Autoantibodies to c-myc protein: elevated levels in patients with African Burkitt's lymphoma and normal Ghanians.

Sera from U.S. patients with SLE, RA, and various malignancies, clinically normal individuals with sero-activity to HIV, AIDS, and from pregnant women were tested for the presence of anti-c-myc antibodies. In an ELISA using recombinant human c-myc protein as the antigen, no difference in mean antibody titer was generally detected in these sera when compared to normal controls. Only three malignancy sera (two myeloid leukemia and only one lymphoma) and two patients with AIDS-related lymphoma exhibited exceedingly higher levels of anti-c-myc antibody. However, significantly elevated anti-c-myc antibody levels were found among 20 patients with African Burkitt's lymphoma (Ghana) and 20 normal Ghanians, thus apparently reflecting an autoimmune phenomenon prevalent in the endemic region. These findings indicated that elevated levels of anti-c-myc antibodies are not a general characteristic of patients with diseases that have been associated with increased expression of c-myc.

Acute and chronic effects of diethylstilbestrol on serum levels of alpha melanocyte stimulating hormone and prolactin in the hamster.

Continuous exposure to diethylstilbestrol (DES) induces renal tumors in male hamsters. The tumor formation is preceded by an increase in pituitary weight and elevation of the pituitary hormones-alpha melanocyte stimulating hormone (aMSH) and prolactin (Pr1). A decline in Pr1 (to normal levels) but not aMSH then accompanies the development of tumors and the enlargement of the intermediate lobe of the pituitary. Hypophysectomy, castration and thymectomy reduced serum levels of aMSH. DES administered for one week increased the serum levels of both hormones in normal and castrated animals, but not in hypophysectomized hamsters.

Immunocytochemical localization of glucocorticoid receptors in cells, cytoplasts, and nucleoplasts.

A monoclonal antibody has been used to assess the intracellular localization of the glucocorticoid receptor in rodent L-929 fibroblasts and GH3 pituitary tumor cells. Whole cells from both cell lines showed immunoreactivity in the cytoplasm and nucleus. However, when cytoplasts and nucleoplasts of these cells were examined, only L-cells showed strong antibody binding in both fractions; in contrast, GH3 cells exhibited nuclear staining and slight cytoplasmic staining. These results are discussed in terms of the current findings regarding the intracellular location of steroid hormone receptors.

Reticulocyte lipoxygenase, ingensin, and ATP-dependent proteolysis.

Lipoxygenase purified from rabbit reticulocyte lysate has a molecular mass of 68 kDa on SDS gel and a pI of 5.97. Lipoxygenase is inhibited by nordihydroguaiaretic acid (NDGA), 3-amino-1-(m-(trifluoromethyl)phenyl)-2-pyrazoline (BW755C), 5,8,11,14-eicosatetraynoic acid (ETYA), salicylhydroxamate (SHAM) or hemin. Metal ions or nucleotides do not affect its activity. The addition of certain of these inhibitors to the reticulocyte extract also inhibited the ATP-dependent proteolysis of casein, one of the distinct characteristics of reticulocytes. No clear correlation between lipoxygenase activity and ATP-dependent proteolysis could be detected. Hemin and NDGA inhibited both processes, but the concentrations necessary for inhibition were quite different. SHAM completely inhibited lipoxygenase, but not proteolysis. o-Phenanthroline inhibited ATP-dependent proteolysis, but had no effect on lipoxygenase activity. We have also purified a high-molecular-mass protease, ingensin, from reticulocyte extract. This protease accounted for more than 90% of the casein-degrading activity in reticulocyte extract. NDGA inhibited ingensin at the same concentrations required for inhibition of ATP-dependent proteolysis. These results suggest that lipoxygenase is not indispensable for the ATP-dependent proteolysis and the novel high-molecular-mass protease, ingensin, may be involved in the process.

A cytosolic binding protein for 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in the uterus and deciduoma of rats.

The cytosol fraction of the uterus of proestrous rats and of deciduoma specifically binds 3H-2,3,7,8-tetrachlorodibenzo-p-dioxin (3H-TCDD). The 3H-TCDD binding protein has a sedimentation coefficient of 9 S in low ionic 10-40% sucrose density gradients. The binding of 3H-TCDD in the 9 S region is abolished by a 500-fold molar excess of unlabeled benzo[a]pyrene, 3-methylcholanthrene or by a 100-fold molar excess of unlabeled TCDD. Incubation of the binding protein with TCDD in amounts in excess of 500 nM causes aggregation of the TCDD binding protein. Neither estradiol, progesterone, testosterone, dihydrotestosterone nor cortisol competed with TCDD in binding to this 9 S protein. The decidual tissue contains two binding components for TCDD as shown by Scatchard analysis. One of the components has a high affinity for TCDD (Kd = 1.68 nM) and is saturable. The number of binding sites is about 75 fmol/mg protein. The TCDD binding protein eluted through a DEAE-cellulose column using a gradient of 0.25 M KCl. The binding of estradiol and progesterone to their respective receptors was not affected by TCDD or by other polycyclic aromatic hydrocarbons as shown by sucrose density gradients and by microtiter competition assays. These results suggest that TCDD acts by binding to its own receptor system in the target tissue and not by competing with estrogen or progesterone for binding to their receptors. The possible role of the receptor in teratogenesis is discussed.

Phosphorylation of placental membrane proteins by a calcium- and phospholipid-dependent protein kinase.

The 30 000 g precipitate of homogenized rat placenta was incubated with 32P-adenosine triphosphate (ATP); several endogenous proteins were specifically phosphorylated in the presence of 0.5 mM calcium and phosphatidylserine (105K protein at mid pregnancy, and 78K protein at the latter part of pregnancy). The calcium- and phospholipid-dependent protein kinase activity in the 30 000 g precipitate was six times greater than the activity in the supernatant fraction. The total protein kinase C activity in the precipitate was considerably greater at the end of pregnancy than it was at mid pregnancy. Diethylaminoethyl cellulose-purified membrane-bound protein kinase C was slightly inhibited by inhibitors of lipoxygenase, NDGA or ETYA, but not by SHAM or BW755C. Haemin and polylysine strongly inhibited this activity.

Characterization and control of cytosolic binding proteins for 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in the rat lung.

The presence of a high-affinity, low-capacity 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) binding complex was demonstrated in cytosol from rat lung. When analyzed by sucrose density gradient centrifugation, the 3H-TCDD binding complex sedimented at 8-9 S and 6.5 S in low and high ionic media, respectively. The apparent dissociation constant (Kd) of the 3H-TCDD binding complex was determined to be 2.9 nM and the number of binding sites (Bmax) was approximately equal to 69 fmol/mg of cytosolic protein. The entity was sensitive to heat and to proteases but not to DNAse or RNAse, indicating that it was a protein. An excess of unlabeled TCDD, benzo[a]pyrene, 3-methylcholanthrene, 7,12-dimethylbenzo[a]anthracene and 9-hydroxy ellipticine all competed with 3H-TCDD for binding. A single injection of either benzo[a]pyrene (20 mg/kg body weight) or 9-hydroxy ellipticine (20 mg/kg body weight) had different effects on the concentrations of 3H-TCDD binding proteins in the lung but none of the chemicals had a significant effect on the synthesis of surfactant as assayed by total phospholipid content, 72 h after the injection.

Survival from sepsis. The significance of altered protein metabolism regulated by proteolysis inducing factor, the circulating cleavage product of interleukin-1.

Amino acid (AA) arterial blood plasma concentrations, K1 (peripheral production + infusion rates), and central plasma clearance rates (K1 divided by arterial concentration) (CPCR-AA) were measured in 70 seriously septic patients. All of these people were in the "hyperdynamic" state at the time of observation. Thirty-seven recovered and 33 died. In addition, 10 noninfected, nontraumatized patients about to undergo laparotomy were studied. In 31 patients receiving parenteral alimentation, CPCR-AA was 326 +/- 38 in survivors and 160 +/- 17 ml/M2/min in the deaths (p less than 0.005). In 58 patients studied, while fasted with no intravenous amino acid infusion, values for CPCR-AA were: survivors 202 +/- 22 (28) and deaths 112 +/- 16 (30) ml/M2/min (p less than 0.002). The CPCR-AA in 10 noninfected patients was only 68 +/- 11 ml/M2/min. CPCR-AA in 19 patients correlated with hepatic protein synthetic rates in liver biopsies obtained simultaneously (r = 0.658, p less than 0.01), which shows that CPCR-AA is an indicator of visceral protein synthesis. To study the regulation of amino acid metabolism by synthesis. To study the regulation of amino acid metabolism by proteolysis inducing factor (PIF), the proteolysis inducing activity (PIA) of the plasma fraction (0-50,000 D) was measured 55 times in conjunction with metabolic studies. No significant differences existed in PIA between survivors and deaths. However, in those patients who recovered, PIA was significantly correlated to both peripheral amino acid production (r = 0.773, p less than 0.001) and to CPCR-AA (r = 0.721, p less than 0.001). This observation demonstrates the presence of one or more circulating agents affecting amino acid flux. PIA measured simultaneously in vivo correlated with in vitro protein synthetic rate in incubated liver biopsies (r = 0.653, p less than 0.01). PIF (4,000 D), isolated by chromatography, in patients without amino acid infusion was 35 +/- 3% in survivors and 33 +/- 6% in deaths (N.S.) and only 9 +/- 3% over control in noninfected patients. In patients who recovered, PIF titre was strongly correlated with peripheral amino acid production (r = 0.798, p less than 0.001) and with CPCR-AA (r = 0.835, p less than 0.001). However, values for patients who later died were significantly less for a given PIF titre. Thus, it is concluded that survival from sepsis is, in part, dependent on a significantly elevated CPCR-AA and hepatic protein synthesis, both of which appear to be related to the blood plasma PIF titre.

The role of transferrin and ferritin in the fetal-maternal-placental unit.

The rapidly growing human fetus requires a large supply of iron, which is obtained from the iron stores of the mother. Iron is transported from mother to fetus against a concentration gradient. The placenta plays a key role in regulating the supply of iron in the fetus. In both anemic and nonanemic patients serum ferritin levels decreased and total iron-binding capacity increased as gestation progressed. The total iron-binding capacity is higher in maternal than in umbilical cord blood at delivery; this suggests that little or no ferritin or transferrin is transferred from mother to fetus. Mother and fetus appear to have independent systems controlling iron metabolism. Transferrin was localized on the site facing the intervillous space, on the surface of the microvilli of the syncytiotrophoblasts. The removal of transferrin from the surface of the trophoblast by thiocyanate and its rebinding were demonstrated. Ferritin was shown to be present in all layers of the trophoblast and especially in the syncytiotrophoblast.

A metabolite of riboflavin binds to the 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) receptor.

A cytosolic receptor to which TCDD binds with high affinity has been reported in a number of rodent tissues, but the endogenous/natural ligand is not known. However, lumichrome, a metabolite of riboflavin, competed with 3H-TCDD for binding to the cytosolic receptor. Neither riboflavin nor riboflavin-5-phosphate competed for binding to the TCDD receptor in rat liver cytosol. Lumichrome is the first known endogenous chemical in the rat to exhibit affinity for the TCDD receptor.

Control of 2,3,7,8-tetrachlorodibenzo-p-dioxin binding protein(s) in the hamster kidney.

Hamster renal cytosol binds [3H]-2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) with high specificity. Sucrose density gradient centrifugation revealed two binding entities- one with a low sedimentation coefficient of 4-5 S which was displaced by neither TCDD nor other polycyclic aromatic hydrocarbons (PAHs) and another with a high sedimentation coefficient of 7-8 S which was displaced by TCDD, benzo[a]pyrene (BP), 2-methylcholanthrene (MC), and 7,12-dimethylbenzo[a]anthracene (DMBA) but not by estradiol (E), progesterone (P), cortisol (F), testosterone (T), 5 alpha-dihydrotestosterone (DHT), or methyltrienolone (R-1881), a synthetic androgen. Cytosol from intact male hamsters showed maximum binding of labelled TCDD to the 7-8 S binding site. Castration or hypophysectomy reduced this binding. Pretreatment with DMBA increased binding, whereas diethylstilbestrol (DES) decreased binding. Sex difference was observed in the binding capacity of renal cytosol. This is the first report of endocrine control over TCDD binding and its modulation by other PAHs and steroids.

The uptake of [3H]estradiol by mouse preimplantation embryos in vitro.

Mouse blastocysts collected on day 4 were cultured for 20 hours in media containing various concentrations of [3H]estradiol with/without 10(-6) M unlabelled estradiol. There was a significant reduction in the radioactivity of embryos cultured at 4 degrees C compared with that of embryos cultured at 37 degrees C. The radioactivity of embryos kept in the washing solution after washing was slight lower but showed no significant difference when it was compared with that of embryos not kept in this way. There was no significant difference between the radioactivity of embryos cultured in 2 X 10(-8) M [3H]estradiol and that of embryos cultured in 2 X 10(-8)M [3H]estradiol plus 10(-6)M non-labelled estradiol. Furthermore the radioactivity of embryos incubated in 2.5 X 10(-8)M [3H]estradiol is more than twice that of embryos incubated in 10(-8)M [3H]estradiol. These results demonstrate that preimplantation mouse embryos are capable of uptake and retaining of estrogen and that the mechanism of uptake is neither selective nor receptor mediated.

Effect of estradiol, prostaglandin E2 and prostaglandin F2 alpha on incorporation of [3H]uridine by preimplantation mouse embryos in vitro.

To determine whether estrogen and prostaglandins have a direct effect on the preimplantation embryo, the effect of these compounds added to mouse embryos in vitro was examined. Embryos were incubated in culture media containing [3H]uridine with or without the substances to be tested. The addition of estradiol (10(-8)M) and prostaglandin F2 alpha (1 microgram/ml or 10 micrograms/ml) stimulated the incorporation of uridine into RNA. However, prostaglandin E2 at a concentration of 10 micrograms/ml had an inhibitory effect. These findings indicate that estradiol and prostaglandin F2 alpha may have, in addition to an indirect effect mediated by uterine factors, a direct effect on embryonic growth that activates embryos to implant.

Proteins synthesized by the rat endometrium during early pregnancy.

Rat uteri from animals at pro-oestrus and Days 3-6 of pregnancy were incubated in vitro in the presence of [35S]methionine. Labelled endometrial proteins from each sample were separated by two-dimensional gel electrophoresis and resolved by fluorography. A group of 16 proteins that are synthesized only on specific days was defined. On Day 5, the day of embryo implantation, only 3 of these 16 proteins were synthesized. Of 8 proteins synthesized on both Days 3 and 6, 5 were also found on Day 4, but only 1 was synthesized on Day 5. These results demonstrate that during the interval in which implantation is initiated, no unique proteins are produced but several protein species are no longer synthesized by the endometrium.

Effect of indomethacin and prostaglandin F2 alpha on incorporation of [3H]uridine by preimplantation mouse embryo.

Indomethacin, an inhibitor of prostaglandin synthesis, depressed the incorporation of [3H]uridine into RNA of mouse preimplantation embryo, when it was injected in vivo or added in vitro. In contrast, prostaglandin F2 alpha decreased the inhibitory effect of indomethacin, when it was added in vitro with indomethacin. The results of these experiments suggest that prostaglandin F2 alpha plays a role in the process of implantation and that the mouse preimplantation embryo may be able to produce prostaglandin F2 alpha.

Melanocyte-stimulating hormone and prolactin secretion in cell culture of estrogen-induced pituitary tumors in the hamster.

Pituitary cells from hamsters bearing diethylstilbestrol induced renal adenocarcinomas were cultured in vitro. Dispersed cells in plastic dishes were viable for up to two weeks in Dulbecco's modified Eagle's medium supplemented with 17.5% of 6:1 horse serum to fetal calf serum. The secretion of alpha-melanocyte stimulating hormone and prolactin into the medium were measured by radioimmunoassay. The concentrations of both were elevated by day 3 in the medium from the hyperplastic pituitaries obtained from the estrogen treated, tumor bearing hamsters. Neither DES (10(-8)M) nor tamoxifen (10(-7)M) influenced the secretion of either hormone and neither altered either cell number or DNA synthetic activity as measured by thymidine incorporation. The secretion of hormones and the growth of the pituitary cells were, however, decreased by charcoal treatment of the serum. The results suggest that the elevation of serum alpha-MSH and prolactin observed in DES implanted hamsters is due to pituitary secretion of the hormones but that DES probably does not act directly on the pituitary to control the secretion.

Muscle proteolysis induced by a circulating peptide in patients with sepsis or trauma.

Accelerated proteolysis of muscle is characteristic in patients with trauma or sepsis, but its cause is not well understood. Using rat muscle in vitro, we developed a bioassay to compare the proteolytic activity of plasma from 50 patients with trauma or sepsis with that of plasma from 14 normal volunteers and from 15 patients who had undergone "clean" elective surgical procedures. The mean proteolytic activity in the plasma of patients with trauma or sepsis was found to be 190 +/- 8.0 per cent of the control value (rat muscle incubated in medium alone), whereas the activity in normal plasma was 124 +/- 4.5 per cent (P less than 0.001). The activity in the plasma of patients who had undergone elective surgery was slightly elevated at 142 +/- 2.5 per cent (P less than 0.005). In 25 of the patients with trauma or sepsis the rate of amino acid release from one leg was measured by subtracting the concentration of tyrosine plus phenylalanine in the femoral artery plasma from that in the femoral vein; this rate correlated well with the bioactivity of the plasma in the bioassay system (r = 0.67, P less than 0.001). By means of ultrafiltration and chromatography, the plasma factor inducing proteolysis was isolated and found to be a peptide, probably containing sialic acid, with a chain of 33 amino acids and a molecular weight of approximately 4274 daltons.

Further characterization of the dioxin receptor in the rat deciduoma.

The rat deciduoma cytosol contains a protein which binds radio-labeled dioxin and sediments as an 8-9 S entity on 10-40 per cent (w/v) sucrose density gradients. Incubation of cytosol with [3H]-TCDD at 37 degrees C for ten minutes shifted the sedimentation coefficient from 8-9 S to 4-5 S, whereas incubation of cytosol at room temperature for 30 minutes has no effect on the S value. At high concentrations of [3H]-TCDD the dioxin receptor complex tends to aggregate. Cytosol eluted with 0.25 M KCl from a DEAE cellulose column and complexed with [3H]-TCDD sedimented at 9S in low ionic strength buffer, but sedimented slower (5S) in the presence of 0.4 M KCl in the buffer. The effect of salt and temperature on the sedimentation behavior is compared with that of steroid receptors. The usage of DEAE cellulose column chromatography in purification of the receptor complex is also discussed.