Effect of sex hormones on plasma cholesterol in castrated and noncastrated male rats

The administration of estradiol to both castrated and noncastrated male rats was associated with significantly increased plasma cholesterol levels as compared to controls, the estradiol in the noncastrated rats overriding the tendency of testosterone to lower plasma cholesterol.     

A sharp lithosphere-asthenosphere boundary imaged beneath eastern North America

Plate tectonic theory hinges on the concept of a relatively rigid lithosphere moving over a weaker asthenosphere, yet the nature of the lithosphere-asthenosphere boundary remains poorly understood. The gradient in seismic velocity that occurs at this boundary is central to constraining the physical and chemical properties that create differences in mechanical strength between the two layers. For example, if the lithosphere is simply a thermal boundary layer that is more rigid owing to colder temperatures, mantle flow models indicate that the velocity gradient at its base would occur over tens of kilometres. In contrast, if the asthenosphere is weak owing to volatile enrichment or the presence of partial melt, the lithosphere-asthenosphere boundary could occur over a much smaller depth range. Here we use converted seismic phases in eastern North America to image a very sharp seismic velocity gradient at the base of the lithosphere-a 3-11 per cent drop in shear-wave velocity over a depth range of 11 km or less at 90-110 km depth. Such a strong, sharp boundary cannot be reconciled with a purely thermal gradient, but could be explained by an asthenosphere that contains a few per cent partial melt or that is enriched in volatiles relative to the lithosphere.     

Prostaglandin I3 is formed in vivo in man after dietary eicosapentaenoic acid

Greenland Eskimos who live on a traditional marine diet rich in long chain omega 3-polyunsaturated fatty acids have a low incidence of cardiovascular disease and myocardial infarction. In their plasma and platelet lipids, arachidonic acid, the precursor of dienoic prostanoids, is partly replaced by eicosapentaenoic acid (C20:5, omega 3; EPA), the precursor of trienoic prostanoids. Studies with an Eskimo diet or a Western diet supplemented with sea fish or fish oil rich in EPA resulted in an 'Eskimo-like' pattern of plasma and platelet lipids. Moreover, less reactive platelets, a reduced ex vivo formation of proaggregatory thromboxane A2 and a blunted circulatory response to pressor hormones were reported. These favourable functional effects may be induced by a shift of prostanoid formation from the dienoic to the trienoic series. We show here that the major urinary metabolite of endogenous prostaglandin I3 is present in subjects that have ingested either cod liver oil (approximately 4 g EPA per day) or mackerel (approximately 10-15 g EPA per day). Our studies provide the first direct evidence for in vivo formation of prostaglandin I3 in man.     

Quinine dimorphism among ‘non-tasters’ of 6-n-propylthiouracil

Zusammenfassung Geschmacksblinde gegenüber 6-n-Propylthiouracil zerfallen in zwei Gruppen (Dimorphismus): eine mit niedrigen und eine mit hohen Geschmacksschwellenwerten gegenüber Chinin. Jene der ersten Gruppe haben niedrige Schwellenwerte auch gegenüber den andere Geschmacksqualitäten — sauer, salzig und süss — und gehören zur -Geschmacksgruppe. Vertreter der zweiten Gruppe, das heisst 6-n-Propylthiouracil-Geschmacksblinde mit hohen Geschmacksschwellenwerten gegenüberChinin gehören zu der -Geschmacksgruppe. Patienten mit paroxysmal vaskulärem Kopfschmerz (Migräne mit familiärer Komponente), jedoch ohne elektronencephalographische Anomalie, gehören ausschliesslich zu der -Geschmacksgruppe. Die Eltern von mongoloiden Kindern weisen hohe Geschmacksschwellenwerte gegenüber Chinin auf, wobei die Väter zur -Geschmacksgruppe gehören.

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MeinerAlma Mater, der Universität Basel, zu ihrem 500jährigen Jubiläum in Dankbarkeit gewidmet.

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Acknowledgements. This work has been supported by the State of Ohio, Department of Mental Hygiene and the U.S. Public Health Service, National Institutes of Health, Division of Mental Health, Grant No. M-2731. The active interest and helpful suggestions of Dr.B. Pasamanick is thankfully acknowledged. Our very special and sincere thanks go to Mr.S. England for his most valuable assistance, advice, and skillful help during many phases of this study.     

Effect of thymectomy on immune response in adult rats

Zusammenfassung Röntgenbestrahlung thymectomi-sierter Ratten ergab eine abgeschwachte Immunreaktion. Für eine Immunreaktion adulter Tiere scheint jedoch der Thymus nicht notwendig zu sein. In Abhängigkeit von Zeit und Alter der Tiere zeigten sich Unterschiede in der Stärke der Immunreaktion.     

Cloning and characterization of the cDNAs for human and rat corticotropin releasing factor-binding proteins.

Corticotropin-releasing factor (CRF), is a potent stimulator of synthesis and secretion of preopiomelanocortin-derived peptides. Although CRF concentrations in the human peripheral circulation are normally low, they increase throughout pregnancy and fall rapidly after parturition. Maternal plasma CRF probably originates from the placenta, which responds to the bioactive peptide and produces the peptide and its messenger RNA. Even though CRF concentrations in late gestational maternal plasma are similar to those in rat hypothalamic portal blood and to those that can stimulate release of adrenocorticotropic hormone (ACTH) in vitro, maternal plasma ACTH concentrations increase only slightly with advancing gestation and remain within the normal range. Several groups have now reported the existence of a CRF-binding protein in human plasma which inactivates CRF and which has been proposed to prevent inappropriate pituitary-adrenal stimulation in pregnancy. The binding protein was recently purified from human plasma. We have now isolated and partially sequenced the binding protein, allowing us to clone and characterize its complementary DNA from human liver and rat brain. Expression of the cDNAs for human and rat binding protein in COS7 cells showed that these proteins bind CRF with the same affinity as the native human protein. Both rat and human recombinant binding proteins inhibit CRF binding to a CRF antibody and inhibit CRF-induced ACTH release by pituitary cells in vitro.     

Nonresponse of native cottonwood trees to water additions during summer drought

Studies have demonstrated that some riparian trees may switch their reliance on surface soil water (unsaturated or vadose zone) to groundwater (saturated zone) sources during the growing season in association with changes in moisture availability. A closely related question is: How do these trees respond to pulse increases in water availability in previously dry zones? We tested the whole-tree physiological response of 6 natural Populus genotypes to water additions during the peak of summer drought in northern Utah, USA. We found clear evidence that trees were insensitive to water additions to the surface soil that were twice the magnitude of whole-tree transpiration rates. Our results suggest that some cottonwoods may have little immediate transpiration or leaf conductance response to pulse soil moisture increases. This lack of response may be related to a water-use strategy associated with regional climate patterns (i.e., genetic or environmental programming), cavitation recovery, or other physical determinants of water use such as depth to groundwater. Our data suggest that it is important to consider potential nonresponsiveness to changes in soil water availability when evaluating the impact of climate change on these important and productive ecosystems.     

First records of the Glacuous-winged Gull in Utah

First occurrences of the Glaucous-winged Gull ( Larus glaucescens ), and hybrids between it and the Western ( L. occidentalis ) and Herring Gull ( L. argentatus ), in Utah are documented. Sightings of 14 individuals over two winters (1984-86) may represent an inland expansion of the winter range of this species.