Ultrasensitive Fluorescence Detection of Alzheimer's Disease Based on Polyvalent Directed Peptide Polymer Coupled to a Nanoporous ZnO Nanoplatform.

Amyloid-beta 42 (Aß42), the key biomarker of Alzheimer's disease (AD), aggregates to form neurotoxic amyloid plaques. In this work, we modified two fluorescein isothiocyanate-labeled Aß42-targeting peptides and designed an Aß42-specific ultrasensitive polyvalent-directed peptide polymer (PDPP) to enhance AD diagnosis sensitivity. The dissociation constant of Aß42 by PDPP was 103-fold higher than the single-site-directed peptide. The improved binding was due to the ability of PDPP to detect multiple receptors on the target. The power of the PDPP diagnostic probe was verified in its application to detect Aß42 in cerebrospinal fluid (CSF), which showed a lower limit of detection (LOD) in the fg mL-1 range that is more sensitive than detection by antibodies or single peptides. In addition, we present a novel ultrasensitive diagnostic system using an array of nanoporous ZnO nanoparticles, which play a role in fluorescence signal amplification, to further improve AD diagnosis sensitivity. We enhanced the signal on the basis of the properties of nanoporous ZnO nanoparticles and measured and quantified an ultralow concentration (ag mL-1 range) of Aß42. This PDPP coupled to the nanoporous ZnO-based system is a novel approach to AD diagnosis that might also be useful for the detection of other target biomarkers and clinical applications.

A New Platform for Profiling Degradation-Related Impurities Via Exploiting the Opportunities Offered by Ion-Selective Electrodes: Determination of Both Diatrizoate Sodium and Its Cytotoxic Degradation Product.

Although the ultimate goal of administering active pharmaceutical ingredients (APIs) is to save countless lives, the presence of impurities and/or degradation products in APIs or formulations may cause harmful physiological effects. Today, impurity profiling (i.e., the identity as well as the quantity of impurity in a pharmaceutical) is receiving critical attention from regulatory authorities. Despite the predominant use of spectroscopic and chromatographic methods over electrochemical methods for impurity profiling of APIs, this work investigates the opportunities offered by electroanalytical methods, particularly, ion-selective electrodes (ISEs), for profiling degradation-related impurities (DRIs) compared with conventional spectroscopic and chromatographic methods. For a meaningful comparison, diatrizoate sodium (DTA) was chosen as the anionic X-ray contrast agent based on its susceptibility to deacetylation into its cytotoxic and mutagenic degradation product, 3,5-diamino-2,4,6 triiodobenzoic acid (DTB). This cationic diamino compound can be also detected as an impurity in the final product because it is used as a synthetic precursor for the synthesis of DTA. In this study, four novel sensitive and selective sensors for the determination of both DTA and its cytotoxic degradation products are presented. Sensors I and II were developed for the determination of the anionic drug, DTA, and sensors III and IV were developed for the determination of the cationic cytotoxic impurity. The use of these novel sensors not only provides a stability-indicating method for the selective determination of DTA in the presence of its degradation product, but also permits DRI profiling. Moreover, a great advantage of these proposed ISE systems is their higher sensitivity for the quantification of DTB relative to other spectroscopic and chromatographic methods, so it can measure trace amounts of DTB impurities in DTA bulk powder and pharmaceutical formulation without a need for preliminary separation.

Do iodinated nano-emulsions designed for preclinical vascular imaging alter the vascular reactivity in rat aorta?

This study proposes a new methodology to evaluate the putative consequences of the long-lasting circulation in the blood pool of nanoparticulate systems widely used in nanomedicine, Indeed, the blood pool contrast agent for micro-computed tomography, i.e. iodinated nano-emulsions, have recently been developed, for their great potential in medical applications such as advanced diagnosis, image-guided surgery, personalized medicine or theragnostics. Stealth nanoparticles exhibit a low recognition by the reticuloendothelial system, resulting in a prolonged circulation in the bloodstream and long-lasting contact with the endothelium. Therefore, the aim of the present study is to determine whether this prolonged interaction could induce an alteration of the vascular reactivity in rat aorta. The Iodinated nano-emulsions were intravenously injected in anesthetized rats. After 1h of contrast agent circulation in the blood pool, the thoracic aorta was removed for the study of vascular reactivity. These animals were compared with control (untreated) rats and a third group of rats receiving an injection of phosphate buffered saline (i.e. dispersing phase of the nano-emulsions). Phenylephrine-induced concentration-dependent contractions of the isolated rat thoracic aorta were not modified whatever the group. Sodium nitroprusside (a nitric oxide (NO) donor)-induced relaxations of endothelium-denuded aorta were also unaltered in response to the different administrations. In contrast, in comparison with control animals, endothelium-dependent NO-mediated relaxations to acetylcholine were significantly impaired in thoracic aorta from PBS-treated rats, but not in animals receiving the iodinated nano-emulsion. In addition, neither isoprenaline-induced nor levcromakalim-induced relaxations were modified in the aorta from the three groups of animals. These findings indicate that even with a long-lasting residence time of the iodinated nano-emulsion in the blood flow, these iodinated nano-emulsions do not alter the vascular reactivity and thus can be used as contrast agent for preclinical vascular imaging on small laboratory animals.

Comparison of liver perfusion parameters studied with conventional extravascular and experimental intravascular CT contrast agents.

RATIONALE AND OBJECTIVES: To compare liver perfusion parameters obtained by using an extravascular contrast agent and a blood-pool agent. MATERIALS AND METHODS: Fifteen rabbits were imaged with a continuous 40-second single-slice computed tomography acquisition after a bolus injection of contrast agent (physiologic bolus duration 4-5 seconds, extravascular iohexol, n = 7; experimental nanoparticulated blood-pool agent WIN8883, n = 8). Time-density curves were generated for the aorta, portal vein, and liver. From the curves, arterial, portal, and total blood flows and hepatic perfusion index (HPI, arterial-to-total perfusion ratio) were determined by using two commonly applied fundamentally different analyzing methods: the single-compartment model and the peak gradient (PG) method. Also, the gamma variate fitting method was used. RESULTS: By using the single-compartment model, the obtained HPI and total blood flow were 0.14 +/- 0.04 and 2.29 +/- 0.40 (mL/min/mL(tissue)) for WIN8883, and 0.15 +/- 0.06 (P = .54) and 4.60 +/- 1.14 (mL/min/mL(tissue)) (P = .0002) for iohexol, respectively. With the PG, HPI and total blood flow were 0.15 +/- 0.08 and 1.27 +/- 0.24 (mL/min/mL(tissue)) for WIN8883, and 0.20 +/- 0.06 (P = .12) and 2.11 +/- 0.25 (mL/min/mL(tissue)) (P = .00002) for iohexol, respectively. With the blood pool agent, similar contrast enhancement to the conventional agent was achieved with about 36% reduced dosage of iodine per body weight (mg I/kg). CONCLUSIONS: HPI was found to be quite insensitive to different contrast agent types and analyzing methods. However, the arterial, portal and total liver blood flow values strongly depend on contrast agent type and modeling method.

[Which imaging in case of sigmoid diverticulitis? The value of ultrasound (Conventional B-mode in combination with hydrocolonsonography and colour flow Doppler) in comparison to the well-established modalities like contrast enema and helical computertomography]. / Welche bildgebende Diagnostik bei Verdacht auf eine Sigmadivertikulitis? - Wertigkeit der sonographischen Untersuchungsverfahren (konventionelle B-Bild-Diagnostik in Kombination mit der Hydrokolonsonographie und der farbkodierten Duplexsonographie) im Vergleich mit den etablierten Verfahren wie dem Kolon-Kontrasteinlauf und der Spiral-Computertomographie -

Sigmoid diverticulitis is in case of complications like perforation, abscess and peritonitis a life-threatening disease. A diagnostic work up with high sensitivity is mandatory. In a prospective study upon 247 patients with the possible diagnosis of acute diverticulitis ultrasound is a screening method with a high specificity (97 %) and leads in combination with the hydrocolonsonography and the colour flow doppler to a high sensitivity (76 %). Without any typical findings in ultrasound, helical CT scan is the best method in the evaluation of the acute diverticulitis (sensitivity and specificity 100 %), because contrast enema is inferior to CT in the evaluation of abscesses (6 %) and perforation (53 %). CT has in case of perforation and of abscesses a sensitivity of 90 % and 100 %, while ultrasound has a sensitivity of 12 % to perforation and of 39 % to abscesses.

Physical stability of ethyl diatrizoate nanocrystalline suspension in steam sterilization.

PURPOSE: To study the effects of formulation variables on the physical stability of a submicron crystal (nanocrystal) suspension under steam sterilization conditions. METHODS: Suspensions of ethyl diatrizoate nanocrystals were prepared by wet milling in the presence of the surfactant poloxamine 908. Particle size distribution and zeta potential were measured by photon correlation spectroscopy. RESULTS: On heating, the mean particle size of the nanocrystal suspension remained essentially unchanged up to 110 degrees C, the cloud point of the stabilizing surfactant, but increased significantly above that temperature. The increase in particle size was a result of particle aggregation rather than crystal growth. Adding a cloud point booster to the suspension significantly minimized the particle aggregation at high temperatures. The purity of poloxamine 908 and the tonicity agent and buffer salt used also affected the heat stability of the suspension, the latter agents apparently through altering the surfactant cloud point. CONCLUSIONS: The aggregation of the ethyl diatrizoate nanocrystalline suspension under steam sterilization conditions was a result of phase separation of the stabilizing surfactant at its cloud point. When formulated with a cloud point booster to prevent the phase-separation, the suspension maintained its physical stability under steam sterilization without any significant change in particle size distribution.

Assay and purity analysis of diatrizoate sodium in drug product by LC.

An LC procedure was developed to separate diatrizoate sodium from three known impurities. These impurities are 2,4- and 2,6-diiodo-3,5-diacetamidobenzoic acid (DDZA), and the free amine (5-acetamido-3-amino-2,4,6-triiodobenzoic acid). The separation was achieved using a Hamilton, PRP-X100, anion exchange column. The retention of diatrizoate sodium and the impurities was dependent on pH, potassium chloride concentration and phosphate concentration. Increasing any of these mobile phase modifiers decreased the retention time of all of the components. The eluent for assay and purity determination of drug product consisted of 0.1 M potassium chloride and 0.05 M potassium phosphate dibasic in water/acetonitrile (900:100). The mean concentration of diatrizoate sodium in Hypaque Sodium 50% determined over 3 days was 102.3% of label claim with an R.S.D. of 1.3. The accuracy of the purity method, determined by spiking known amounts of the impurities at five concentrations ranging from 0.025 to 0.06% (w/w) into drug product, was 100.1% for DDZA and 94.2% for the free amine. The decomposition of diatrizoate sodium in 0.1 N potassium hydroxide at 85 degrees C followed pseudo first-order kinetics. The calculated half-life was 2 days.

Functional CT with an experimental intravascular contrast agent in the assessment of liver vascular physiology.

RATIONALE AND OBJECTIVES: We evaluated liver vascular physiology with a functional spiral computed tomography (CT) technique and an intravascular contrast agent. METHODS: Eleven rabbits were studied by means of continuous 40-second single-section data acquisition after bolus injection of an experimental contrast agent. Sequential images were reconstructed at 200-msec intervals. Aortic, portal and hepatic venous, and liver time-HU curves were obtained. From these, hepatic blood volume and flow, tissue transit times, and arterial and portal contributions to total liver blood supply were assessed. RESULTS: The following measures were obtained: hepatic blood volume fraction, 0.33 +/- 0.03 (mean +/- standard error); total flow, 241.1 mL/min +/- 33.6 per 100 g of tissue (arterial component, 11.3 mL/min +/- 3.0 per 100 g of tissue; portal component, 226.4 mL/min +/- 30.7 per 100 g of tissue); arterial transit time, 8.7 seconds +/- 1.6; portal transit time, 8.7 seconds +/- 1.3; arterial to portal perfusion ratio, 0.06 +/- 0.01; and calculated arterial and portal perfusion indexes, 0.05 +/- 0.01 and 0.95 +/- 0.01, respectively. CONCLUSION: Functional CT is a promising, high-resolution tomographic imaging technique for evaluating liver perfusion.

Indirect computed tomography lymphography of subdiaphragmatic lymph nodes using iodinated nanoparticles in normal dogs.

RATIONALE AND OBJECTIVES: We evaluated the imaging characteristics of an iodinated particulate contrast agent for indirect computed tomography (CT) lymphography of normal subdiaphragmatic lymph nodes in dogs. METHODS: Four milliliters of a 15% (wt/vol) iodinated nanoparticle suspension was injected into the gastric, colonic, rectal, or cervical submucosa, loose paraprostatic fascia, or metatarsal subcutaneous tissues in 10 healthy beagles. Endoscopic, CT, or ultrasound guidance was used when necessary to facilitate contrast agent delivery. CT and radiographic images were obtained prior to contrast administration and at 4 hr, 24 hr, and 7 days postcontrast injection. Postmortem examinations were then conducted. RESULTS: CT images showed enhancement of regional lymph nodes draining the various injection sites. The mean attenuation of opacified nodes was 678 +/- 463 Hounsfield units 24 hr after injection and remained elevated 7 days later. Lymph node opacification on CT images correlated well with the node location observed on postmortem examinations. CONCLUSION: Subdiaphragmatic lymph nodes can be effectively opacified using an iodinated nanoparticle contrast agent for indirect CT lymphography.

Percutaneous computed tomography lymphography in the rabbit by subcutaneously injected nanoparticulates.

RATIONALE AND OBJECTIVES: Surgical lymphangiography is infrequently used in staging cancer because of its inherent limitations. Radiopaque nanoparticulates target lymph nodes draining interstitial tissues and could make percutaneous lymphography feasible. METHODS: Experimental nanoparticulate contrast agent formulations were injected subcutaneously in the forepaw or hindpaw of normal rabbits or rabbits with induced reactive nodal hyperplasia. Axillary and popliteal nodes were imaged with thin-section computed tomography (CT) using quantitative methods to measure node enhancement. Dose-response (0.1-2.0 ml) and time course (4 hr to 10 weeks) of enhancement were assessed. RESULTS: Nodal enhancement above 100 Hounsfield units was consistently obtained. Enhancement was significantly related to dose and peaked at 10 hr with slow washout over the observation period. Nodes with reactive hyperplasia were larger and had heterogeneous enhancement patterns distinctly different from normal nodes. CONCLUSION: Percutaneous CT lymphography effectively depicts the macroscopic intranodal architecture in rabbits.

Iodinated nanoparticles for indirect computed tomography lymphography of the craniocervical and thoracic lymph nodes in normal dogs.

RATIONALE AND OBJECTIVES: We evaluated the imaging characteristics of an interstitially or intraperitoneally delivered iodinated particulate contrast agent for computed tomography (CT) lymphography of the craniocervical and thoracic lymph nodes. METHODS: We injected 2-4 ml of 15% wt/vol iodinated nanoparticle suspension subcutaneously, submucosally, or intraperitoneally in eight normal dogs. CT and plain radiographic images were obtained prior to contrast administration and 4 hr, 24 hr, and 7 days after injection. Correlation was made to detailed postmortem assessment. RESULTS: CT images showed enhancement of regional nodes draining injection sites. Mean attenuation of opacified nodes was 313 +/- 297 (mean +/- standard deviation), 536 +/- 453, and 492 +/- 372 Hounsfield units at 4 hr, 24 hr, and 7 days postinjection, respectively. Lymph node opacification on CT images correlated well with node location found at postmortem. CONCLUSION: Craniocervical and thoracic lymph nodes can be effectively opacified from interstitial or intraperitoneal delivery of this iodinated nanoparticulate contrast agent.

[Inter-individual testing of water-soluble oral contrast media with reference to their diagnostic value, side effects and taste]. / Interindividuelle Prüfung wasserlöslicher oraler Kontrastmittel hinsichtlich diagnostischer Wertigkeit, Nebenwirkungen und Geschmack.

Three groups of patients (n = 55, 53 and 54) were examined with the x-ray contrast media Gastrografin, Peritrast-Oral GI, and Telebrix Gastro and Telebrix Gastroo assess the diagnostic ranking, side effects and taste of water-soluble oral contrast media. No significant differences were seen in respect of diagnostic ranking and side effects. Side effects were exclusively abdominal symptoms; there was no difference with regard to laxative action. Telebrix Gastroas accepted significantly better in respect of taste than Gastrografin and Peritrast-Oral GI.

Renografin-60 for urography: effect on serum electrolytes and proteins in adults.

A prospective study was done on 27 adults to assess the changes in serum electrolytes and proteins induced by bolus administration of 100 ml of the ionic contrast medium diatrizoate meglumine and sodium (Renografin-60) for IV urography. Statistically significant changes in serum sodium, chloride, potassium, calcium, bicarbonate, phosphate, total proteins, and albumin were shown at 5 min postinjection. The mean percentage decreases were sodium 2%, chloride 2%, potassium 9%, calcium 13%, bicarbonate 9%, phosphate 10%, and proteins 15%. A mean 3% increase in serum osmolality was observed. By 30 min, sodium and chloride levels had returned to baseline; potassium, calcium, and albumin values were incompletely recovered; bicarbonate was not significantly changed from 5 min; and phosphate values continued to decrease. An in vitro dialysis experiment in which different volumes of Renografin-60 were dialysed against an electrolyte solution (pseudoserum) produced a dilutional factor of 5 to render a given volume of the contrast isoosmotic with plasma. The observed changes from the baseline values of the electrolytes and proteins up to 10% are therefore assumed to be due to hemodilution resulting from movement of fluid from the extravascular to the intravascular compartment. This study confirms alterations in serum levels of several electrolytes after the use of ionic contrast media beyond simple hemodilution. Although these changes appear not to be clinically significant in this investigation, the alterations in potassium and calcium may contribute to arrhythmias, particularly when hypokalemia or hypocalcemia preexists.

Early diagnosis and intrauterine therapy of meconium plug syndrome in the fetus: risks and benefits.

Two cases are reported of patients in the third trimester of pregnancy in whom routine ultrasound examination revealed progressive dilatation of the fetal intestines. Intestinal obstruction was suspected and amniocentesis as well as amniography with Urografin were done. In both cases a regression in dilatation of bowel was noted on ultrasonography. The Urografin swallowed by the fetus was deemed to have relieved the obstruction of the fetal intestine. The babies were delivered in good condition and passed large amounts of watery meconium per rectum. In spite of the risks inherent in the use of Urografin amniography, as well as of amniocentesis, there appear to be a great number of advantages to the treatment of meconium obstruction of the fetus in utero.

Effects of contrast media on cultured myocardial cells.

To quantify and characterize mechanisms of negative inotropic effects of ionic and nonionic angiographic contrast media, spontaneously contracting monolayers of cultured chick ventricular cells were studied using the Renografin-76 and iohexol as characteristic ionic and nonionic contrast agents. Utilizing microscopic video-motion detector techniques the effect of each contrast agent on contraction amplitude was measured. Also, the effect of changes in the ionized calcium concentration and osmolality induced by the contrast agents was evaluated. The study demonstrated a linear depression of contractility by increasing contrast concentrations. The negative inotropic effect of Renografin-76 was significantly greater than that of iohexol. Renografin-76 demonstrated significant calcium binding, whereas iohexol had none. Correction for calcium binding by Renografin-76 partially reversed the negative inotropic effect of this agent. Hypertonic sugar solutions of equivalent osmolality to the contrast agents demonstrated dose-related negative inotropic effects such that, in this preparation, calcium binding by Renografin-76 and its high osmolality accounted for all its negative inotropic effect. In contrast, iohexol demonstrated an intrinsic negative inotropic effect not completely explained by its osmolality.

High- and low-osmolar contrast agents in urography: a comparison of the appearances with respect to pyelotubular opacification and renal length.

The incidence of pyelotubular opacification and the change in renal length during intravenous urography with iohexol (Omnipaque) was compared with sodium/meglumine diatrizoate (Urografin). Pyelotubular opacification was seen in 14 out of 29 urograms performed with iohexol compared with one out of 28 urograms performed with sodium/meglumine diatrizoate. This increased incidence is statistically significant and has not been previously documented. The increase in renal length following intravenous contrast medium was similar for both iohexol and sodium/meglumine diatrizoate. The significance of these findings with respect to the interpretation of urograms performed with iohexol is discussed.