The effects of polyamines on the immunogenicity of polynucleotides

Polyamines--putrescine, spermidine, and spermine--are small organic cations that are present in all living cells. Recent studies revealed that polyamines could provoke a left-handed Z-DNA conformation in poly(dA-dC).poly(dG-dT) and related alternating purine-pyrimidine sequences. In order to examine whether polyamine-induced Z-DNA conformation of poly(dA-dC).poly(dG-dT) is capable of eliciting anti-Z-DNA antibodies, we immunized rabbits with poly(dA-dC).poly(dG-dT) in the presence and absence of spermidine and spermine. Rabbits immunized with the polynucleotide alone produced antibodies reacting toward poly(dA-dC).poly(dG-dT) and heat-denatured calf thymus DNA (ssDNA). In contrast, immunization with poly(dA-dC).poly(dG-dT) complexed with spermidine or spermine produced antibodies reacting with Z-DNA in addition to those binding toward poly(dA-dC).poly(dG-dT) and ssDNA. Antibodies elicited by polynucleotide.polyamine complexes had no reactivity toward polyamines. Solution inhibition studies suggested that anti-poly(dA-dC).poly(dG-dT), anti-ssDNA and anti-Z-DNA antibodies are distinct populations that favor each one of these antigens. Our results suggest that natural polyamines are capable of altering the immunogenicity of polynucleotides by mechanisms involving the stabilization of Z-DNA conformation. This result may have implications in the recent findings of high levels of polyamines and anti-Z-DNA antibodies in the sera of lupus patients and autoimmune mice.

Effects of spherical and astigmatic defocus on acuity and contrast sensitivity: a comparison of three clinical charts

Two contrast sensitivity charts (Vistech and Pelli-Robson) have become available to the eye care practitioner. Their value as clinical tools for the assessment of visual function may be enhanced because of either an insensitivity to the effects of optical focus or a hypersensitivity to defocus. We compared the sensitivity to defocus of these charts to the traditional Snellen chart by examining the effect of up to +/- 5.00 D of spherical and astigmatic defocus on performance with each chart. In order to simulate the two types of clinical examination scenarios, tests were performed both with and without mydriatic/cycloplegic agents. The Pelli-Robson contrast sensitivity chart was very resistant to the effects of all types of optical defocus. As predicted, the high spatial frequencies on the Vistech chart were sensitive to defocus. However, although contrast sensitivities for the low frequencies were affected less, optical defocus produced significant decreases in low frequency Vistech contrast sensitivity. In addition, the Vistech chart was very insensitive to axis 180 blurring lenses. There was no indication that either contrast sensitivity chart was more sensitive to defocus than the standard Snellen chart.

Open versus closed nailing of femoral fractures in the polytrauma patient

Thirty-four patients with severe multiple injuries underwent either open or closed nailing of 35 femoral fractures. Open nailing was performed in 17 femurs and closed nailing in 18 femurs. The average abbreviated injury score was 27 in both the open group (range: 17-45) and closed group (range: 22-36). Soft tissue injuries were present in eight (47%) cases in the open group compared to three (16%) in the closed group. The treatment protocol was similar in both groups. Intramedullary nailing was delayed an average of 11 days in the closed group. This was significantly different than the open group where the average time to nailing was less than 24 hours (p less than 0.001). Reamed nails were used in all cases except for two in the closed group. The median time to fracture healing was 5.0 months in the open group and 4.1 months in the closed group, with an average follow-up of 18 months in both groups. Two cases required reoperation (one nonunion and one shortening at the fracture site). Both these cases were in the open group. There were no superficial or deep infections in either group. Closed reamed intramedullary nailing is recommended for treatment of diaphyseal femur fractures in patients with severe coexistent injuries. Open nailing should be reserved for cases in which an adequate reduction cannot be achieved by closed methods.

Acute plastic deformation of the ulna in a skeletally mature individual

Acute plastic deformation of a bone refers to traumatic bending or bowing without a detectable cortical defect. We present a case that is unusual in that bowing of the ulna occurred in a skeletally mature individual and was associated with injury to the distal radioulnar joint. In this patient, the symptoms were severe enough to warrant an ulnar osteotomy. The patient regained satisfactory function. Acute plastic deformity should be suspected whenever abnormal curvature of a long bone is noted, even in adults. If the distal radioulnar joint is dislocated, the deformation should be corrected as soon as possible to avoid permanent loss of forearm rotation.

Polyamine-induced B-DNA to Z-DNA conformational transition of a plasmid DNA with (dG-dC)n insert

We investigated the ability of natural polyamines putrescine, spermidine, and spermine to provoke a left-handed Z-DNA conformation in a recombinant plasmid (pDHg16) with a 23-base pair insert of (dG-dC)n.(dG-dC)n sequences. Using a monoclonal anti-Z-DNA antibody (Z22) and an enzyme-linked immunosorbent assay protocol, we found that spermidine and spermine were capable of converting pDHg16 to the Z-DNA form. The concentrations of spermidine and spermine at the midpoint of the B-DNA to Z-DNA transition were 280 and 5 microM, respectively, in buffer containing 50 mM NaCl, 1 mM sodium cacodylate, and 0.15 mM EDTA, pH 7.4. A plot of ln[Na+] versus ln [spermine4+], where [Na+] is the bulk NaCl concentration and [spermine4+] is the spermine concentration at the midpoint of the B-DNA to Z-DNA transition, gave a straight line with a slope of 1.2. Structural specificity was clearly evident in the efficacy of three spermidine homologs to induce the Z-DNA conformation in pDHg16. Putrescine and acetylspermidines had no effect on the conformation of the plasmid DNA up to a 3 mM concentration. Control experiments with the parental plasmid (pDPL6) showed no binding of the plasmid DNA with Z22. These results indicate that spermidine and spermine are capable of provoking the left-handed Z-DNA conformation in small blocks of (dG-dC)n sequences embedded in a right-handed B-DNA matrix. Since blocks of (dG-dC)n sequences are found in certain native DNAs, conformational alterations of these regions to the Z-DNA form in the presence of polyamines may have important gene regulatory effects.

Restoration of the DNA binding activity of estrogen receptor in MRL-lpr/lpr mice by a polyamine biosynthesis inhibitor

Diverse data link estrogen influences to both the frequency and severity of systemic lupus erythematosus in humans and to murine lupus. A fundamental mechanism of action of estrogen involves the interaction of the hormone with its receptor protein, which is then transformed into the DNA binding form. We measured the concentration of uterine estrogen receptor and its DNA binding in normal BALB/c mice, lupus-prone MRL-lpr/lpr mice, and MRL-lpr/lpr mice that had been treated with 1% difluoromethylornithine (DFMO). Uterine estrogen receptor levels in 20-week-old mice from the 3 groups were not significantly different. In contrast, DNA binding activity was significantly higher in BALB/c mice (mean +/- SD 775 +/- 100 fmoles/mg of DNA) than in untreated MRL-lpr/lpr mice (80 +/- 16 fmoles/mg of DNA) (P less than 0.001). Treatment with 1% DFMO was associated with an increase in uterine estrogen receptor DNA binding (1,100 +/- 218 fmoles/mg of DNA) in MRL-lpr/lpr mice (P less than 0.001). Polyamine levels were 2-6-fold higher in the uterine tissues of untreated MRL-lpr/lpr mice compared with the BALB/c mice and were significantly reduced by DFMO treatment. Our results link uterine polyamine production to a dysfunction of the estrogen receptors in MRL-lpr/lpr mice. Reduction of the polyamine level by the irreversible inhibition of ornithine decarboxylase with DFMO restores estrogen receptor function.

Macronutrient intake and utilization by rats: interactions with type I adrenocorticoid receptor stimulation

Corticosterone-free (adrenalectomized, ADX) and intact rats were offered experimentally compounded diets in which 65% of available calories were supplied by a single macronutrient (single-diet study). ADX impaired the intake, weight gain (especially as body fat), and efficient utilization of high-protein and high-fat diets. In contrast, no behavioral, metabolic, or compositional changes could be found among ADX rats maintained on a diet high in carbohydrates. When ADX rats were given separate sources of macronutrients (self-selection study) they did not self-select a high-carbohydrate diet. Instead, they displayed a strong fat avoidance and a relative increase in protein intake, the macronutrient they utilize least efficiently. Separate groups of ADX animals were continuously infused with 25 or 125 micrograms.kg-1.day-1 aldosterone, a specific type I adrenocorticoid receptor agonist. Type I receptor stimulation eliminated all ADX-related deficiencies found in the single-diet and self-selection studies: caloric intake, feeding efficiency, carcass composition, and macronutrient preferences were restored to or beyond the corresponding values of adrenal-intact rats. The normal rat's ability to ingest and utilize macronutrients optimally is dependent on corticosterone's stimulation of type I receptors.

Potassium supplementation in the treatment of idiopathic postural hypotension

We studied the effects of potassium supplementation (60 mmol/day) and matching placebo on the postural blood-pressure fall in ten elderly patients with symptomatic idiopathic postural hypotension in a double-blind, randomized cross-over trial. There was a significant decrease in the orthostatic fall in systolic blood pressure (SBP 33 +/- 5 mmHg to 16 +/- 9 mmHg, p less than 0.01) and in supine SBP (162 +/- 7 to 150 +/- 7 mmHg, p less than 0.01) between placebo and potassium phases. Supine diastolic and erect blood pressures were unchanged, though pulse rate showed a greater orthostatic increase (7 +/- 3 beats/min to 14 +/- 2 beats/min, p less than 0.05) following potassium therapy. No significant changes were seen in intracellular electrolytes, plasma renin activity, aldosterone levels or body weight. Seven patients reported symptomatic improvement with potassium, but none during the placebo phase. Potassium therapy was well tolerated and may be a successful and safe method of treating idiopathic postural hypotension.

GABAB agonists modulate a transient potassium current in cultured mammalian hippocampal neurons

Depolarization of voltage-clamped cultured rat hippocampal neurons from holding potentials more negative than -60 mV produced a transient outward current with the characteristics of an A-current: it was 50% inactivated at a holding potential of -85 mV and blocked by 4-aminopyridine (1 mM). In the presence of GABA or baclofen (50-200 microM), with or without bicuculline, inactivation of this current was shifted to more positive potentials so that there was little inactivation at -70 mV. Activation of the A-current was also shifted to more positive potentials by these agonists, but the voltage dependence of activation of the sodium current was unaffected. If A-currents with similar properties can influence the time course of action potentials in presynaptic terminals. GABAB agonists could make action potentials briefer by potentiating the A-current and hence depress transmitter release.

Regulation of polyamine biosynthesis by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)

We have examined the effect of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on tissue polyamine concentrations in CD1 mice. Two days after a low dose treatment with TCDD, polyamine content of the liver and thymus of treated mice showed a 49-82% decrease, but that of spleen was not affected. Based on this finding, we examined the role of alterations in polyamine levels in the toxicity of TCDD. We administered the polyamine biosynthetic inhibitor difluoromethylornithine (DFMO) to animals treated with a toxic dose of TCDD. DFMO dramatically increased the toxicity of TCDD as measured by mortality, ascites and changes in organ weights. In addition, administration of the polyamine putrescine was able to reduce the toxicity of TCDD. These results suggest that a decrease in polyamine concentrations in critical organs may play an important role in the toxic effects of TCDD.

Gene expression in regenerating and acute-phase rat liver

The integration of growth and the acute-phase response is investigated by comparing the mRNA levels in rat liver during acute inflammation with those after partial hepatectomy. Northern analysis is carried out for the mRNAs for thiostatin, alpha 2-macroglobulin, alpha 1-antitrypsin, inter-alpha-trypsin inhibitor subunit 1, haptoglobin, ceruloplasmin, transferrin, vitamin D-binding protein, alpha 1-acid glycoprotein, beta-fibrinogen, apolipoproteins A-IV and E, albumin, transthyretin, alpha 2-HS-glycoprotein, retinol-binding protein, beta-tubulin, c-myc protooncogene, glyceraldehyde-3-phosphate dehydrogenase, phosphoenolpyruvate carboxykinase, ornithine transcarbamylase, and alcohol dehydrogenase. The acute-phase response dominates during the first 18 h. Changes in mRNA levels related to growth of the liver become important thereafter, and the capacity for an acute-phase response of plasma protein synthesis becomes greatly reduced. The early increase in the level of ceruloplasmin mRNA observed during inflammation is abolished during regeneration, and that of vitamin D-binding protein mRNA is converted into a decrease. The mRNAs levels of glyceraldehyde-3-phosphate dehydrogenase increase, and those for phosphoenolpyruvate carboxykinase decrease during regeneration. Ornithine transcarbamylase mRNA levels are found to exhibit negative acute-phase regulation. The pattern of transcriptional regulation is similar during inflammation and regeneration.

Plasma protein synthesis and secretion in the visceral yolk sac of the fetal rat: gene expression, protein synthesis and secretion

This report compares the relative levels of messenger RNA species coding for plasma proteins in rat visceral yolk sac and fetal liver from 12.5 days to 21.5 days gestation. Transthyretin, retinol-binding protein, transferrin and alpha 1-fetoprotein mRNAs were detected in both tissues, although relative levels were much higher in the yolk sac compared to fetal liver, in early gestation. Messenger RNA coding for the positive acute phase proteins thiostatin, fibrinogen, alpha 2-macroglobulin and alpha 1-antitrypsin were detected at a low but significant level in yolk sac, while the levels in fetal liver steadily increased from 16.5 days gestation and, with the exception of alpha 1-antitrypsin, reached levels higher than those found in adult liver just prior to birth. Albumin, inter-alpha 1-trypsin inhibitor, alpha 1-acid glycoprotein, haptoglobin, vitamin D-binding protein and ceruloplasmin messenger RNA levels were either very low or undetectable in yolk sac and fetal liver. Secretion of proteins by yolk sac endoderm occurred largely across the basolateral surface, i.e. towards the fetal compartment. These data support the hypothesis that one function of the yolk sac in the rat is the synthesis and secretion of a select group of plasma proteins to maintain homeostasis in the fetal compartment in the period before the fetal liver has matured sufficiently to carry out this function.

Conformational transitions of polynucleotides in the presence of rhodium complexes

We studied the effects of hexammine and tris(ethylene diamine) complexes of rhodium on the conformation of poly(dG-dC).poly(dG-dC) and poly(dG-m5dC).poly(dG-m5dC) using spectroscopic techniques and an enzyme immunoassay. Circular dichroism spectroscopic measurements showed that Rh(NH3)6(3+) provoked a B-DNA----Z-DNA----psi-DNA conformational transition in poly(dG-dC).poly(dG-dC). Using the enzyme immunoassay technique with a monoclonal anti-Z-DNA antibody, we found that the left-handedness of the polynucleotide was maintained in the psi-DNA form. In addition, we compared the efficacy of Rh(NH3)6(3+) and Rh(en)3(3+) to provoke the Z-DNA conformation in poly(dG-dC).poly(dG-dC) and poly(dG-m5dC.poly(dG-m5dC). The concentrations of Rh(NH3)6(3+) and Rh(en)3(3+) at the midpoint B-DNA----Z-DNA transition of poly(dG-dC).poly(dG-dC) were 48 +/- 2 and 238 +/- 2 microM, respectively. The psi-DNA form of poly(dG-dC).poly(dG-dC) was stabilized at 500 microM Rh(NH3)6(3+). With poly(dG-m5dC).poly(dg-m5dC), both counterions provoked the Z-DNA form at approximately 5 microM and stabilized the polynucleotide in this form up to 1000 microM concentration. These results show that trivalent complexes of Rh have a profound influence on the conformation of poly(dG-dC).poly(dG-dC) and its methylated derivative. Furthermore, the Rh complexes are capable of maintaining the Z-DNA form at concentration ranges far higher than that of other trivalent complexes. Our results also demonstrate that the efficacy of trivalent inorganic complexes to induce the B-DNA to Z-DNA transition of poly(dG-dC).poly(dG-dC) and poly(dG-m5dC).poly(dG-m5dC) is dependent on the nature of the ligand as well as the polynucleotide modification. Differences in charge density and hydration levels of counterions or base sequence- and counterion-dependent specific interactions between DNA and metal complexes might be possible mechanisms for the observed effects.

A new radioimmunoassay for human alpha atrial natriuretic peptide and its physiological validation

A new sensitive, specific radioimmunoassay for human alpha atrial natriuretic peptide (hANP) and a novel extraction method for hANP have been developed. Antiserum to hANP (Keq = 1.923 x 10(11) l/mol) showed no cross-reactivity with related analogues. Displacement of 50% bound 125I-hANP occurred at 4.7 +/- 0.1 fmol/tube (n = 15). The limit of detection of plasma hANP after extraction of 2 ml plasma with Florisil was 1.2 pmol hANP/litre plasma. The recovery of synthetic hANP from plasma over the range 6.5-162.5 pmol/l was 71.2 +/- 1.9%. Inter- and intra-assay coefficients of variation were 13.1% and 10.1% respectively. Extracted plasma was stored at -80 degrees C without loss in immunoreactivity. The radioimmunoassay was physiologically validated in man by measuring plasma hANP following central volume expansion - (a) plasma hANP rose from 2.5 +/- 0.5 to 4.1 +/- 0.6 pmol/l in 9 normal volunteers after postural change from seated to lying (b) infusion of normal saline (2 litre/2 hour) increased hANP from 1.6 to 4.3 pmol/l (n = 2). Infusion of hANP (2 pmol/kg/min) increased plasma hANP to 19.9 +/- 3.4 pmol/l (n = 6).

The haemodynamic effects of correction of anaemia in haemodialysis patients using recombinant human erythropoietin

STUDY OBJECTIVE

To evaluate the acute and long-term haemodynamic response to recombinant human erythropoietin (rHuEpo) correction of chronic anaemia in haemodialysis-supported patients.

DESIGN

Prospective analysis of randomly chosen patients undergoing the multicentre phase III clinical recombinant erythropoietin trial.

SETTING

Chronic haemodialysis patients supported in one of two dialysis centres of a large urban tertiary referral centre.

PATIENTS

Thirteen of the 59 patients who met the criterion for participation in the multicentre clinical phase III trial of recombinant erythropoietin were randomly chosen. Mean age (42.6 years), and time on dialysis (3.4 years) was representative of the study population. Ten patients were receiving antihypertensive therapy, which remained unchanged throughout the study.

INTERVENTIONS

Haemodynamic testing was done in a fasting state, in the supine position, utilising radionuclide angiocardiography. Plasma volume was determined by 125I-labelled serum albumin. Echocardiographic and hormonal evaluations were also performed at each haemodynamic evaluation. All testing was done immediately prior to first dose of drug, upon reaching target haematocrit, and at 6 months and 1 year of continued non-anaemia.

MEASUREMENTS AND MAIN RESULTS

Mean arterial pressure did not seem to change at any of the study periods, while total peripheral resistance did drop at target (34 +/- 2.5 vs 27.2 +/- 3.2 microns2, P = 0.05). Cardiac output (5.6 +/- 0.5 vs 7.6 +/- 0.8 l/min, P = 0.005) and stroke volume (77 +/- 9.6 vs 116 +/- 15.4 ml, P = 0.005) also rose at this same period but returned to baseline during later periods. Ejection fraction increased over baseline at both target and 1 year study points (50 +/- 2.7 vs 57.7 +/- 3 vs 63 +/- 4.3, P = 0.05) while the haematocrit was increased at target (21.8 +/- 0.9 vs 35.6 +/- 1.0, P less than 0.0005), and maintained at this new level throughout the study. Total blood volume (118 +/- 6.7 vs 100.4 +/- 8.1 ml/cm, P less than 0.05) and plasma volume (150 +/- 8.2 vs 108.5 +/- 9.4 ml/cm, P less than 0.001) decreased at 1 year.

CONCLUSION

Recombinant human erythropoietin is effective in correcting the anaemia of chronic renal failure. Any haemodynamic changes which may be induced seem to occur early in the course of therapy, are different from those changes induced by blood transfusions, and tend to return to baseline with continued treatment.

Increase in glomerular filtration rate in patients with insulin-dependent diabetes and elevated erythrocyte sodium-lithium countertransport

Increased sodium-lithium countertransport in erythrocytes is found in patients with insulin-dependent diabetes mellitus (IDDM) and nephropathy. To determine whether such an increase precedes the onset of nephropathy and, if so, whether it is associated with changes in renal function, we measured erythrocyte sodium-lithium countertransport in 52 patients with IDDM but not nephropathy or hypertension and in 32 control subjects. Seventeen of the 52 patients with IDDM (33 percent) had sodium-lithium countertransport activity that exceeded the maximal activity in the control subjects (0.39 mmol of lithium per hour per liter of cells). Eighteen of the 52 patients with IDDM were studied in more detail. The 7 patients with raised sodium-lithium countertransport values had glomerular filtration rates (median, 159 ml per minute per 1.73 m2 of body-surface area; range, 134 to 197) that were significantly higher (P less than 0.01) than those in the remaining 11 patients with IDDM and normal sodium-lithium countertransport (median, 126 ml per minute per 1.73 m2; range, 110 to 176) or in the 10 control subjects (median, 128 ml per minute per 1.73 m2; range, 93 to 151). In the seven patients with elevated sodium-lithium countertransport, the filtration fraction (median, 0.27; range, 0.22 to 0.37) was also greater (P less than 0.01) than that in control subjects (median, 0.22; range, 0.18 to 0.28). There were no differences in renal function between the patients with IDDM and normal sodium-lithium countertransport and the control subjects. We conclude that sodium-lithium countertransport is increased in patients with IDDM before the onset of nephropathy and is associated with hyperfiltration. Thus, elevated sodium-lithium countertransport activity may be an early marker of diabetic nephropathy.

Ethanol predominantly alters sodium influx in human leucocytes

1. Although ethanol appears to alter cellular sodium transport, the exact nature of its effects has not been clearly defined. We have studied the effects of different concentrations of ethanol on human leucocyte sodium content, and on the rise in leucocyte sodium content which occurs during sodium pump blockade with ouabain. 2. Sodium content was significantly reduced after a 20 min incubation with ethanol at concentrations between 17 and 170 mmol/l. 3. The rise in sodium content during a 20 min incubation with ouabain was significantly less in the presence of 170 mmol/l ethanol as compared with 17 mmol/l ethanol. 4. These results suggest that the effect of ethanol on intracellular sodium content is independent of sodium pump activity, i.e. it is mediated through reduced sodium influx.

Sodium content and transport of white and red blood cells in undialysed uraemic and continuous ambulatory peritoneal dialysis patients

Leukocyte cation content and sodium pump transport were measured in 14 undialysed uraemic and 15 CAPD patients and compared with results from healthy controls. Sodium content was elevated in the undialysed group compared with the CAPD group (P = 0.05) or the healthy controls (P less than 0.001), but this abnormality could not be clearly attributed to increased sodium influx or reduced sodium pumping. Sodium content correlated with plasma urea (rs = 0.69, P = 0.005) and creatinine (rs = 0.56, P = 0.031) concentrations in the CAPD group only. In subgroups of 12 undialysed and ten CAPD patients, erythrocyte sodium content and pump transport were measured at the same time as the leukocyte studies. Erythrocyte sodium was less in the undialysed group (P less than 0.01) and again there was no evidence of significant sodium-pump inhibition. The abnormalities in sodium content in undialysed patients were therefore in opposite directions in the two cell types, and were significantly less in both cell types in CAPD patients. These results emphasise the dangers of assuming that abnormalities of sodium transport seen in a single cell type can be taken as evidence of a generalised abnormality.

Regulation of ornithine decarboxylase gene expression in MCF-7 breast cancer cells by antiestrogens

Ornithine decarboxylase (ODC) is an enzyme intimately related to cell growth regulation. The metabolic products of ODC, the polyamines, are known to play a vital role in the structure and function of biological macromolecules including nucleic acids and proteins. The activity of ODC is stimulated by estrogens in their target cells. In order to gain insight into the molecular mechanism of action of antiestrogens in human breast cancer, we studied the effect of tamoxifen and 4-hydroxytamoxifen on the concentration of ODC mRNA, ODC activity, and the polyamine levels in a hormone-responsive breast cancer cell line, MCF-7. ODC mRNA concentration was reduced to 40% of the controls after 6 h of treatment of the cells with 100 nM 4-hydroxytamoxifen, but tamoxifen had no significant effect on ODC mRNA after treating with even 1 microM concentration for 36 h. ODC activity was, however, reduced to 40 and 75% of the controls after 24 h of treatment with 4-hydroxytamoxifen and tamoxifen, respectively. There was a significant reduction in the concentration of putrescine to 63% of control in tamoxifen-treated cells, but spermidine and spermine levels were not affected. With 4-hydroxytamoxifen, putrescine, spermidine, and spermine levels were reduced to 41, 62, and 79% of the control, respectively. In addition, exogenous putrescine was able to reverse the growth inhibitory effects of 4-hydroxytamoxifen. Overall, these results indicate that ODC and polyamine levels in MCF-7 cells are controlled by antiestrogens, and that suppression of polyamine biosynthesis plays a critical role in the growth inhibitory effects of antiestrogens.

Up-regulation of estrogen receptors by nonsteroidal antiestrogens in human breast cancer

Development of resistance to hormonal therapy in breast cancer is frequently associated with a decline or loss of cellular estrogen receptors. Agents which up-regulate the receptor may reduce the incidence of hormonal resistance. Antiestrogens at concentrations ranging from 0.1 to 1 microM produced a 2- to 4-fold increase of estrogen receptors in MCF-7 and T-47D breast cancer cells. This increase, which occurred as early as 3 h and was sustained throughout the 4 days of continuous exposure to tamoxifen, was primarily due to an enhancement in receptor synthesis.

High affinity binding of estrogen receptor to recombinant plasmids containing (dA-dC)n.(dG-dT)n sequences

Estrogen receptor is a gene regulatory protein that is present in a subset of breast tumors and in normal sex accessory tissues of vertebrates. The receptor protein forms a high affinity complex with estradiol and mediates its action. The mechanism of action of estrogen receptor (ER) involves its binding to specific DNA sequences in the genome and the stimulation of the expression of estrogen-responsive genes. In order to understand the molecular characteristics of ER-DNA interactions, we studied the relative binding affinity of rabbit uterine ER to recombinant plasmids: pDHf2 with 23-base pair (dA-dC)n.(dG-dT)n insert; pDHf14 with 60-base pair (dA-dC)n.(dG-dT)n insert; pDHg16 with 23-base pair (dG-dC)n.(dG-dC)n insert; and the parental plasmid pDPL6 without any insert. We conducted this study by using a DNA-cellulose elution assay in which the receptor was bound to DNA-cellulose and then eluted with different concentrations of plasmid DNAs in 10 mM Tris.HCl and 1 mM dithiothreitol, pH 7.4. The efficacy of a plasmid to bind to ER was determined from the concentration of the plasmid DNA required to elute 50% of the receptor from DNA-cellulose. The 50% elution concentrations were as follows: pDHf2, 3.2 micrograms/ml; pDHf14, 0.85 micrograms/ml; pDHg16, 200 micrograms/ml; and pDPL6, 340 micrograms/ml. Linearization of pDHf14 with HindIII reduced its binding efficacy only slightly, with a 50% elution concentration of the linear plasmid at 3.2 micrograms/ml. In contrast, the linear polynucleotide, poly(deoxyadenylate-deoxycytidylate).poly(deoxyguanylate-deoxythymidylat e [poly(dA-dC).poly(dG-dT)] and calf thymus DNA were 1650 and 880-fold less efficient, respectively, than pDHf14 in eluting ER from DNA-cellulose. These results show that the presence of short stretches of (dA-dC)n.(dG-dT)n sequences has a dramatic effect in increasing the binding affinity of ER to DNA. Since these sequences are reported to be conformationally ultrapolymorphic, a possible explanation for this increased binding might be the assumption of a conformational state of the inserted sequence to a form that has high affinity for ER.

Developmental patterns of gene expression of secreted proteins in brain and choroid plexus

The proteins secreted by the choroid plexus throughout rat brain development were analyzed by two-dimensional polyacrylamide gel electrophoresis following biosynthetic labeling of choroid plexus pieces with [14C]leucine in vitro. Approximately 20 major protein species were resolved which, with the exception of transferrin, transthyretin, and alpha 2-macroglobulin, appear to be unrelated to proteins found in high concentrations in plasma. Several patterns of developmental regulation were observed. At least two of the proteins were synthesized and secreted at high levels only by fetal choroid plexus, whereas the secretion of several other proteins including transferrin and proteins comigrating with cystatin C and alpha 2-macroglobulin increased only after birth. The levels of mRNA coding for transferrin, ceruloplasmin, cystatin C, alpha 2-macroglobulin, beta 2-microglobulin, and transthyretin were measured in the brain during development by dot hybridization and northern gel analysis. No mRNA was detected coding for the proteins alpha-fetoprotein, alpha 1-antitrypsin, haptoglobin, and thiostatin in the brain at any stage. For those proteins, which are produced in other parts of the brain as well as by the choroid plexus, the changes in their corresponding mRNA levels measured in whole brain paralleled the changes in their secretion by the choroid plexus. The results presented in this paper show that the choroid plexus is active in protein secretion at all stages studied. The changing pattern of protein secretion by the choroid plexus, combined with its early development compared with other tissues in the brain, suggests that it is active in providing the appropriate extracellular environment for the growth and differentiation of the brain.

Carrot (Daucus carota) hypocotyl transformation usingAgrobacterium tumefaciens

Daucus carota hypocotyl sections were transformed withAgrobacterium tumefaciens LBA4404 containing CaMV 35S promoter, β-glucuronidase coding sequence and the nopaline synthase (Nos) poly adenylation sequences in Bin 19. Sliced sterile seedling hypocotyl segments were preincubated for 2 days, co-cultivated withAgrobacterium for an additional 2 days, and then transferred to medium containing 100ug/ml of kanamycin and 400ug/ml carbenicillin. In 6 weeks kanamycin resistant calli were obtained in 5.8% of the explants from one variety. Calli were subcultured on solid medium, and in 4 weeks introduced into suspension culture. NPTII and Southern blot analysis confirmed that three selected lines were transformed with 1-3 copies of the GUSII construction. GUS activity in transformants was 5 to 250 fold over background.

Direct evidence for the presence of left-handed conformation in a supramolecular assembly of polynucleotides

Hexammine cobalt(III) chloride (Co(NH3)6(3+) provokes a B-DNA----Z-DNA----psi-DNA conformational transition in poly(dG-dC).poly(dG-dC) and poly(dG-m5dC).poly(dG-m5dC). The circular dichroism spectrum of psi-DNA is characterized by a manyfold increase of positive ellipticity in the range of 300-225 nm and the complete absence of a negative peak. In order to ascertain the helical handedness of psi-DNA, we used a recently developed enzyme immunoassay technique. This method consisted of treating the polynucleotides with Co(NH3)6(3+) to convert them to the Z- or psi-DNA forms and immobilizing these conformations on a microtiter plate. The plates were subsequently treated with a monoclonal anti-Z-DNA antibody Z22, alkaline phosphatase conjugated, affinity purified immunoglobulins, and the phosphatase substrate. The enzyme-substrate reaction was monitored by reading the absorbance at 405 nm with a microplate autoreader. The monoclonal anti-Z-DNA antibody had no reactivity to the B-DNA form, but bound strongly to both the Z- and psi-DNA forms, showing that Co(NH3)6(3+)-induced psi-DNA form of the polynucleotides exists in the left-handed Z-DNA conformation.

Common amino acid sequence domains among the LEA proteins of higher plants

LEA proteins are late embryogenesis abundant in the seeds of many higher plants and are probably universal in occurrence in plant seeds. LEA mRNAs and proteins can be induced to appear at other stages in the plant's life by desiccation stress and/or treatment with the plant hormone abscisic acid (ABA). A role in protecting plant structures during water loss is likely for these proteins, with ABA functioning in the stress transduction process. Presented here are conserved tracts of amino acid sequence among LEA proteins from several species that may represent domains functionally important in desiccation protection. Curiously, an 11 amino acid sequence motif is found tandemly repeated in a group of LEA proteins of vastly different sizes. Analysis of this motif suggests that it exists as an amphiphilic α helix which may serve as the basis for higher order structure.

The expression of alpha(1)-acid glycoprotein mRNA during rat development. High levels of expression in the decidua

During the acute phase response to inflammation the plasma concentration of some proteins, such as alpha(1-acid glycoprotein (AGP), increases dramatically. Since breakdown and remodeling of tissue is common to both nidation and inflammation we studied the tissue distribution and regulation of AGP mRNA levels during the embryonic development of the rat. High levels of mRNA coding for AGP were detected in the placenta during early fetal development. Expression of this mRNA was confined to the decidua and was first observed approximately 1 day after implantation when proliferation of the decidua is already well advanced. Maximum levels were attained about 5 days after implantation, after which the levels decreased rapidly. In contrast to the high levels of AGP mRNA in the decidua only very low levels were detected in fetal liver and visceral yolk sac, and there was only a small increase in the levels in maternal liver. Corticosteroid hormone responsiveness of AGP mRNA synthesis by hepatocytes appeared 3 days before birth. It is likely that the synthesis of AGP by the cells of the decidua is important in establishing the precisely controlled interaction between mother and embryo during nidation.

The expression of genes coding for positive acute-phase proteins in the reproductive tract of the female rat. High levels of ceruloplasmin mRNA in the uterus

High levels of ceruloplasmin mRNA were measured in the uterus of both pregnant and non-pregnant rats. No mRNA for alpha 2-macroglobulin and alpha 1-acid glycoprotein could be detected in the uterus in contrast to the high levels of those two mRNAs found in the decidua in the mid-gestation period. Synthesis of plasma proteins with a protective function in the decidua or uterus may be important in maintaining homeostasis at different stages of reproduction. In addition, ceruloplasmin synthesis by the uterus may be part of a system transporting copper to the fetus.

Lung cancer in motor exhaust-related occupations

The association between employment in motor exhaust-related occupations and the risk for lung cancer was examined in 2,291 male cases of lung cancer and 2,570 controls in data pooled from three U.S. case control studies carried out by the National Cancer Institute between 1976 and 1983. Most analyses were limited to subjects providing direct, in-person interviews, including 1,444 cases and 1,893 controls. For those providing direct interviews and employed 10 years or more in motor exhaust-related (MER) occupations, the age, smoking, and study area adjusted odds ratio (OR) for lung cancer was 1.5 (95% CI = 1.2-1.9). Risk was elevated for truck drivers (OR = 1.5; 95% CI = 1.1-1.9) and for other MER occupations (OR = 1.4; 95% CI = 1.1-2.0). The odds ratios associated with MER employment of 10+ years were 1.6 (95% CI = 1.2-2.1) for whites and 1.4 (95% CI = 0.9-2.1) for nonwhites; 1.2 (95% CI = 0.7-2.0) [corrected] for those with possible exposure to other recognized or reported lung carcinogens; and 1.6 (95% CI 1.2-2.1) for those without such exposure. The 50% excess risk for lung cancer associated with employment in motor exhaust-related occupations could not be explained by greater use of cigarettes or by other occupational exposures among these workers.

Corticosterone's dual metabolic actions

Corticosterone possesses two distinctly opposite metabolic actions. The actions are strictly dose-dependent and are linked to type I and type II corticosteroid receptor binding. These conclusions are drawn from continuous infusion studies where corticosterone yields a bitonic dose-response curve for body weight gain and feeding efficiency. Anabolic at low serum levels, corticosterone concentrations above 2 micrograms/dl bring about an opponent catabolic process that intensifies and eventually masks the anabolic action. Relatively pure type I (aldosterone) and type II (RU28362 and dexamethasone) corticosterone receptor agonists produce opposite monotonic functions that respectively mimic the ascending and descending arms of the corticosterone dose-response curve. Stimulation of either receptor increases the proportion of carcass fat to lean body mass by either increasing carcass lipids (type I) or by reducing protein (type II).

Proportion of lung cancers in males, due to occupation, in different areas of the USA

Occupational data from 5 case-control studies in the United States involving 2,973 male cases and 3,210 controls were analyzed to estimate the percentage of lung cancer attributable to well-known and suspected lung carcinogens. The studies were conducted in areas heterogeneous in terms of industrial activities. The percentage of lung cancers attributable to occupations entailing potential exposure to well-recognized carcinogens ranged, by study area, from 3 to 17%. The further inclusion of occupational groups with suspect carcinogenic exposures changed these estimates very little. Exclusion of data derived from next-of-kin interviews influenced the estimates of attributable risks, but not in a systematic fashion. The estimates also varied according to ethnic group, smoking status and birth cohort, with higher values in non-whites, non-smokers and among members of more recent birth cohorts. Possible errors in exposure classification, which may make these estimates conservative, are discussed.

Morbidity profile of the Mamre community

Various morbidity parameters in Mamre, a village of 4,623 residents in the western Cape, are described. Acute morbidity (either injury or illness) occurring in the 2 weeks before the survey was reported by 4% of respondents. Investigation of several chronic conditions for which people said that they were receiving treatment yielded rates of 57/1,000 for hypertension, 29/1,000 for 'nerves', 13/1,000 for diabetes and 19/1,000 for tuberculosis; 9.9% of respondents reported disability. Reported morbidity increased with age, was commoner in women than in men, and agreed with perceptions of individuals' health. Tuberculosis, inadequate sewerage and water facilities, alcohol abuse and dusty roads were perceived to be the main health problems by the community. The morbidity profile and the relatively high rate of pscyhosocial problems found are consistent with a process of urbanisation in a predominantly working-class community.

Mamre Community Health Project--demographic, social and environmental profile of Mamre at baseline

Demographic, social and environmental information was collected from 4,623 residents in 870 Mamre households: 34.3% of the population were under 15 years and 4.4% over 65 years of age, while 2.7% of adults had had no education, 42.1% had only primary school education, 51.1% secondary school education and 4.1% had had some tertiary education. Education and age were inversely related. Of employable adults 64.7% were working. Community, social and personal services and manufacturing accounted for 76% of the male and 92% of the female jobs. Cape Town or Atlantis was the workplace for 78% of male and 87.2% of female workers. Of the labour supply 17.2% were unemployed; 75% of employed people were semi-skilled and unskilled workers. There was a mean of 5.3 persons per household, with a median of 3 rooms per household. Of the houses 18.4% were older than 80 years; 38% of households had inside taps and 98% had outside tap(s). Sewage disposal by the bucket system was used in 86% of households while 13% used flush toilets. The mean amount of money spent on fuel was R10.92 per person per month. The Mamre community is well past the initial phase of rural-urban transition in terms of its sociodemographic profile. At present, critical environmental infrastructural changes are being introduced.

The expression of transthyretin mRNA in the developing rat brain

Specific cDNA and oligonucleotide probes were used to study the appearance of transthyretin mRNA in developing rat brain using Northern gel analysis, cytoplasmic dot hybridization, and in situ hybridization. Transthyretin mRNA in embryonic rat brain was found to be confined to the epithelial layer of the choroid plexus primordia appearing first in the fourth ventricle, followed by appearance in the lateral ventricles, and subsequently in the third ventricle. Transthyretin mRNA was localized in these cells from early stages of neuroepithelium differentiation, showing that it is a sensitive marker for the differentiation of the choroid plexus within the fetal brain.

A twenty-two-fold increase in the relative affinity of estrogen receptor to poly (dA-dC).poly (dG-dT) in the presence of polyamines

We studied the relative efficacy of polyamines to facilitate the binding of estrogen receptor to poly(dA-dC).poly(dG-dT). In the absence of polyamines, 1,400 micrograms/ml of this polynucleotide eluted 50% of bound estrogen receptor from DNA-cellulose. In contrast, 50% estrogen receptor was eluted by 65 micrograms/ml of poly(dA-dC).poly(dG-dT) complexed with 150 microM spermidine. Putrescine and spermine also enhanced the ability of poly(dA-dC).poly(dG-dT) to elute estrogen receptor, but the magnitude of the effect was not as high as that of spermidine. Control experiments with calf thymus DNA and poly(dA-dT).poly(dA-dT) showed 6- and 3-fold increase, respectively in their affinity for estrogen receptor in the presence of spermidine. The dramatic increase in the affinity of poly(dA-dC).poly(dG-dT) for estrogen receptor in the presence of polyamines might be a result of the conversion of the polynucleotide to the left-handed Z-DNA form. These results show that polyamines are capable of participating in estrogenic regulation of gene expression by altering the affinity of the receptor for specific DNA sequences.

Modulation of the binding of progesterone receptor to DNA by polyamines

Putrescine, spermidine, and spermine are a group of small organic cations, collectively known as polyamines. They are present in all living cells, and their levels are generally increased in tumor cells. Progesterone receptor is a gene-regulatory protein that plays a major role in gestation and in hormonal responsiveness of breast cancer. We studied the effects of putrescine, spermidine, 2 lower homologues of spermidine, N1- and N8-acetyl spermidines, spermine, and N1-acetyl spermine on the sedimentation profile and DNA binding of progesterone receptor from rabbit uterus. Progesterone receptor, prepared in hypotonic buffer, sedimented at the 7S region of sucrose gradients. In the presence of 1 mM putrescine, a part of the receptor was converted to a 5S form. In the presence of 1 mM spermidine or 0.25 mM spermine, the receptor was completely transformed to the 5S form. The DNA binding of the 7S form of progesterone receptor was 7 +/- 3%. After incubating this receptor with 1 mM putrescine, 1 mM spermidine, or 0.25 mM spermine, its DNA binding increased to 16 +/- 4, 37 +/- 3, and 44 +/- 5%, respectively. The structural specificity of polyamines in facilitating the DNA binding of progesterone receptor was examined by using two spermidine homologues. The first homologue with one methylene group less than that of spermidine was as effective as spermidine in transforming progesterone receptor. Removal of two methylene groups, however, had a dramatic effect in reducing the efficacy of the resulting molecule to the level of putrescine. Taken together, our results show that natural polyamines are capable of modulating the binding of progesterone receptor to DNA. Since progesterone receptor is associated with the hormonal responsiveness of human breast cancer, polyamine levels in tumor cells might play an important role in the gene-regulatory function of progesterone receptor.

The development of rat alpha 2-macroglobulin. Studies in vivo and in cultured fetal rat hepatocytes

During inflammation and tissue injury, there is an increase in the plasma concentration of several proteins, the acute-phase proteins. The levels of some acute-phase proteins have been reported to increase in pregnant and tumour-bearing animals. Rat alpha 2-macroglobulin is classified as an acute-phase protein. In this study we report the expression of alpha 2-macroglobulin in various tissues during development of the rat embryo by analysis of mRNA. The tissues studied are liver, visceral yolk sac, placental labyrinth, decidua and trophoblast. In addition, the sites of alpha 2-macroglobulin expression are localized by in situ hybridization of cDNA for alpha 2-macroglobulin to mid-sagittal cryosections of rat embryos. The level of mRNA coding for alpha 2-macroglobulin is determined in the liver of rats aged between 12 days gestation and 2 days postnatal. alpha 2-Macroglobulin mRNA is first observed in fetal liver from 12 days of gestation and increases after day 17, reaching a maximum on day 20. At this time the level is greater than that found in the liver of an adult rat suffering from acute inflammation. alpha 2-Macroglobulin mRNA is detectable in the yolk sac, placental labyrinth, trophoblast tissue and decidua. In the decidua the alpha 2-macroglobulin message is first detected at 8 days of gestation, with high levels observed from 10 to 21 days of gestation. These observations are supported by in situ hybridization studies. Experiments using cultured hepatocytes show that cells derived from rats at 15 days and 19 days of gestation are capable of synthesizing and secreting alpha 2-macroglobulin. Both synthesis and secretion can be induced by the addition of dexamethasone to the culture medium.

Structure and expression of the rat transthyretin (prealbumin) gene

The rat transthyretin gene, 7.3 kilobase pairs (kb) long, with 14.5 kb of 5' flanking and 12.2 kb of 3' flanking region was cloned and characterized. The gene contained four exons. A "TATA box" sequence (5'-TATATAA-3') and a "CAAT box" sequence (5'-GTCAAT-3') were located 23 and 95 nucleotides upstream, respectively, from the major transcription start site. Nucleotides -51 to -189 were highly conserved (93% homology between rats and humans, 97% homology between rats and mice). Tandem repeats of sequences of 5'-AC-3' and 5'-ACACATGC-3' in the 5' flanking region, of 5'-GAAA-3' in the first intron, and of 5'-GT-3' in the third intron of the gene were observed. Using specific cDNA probes, tissue specificity and regulation of transthyretin mRNA biosynthesis during embryogenesis were analyzed. Transthyretin expression occurred first in the yolk sac, then decreased when expression increased in fetal liver. Presumptive choroid plexus cells in the inner lining of the neural tube expressed transthyretin early in gestation (11 days before birth) with a maximum immediately preceding the spurt of brain growth around birth. Partial hepatectomy of adult rats induced both an acute phase response and regenerative growth in liver. The decrease in transcription of the transthyretin gene in liver, which is characteristic for the acute phase response, was overridden by stimulation of gene expression after partial hepatectomy. This stimulation also affected transthyretin expression in choroid plexus.

Separation and characterization of the subunits of the laminin of EHS sarcoma

A rapid and sensitive method was developed for the preparative separation of laminin subunits. Laminin was extracted and purified from mouse EHS sarcoma. On SDS-PAGE, the reduced and carboxymethylated molecule separated into two components corresponding to molecular weights of about 400 KDa (subunit A) and 200 KDa (subunit B). These two subunits were preparatively separated using heparin-agarose affinity chromatography. The larger subunit quantitatively adhered to the affinity column while the smaller one did not adhere. Amino acid analyses of the separated subunits showed distinct differences. Subunit B was further resolved into two distinct polypeptides of 200 KDa, B1 and B2, by means of reverse-phase HPLC. Although the amino acid compositions of B1 and B2 were very similar, the peptide maps generated by digestion of the B1 and B2 chains with Staphylococcus aureus V8 protease or by cyanogen bromide showed B1 and B2 to differ from each other. Thus, at least three different polypeptide subunits are present in this laminin and probably arise from separate gene origins. These studies provide a basis for the subsequent localization and analysis of the specialized structural and functional domains of laminin.