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Biomedical subjects

C Christensen

Publications and source records attributed to C Christensen.

At least 91 records · Page 5Linked to original sources
PubMed1983

Induction of porcine uterine estrogen sulfotransferase activity by progesterone.

Studies have been carried out which were designed to examine the hormonal requirement for the appearance of estrogen sulfotransferase activity in porcine uteri. Mature, ovariectomized (OVX) gilts were housed for 3 weeks before being treated with various regimens of estradiol-17 beta (E2) and progesterone (P). Uteri were then removed, minced, incubated for 2 h with [3H] E2 (10(-8) M) and Na2 35SO4 (10(-4) M) and the labeled metabolic products were extracted and analyzed. Endometrial samples were also taken for the determination of E2 and P cytoplasmic and nuclear receptors (R). It was found that 4 daily injections of 250 micrograms of E2 was sufficient to bring plasma E2 concentrations to that representative of a normal estrous cycle (approx. 30 pg/ml) and to induce cytoplasmic PR to high levels (7000--19000 fmol/mg DNA). Estrogen sulfotransferase activity, which was negligible in OVX and E2-treated pigs, increased to near normal secretory levels (4 pmol product/h per 0.4 g tissue) only in pigs primed with E2 and subsequently treated with E2 and P (25--250 mg/day, 3 days). This treatment also brought about the translocation of PR to the nuclear compartment. The steroid alcohol sulfotransferase activity in these tissues decreased upon ovariectomy and remained unaffected by the hormone treatments. Endometria from treated and untreated pigs were cultured for a period up to 7 days. During this time E2 (10(-8) M) induced and/or maintained PR and P (10(-6) M) was shown to stimulate estrogen sulfurylation concomitant with the translocation of PR to the nucleus. These studies have demonstrated that, in OVX pigs and endometrial cultures, P stimulated uterine estrogen sulfotransferase activity to a level normally found in secretory uteri. In order for P to bring about elevated levels of estrogen sulfurylation it was necessary that the endometrium contain adequate concentrations of cytoplasmic PR (which required E2 priming of the system) and the P receptor complex must display nuclear translocation.

Animals↗
PubMed1982

Renal contribution to plasma catecholamines--effect of age.

In 18 subjects undergoing diagnostic cardiac catheterization renal venous noradrenaline during rest (296 +/- 26 ng/l, mean +/- SE) was significantly increased over arterial noradrenaline concentrations (250 +/- 20 ng/l, P less than 0.01) while, in contrast, the arterial adrenaline level (79 +/- 9 ng/l) was higher than the renal venous (41 +/- 4 ng/l, P less than 0.001). Age correlated positively with both renal venous noradrenaline (r = 0.56) and the renal venous-arterial difference of noradrenaline (r = 0.56), and negatively with arterial (r = -0.52) and renal venous adrenaline (r = -0.48). According to our data, a net renal venous secretion of noradrenaline and at the same time an uptake of adrenaline from the renal circulation take place at an extent that may influence plasma concentrations of both. With increasing age renal uptake of plasma adrenaline seems to decrease and net release of noradrenaline to increase. The fall in plasma adrenaline may be due to age-dependent involution of the adrenal medulla. In studies of plasma adrenaline concentrations and of the renal handling of plasma catecholamines the influence of age must be taken into account.

Adolescent↗
PubMed1978

Nuclear and cytosolic estrogen receptor in gilt endometrium throughout the estrous cycle.

The levels of nuclear and uncharged cytoplasmic estrogen receptors were determined in gilt endometrium throughout the estrous cycle. Nuclear estrogen receptor was found to reach its highest level of 1.3 (range, 1.0-1.5) pmol/mg DNA on day 1 of the cycle just before ovulation (day 2), after which the values dropped sharply to 0.3 (range, 0.1-0.4) pmol/mg DNA. This level of nuclear receptor was consistently found through day 9. Between days 9-14, the estrogen receptor present in the nucleus decreased to zero, where it remained until the return of estrus (day 1). The dissociation constant (Kd +/- SD) for the nuclear estrogen receptor was 1.6 (+/- 1.4) x 10(-9) M. Initially, the nuclear estrogen receptor peak at day 1 was preceded by elevation (0.04-0.05 pmol/mg DNA) in cytoplasmic receptor at day 19, which declined when the receptor appeared in the nucleus. There was an even larger peak (range of maximal values, 0.07-0.26 pmol/mg DNA) of uncharged receptor in the cytosol near day 5. Throughout the rest of the cycle the values ranged from 0.01-0.03 pmol/mg DNA. Kd( +/- SD) for the cytoplasmic estrogen receptor was 2.4 (+/- 1.5) x 10(-9) M. The fluctuations of these two pools of endometrial estrogen receptor are discussed in relation to the previously observed cyclic variations in porcine uterine oxidation and sulfurylation of 17 beta-estradiol (Pack and Brooks, Endocrinology 95: 1680, 1974).

Animals↗
PubMed1967

Come to the fair.

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Central Supply, Hospital↗
PubMedDate not supplied

Plasmid stabilization of an Escherichia coli culture through cycling.

The problem of plasmid instability of fermentations that involve plasmid-bearing recombinant organisms is dealt with in this work. Previous theoretical work demonstrated that under certain conditions (where plasmid-bearing species are slower in responding to changes in the fermentation environment than the wild species) the washout of the plasmid-bearing species can be prevented. In the sequel, Weber and San showed that cycling the dilution rate can delay the washout of plasmid-bearing species for a plasmid-bearing Escherichia coli culture. This work shows that it is indeed possible to secure the presence of the plasmid-bearing species at all times through appropriate cycling.

Ampicillin↗