A nephroprotective iodinated contrast agent with cardioprotective properties: A pilot study

BACKGROUND AND PURPOSE

Evaluation and treatment of acute ischemic syndromes, in the heart and brain, require vessel visualization by iodinated X-ray contrast agents. However, these contrast agents can induce injury, in both the kidneys and target organs themselves. Sulfobutylether beta cyclodextrin (SBECD) added to iohexol (SBECD-iohexol) (Captisol Enabled-iohexol, Ligand Pharmaceuticals, Inc, San Diego, CA) is currently in clinical trials in cardiovascular procedures, to determine its relative renal safety in high-risk patients. Preclinical studies showed that SBECD-iohexol reduced contrast-induced acute kidney injury in rodent models by blocking apoptosis. The current study was undertaken to determine whether SBECD-iohexol is also cardioprotective, in the male rat ischemia-reperfusion model, compared to iohexol alone.

METHODS

After anesthesia, the left coronary artery was ligated for 30 min and the ligation released and reperfusion followed for 2 h prior to sacrifice. Groups 1-4 were injected in the tail vein 10 min prior to ischemia with: (1) vehicle; (2) iohexol; (3) SBECD; and (4) SBECD-iohexol. Infarct size, hemodynamics, and serum markers were measured.

RESULTS

An eight-fold increase in serum creatine kinase in the iohexol-alone group was observed, compared with no increase in the SBECD-iohexol group. The mean arterial pressure and rate pressure product were depressed in the iohexol-alone group, but not in the SBECD-iohexol group, or controls. No difference in infarct size or serum creatinine among the groups was observed.

CONCLUSION

The results of this study suggest that SBECD-iohexol is superior to iohexol alone, for both the preservation of cardiomyocyte integrity and preservation of myocardial function in myocardial ischemia.

Preclinical Studies of a Kidney Safe Iodinated Contrast Agent

BACKGROUND AND PURPOSE

Contrast-induced acute kidney injury (CI-AKI) is a serious complication of the use of iodinated contrast agents. This problem is particularly acute in interventional neurology and interventional cardiology, probably due to the intra-arterial route of injection, high contrast volumes, and preexisting risk factors of these patients. In an attempt to develop a contrast agent that is less damaging to the kidneys, we have studied the effects of adding a small amount of the substituted cyclodextrin, sulfobutyl-ether-β-cyclodextrin (SBECD), to iohexol in rodent models of renal toxicity.

METHODS

Renally compromised mice and rats were injected with iohexol and iohexol-SBECD via the tail vein. The renal pathology, creatinine clearance, and survival benefits of iohexol-SBECD were studied. The safety of direct intra-arterial injection of the iohexol-SBECD formulation was studied in a dog heart model system. Mechanism of action studies in cell culture model using a human kidney cell line was performed using flow cytometry.

RESULTS

Nephrotoxicity was significantly reduced using iohexol-SBECD compared to iohexol alone, at mole ratios of iohexol:SBECD of 1:0.025. SBECD increased survival from 50% to 88% in a rat survival study. In the dog heart model, iohexol-SBECD was safe. Cell culture studies suggest that SBECD interferes with the early stages of contrast-induced apoptosis in a human renal cell line.

CONCLUSION

We have shown that the addition of a small amount of SBECD (one molecule of SBECD per 40 iohexol molecules) significantly protects rodent kidneys from CI-AKI. Further development of this new formulation of iodinated contrast is warranted.

Rat serum stimulates serotonin N-acetyltransferase activity in pineal monolayer cultures

The effects of rat serum on serotonin N-acetyltransferase (NAT) activity and indole synthesis in monolayer cultures of neonatal rat pineal glands was examined. The addition of 5% rat serum to these cultures resulted in stimulation of NAT activity equal to that obtained with optimal concentrations of the adrenergic agonist norepinephrine (NE). Rat serum also increased the synthesis of both N-acetylserotonin and melatonin from tryptophan. Stimulation of NAT activity by rat serum was partially blocked by metoprolol and propranolol, but not by phentolamine or butoxamine. The serum factor responsible for the stimulation was stable to both freezing and boiling. No significant amounts of epinephrine, norepinephrine, or dopamine were detected in the serum.

Cockayne syndrome: an atypical case

We report a case of Cockayne syndrome with several atypical features. The patient displayed many of the typical features, including cachectic bird-headed dwarfism, photodermatitis, normal pressure hydrocephalus, and extraphyramidal and pyramidal tract signs. However, she also displayed the unusual and previously unreported features of late age at onset, relative stability until age 19, and fertility, with a successful pregnancy. Brain biopsy showed hypomyelination, no active demyelination, and fibrillary gliosis.