Human pharmacokinetics of a perfluorocarbon ultrasound contrast agent evaluated with gas chromatography.

The purpose of this study was to prospectively study the human pharmacokinetics of an ultrasound (US) contrast agent through its active ingredient, dodecafluoropentane (DDFP). Expired air and blood samples were collected from 24 volunteers after IV administration from 0.01 to 0.1 mL/kg. They were analyzed by a gas chromatographic method specially adapted to the study of DDFP. Blood data fitted to an open one-compartment model. Elimination half-life range was 1.8 to 2.5 min. The area under the curve was correlated to the dose (r(2) = 0.99). Mean blood clearance ranged from 30 to 49 mL/min kg. Blood apparent distribution volume ranged from 0.09 to 0.15 L/kg. In expired air, DDFP concentration exhibited a biexponential decay. The percentage of recovery was 98 +/- 19% at 2 h. No extraneous peaks were observed, indicating no detectable DDFP metabolites. It was concluded that DDFP pharmacokinetics in blood fitted to an open one-compartment model with a fast elimination half-life. Recovery in expired air was almost complete 2 h after administration.

Formulation development and antitumor activity of a filter-sterilizable emulsion of paclitaxel.

PURPOSE: Paclitaxel is currently administered i.v. as a slow infusion of a solution of the drug in an ethanol:surfactant:saline admixture. However, poor solubilization and toxicity are associated with this drug therapy. Alternative drug delivery systems, including parenteral emulsions, are under development in recent years to reduce drug toxicity, improve efficacy and eliminate premedication. METHODS: Paclitaxel emulsions were prepared by high-shear homogenization. The particle size of the emulsions was measured by dynamic light scattering. Drug concentration was quantified by HPLC and in vitro drug release was monitored by membrane dialysis. The physical stability of emulsions was monitored by particle size changes in both the mean droplet diameter and 99% cumulative distribution. Paclitaxel potency and changes in the concentration of known degradants were used as chemical stability indicators. Single dose acute toxicity studies were conducted in healthy mice and efficacy studies in B 16 melanoma tumor-bearing mice. RESULTS: QW8184, a physically and chemically stable sub-micron oil-in-water (o/w) emulsion of paclitaxel, can be prepared at high drug loading (8-10 mg/mL) having a mean droplet diameter of <100 nm and 99% cumulative particle size distribution of <200 nm. In vitro release studies demonstrated low and sustained drug release both in the presence and absence of human serum albumin. Based on single dose acute toxicity studies, QW8184 is well tolerated both in mice and rats with about a 3-fold increase in the maximum-tolerated-dose (MTD) over the current marketed drug formulation. Using the B16 mouse melanoma model, a significant improvement in drug efficacy was observed with QW8184 over Taxol. CONCLUSIONS: QW8184, a stable sub-micron o/w emulsion of paclitaxel has been developed that can be filter-sterilized and administered i.v. as a bolus dose. When compared to Taxol, this emulsion exhibited reduced toxicity and improved efficacy most likely due to the composition and dependent physicochemical characteristics of the emulsion.

Preclinical evaluation of MnDPDP: new paramagnetic hepatobiliary contrast agent for MR imaging.

Manganese(II)-N,N'-dipyridoxylethylenediamine-N,N'-diacetate-5,5'-bis (phosphate) (MnDPDP) is a paramagnetic complex designed for use as a hepatobiliary agent. The T1 relaxivity of MnDPDP (2.8 [mmol/L]-1.sec-1 in aqueous solution) was similar to that of gadolinium diethylenetriaminepentaacetic acid (DTPA) (4.5 [mmol/L]-1.sec-1) and gadolinium tetraazocyclodecanetetraacetic acid (DOTA) (3.8 [mmol/L]-1.sec-1). However, in liver tissue the T1 relaxivity of MnDPDP (21.7 [mmol/L]-1.sec-1) was threefold higher than that reported for Gd-DOTA (6.7 [mmol/L]-1.sec-1). Maximum liver T1 relaxation enhancement occurred 30 minutes after injection of MnDPDP, at which time 54MnDPDP biodistribution studies indicated that 13% of total body activity was in the liver. Enhanced (MnDPDP, 50 mumol/kg) MR images showed a fivefold increase in tumor-liver contrast-to-noise ratio over baseline unenhanced images. Results of the authors' acute and subchronic toxicity studies suggest that MnDPDP will be safe at the doses necessary for clinical imaging; at 10 mumol/kg, the safety factor (LD50/effective dose) for MnDPDP is 540, significantly greater than the safety factor of Gd-DTPA (ie, 60-100).

Gadodiamide injection: nonionic gadolinium chelate for MR imaging of the brain and spine--phase II-III clinical trial.

Seventy-three patients with clinically suspected central nervous system abnormalities (44 intracranial, 29 medullospinal) were studied with magnetic resonance (MR) imaging before and after administration of nonionic gadodiamide injection. MR imaging showed intracranial lesions in 37 patients. Eight patients had spinal tumors, and 21 had disk disease. Structural abnormalities were shown in 37 of 44 head studies and in all 29 spine studies. Lesions enhancement was seen in 31 head studies and 28 spine studies, and distinction of lesion(s) from associated edema was possible in 10 head studies and in one study of intrinsic cord tumor. Administration of gadodiamide injection provided improved definition of lesion borders in 19 of 44 head studies and 26 of 29 spine studies. The use of the contrast agent changed the diagnosis that was based on the unenhanced images in nine head studies and 13 spine studies. Early postcontrast, T1-weighted spin-echo images of postoperative spines were adequate in distinguishing epidural scar (enhancing) from herniated disk (nonenhancing). The contrast agent was well tolerated, and no drug-related adverse events occurred.

The interaction between excimer laser energy and vascular tissue.

The effects of XeF1 excimer laser on isolated normal and atherosclerotic aorta were studied. Experiments were performed in flowing water at constant temperature, flow rate, water depth, pulse width (10 nsec), wavelength (351 nm), beam size (1 mm2) and focal length (50 cm). The number of pulses, the pulse energy, and the pulse frequency were varied, and the vascular tissue was studied histologically. The following observations were made: tissue ablation required a minimum threshold pulse energy and was nonlinearly proportional to the number of pulses and the pulse energy delivered; precise tissue ablation occurred at low pulse frequencies, but changes resembling a thermal process were seen as pulse frequency increased; calcified plaque was more photoresistant than atheroma or normal vessel; excimer laser energy was markedly attenuated by blood; and the time interval between pulses and high peak power are related to the precision of ablation by pulsed excimer laser. It is concluded that excimer laser can rapidly and precisely ablate vascular tissue by a photothermal process.

Biochemical studies of immune complexes. II. Purification of immune complexes from sera of patients with malignant melanoma.

Circulating immune complexes (CICs) from serum samples of patients with malignant melanoma were isolated in high yield utilizing a bifunctional chromatography matrix that binds all normal serum proteins except IgG-containing immune complexes (ICs), IgG, and transferrin. Protein fractions were subsequently analyzed by polyacrylamide gel electrophoresis (PAGE) and characterized by molecular weight. By this method, one common and several unique component nonimmunoglobulin proteins of the ICs were identified. These proteins possess similar molecular weights to several previously described human melanoma antigens. This technique should permit biochemical and immunological characterization of the component antigens of CICs in melanoma and other malignancies.

Papillary carcinoid tumor of the lung.

Carcinoid tumors of the lung have a wide histologic spectrum. The histologic differential diagnosis of papillary tumors in the lung generally does not include carcinoid. A carcinoid tumor that formed a discrete coin lesion on chest radiograph is presented in this report. On gross examination the center appeared and felt spongy. On microscopic examination delicate, compacted papillae were separated by a serpentine space continuous with air spaces at the periphery of the tumor. The papillae were each composed of a fibrovascular core, an undulating basement membrane separating stroma from epithelial cells, and cuboidal clear and dark cells that proved to be, respectively, healthy and degenerate cells of carcinoid tumor with neurosecretory granules. Upon the carcinoid cells, draped in the manner of an umbrella, were nonciliated, respiratory cells that proved to be Clara cells. The various histologic patterns of bronchopulmonary carcinoids and the differential diagnosis of papillary tumors within the lung are tabulated.

Carcinosarcoma of the skin. Case report and review.

A carcinosarcoma of the skin in a 74-year-old man is reported. The epithelial element consisted of a highly anaplastic basal cell carcinoma with focal keratinization. The mesenchymal component included elements of fibrosarcoma, chondrosarcoma, osteogenic sarcoma, and synovial sarcoma. This is, to our knowledge, the second reported case of carcinosarcoma arising in the skin.

Tumor shedding and coagulation.

Three syngeneic carcinomas from two species shed plasma membrane vesicles when cultured in vitro or grown in the ascites tumor form in vivo. Shed vesicles carry procoagulant activity that can account for the activation of the clotting system and the fibrin deposition associated with these and many other types of malignancy in animals and man.

Carcinosarcoma of the prostate: case report and review of the literature.

We report the third case of carcinosarcoma of the prostate. The epithelial element consisted of a highly malignant adenocarcinoma. The mesenchymal component was composed of malignant osteosarcoma and chondrosarcoma.

Contamination of Hodgkin's disease cell cultures.

Several laboratories have recently reported the establishment and characterization of long-term cell lines thought to be related to the neoplastic cell of Hodgkin's disease. Here, Harris et al. discuss evidence that some of these lines are, in fact, not related to Hodgkin's disease but are non-human contaminants.

Reaction of immune complexes with Hodgkin's disease tissue cultures: radioimmune assay and immunoferritin electron microscopy.

We examined the binding of soluble immune complexes in sera from patients with Hodgkin's disease to established tissue cultures derived from the tumor. Circulating immune complex levels were determined by the Raji cell assay, and the reaction of serum with cultured cells was examined with a radioimmune assay and by immunoferritin electron microscopy. Serum with elevated immune complexes was found to react with cells of Hodgkin's disease monolayers when tested with radioiodine-labeled antisera against human IgG heavy and light chains and the complement 3 (C3) component. When examined with the electron microscope, monolayers incubated with Hodgkin's disease serum containing immune complex and labeled with ferritin-conjugated antiserum to C3 contained surface-bound ferritin particles with a uniform but discontinuous pattern. Absorption of Hodgkin's disease serum with monolayer cells reduced immune complexes and decreased reactivity of the sample with cultured cells by radioimmune assay. Sera of patients with other disorders and aggregated gamma-globulin with complement, despite markedly elevated immune complex levels, did not react positively with monolayers derived from Hodgkin's disease tumors, and none of the sera reacted with normal cultured spleen. The approximate size of serum components reacting with Hodgkin's disease monolayers was estimated by sucrose density gradient centrifugation. Sedimentation fractions in the 19S region reacted with monolayer cells when tested with 125I-labeled antisera to both IgG and C3 and contained immunoglobulin-complement complexes by gel diffusion and immunoabsorption. A component sedimenting at 7-9S contained immunoglobulin not complexed with complement; this component reacted with monolayer cells when tested with anti-IgG antiserum but did not react when tested with antibody to C3. The reaction of Hodgkin's disease monolayers with serum containing immune complexes differed from that of two suspension culture lines composed of cells with surface complement and IgG Fc receptors. Inasmuch as cells of our long-term Hodgkin's disease monolayers do not contain these surface receptors, possibly the antibody component of the immune complex reacts with antigens on the surface of cultured cells.

Regulation of amino acid transport in Escherichia coli by transcription termination factor rho.

Amino acid transport rates and amino acid binding proteins were examined in a strain containing the rho-120 mutation (formerly SuA), which has been shown to lower the rho-dependent, ribonucleic acid-activated adenosine triphosphatase activity to 9% of the rho activity in the isogenic wild-type strain. Tryptophan and proline transport, which occur by membrane-bound systems, were not altered. On the other hand, arginine, histidine, leucine, isoleucine, and valine transport were variably increased by a factor of 1.4 to 5.0. Kinetics of leucine transport showed that the LIV (leucine, isoleucine, and valine)-I (binding protein-associated) transport system is increased 8.5-fold, whereas the LIV-II (membrane-bound) system is increased 1.5-fold in the rho mutant under leucine-limited growth conditions. The leucine binding protein is increased fourfold under the same growth conditions. The difference in leucine transport in these strains was greatest during leucine-limited growth; growth on complex media repressed both strains to the same transport activity. We propose that rho-dependent transcriptional termination is important for leucine-specific repression of branched-chain amino acid transport, although rho-independent regulation, presumably by a corepressor-aporepressor-type mechanism, must also occur.

Glucose uptake and phosphorylation in Pseudomonas fluorescens.

Pseudomonas fluorescens ATCC 13525 and a particulate glucose oxidase (d-glucose:oxygen oxidoreductase, EC 1.1.3.4) mutant of this organism, gox-7, were examined to determine if glucose oxidation via particulate glucose oxidase is a required first step for glucose uptake. Initial [(14)C]glucose-uptake rates in parent and gox-7 cells were qualitatively similar. Initial [(14)C]glucose-uptake product analysis revealed that glucose was accumulated via active transport and was rapidly metabolized to glucose-6-phosphate and gluconate-6-phosphate in both parent and gox-7 cells. Cell extracts contained soluble adenosine 5'-triphosphate specific kinase activity for phosphorylation of glucose. Glucose uptake was induced by glucose and not gluconate, thus, establishing independent regulation of glucose transport and glucose catabolism in p. fluorescens. The results prove that glucose oxidase was not an obligatory reaction for glucose carbon permeation in P. fluorescens. A general unifying scheme for glucose utilization in the aerobic fluorescent pseudomonads is suggested for the purpose of clarifying glucose uptake in these bacteria.