In vivo biodistribution of carboxymethylchitosan/poly(amidoamine) dendrimer nanoparticles in rats

Carboxymethylchitosan/poly(amidoamine) (CMCht/PAMAM) dendrimer nanoparticles, comprised of a PAMAM dendrimer core grafted with chains of CMCht, have recently been proposed for intracellular drug delivery. In previous reports, these nanoparticles had lower levels of cytotoxicity when compared with traditional dendrimers. In this study, the short-term in vivo biodistribution of fluorescein isothiocyanate (FITC)-labeled CMCht/PAMAM dendrimer nanoparticles after intravenous (IV) injections in Wistar Han rats was determined. The brain, liver, kidney, and lung were collected at 24, 48, and 72 h after injection and stained with phalloidin–tetramethylrhodamine isothiocyanate (TRITC, red) and 4′,6-diamidino-2-phenylindole dihydrochloride (DAPI, blue) to trace the nanoparticles within these tissues. The liver, kidney, and lung were also stained for hematoxylin and eosin to assess any morphological alterations of these organs. CMCht/PAMAM dendrimer nanoparticles were observed within the vascular space and parenchyma of liver, kidney, and lung and in the choroid plexus, after each injection period. No particles were observed in the brain parenchyma, nor any apparent deleterious histological changes were observed within these organs. The CMCht/PAMAM dendrimer nanoparticles were stable in circulation for a period of up to 72 h, targeting the main organs/systems through internalization by the cells present in their parenchyma. These results provide positive indicators to their potential use in the future as intracellular drug delivery systems.

Analysis of urinary metanephrines by reversed-phase high-performance liquid chromatography and electrochemical detection

A sensitive and specific direct analysis of urinary normetanephrine (NMN) and metanephrine (MN) was achieved utilizing reversed-phase high performance liquid chromatography and electrochemical detection. Individual specimens from "control" subjects and those with pheochromocytoma were hydrolyzed and the metanephrines separated from other urinary constituents by elution with ammonia from a Dowex CG-50 resin. Chromatographic peaks were identified by retention behavior, co-chromatography with reference compounds, ratio of responses at various oxidation potentials and stopped-flow UV spectra of the collected fractions. The NMN and MN content for the control subjects was between 0.086 and 0.21 (mean - 0.14) microgram/mg creatinine and 0.012 and 0.092 (mean = 0.039) microgram/mg creatinine, respectively. The values for subjects with pheochromocytoma varied from 1.5 to 27.5 (mean = 9.9) microgram/mg creatinine for NMN and 0.10 to 1.60 (mean = 0.86) microgram/mg creatine for MN. The patient with ganglioneuroma had an NMN of 4.1 and an MN of 0.80 microgram/mg creatinine. While this method permits discrimination between those patients with pheochromocytoma and the overwhelming majority of hypertensive patients, it may ultimately be further extended to separate normal subjects from those with more subtle derangements in catecholamine metabolism.

Endogenous levels of free and conjugated urinary 3-methoxy-4-hydroxyphenylethyleneglycol in control subjects and patients with pheochromocytoma determined by reversed-phase liquid chromatography with electrochemical detection

A sensitive and specific reversed-phase liquid-chromatography (HPLC) method for the determination of urinary free and conjugated 3-methoxy-4-hydroxyphenylethyleneglycol (MHPG) was developed. Sample preparation is minimal and the method is ideally suited for routine clinical assays of this catecholamine metabolite. Reported in this paper are excretion profiles of controls subjects and patients with pheochromocytoma. Quantitative results were expressed as microgram MHPG per mg creatinine, in order to eliminate variations associated with the 24-h urine collection. The levels of free and conjugated MHPG, determined in 20 control subjects ranged between 0.04--0.11 microgram/mg of creatinine and 0.48--1.25 microgram/mg of creatinine, respectively. The corresponding levels of free and conjugated MHPG in 8 patients with pheochromocytoma were 0.29--1.21 microgram/mg of creatinine and 2.47--15.98 microgram/mg of creatinine, respectively. The described liquid-chromatographic analysis, coupled with the highly sensitive electrochemical detection, provides a simple and reliable method for metabolic profiling of catecholamine by-products at their endogenous levels. This offers an attractive possibility for the detection of neural crest lesions which may cause problems in diagnosis because of their small size, infrequent occurrence and symptoms similar to those of essential hypertension.