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Featured researches published by J. E. Oldfield.


Environmental Bioindicators | 2009

Selenium and mercury interactions with emphasis on fish tissue.

Spencer A. Peterson; Nicholas V.C. Ralston; P. D. Whanger; J. E. Oldfield; Wayne D. Mosher

This review addresses the effects of mercury (Hg) in fish as it relates to the health of the fish themselves as well as potential risks of toxicity in wildlife and humans that consume fish. In particular, it addresses selenium (Se) as a bioindicator of susceptibility to harmful effects of Hg exposures and evaluates how Se moderates the toxic effects of Hg in a variety of test animals, emphasizing the importance of these potential effects in fish. A major conclusion of this review is that Hg toxicity risks to animal life cannot be accurately assessed without considering the moderating effects of Se. Therefore, Se:Hg molar ratios and their mathematical inverse are important factors that need to be considered when assessing risks from Hg exposures because exposures are related directly to toxicity outcome. In addition, actual measurement of both beneficial nutrients (e.g., Se, omega-3 fatty acids) and contaminants (e.g., Hg, polychlorinated biphenyls [PCB]) in fish tissue, rather than gross associations betw...


General and Comparative Endocrinology | 1987

Apparent role of melatonin and prolactin in initiating winter fur growth in mink.

Jack Rose; J. E. Oldfield; Fredrick Stormshak

A study was conducted to determine the effects of exogenous melatonin and bromocriptine (CB-154), an inhibitor of prolactin synthesis and secretion, on the induction of winter fur growth in mink. Melatonin (10 and 120 mg) was administered to mink (N = 5/group) via silastic implants inserted sc over the scapular area during the last week of June 1985. Treatment of mink (N = 5) with CB-154 alone or in combination with 10 mg melatonin (N = 5) consisted of daily sc injections of 2 mg of the drug in sterile saline from June 25 through July 30. Control animals (N = 5) did not receive injections of vehicle or sham implants. Administration of CB-154 alone or in combination with 10 mg melatonin, as well as 120 mg melatonin alone, initiated growth of the winter fur significantly earlier than that of controls or mink treated with 10 mg melatonin (P less than 0.05). These data suggest that inhibition of prolactin secretion by melatonin is requisite for induction of molt of summer fur and growth of winter fur of mink.


Experimental Biology and Medicine | 1960

Selenium and vit. E as related to growth and white muscle disease in lambs.

J. E. Oldfield; O. H. Muth; J. R. Schubert

Summary 1) Selenium, given pre-natally per os to ewes or post-natally by injection to lambs, prevented WMD and resulted in increased growth of lambs as compared to untreated controls. 2) Growth response to selenium fed pre-natally was greater than that to selenium injected post-natally. 3) Massive doses of Vit. E at birth protected lambs from WMD, but did not result in improved growth. 4) Evidence suggests an essential role for selenium in supporting growth of lambs.


Journal of Pineal Research | 1985

The effects of photoperiod and melatonin on serum prolactin levels of mink during the autumn molt

Jack Rose; Fredrick Stormshak; J. E. Oldfield; John Adair

An experiment was conducted to determine the effects of a reduced daily photoperiod and exogenous melatonin on serum prolactin levels of mink during the autumn molt and growth of the winter pelage. During the last week of June, adult standard dark female mink (Mustela vison) were exposed to natural changes in daylength (controls), a reduced photoperiod of 6 h light: 18 h dark (6L: 18D) or exposure to natural changes in daylength and treated with melatonin (10 mg) in a Silastic implant inserted subcutaneously over the scapular area. Beginning July 2, and continuing through October 22, blood samples were collected at nine biweekly intervals, and serum prolactin concentrations were quantified by a heterologous double antibody radioimmunoassay. Both reduced photoperiod and exogenous melatonin caused serum prolactin levels to decline rapidly after mid‐July, resulting in concentrations that were significantly lower than those of controls 6 to 8 wk earlier. These data suggest that growth of the winter pelage of mink is strongly associated with declining prolactin levels. It appears that part of the photoperiodic‐induced effects on fur growth of the mink are mediated through melatonin and its effects on prolactin synthesis and/or secretion.


Molecular and Cellular Endocrinology | 1983

Prolactin binding sites in the uterus of the mink

Jack Rose; Fredrick Stormshak; John Adair; J. E. Oldfield

The present study was conducted to determine if specific binding sites for prolactin (PRL) are present in the uterus of the mink. Uteri of anestrous mink were homogenized and subjected to differential centrifugation into three particulate fractions, 1500, 15 000 and 50 000 X g. Binding of [125I]oPRL to membranes in an aliquot (200-400 micrograms protein) of the 50 000 X g particulate fraction was quantified. Time and temperature for optimal binding were 18 h at 25 degrees C. Scatchard plot analysis revealed a single set of binding sites for PRL with a Kd of 8.25 X 10(-11) +/- 0.68 M. The maximum amount of [125I]oPRL bound was 28 fmoles/mg protein. Prolactin binding sites were detected in both the uterus and kidney of mink, but not in skeletal muscle, spleen, diaphragm or lung. These data indicate that uterine cell membranes of the mink contain sites that bind prolactin with high affinity.


Archive | 2006

Selenium: A historical perspective

J. E. Oldfield

The path followed in the biochemistry of selenium has taken some sharp turns during its development. At first, feared as a poisoner of livestock and later impugned as a carcinogen, selenium has about-faced and is now recognized as an essential micronutrient with anti-carcinogenic properties. While early studies on selenium have focused on the role of this trace element in animal physiology and studies with microorganisms, the field has matured to employ molecular biology to explain and employ the protective effects of selenium against a number of human maladies, including cancer and heart disease. The emphasis of this chapter is an examination of selenium’s early history as a toxin, its later recognition as an essential micronutrient in the diet of mammals and its impact in the livestock industry that provided the foundations for the vast amount of the current basic and health research on this fascinating element.


Biological Trace Element Research | 1989

Selenium in animal nutrition: The Oregon and San Joaquin Valley (California) experiences—Examples of correctable deficiencies in livestock

J. E. Oldfield

White muscle disease and other selenium deficiency syndromes, once extremely common in young calves and lambs in Oregon, especially in the areas of volcanic origin east of the Cascade mountain range, prompted extensive investigations in the Oregon Agricultural Experiment Station that resulted in the implementation of large-scale selenium supplementation programs. Although selenium deficiency in livestock is consequently now rare in Oregon, selenium-deficient soils and attendant selenium deficiency conditions have been reported near the Kesterson Wildlife Refuge in the Northern part of the San Joaquin Valley, California, where, paradoxically, selenium toxicity in wildfowl, nesting near evaporation ponds, occurred and attracted wide attention. This review cites studies which explain why there is no evidence of selenium toxicity in livestock, but some selenium deficiency on the east side of the San Joaquin Valley. They also show that there is no threat to the food supply owing to excessive selenium in this area and that the consumption of meat and milk from the herds would not exceed the safe range of selenium for humans.


Experimental Biology and Medicine | 1960

Enhanced 5-nucleotidase activity associated with white muscle disease.

J. R. Schubert; O. H. Muth; J. E. Oldfield; L. F. Remmert

Summary Suitable conditions for assay for 5-nucleotidase activity in lamb skeletal muscle tissue are described. The activity of this enzyme was significantly greater in tissues from lambs affected by white muscle disease than in tissues from normal lambs. The authors acknowledge efficient technical assistance of Pauline Fleetwood.


Experimental Biology and Medicine | 1956

Identification of Cystine Calculi in Mink

J. E. Oldfield; Paul H. Allen; John Adair

Summary One hundred forty small (0.3 to 3.1 mm dia.) calculi were obtained from the bladder of a male mink on autopsy. Both qualitative and quantitative analyses of these stones indicated that they were almost entirely composed of cystine.


Experimental Biology and Medicine | 1969

The role of selenium in the placental transfer of vitamin E in the rat.

P. R. Cheeke; R. C. Bull; J. E. Oldfield

Summary Transfer of tritium-labeled α-to-copherol across the placental membrane was significantly lower (p<0.005) in rats receiving dietary selenium supplementation than in a selenium- and vitamin E-deficient group. Approximately equal fetal uptake of radioactivity was observed in groups receiving either supplementary selenium or vitamin E, while the lowest placental transfer occurred in rats receiving coincidental dietary supplementation with both selenium and vitamin E. Whether these differences in transfer of α-to-copherol to the fetuses relate to a sparing effect of selenium for vitamin E in the fetal tissue, or are due to variations in the amount of maternal tissue retention of the administered dose, thus limiting the amount available for fetal uptake, remains to be determined.

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P. H. Weswig

Oregon State University

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O. H. Muth

Oregon State University

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John Adair

Oregon State University

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Jack Rose

Oregon State University

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F. M. Stout

Oregon State University

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D. P. Moore

Oregon State University

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