Aberrant nuclear factor-kappaB/Rel expression and the pathogenesis of breast cancer.

Expression of nuclear factor-kappaB (NF-kappaB)/Rel transcription factors has recently been found to promote cell survival, inhibiting the induction of apoptosis. In most cells other than B lymphocytes, NF-kappaB/Rel is inactive, sequestered in the cytoplasm. For example, nuclear extracts from two human untransformed breast epithelial cell lines expressed only very low levels of NF-kappaB. Unexpectedly, nuclear extracts from two human breast tumor cell lines displayed significant levels of NF-kappaB/Rel. Direct inhibition of this NF-kappaB/ Rel activity in breast cancer cells induced apoptosis. High levels of NF-kappaB/Rel binding were also observed in carcinogen-induced primary rat mammary tumors, whereas only expectedly low levels were seen in normal rat mammary glands. Furthermore, multiple human breast cancer specimens contained significant levels of nuclear NF-kappaB/Rel subunits. Thus, aberrant nuclear expression of NF-kappaB/Rel is associated with breast cancer. Given the role of NF-kappaB/Rel factors in cell survival, this aberrant activity may play a role in tumor progression, and represents a possible therapeutic target in the treatment of these tumors.

Synthesis of a potential water-soluble radiographic contrast medium, 2, 4, 6-triiodo-3-acetamido-5-N-methylcarboxamidophenyl beta-D-glucopyranoside.

Starting from 3,5-dinitrobenzoic acid, the infinitely water-soluble compound, 2, 4, 6-triiodo-3-acetamido-5-N-Methylcarboxamidophenyl Beta-D-glucopyranoside (9), was synthesized in nine steps. Glucoside 9, the first example of potentially a new class of water-soluble x-ray contrast media, is rapidly excreted from dog's plasma into the urine, unchanged. It has low intravenous toxicity in mice (LD50 = 24.5 g/kg). Thin-layer chromatography of aqueous solutions of 9 revealed first appearance of aglycon 7 after 1 week at room temperature.

Studies in the design of x-ray contrast agents. Synthesis, hydrophobicity, and solubility of some iodoresorcyl bis(beta-glucosides).

Two diiodo- and two triiodoresorcyl bis(beta-glucosides) were prepared and their hydrophobicity (log P octano) and water solubility were compared to a triiodophenyl beta-glucoside and several experimental nonionic, water-soluble, x-ray contrast agents. The data indicate steric overlap of the halogen substituents by the bulky hydrophilic O-beta-glucosyl substituents; high water solubility is attained only at observed log P octanol approximately 1.5 or lower. Of the new compounds, only 2,4,-6-triiodo-5-N-methylcarboxamidorescorcy bis(beta-glucoside) (6) was highly water soluble. At the physiological pHin dog's plasmia in vitro, compound 6 rapidly hydrolyzed. Poorly water-soluble but more stable compounds of this series were not appreciably absorbed from dog's duodenum.

Differential accumulation of radiopaque contrast material in acute myocardial infarction.

The differential accumulation of radiographic contrast materials in ischemically damaged and normal myocardium was assessed with direct measurement (fluorescent excitation analysis) of the iodine content of tissue samples from dogs with 48 hour old myocardial infarctions. Tissue samples were obtained 10, 30, 60 and 180 minutes after the intravenous administration of 2 ml/kg body weight of diatrizoate meglumine and sodium (Renografin-76). At all time intervals, the iodine concentration of infarcted tissue was at least threefold greater than that of normal myocardium. At 180 minutes the ratio between iodine concentration in infarcted myocardium and that in normal myocardium was 8.5 and between that in infarcted myocardium and that in blood was 2.6. The iodine concentration in the liver was similar to or greater than that in the infarcted area at time intervals after 10 minutes. These results suggest that the intravenous administration of contrast material may facilitate the identification of acutely infarcted myocardium with computerized X-ray transmission tomography.

The need for improved contrast media. Ioxilan: updating design theory.

Because of computed tomography (CT) and digital subtraction angiography (DSA), other diagnostic procedures assisted by urovascular contrast media (CM) have decreased, but the annual total remains at 10 to 11 million procedures since 1980. This trend, expected to continue, suggests that CM will remain vital to medical imaging. The current nonionic CM are not universally affordable, and may elicit pain in peripheral angiography. The author and co-workers explored conversion of ionic into nonionic CM, and have arrived at Ioxilan, 5-(N-2,3-dihydroxypropylacetamido)-2,4,6-triiodo-N-(2-hydroxyethyl )-N'-(2,3- dihydroxypropyl)-isophthalamide; a stable, water-soluble and well-tolerated CM. Ioxilan has unexpectedly low osmolality (570 mOsm at 300 mgI/mL), attributable to the region of double-methylenes that, by hydrophobic bonding, transiently associates the Ioxilan molecules. The high overall hydrophilicity, and thus good biological tolerance, of Ioxilan is accomplished by masking the hydrophobic region with a hydrophilic group. The author suggests that improved urovascular nonionic CM can be designed using this principle.

Syntheses of new nonionic radiographic contrast media: acylamino-triiodophenyl ethers of sugars.

New, potentially useful radiographic contrast media, employing hexoses attached to the triiodophenyl moiety by an ether bond, have been synthesized and tested. Two of the nitro groups in trinitrobenzene were displaced by two fully protected glycose-3-yl residues. The bis-ethers (IV) were successively reduced, iodinated, acylated, and then subjected to base and/or acid catalyzed deprotection to obtain the acylamino-triiodophenyl ethers (VIII). The bis-glucose-3-yl ether (VIIIa) was converted into the corresponding bis-arabinos-2-yl ether (XIII) by standard methods. These sugar ethers have high water solubility, hydrolytic stability, and low toxicity. The glycolyl-bis-hexose ether DL-2-98, which has the lowest neurotoxicity in this series of compounds, is comparable to iopamidol, and is potentially useful as a new nonionic radiographic contrast agent.

Stability of nonionic water-soluble contrast media: implications for their design.

The stability of the nonionic contrast media metrizamide, P-297, iopamidol, and nonionic phenyl ether DS-1-132 was studied by exposing their aqueous solutions to 120 C. Metrizamide showed decomposition of the sugar residue, while in P-297 the sugar substituent was cleaved off the triiodoaniline moiety. Iopamidol and DS-1-132 showed no decomposition. For stability, sugar moieties should be attached either by an ether linkage or as amides, as long as the acylamino group is not on a carbon adjacent to the anomeric carbon. Polyhydroxyalkylamines are less hydrophilic but more stable than sugars.

Release of serotonin from human platelets in vitro by radiographic contrast media.

Both ionic and nonionic, monomeric and dimeric contrast media were found to release serotonin from intact human platelets in vitro. The monomeric contrast media were compared at the concentration range of 25 mg I/ml. Iothalamate was the strongest and the statistically equal metrizamide iopamidol, and P-297 were the weakest releasers. Monomeric and dimeric contrast media were compared at concentration ranges of 50 and 100 mg I/ml. They ranked, in descending order of serotonin releasing potency: iodipamide, iothalamate, P-127, iopamidol, and a statistically indistinguishable group of the monoacid dimer P-286, the nonionic dimer ZK 74 435, and metrizamide. The capability of contrast media to release serotonin seems to be a composite result of their specific physical and molecular structural properties.

Isomerism in iohexol and ioxilan. Analysis and implications.

Pharmacologically useful contrast media (CM) must be highly water-soluble to form stable supersaturated solutions. Iohexol and ioxilan both contain centers of potential isomerism stemming from the D,L hydroxyalkyls, the carbamoyl substituents, the alkylated anilide nitrogen and the acetylated anilide. The D,L isomers are individual compounds, both highly water-soluble and equally highly hydrophilic. The carbamoyl rotamers result from steric restriction by the adjacent iodines, and are interconvertible at physiologic temperature ranges; only at low temperatures can high field nuclear magnetic resonance (NMR) identify them. The isomers resulting from the alkylated anilide are fixed, but since they can exist only by reference to fixed carbamoyls, they are not relevant at physiologic temperatures. The N-acetyl endo-/exo-isomers are crystallizable from alcoholic solvents and identifiable by high-pressure liquid chromatography (HPLC) and hydrogen-1 (1H) and 13C NMR. They interconvert rapidly in water, forming stable and highly soluble mixtures. All isomers of iohexol or ioxilan, based on HPLC, are similarly highly hydrophilic, and are expected to show low binding to biomacromolecules with a concomitantly high biological tolerance. Since these mixtures are unavoidable, they must be considered a pharmacologic entity.

Spectral analysis of Lapine EEG: neurotoxicologic evaluation of new nonionic contrast media.

Effects of the injection of 0.25 ml of nonionic radiocontrast media (280 mg I/ml) and/or istonic and/or hypertonic mannitol into the subarachnoid space on the low frequencies (2--5 Hz) of the EEG were studied in nonanesthetized, curarized rabbits. Compared to the noninjected controls, mannitol did not cause any significant EEG spectrum shifts. P-297 and iopamidol caused a slight decrease in the energy content of the 2--5-Hz band, while DS-1-132 and the nonionic dimer ZK 32347 caused a moderate increase. Since an increase in the slow-wave component of the EEG indicates a pacemaking activity, while a decrease indicates stimulation or irritation, none of the tested nonionic media appear to be biological inert. In this test P-297, iopamidol, and DS-1-132 caused fewer disturbances than metrizamide.

Determination of lethal dose in a protozoa: screening of contrast media toxicity.

Suitability of a protozoan culture for determination of contrast media (CM) toxicity was investigated. A culture of Blepharisma americanum was exposed to varying concentrations of CM and the time elapsed until 50% cell mortality was determined. The cultures were standardized using solutions of Na iothalamate and/or Metrizamide. A standardized culture responded reproducibly between days 6 and 10 of the culture age. Comparison of concentrations of CM needed to achieve LD50 at 7 minutes ranked CM in order of decreasing toxicity as follows: oral cholecystopaques, intravenous cholecystopaques, and urographic agents; ie ionic monomers, ionic dimers, monovalent dimers, nonionic monomers, nonionic dimers. Comparison of CM toxicity determined by protozoa LD50 at 7 minutes with i.v. LD50 in mice showed a good correlation, suggesting usefulness of the protozoan assay as a complementary or screening toxicologic method.

Current contrast media and ioxilan. Comparative evaluation of vascular pain by aversion conditioning.

Vascular pain caused by contrast media (CM) cannot be quantified by subjective patient reports or manifest pain reactions in experimental animals. Therefore, conditioned taste aversion (CTA), a psychopharmacological method, was used in double-blind femoral arteriography in rats to compare a new nonionic monomeric CM, ioxilan, with iohexol, iopamidol (all at 350 mgI/mL) and 22% sorbitol. A chronically implanted femoral artery catheter was used to inject 0.2 mL/kg body weight. By measuring the intake of water laced with the flavor that thirsty rats had learned to associate with the injection, the degree of aversion, assumed proportional to pain, was determined. Ioxilan (690 mOsm) produced the least pain, followed by iopamidol (810 mOsm), iohexol (844 mOsm) and sorbitol (1410 mOsm). Since all test substances are highly and similarly hydrophilic and nonionic, the intensity of vascular pain must depend on solution osmolality, rather than on chemotoxicity or ionicity. Compounds of the lowest osmolality, ig, ioxilan, elicit the least vascular pain.

Evaluation of intrathecal contrast media by aversion conditioning in rats.

A method for quantification of aversion conditioning in rats was adapted to assess intrathecal neurotoxicity of contrast media (CM). Metrizamide, iopamidol, nonionic dimers DL-2-87 and DL-3-117, experimental iodophenyl glucose ethers DL-2-98 and DS-1-132, and Ringer's solution were injected into non-anesthetized rats drank water mixed with their preferred flavors, and subsequently were injected with 22.5 and/or 45 mgI/kg (200 and/or 400 mgI/ml concentration). From the intake of the preferred flavored water, expressed as percentage of total fluid intake consumed during a preference test and during a subsequent free choice test, a percentage avoidance/preference score was calculated as a measure of conditioning. At 12.5 mgI/Kg level, DL-2-87, which unexpectedly precipitated from solution in vivo, caused the most aversion, followed by metrizamide. The remaining compounds induced no significant aversion and were statistically indistinguishable from one another. At 45 mgI/kg dose level, all monomeric CM induced aversion of a statistically equal degree, while DL-3-117 proved nonaversive, equal to Ringer's solution.

Combined methods for assessment of neurotoxicity: testing of new nonionic radiographic media.

A battery of tests for toxicity assessment of new contrast media is reviewed. Cell toxicity in a protozoan culture (Blepharisma americanum); lethal dose determination in mice; EEG Spectral analysis following cisternography in rabbits; ED50 and LD50 determination by intra- and pericerebral injection in rats; intracisternal injection in chronically cannulated, nonanesthetized rats; and aversive conditioning by intracisternal injection in rats were found complementary. By these methods, novel nonionic media phenyl-sugar-ether DS-1-132 and DL-2-99 were found comparable to iopamidol, while all three compounds were superior to metrizamide.

Vasocilators in the canine mesenteric circulation. Evaluation of a potential aid in the diagnosis of gastrointestinal bleeding.

Radiodiagnostic potential of intra-arterially injected vasodialting agents was investigated by their effect on total and segmenal resistances (VR) of mesenteric vasculature, blood flow in superior mesenteric artery and its bleeding branch; heart rate and ventricular and systemic blood pressure. Dipyridamole, isoxsuprine, protricular and systemic blood pressure. Dipyridamole, isoxsuprine, prochlorperazine, lidocaine, meglumine diatrizoate and carbon dioxide were poor dilators. Phentolamine produced hypotension; glucagon and serpasil an extremely long dilation. A large and short vasodilation was produced with tolazoline and nylidrin, but both agents increased VR of the postcapillary segment and caused transient hypotension and arrhythmias, nylidrin's side effects were smaller. Oxygen produced large and long vasodilation and minimal systemic effects. It is concluded that oxygen or possibly nylidrin are suitable agents should an intermittently bleeding mesenteric artery be dilated for diagnostic purposes prior to angiography.

Why does kidney size change during I.V. urography?

Meglumine iothalamate (280 ml I/ml) and sodium iothalamate (400 mg I/ml) in doses of 700 mg I/kg bw, were injected i.v. as a bolus in dogs. Renal size, urine flow rate, arterial pressure, renal blood flow and mean transit time and renal blood volume were measured before and after injection. All changes were qualitatively and quantitatively identical for both drugs. They produced a small transient renal shrinkage followed by a greater and prolonged renal enlargement. During the period of renal enlargement, urine flow increased. The time course of the enlargement paralleled the increase of urine flow rate. Renal blood flow also increased but both the mean transit time and renal vascular volume decreased. Therefore, the kidney size increase after i.v. injection of large doses of urographic contrast media cannot be attributed to an increased volume of the vessels. Most likely it is caused by diuresis-induced increase in the volume of the tubules.

Investigation of a new arthrographic contrast agent: Iotrol.

A new nonionic dimer (Iotrol; Schering AG) and diatrizoate meglumine-diatrizoate sodium (Renografin-60; Squibb) were compared as arthrographic agents by injecting these substances into the knees of rabbits. Three experienced arthrographers judged the image quality produced by Iotrol to be superior to that of Renografin-60. Following animal sacrifice, histologic examination of the synovium revealed a significant difference in the inflammatory response evoked by the contrast agents: Iotrol caused less inflammation. In a second group of rabbits, methylprednisolone was subcutaneously injected 24 hours before the arthrographic studies. The methylprednisolone significantly reduced the inflammation in the Renografin-60 subgroup when compared with the nonmedicated counterparts. No significant effect was noted in a like comparison with Iotrol. In addition, the administration of methylprednisolone led to a deterioration of the radiographic images. Based upon our data, we believe Iotrol is superior to Renografin-60 as an arthrographic agent.

Uptake of contrast materials by experimental acute myocardial infarctions: a preliminary report.

The concentration of iodine within infarcted and normal myocardium after intravenous administration of contrast material was determined by fluorescence excitation analysis in seven dogs at 48 hours after coronary arterial ligation. The iodine concentration of infarcted myocardial tissue was several times greater than normal myocardium after administration of meglumine/sodium diatrizoate, iodipamide, and an experimental polymer of iothalamic acid.

Direct myocardial effects of intracoronary administration of new contrast materials with lost osmolality.

The effects of LV dynamics of the intracoronary administration of three new contrast materials with reduced osmolality were compared with those of a monomeric ionic material, sodium iothalamate, and the nonionic material, metrizamide. In eight anesthetized dogs, the monacid dimer, P286, caused increases in LV dimensions and decreases in LV systolic pressure and parameters of the contractile state. The changes were less than those caused by sodium iothalamte. The alterations in LV function tended to be greater, but not significantly so, during systemic hypoxemia compared to the normal state. The nonionic materials, P297 and iopamidol, like metrizamide, caused no deleterious effects on LV dynamics in either the normal or hypoxemic state. Nonionic materials actually caused a slight increase in parameters of the LV contractile state.

Development and preliminary pharmacologic evaluation of a zwitterionic oral cholecystographic agent.

A new zwitterionic iodinated molecule, 2-[3-(N-ethyl-2-hydroxyethyl) amino-acetamido-2, 4, 6-triiodobenzyl]-butyric acid (RCK-136) was synthesized, and its potential as an oral cholecystopaque was tested. In rats, 15 minutes following intravenous injection, RCK-136 reached maximum biliary concentration; 84% of the dose was excreted into bile. Biliary excretion of RCK-136 elicited a strong choleresis (44 ml of bile flow per mmol compound). Intravenous LD50 in rats averaged 390 mgI/kg. ED50 in rats, intradiencephalic, averaged 1.98 mgI/kg. The average densities of cholecystograms produced in three dogs with iosumetic acid and/or RCK-136 were comparable.