Monomeric M2e antigen in VesiVax® liposomes stimulates protection against type a strains of influenza comparable to liposomes with multimeric forms of M2e.

Given the interest in the ectodomain of the matrix 2 (M2e) channel protein as a target for development of a universal influenza vaccine, we examined the role of the antigen configuration of M2e in generating a protective immune response. A series of M2e mutations and a truncated M2e segment were prepared as a means of controlling the formation of monomer, dimer, and higher order multimeric forms of M2e. Each of these M2e peptides was incorporated into a liposome-based vaccine technology platform previously shown to stimulate a protective response to influenza A infection using M2e as a mixture of monomers, dimers and multimers (L-M2e1-HD/MPL). Our results using these modified forms of M2e produced 90-100% survival following lethal challenge with H1N1 (A/PR/8/34) in both inbred BALB/c and outbred Swiss Webster mice vaccinated with a truncated monomeric form of the M2 protein, M2e1-15 in liposomes. These observations show that a tetrameric configuration is not required to elicit significant protection when the M2e antigen is formulated in immunogenic liposomes and further, that the first 15 amino acids of M2e likely play a primary role in providing the protective immune response.

Equilibrium and kinetics of metal biosorption by sludge from a biological nutrient removal system.

This study investigated the biosorption kinetics and equilibrium of cadmium, nickel and zinc by activated sludge from a biological nutrient removal (BNR) process. A series of batch experiments with different initial metal concentrations were conducted to determine the metal removal in BNR sludge. The harvested sludges were from a continuous-flow anaerobic-anoxic-oxic (A2O) system operated under a 10 days of sludge retention time. Batch tests were specially designed to isolate the precipitation effects of metal ions in solution so as to compare the isotherm constants of biosorption with and without precipitation isolation. Experimental results revealed that BNR sludge exhibited two stages of biosorption, i.e., passive and then active uptake, for all three metals. The biosorption kinetic data of three tested metals can be effectively simulated by pseudo-second-order rate equations. Besides, the biosorption isotherm showed that metal biosorption behavior was statistically in agreement with the Freundlich model. The capacity constants k of the Freundlich model for Cd, Ni and Zn are 0.50, 0.23 and 0.41; the affinity constants 1 / n are 0.96, 0.81 and 0.31, respectively. Additionally, precipitation behaviors of metals obviously should be carefully examined during biosorption batch tests with activated sludge; otherwise the biosorption effect could be significantly overestimated.

Heavy metal removal from aqueous solution by wasted biomass from a combined AS-biofilm process.

This study evaluated the capability of metal biosorption by wasted biomass from a combined anaerobic-anoxic-oxic (A2O)-biofilm process with simultaneous nitrogen and phosphorus removal. Zinc, cadmium and nickel were rapidly adsorbed in 20 min by the harvested sludge from a continuous-flow pilot-plant. Biosorption equilibrium was then reached in 6h. The biosorption isotherm showed that metal biosorption behavior had fitted well to the Freundlich isotherm, but not Langmuir isotherm. The capacity constants k of Freundlich model for nickel, zinc and cadmium were 0.471, 0.298 and 0.726, respectively; the affinity constants 1/n were 0.444, 0.722 and 0.718, respectively. The order of metal affinity for the wasted biomass was Zn > Cd > Ni, which was in conformity to the other biosorption results with different biological sludge.

Molecular imaging of pancreatic islet transplantation.

Islet replacement therapy, pancreatic islet transplantation, is considered as a potential option for curing T1DM. However, the significant loss of implanted islets after islet transplantation prevents it from becoming a mainstream treatment modality. Due to the lack of reliable noninvasive real-time imaging techniques to track the survival of the islets, it is impossible to discover the specific causes for the loss of implanted islets, not to mention taking interventions in the early stage. Current achievements in molecular imaging has provided with several promising techniques, including optical imaging, PET and MRI, for noninvasive visualization, quantification and functional evaluation of transplanted islets in experimental conditions. Optical imaging seems to be the most convenient and cost-efficient modality, but the limited penetration distance hinders its application in large animal and human studies. PET combined with target-specific tracers is characterized by high specificity and sensitivity for detection of islet grafts, but observation time is rather short (i.e., several hours). MRI stands out for its long-term visualization of transplanted islet grafts with the aid of contrast agents. However, quantification of islets remains a problem to be solved. A novel technique, microencapsulation, provides a new perspective in multimodal imaging by optimizing the strengths of several modalities together. Although the application of molecular imaging in clinical settings is still limited, significant success and valuable information is achieved in the basic and clinical trials. However, islet transplantation still remains an experimental procedure, with ongoing researches focusing on islets availability, appropriate sites for implantation, new methods using biomaterials (e.g. microencapsulation), immune modulation and more.

Pharmacology and toxicology of a liposomal formulation of amphotericin B (AmBisome) in rodents.

AmBisome is a lyophilized preparation of liposomal amphotericin B. The acute intravenous toxicity of AmBisome was evaluated in mice and rats, and the LD50S were found to be greater than 175 and 50 mg/kg, respectively. The corresponding LD50S for conventional amphotericin B were approximately 2.3 and 1.6 mg/kg for mice and rats, respectively. The multiple dose toxicity test confirmed that AmBisome was well tolerated by both species. There were no deaths observed among mice receiving 25 or 50 mg/kg AmBisome for 14 days, and only two deaths among mice receiving 75 mg/kg AmBisome. One rat died in the group receiving 25 mg/kg AmBisome for 30 days. However, five of ten and nine of ten rats died in the groups treated with 50 and 75 mg/kg AmBisome, respectively. Hepatotoxicity was evident by elevation in serum liver enzyme levels for these groups. Initial pharmacokinetic evaluations demonstrated that peak plasma concentrations of 87 and 118 mg/kg, respectively, were attained in mice and rats after injection with 5 mg/kg AmBisome. Terminal plasma half-lives of 3.36 and 7.56 h were calculated for mice and rats, respectively. Tissue accumulations of amphotericin B resulting from multiple dose intravenous administration of either conventional amphotericin B or AmBisome were determined. At equivalent doses of 1 mg/kg, AmBisome treatment resulted in higher liver and spleen uptake of drug, but lower kidney and lung uptake than amphotericin B. At 5 mg/kg, AmBisome treatment resulted in concentrations of drug in the kidney and lungs that were comparable to corresponding tissue levels observed in the group treated with 1 mg/kg conventional amphotericin B.(ABSTRACT TRUNCATED AT 250 WORDS)

Treatment of murine candidosis and cryptococcosis with a unilamellar liposomal amphotericin B formulation (AmBisome).

This investigation examined the therapeutic efficacy of AmBisome, a unilamellar (55-75 nm) liposome amphotericin B preparation with a murine LD50 by the intravenous route of greater than 175 mg/kg amphotericin B. Both fungal burden and survival were used to evaluate the drug's efficacy against murine candidosis and cryptococcosis. Single and multiple dose intravenous treatment with AmBisome (2.5, 5.0 and 10.0 mg/kg) reduced the colony forming units/mg kidney in candida-infected mice by 99% and improved survival by at least 40% relative to untreated control mice. Repeated intravenous dosing of candida-infected mice with equivalent amounts (0.75 mg/kg) of conventional amphotericin B (Fungizone) or AmBisome showed comparable reduction of yeasts in the kidneys. When mice were infected systemically with Cryptococcus neoformans, all but one of the 30 mice given AmBisome (5.0, 7.5 or 10.0 mg/kg) survived until the experiment was terminated 35 days after infection. Liver and spleen cultures from AmBisome-treated mice were negative for fungal growth. All the mice given conventional amphotericin B intraperitoneally at 4.5 mg/kg survived and cleared the infection from the livers although some of the mice had infected spleens. The percentage of cultured brains free of cryptococcus was 89% following treatment with 10.0 mg/kg AmBisome, and 80% with 4.5 mg/kg conventional drug. These preclinical studies of systemic candidosis and cryptococcosis demonstrate comparable efficacy of AmBisome and conventional amphotericin B at low doses and improved efficacy with AmBisome at doses higher than can be safely administered of the conventional drug.

Liposomal amikacin: improved treatment of Mycobacterium avium complex infection in the beige mouse model.

Disseminated Mycobacterium avium complex (MAC) infection has reached epidemic proportions and is a major cause of morbidity and mortality in AIDS patients. We have developed a liposomal preparation of amikacin, VS107, which incorporates the drug in 54-65 nm diameter unilameller phospholipid vesicles and is stable at 4 degrees C for more than 4 months. VS107 exhibits superior microbiological and pharmacological activity over the free amikacin and improves the survival of mice in the established model for MAC infection. The serum half-life of VS107 in mice was 9.1 h and a peak serum level of 730 mg/L was obtained after administering three doses of 160 mg/kg. For the therapeutic study, beige mice infected with 10(7) cfu M. avium complex strain 101 were randomised to be treated with placebo liposomes, buffer, free amikacin or VS107 The drugs were administered via the caudal vein thrice weekly for 1, 3, 5 or 7 weeks beginning 5 days after infection. After 51 days of treatment with VS107, the number of viable M. avium in the liver and spleen was a 100 fold lower than was achieved with conventional amikacin (P < 0.01), and more than six decimal logarithms lower than was found untreated controls (P < 0.001). VS107 was well tolerated and might be a suitable candidate for treating human MAC infections.