degrees C-acclimated animals had the highest oxygen affinity and the lowest cooperativity. When tested at their own acclimation temperature, and at normal hemolymph pH for that temperature, all three hemocyanins showed oxygen pressure for half-saturation of hemoglobin of 6-7 Torr. Thus acclimation keeps oxygen affinity centered around a narrow range of values. The acclimation response probably eliminates hemocyanin oxygen affinity as a major factor in the decline of oxygen uptake ability in the crayfish above 20 degrees C. The structural basis for the observed functional changes in the hemocyanin is not yet clear.

Acclimatization↗
PubMed1981

Circulation, oxygen transport, and activity in the crayfish.

Heart and ventilation frequencies, oxygen uptake rate, hemocyanin concentration, and pre- and postbranchial PO2 and pH were measured in unrestrained crayfish (Pacifastacus leniuculus) immediately following routine and forced (maximum) activity. Experiments were performed at 20 degrees C, the temperature of maximum scope for activity in this species, and at 10 and 25 degrees C. A procedure for using N-ethylmaleimide as an anticoagulant in hemolymph sampling is described. Hemocyanin oxygen saturation, oxygen content of pre- and postbranchial hemolymph, cardiac output, and stroke volume were estimated from the measured parameters. PO2 of postbranchial hemolymph sampled immediately after routine activity was low (9-12 Torr), accompanied by hemocyanin oxygen saturations of 55-75%. Maximum forced activity for 10 min caused further reduction in these values. Thus hemocyanin is apparently not usually saturated with oxygen in these crayfish. Cardiac output, as estimated by the Fick principle, was high (at 20 degrees C, 236 ml x kg-1 x min-1 for routine activity and 969 ml x kg-1 x min-1 for forced activity). Evidence is presented that ventilation, rather than circulation, limits active oxygen uptake and scope for activity both above and below 20 degrees C.

Animals↗