Immunoliposomes as targeted delivery vehicles for cancer therapeutics (Review)

Advances in liposome technology over the last decade has seen the development of stealth liposomes for drug delivery and cationic liposomes for gene delivery. Many of these liposome formulations are now in clinical trials for the treatment of a variety of malignancies. Whilst some clinical efficacy has been demonstrated, the goal of specific tumor targeting is yet to be attained. For this reason, antibodies have been attached to the surface of liposomes to produce immunoliposomes. These liposomes have shown preferential binding to specific tumor cells in animal models. The construction of the immunoliposome, and in particular the optimal method of antibody coupling to its surface is, however, yet to be determined. Despite these difficulties, immunoliposomes have demonstrated anti-tumor properties, both in vitro and in vivo, and show great promise as targeted delivery vehicles for the treatment of cancer.     

Hormone dependence of breast cancer cells and the effects of tamoxifen and estrogen:31P NMR studies

Many breast tumors appear to progress from estrogen-dependent growth to a more malignant phenotype characterized by estrogen-independent growth, antiestrogen resistance, and a high metastatic potential. Utilizing³¹P NMR spectroscopy on human breast cancer cells growingin vitro, we have investigated the effects of 17-estradiol and tamoxifen on the metabolic/bioenergetic spectra of a series of human breast cancer cells that vary in their estrogen and antiestrogen responsiveness. A comparison of baseline spectra associates higher levels of phosphodiesters and UDP-glucosides (e.g. UDP-glucose, UDP-N-acetylglucosamine), and lower phosphocholine/glycerylphosphocholine and phosphocholine/phosphoethanolamine ratios, with the acquisition of estrogen-independent growth in estrogen receptor expressing cells. No metabolic changes are clearly associated with the metastatic phenotype. Whilst estrogen treatment produces no consistently significant spectral changes in any of the cell lines, the estrogen-independent and estrogen-responsive MCF7/MIII cell line responds to tamoxifen treatment by significantly increasing all spectral resonances 30%-40% above baseline values. This may reflect a tamoxifen-induced change to a more differentiated or apoptotic phenotype, or an attempt by the cells to reverse the inhibitory effects of the drug. The ability to detect metabolic changes in response to tamoxifen by NMR spectroscopy may provide a novel means to identify those tumors that are responsive to antiestrogen therapy.Abbreviations CCS-IMEM steroid-deprived Improved Minimal Essential Medium - E2 17-estradiol - ER estrogen receptor - P_i inorganic phosphate - GPE glyceryl-phosphoethanolamine - GPC glyceryl-phosphocholine - PC phosphocholine - PE phosphoethanolamine - PDE phosphodiesters - PME phosphomonoesters - TAM tamoxifen (trans-1-(4--dimethylaminoethoxyphenyl)-1,2-diphenylbut-1-ene) - UDPG uridine diphosphoglycoside     

Multileafkollimator: Erweiterte Qualit?tssicherung an einem GE-Linearbeschleuniger

Hintergrund: Ein Multileafkollimator stellt durch die Vielzahl der Lamellen sehr viel höhere Ansprüche an die Konstanzprüfverfahren als ein konventionelles Blendensystem. Zur täglichen Kontrolle der Lamellenpositionierung wird ein Qualitssicherungskonzept vorgestellt. Methode: Zwei Feldkonfigurationen, die bei maximaler Öffnung der Blockblenden sowohl maximale Öffnung als auch "Overtravel" einzelner Lamellen enthalten, werden in täglichem Wechsel online vom Verifikationssystem zum Linearbeschleuniger übertragen. Im Lichtfeld des Linearbeschleunigers erfolgt eine visuelle Kontrolle der Lamellenpositionen mit Hilfe eines speziellen Prüfkörpers. Abschließend wird die Lamellenpositionierung mittels eines Electronic-Portal-Imaging-Systems dokumentiert und nach Überlagerung eines Gitters mit einer Referenzaufnahme verglichen. Ergebnisse: Die Methode stellt eine schnelle und effektive Möglichkeit dar, die Funktionsfähigkeit des gesamten Systems durch Simulation des "Routinebetriebs" zu überprüfen. Schlußfolgerung: Der Arbeits- und Zeitaufwand für die Qualitätssicherung an einem Multileafkollimator unterscheidet sich nur unwesentlich von dem eines konventionellen Blendensystems. Background: In comparison to a conventional collimator, a multileaf collimator demands a great deal of quality assurance procedures due to its large number of leaves. A concept for daily quality assurance is presented, mainly concerning the positioning accuracy of the leaves. Material and Methods: Two leaf configurations including maximal opening as well as overtravel of single leaves, at a maximal opening of the jaws, are transmitted online in daily exchange from our record- and verify system to the linac. Aiming at a special test phantom a visual control of the positioning accuracy is performed. The leaf positioning is documented by an electronic portal imaging system and is compared with a reference shot by superposition of a grid. Results: This method of quality assurance offers a fast and effective possibility to guarantee the proper function of the whole system by simulating the routine treatment situation. Conclusions: Compared to a conventional collimator only a slightly greater workload is needed for quality assurance of a multileaf collimator.     

Physicochemical Characterization of Protein-Free Low Density Lipoprotein Models and Influence of Drug Loading

Purpose. Drug free and drug loaded protein-free low density lipoprotein (LDL) models consisting mainly of phospholipids, cholesterol, cholesterol esters, and triglycerides in ratios found for physiological LDL have been prepared. Their physicochemical characteristics were compared with those of physiological LDL. Methods. Different characterization methods were used: photon correlation spectroscopy, transmission electron microscopy, X-ray solution scattering, and ¹H nuclear magnetic resonance spectroscopy (NMR). Results. Particle sizes are highly dependent on the preparation method and in particular on the homogenization conditions. Electron microscopy indicates that the size distributions of model systems are much broader than those of physiological LDL. The X-ray solution scattering patterns of the model systems display a temperature dependent maximum near 3.8 nm similar to that found in the patterns of physiological LDL. NMR indicates a comparable mobility of the lipid molecules in model particles and in physiological LDL. The influence of drug loading is similar to that found earlier for physiological LDL. In particular, the incorporation of the anti-cancer drug WB 4291 seems to have a fluidizing effect on the lipids in the core region of the particles. Conclusions. The preparation method of LDL model systems is of crucial importance as only the solvent evaporation method yielded systems in the size range of physiological LDL with acceptable high lipid concentrations. The fluidizing influence of temperature and drug incorporation (WB 4291) may be a disadvantage in drug targeting.     

Abrin Poisoning

Abrin is a toxic protein obtained from the seeds of Abrus precatorius (jequirity bean), which is similar in structure and properties to ricin. Abrin is highly toxic, with an estimated human fatal dose of 0.1–1 µg/kg, and has caused death after accidental and intentional poisoning. Abrin can be extracted from jequirity beans using a relatively simple and cheap procedure. This satisfies one criterion of a potential chemical warfare agent, although the lack of large scale production of jequirity seeds means that quantity is unavailable for ready mass production of abrin for weapons. This contrasts with the huge cultivation of Ricinus seeds for castor oil production. At the cellular level, abrin inhibits protein synthesis, thereby causing cell death. Many of the features observed in abrin poisoning can be explained by abrin-induced endothelial cell damage, which causes an increase in capillary permeability with consequent fluid and protein leakage and tissue oedema (the so-called vascular leak syndrome). Most reported cases of human poisoning involve the ingestion of jequirity beans, which predominantly cause gastrointestinal toxicity. Management is symptomatic and supportive. Experimental studies have shown that vaccination with abrin toxoid may offer some protection against a subsequent abrin challenge, although such an approach is unlikely to be of benefit in a civilian population that in all probability would be unprotected.     

Vaccination of patients with advanced ovarian carcinoma with the anti-idiotype ACA125: immunological response and survival (phase Ib/II).

PURPOSE: A Phase I/IIb multicenter study was conducted to evaluate the safety and immunogenicity of the anti-idiotypic antibody vaccine ACA125 that functionally imitates the tumor antigen CA125 in 119 patients with advanced ovarian carcinoma. A preliminary report on the initial 42 patients demonstrated safety and immunogenicity. EXPERIMENTAL DESIGN: Using the complete intention-to-treat population (n = 119) who received a mean of 9.7 ACA125 applications, survival was analyzed with respect to immunological responses. RESULTS: In 81 patients (68.1%), a specific anti-anti-idiotypic antibody (Ab3) response could be induced. Additionally, the development of CA125-specific antibodies (Ab1') and antibody-dependent cell-mediated cytotoxicity of CA125-positive tumor cells was observed in 50.4% and 26.9% of patients, respectively. The median survival of all patients was 19.4 months (range, 0.5-56.1 months). Ab3-positive patients showed a significantly longer survival (median, 23.4 months; P < 0.0001) as compared with Ab3-negative patients (median, 4.9 months). A positive Ab3 response remained associated with longer survival when controlling for other prognostic factors including FIGO (International Federation of Gynecologists and Obstetricians) stage, response to and type of first-line chemotherapy, number of previous treatments, or concomitant antitumor therapy. With regard to safety, repeated vaccination was well tolerated. No serious adverse events related to the application of ACA125 occurred. CONCLUSIONS: Although the uncontrolled design of this study prevents definitive conclusions with respect to subgroups, the data support a relationship between Ab3 response and survival time. Thus, the need for further randomized, controlled clinical trials to establish efficacy of the vaccine ACA125 seems to be indicated.     

Antiangiogenic properties of 17-(dimethylaminoethylamino)-17-demethoxygeldanamycin: an orally bioavailable heat shock protein 90 modulator.

PURPOSE: The purpose of this study was to investigate the antiangiogenic properties of 17-(dimethylaminoethylamino)-17-demethoxygeldanamycin (17-DMAG; NSC707545), a water-soluble benzoquinone ansamycin. EXPERIMENTAL DESIGN: The activity of 17-DMAG, in vivo, was evaluated for inhibition of fibroblast growth factor (FGF)-2-induced angiogenesis in s.c. implanted Matrigel in mice. In vitro, the activity of 17-DMAG on endothelial cells (human umbilical vein endothelial cells; HUVEC) was tested in FGF-2; and vascular endothelial growth factor (VEGF)-induced proliferation and apoptosis, motility, and extracellular matrix invasion; and on the alignment of capillary like structures in Matrigel. The protein level of heat shock protein (Hsp)90 and client proteins was examined by Western blot in FGF-2 and VEGF-stimulated HUVEC. RESULTS: Daily oral administration of 17-DMAG affected the angiogenic response in Matrigel in a dose-dependent manner. The hemoglobin content in the Matrigel implants was significantly inhibited, and the histological analysis confirmed a decrease of CD31(+) endothelial cells and of structures organized in cord and erythrocyte-containing vessels. In vitro, the compound inhibited dose-dependently the migration and the extracellular matrix-invasiveness of HUVEC and their capacity to form capillary like structures in Matrigel. 17-DMAG treatment also inhibited FGF-2 and VEGF-induced HUVEC proliferation and resulted in apoptosis. Accordingly, the expression of Hsp90 direct client proteins (pAkt and c-Raf-1) or their downstream substrates including pERK was also affected. 17-DMAG consistently increased the expression of Hsp70. Throughout the study similar results were obtained with 17-allylamino-17-demethoxygeldanamycin (17-AAG; NSC330507), the analog compound currently undergoing clinical trials. CONCLUSIONS: We show that the Hsp90 targeting agents 17-DMAG and 17-AAG inhibit angiogenesis. The strong effects on endothelial cell functions, in vitro, indicate that the antiangiogenic activity of 17-DMAG/17-AAG could also be due to a direct effect on endothelial cells. The oral bioavailability of 17-DMAG might be of advantage in investigating the potential of this compound in clinical trials with antiangiogenic as well as antiproliferative endpoints.     

Perinatal exposure to the fungicide prochloraz feminizes the male rat offspring.

Prochloraz is a commonly used fungicide that has shown multiple mechanisms of action in vitro. It antagonizes the androgen and the estrogen receptors, agonizes the Ah receptor, and inhibits aromatase activity. In vivo prochloraz acts antiandrogenically in the Hershberger assay by reducing weights of reproductive organs, affecting androgen-regulated gene expressions, and increasing luteinizing hormone (LH) levels. The purpose of this study was to investigate reproductive toxic effects after exposure during gestation and lactation to prochloraz alone and a mixture of five pesticides (deltamethrin, methiocarb, prochloraz, simazine, and tribenuron-methyl). Prochloraz (30 mg/kg/day) or the mixture (20 mg/kg/day) was dosed to pregnant Wistar dams from gestational day (GD) 7 until postnatal day (PND) 16. Some dams were taken for cesarean section at GD 21, and others were allowed to give birth. Results showed that prochloraz and the mixture significantly reduced plasma and testicular testosterone levels in GD 21 male fetuses, whereas testicular progesterone was increased. Gestational length was increased by prochloraz. Chemical analysis of the rat breast milk showed that prochloraz was transferred to the milk. In males a significant increase of nipple retention was found, and the bulbourethral gland weight was decreased, whereas other reproductive organs were unaffected. In addition cytochrome P450 (CYP)1A activities in livers were induced by prochloraz, possibly as a result of Ah receptor activation. Behavioral studies showed that the activity level and sweet preference of adult males were significantly increased. Overall these results strongly indicate that prochloraz feminizes the male offspring after perinatal exposure, and that these effects are due, at least in part, to diminished fetal steroidogenesis.     

Reducing weight gain in children through enhancing physical activity and nutrition: the APPLE project.

OBJECTIVE: Community-based lifestyle intervention may offer the best means of reducing the global epidemic of childhood obesity and its consequences, yet few successful interventions have been reported. The objective was to determine whether increasing extra-curricular levels of activity could reduce weight gain in children. METHODS: A controlled intervention study was conducted using standardised methods to assess outcomes. Two comparable relatively rural communities in Otago, New Zealand formed intervention and control settings. Height, weight, waist circumference and participation in physical activity (by accelerometry) were measured at baseline and at 1 year in 384 children aged 5 to 12 years representing the majority of children in this age group in intervention and control communities. Community Activity Co-ordinators were employed at each school in the intervention area. Their brief was to widen exposure to activity and engage children not interested in traditional sporting activities by encouraging lifestyle-based activities (e.g. walking) and non-traditional sports (e.g. golf and taekwondo) during extra-curricular time at school, after school and during vacations. Simple dietary advice was offered and the wider community was encouraged to participate. RESULTS: Average accelerometry counts at 1 year were 28% (95% CI: 11 to 47%) higher in intervention compared with control children after adjusting for age, sex, baseline values and school. Intervention children spent less time in sedentary activity (ratio 0.91, p = 0.007) and more time in moderate (1.07, p = 0.001) and moderate/vigorous (1.10, p = 0.01) activity. Adjusted mean BMI Z-score was lower in intervention relative to control children by -0.12 units (95% CI: -0.22 to -0.02). CONCLUSION:. An intervention designed to maximise opportunities for physical activity during extra-curricular time at school and during leisure time through the provision of community-based Activity Co-ordinators significantly increased participation in physical activity and slowed unhealthy weight gain in primary school-aged children.     

Chordoma: Radiological–pathological correlation

This review correlates the imaging findings and histological appearances seen in chordomas in a series of patients presenting at our institution, together with a published literature review. A parallel presentation of photographs of imaging findings and microscopic histological findings is made, with the aim being to enhance recognition of this uncommon but clinically significant entity.