Usefulness of Technetium-99m human serum albumin lymphoscintigraphy in chyluria

Unraveling the versatility of human serum albumin - A comprehensive review of its biological significance and therapeutic potential

Human serum albumin (HSA) is a multi-domain macromolecule with diverse ligand binding capability because of its ability to allow allosteric modulation despite being a monomeric protein. Physiologically, HSA act as the primary carrier for various exogenous and endogenous compounds and fatty acids, and alter the pharmacokinetic properties of several drugs. It has antioxidant properties and is utilized therapeutically to improve the drug delivery of pharmacological agents for the treatment of several disorders. The flexibility of albumin in holding various types of drugs coupled with a variety of modifications makes this protein a versatile drug carrier with incalculable potential in therapeutics. This review provides a brief outline of the different structural properties of HSA, and its various binding sites, moreover, an overview of the genetic, biomedical, and allosteric modulation of drugs and drug delivery aspects of HSA is also included, which may be helpful in guiding advanced clinical applications and further research on the therapeutic potential of this extraordinary protein.

Robotic surgery for treatment of chyluria

Chyle is a milky lymphatic fluid that is normally formed in the small intestine to aid in the absorption of dietary fats. Occasionally, chyle leaks into the kidney, ureter, or bladder, which results in chyluria. Chyluria is most commonly caused by the parasite Wuchereria bancrofti and is therefore extremely rare in the USA. The use of robotic surgery for treatment has been suggested as a viable option, but has not been thoroughly reported in the literature. This article reviews the literature on the various treatment options for chyluria and presents the case of a 75-year-old Indian female from the USA who was diagnosed with non-parasitic, persistent chyluria and treated with right robotic ureterolysis, renal hilar dissection and intraperitonealization of the ureter.

Non-tropical chyluria: CT diagnosis

Chyluria is commonly associated with filariasis, which is prevalent among the population of tropical and subtropical regions. Chyluria is seldom encountered in the United States and other western countries, but may occur if the flow of chyle into the thoracic duct is blocked due to inflammatory, neoplastic, or various other etiologies. We report 10 adult patients, in whom the detection of fat-urine level in their bladder on abdominal CT provided the initial diagnostic clue to the presence of chyluria. This series included 7 men and 3 women, who ranged in age from 25 to 91 years (mean: 62 years). The associated lesions included renal angiomyolipomas (2), lymphangiomas of the kidney and bladder (1), metastatic testicular cancer (1), postoperative status following partial nephrectomy for renal cell carcinoma (4), left radical nephrectomy (1), and segmental cystectomy for carcinomas (1). The clinical and radiological features of this entity are presented along with a brief review of the pertinent literature.

Clinical impact of serum proteins on drug delivery

Among serum proteins albumin and transferrin have attracted the most interest as drug carriers in the past two decades. Prior to that, their potential use was overshadowed by the advent of monoclonal antibodies that was initiated by Milstein and Koehler in 1975. Meanwhile intensive pursuit of exploiting transferrin, but above all albumin as an exogenous or endogenous carrier protein for treating various diseases, primarily cancer, rheumatoid arthritis, diabetes and hepatitis has resulted in several marketed products and numerous clinical trials. While the use of transferrin has clinically been primarily restricted to immunotoxins, albumin-based drug delivery systems ranging from albumin drug nanoparticles, albumin fusion protein, prodrugs and peptide derivatives that bind covalently to albumin as well as physically binding antibody fragments and therapeutically active peptides are in advanced clinical trials or approved products. For treating diabetes, Levemir and Victoza that are myristic acid derivatives of human insulin or glucagon-like peptide 1 (GLP-1) act as long-acting peptides by binding to the fatty acid binding sites on circulating albumin to control glucose levels. Levemir from Novo Nordisk has already developed into a blockbuster since its market approval in 2004. Abraxane, an albumin paclitaxel nanoparticle as a water-soluble galenic formulation avoiding the use of cremophor/ethanol, transports paclitaxel through passive targeting as an albumin paclitaxel complex to the tumor site and is superior to conventional Taxol against metastatic breast cancer. INNO-206, an albumin-binding doxorubicin prodrug that also accumulates in solid tumors due to the enhanced permeability and retention (EPR) effect but releases the parent drug through acid cleavage, either intra- or extracellularly, is entering phase II studies against sarcoma. An expanding field is the use of albumin-binding antibody moieties which do not contain the fragment crystallizable (Fc) portion of, conventional immunoglobulin G (IgG) but are comprised of monovalent or bivalent light and/or heavy chains and incorporate an additional albumin-binding peptide or antibody domain. The most advanced antibody of this kind is ATN-103 (Ozoralizumab), a trivalent albumin-binding nanobody that neutralizes the pro-inflammatory tumor necrosis factor alpha (TNF-α) as a causative agent for exacerbating rheumatoid arthritis. ATN-103 is currently in multi-center phase II trials against this debilitating disease. In summary, because albumin as the most abundant circulating protein cannot only be used to improve the pharmacokinetic profile of therapeutically relevant peptides and the targeting moiety of antibodies but also for peptide-based targeting as well as low-molecular weight drugs to inflamed or malignant tissue, it is anticipated that R&D efforts of academia and the pharmaceutical industry in this field of drug delivery will prosper.

Impact of albumin on drug delivery--new applications on the horizon

Over the past decades, albumin has emerged as a versatile carrier for therapeutic and diagnostic agents, primarily for diagnosing and treating diabetes, cancer, rheumatoid arthritis and infectious diseases. Market approved products include fatty acid derivatives of human insulin or the glucagon-like-1 peptide (Levemir(®) and Victoza(®)) for treating diabetes, the taxol albumin nanoparticle Abraxane(®) for treating metastatic breast cancer which is also under clinical investigation in further tumor indications, and (99m)Tc-aggregated albumin (Nanocoll(®) and Albures(®)) for diagnosing cancer and rheumatoid arthritis as well as for lymphoscintigraphy. In addition, an increasing number of albumin-based or albumin-binding drugs are in clinical trials such as antibody fusion proteins (MM-111) for treating HER2/neu positive breast cancer (phase I), a camelid albumin-binding nanobody anti-HSA-anti-TNF-α (ATN-103) in phase II studies for treating rheumatoid arthritis, an antidiabetic Exendin-4 analog bound to recombinant human albumin (phase I/II), a fluorescein-labeled albumin conjugate (AFL)-human serum albumin for visualizing the malignant borders of brain tumors for improved surgical resection, and finally an albumin-binding prodrug of doxorubicin (INNO-206) entering phase II studies against sarcoma and gastric cancer. In the preclinical setting, novel approaches include attaching peptides with high-affinity for albumin to antibody fragments, the exploitation of albumin-binding gadolinium contrast agents for magnetic resonance imaging, and physical or covalent attachment of antiviral, antibacterial, and anticancer drugs to albumin that are permanently or transiently attached to human serum albumin (HSA) or act as albumin-binding prodrugs. This review gives an overview of the expanding field of preclinical and clinical drug applications and developments that use albumin as a protein carrier to improve the pharmacokinetic profile of the drug or to target the drug to the pathogenic site addressing diseases with unmet medical needs.

Albumin as a drug carrier: design of prodrugs, drug conjugates and nanoparticles

Albumin is playing an increasing role as a drug carrier in the clinical setting. Principally, three drug delivery technologies can be distinguished: coupling of low-molecular weight drugs to exogenous or endogenous albumin, conjugation with bioactive proteins and encapsulation of drugs into albumin nanoparticles. The accumulation of albumin in solid tumors forms the rationale for developing albumin-based drug delivery systems for tumor targeting. Clinically, a methotrexate-albumin conjugate, an albumin-binding prodrug of doxorubicin, i.e. the (6-maleimido)caproylhydrazone derivative of doxorubicin (DOXO-EMCH), and an albumin paclitaxel nanoparticle (Abraxane) have been evaluated clinically. Abraxane has been approved for treating metastatic breast cancer. An alternative strategy is to bind a therapeutic peptide or protein covalently or physically to albumin to enhance its stability and half-life. This approach has been applied to peptides with antinociceptive, antidiabetes, antitumor or antiviral activity: Levemir, a myristic acid derivative of insulin that binds to the fatty acid binding sites of circulating albumin, has been approved for the treatment of diabetes. Furthermore, Albuferon, a fusion protein of albumin and interferon, is currently being assessed in phase III clinical trials for the treatment of hepatitis C and could become an alternative to pegylated interferon. This review gives an account of the different drug delivery systems which make use of albumin as a drug carrier with a focus on those systems that have reached an advanced stage of preclinical evaluation or that have entered clinical trials.

The treatment of chyluria secondary to advanced carcinoma of the prostate

Chyluria has not been previously reported as being associated with carcinoma of the prostate. The most common cause is lymphatic filariasis, a parasitic disease. Non-parasitic chyluria is rare. We describe a case of chyluria associated with carcinoma of the prostate. We describe our successful management in this case and highlight how urologists may overcome problematic chyluria in patients with advanced carcinoma of the prostate.

Pharmaceutical strategies utilizing recombinant human serum albumin

Gene manipulation techniques open up the possibility of making recombinant human serum albumin (rHSA) or mutants with desirable therapeutic properties and for protein fusion products. rHSA can serve as a carrier in synthetic heme protein, thus reversibly carrying oxygen. Myristoylation of insulin results in a prolonged half-life because of self aggregation and increased albumin binding. Preferential albumin uptake by tumor cells serves as the basis for albumin-anticancer drug conjugate formulation. Furthermore, drug targeting can be achieved by incorporating drugs into albumin microspheres whereas liver targeting can be achieved by conjugating drug with galactosylated or mannosylated albumin. Microspheres and nanoparticles of different sizes can, with or without drugs and/or radioisotopes, be used for drug delivery or diagnostic purposes. In vivo implantation of albumin fusion protein expressing cells encapsulated in HSA-alginate coated beads showed promising results compared to organoids in rats. Chimeric peptide strategy with cationized albumin as the transport can deliver drugs via receptor mediated transcytosis through the blood brain barrier. Gene bearing, albumin microbubbles containing ultrasound contrast agents can non-invasively deliver gene after destruction by ultrasound. Various site-directed mutants of HSA can be tailor made depending on the application required.