Biliary excretion of synthetic sex steroids in heterozygous and homozygous Gunn rats.

87.9% of a given dose of [³H]Norethisterone ([³H]N) and 76.7% of [³H]Ethinyloestradiol ([³H]EE₂) were excreted in the bile of male heterozygous Gunn rats in 2 hours Similarly, 86.9% of a given dose [³H]N and 84.0% of [³H]EE₂ were excreted in the bile of male homozygous Gunn rats in 2 hours. In both heterozygous and homozygous rats glucuronide conjugates were present. Despite the lesion in UDP-glucuronyltransferase, the homozygous rats is able to conjugate the synthetic steroids apparently normally.     

Ecto-protein kinase activity in rabbit peritoneal polymorphonuclear leucocytes

An ectoprotein kinase activity has been identified on intact rabbit peritoneal polymorphonuclear leucocytes and the time course of phosphate incorporation into proteins has been followed at different ATP levels. Saturation is reached at around 3 mM ATP and the activity is inhibited by p-chloromercuribenzoate. The possibility that the observed protein phosphorylation arises through the action of a membrane ATPase liberating phosphate for transfer into the cell, incorporation into ATP and its utilisation by endogenous kinases, has been excluded by studying both enzymes concomitantly and measuring the rate of [32P]orthophosphate uptake. Lactate dehydrogenase measurements in the extracellular media also exclude the possibility of kinase liberation from lysed cells. Moreover, the pattern of 32P-labelling of polypeptides when intact cells are exposed to [32P]ATP is quite different from that when homogenates are incubated with [32P]ATP or intact cells with [32P]-orthophosphate. We have been unable to demonstrate any cAMP dependency for this ectokinase activity.     

Metabolic cost of motility in planktonic protists: Theoretical considerations on size scaling and swimming speed

The metabolic cost of swimming for planktonic protists is calculated, on theoretical grounds, from a simple model based upon Stokes' law. Energetic expenditure is scaled over both typically encountered size ranges (1–100 µm) and swimming speeds (100–5,000 µm/sec). In agreement with previous estimates for typical flagellates, these estimates generally suggest a low (<1%) cost for motility, related to total metabolic rate of growing cells. However, the cost of motility in small, fast-moving forms, such as some ciliates and flagellates, may be significant (1–10%) and even substantial (10–100%+) for certain species. In accordance with these predictions, many fast-moving ciliates restrict motility to bursts of activity or jumps. In the absence of a reduction in swimming speed or in the frequency of jumps, it is predicted that this relative cost of motility will be significantly increased in starving heterotrophs or light-limited autotrophs, if such cells reduce cell volumes and specific rates of respiration.     

Wall shear stress estimates in coronary artery constrictions.

Wall shear stress estimates from laminar boundary layer theory were found to agree fairly well with the magnitude of shear stress levels along coronary artery constrictions obtained from solutions of the Navier Stokes equations for both steady and pulsatile flow. The relatively simple method can be used for in vivo estimates of wall shear stress in constrictions by using a vessel shape function determined from a coronary angiogram, along with a knowledge of the flow rate.     

Flavonoid chemistry of arceuthobium (viscaceae)

Flavonoid compounds from 36 of the 38 known taxa of the genusArceuthobium (dwarf mistletoes) were examined. The flavonoid chemistry of the genus is rather uniform, all taxa producing 3-O-glycosides of the flavonols quercetin and myricetin. No infraspecific chemical variation was encountered, and in those instances where subspecific taxa are recognized, their chemistry was uniform. At the subgeneric level, members of subgenusArceuthobium synthesize primarily glucosides, whereas galactosides are more common in subgenusVaginata. In two of the four Old World species of subgenusArceuthobium (A. juniperi- procerae andA. oxycedri) only myricetin 3-O-glucoside was detected. There are no absolute flavonoid differences between subgenera, sections, or series. On the other hand, flavonoids are useful in several instances at the species level. In several cases, chemical data lend support to the recognition of species which in the past have been considered doubtfully distinct on the basis of morphology.     

Systematic relationships in the narrow-leaved species of chenopodium of the Western United States

Brittonia - In a study of ten taxa ofChenopodium occurring primarily in the western United States and designated as the narrow-leaved complex, data from morphology, flavonoid chemistry, and somatic...