Biomedical subjects

D Ciolek

Publications and source records attributed to D Ciolek.

5 recordsLinked to original sources

PubMed1997

Positional isomers of monopegylated interferon alpha-2a: isolation, characterization, and biological activity.

The success of recombinant interferon alpha in the clinic in part is limited by two properties of the protein: short serum half-life and immunogenicity. To improve these properties, interferon alpha-2a was conjugated with polyethylene glycol (PEG-5000). A homogeneous preparation of monopegylated interferon alpha-2a was subjected to vigorous analytical and activity characterization. A newly developed ampholyte-free chromatofocussing-like cation-exchange HPLC method utilizing a sulfopropyl resin was used to separate the monopegylated protein into 11 species. Peptide mapping, sequencing, and mass spectrometric analyses indicated that these species are positional isomers where each isomer represents a single polymer molecule conjugated to one specific lysine residue. No species with a modification at the amino terminus was observed. All 11 isomers show antiviral and antiproliferative activities in the same range as the parent monopegylated interferon alpha-2a.

Animals↗

PubMed1994

Electrophoresis of proteins and protein-protein complexes in native polyacrylamide gels using a horizontal gel apparatus.

Electrophoresis of proteins and protein-protein complexes in polyacrylamide gels under native conditions using a horizontal gel apparatus is described. The advantage of this system is that it permits the detection of both negatively and positively charged proteins as well as protein-protein complexes in the same gel. During electrophoresis, a continuous gel sandwiched between two glass plates is placed horizontally on the platform and submerged in a reservoir buffer. The sample wells are made along the center of the gel, allowing positively and negatively charged proteins to migrate toward the cathode and anode, respectively. Several proteins with varying molecular weights and isoelectric point (pI) values and pairs of proteins capable of forming protein-protein complexes were chosen as model systems to illustrate the methodology. The effects of several parameters on the performance of the gel system including protein molecular weight, pI, and gel concentration were also examined and the results obtained by this method are comparable to those obtained by the vertical system. Following electrophoresis, both negatively and positively charged proteins as well as protein-protein complexes can be transferred by electroblotting onto polyvinylidene difluoride membranes for further analyses.

Electrophoresis, Polyacrylamide Gel↗

PubMed1994

Purification and characterization of a high-molecular-weight form of recombinant human interleukin-2.

During purification of recombinant Interleukin-2 (rIL-2) by reversed-phase HPLC, early fractions are discarded due to the presence of an unidentified form of rIL-2. A procedure has been developed to isolate and purify this unidentified form of rIL-2. The purification process involves two chromatography steps and utilizes a Bakerbond Carboxy-Sulfon (CS) column under two different conditions. This material, designated as a high-molecular-weight form of rIL-2 (HMWrIL-2), exhibits lower mobility during SDS-PAGE and has a pI which is approximately one unit less than that of rIL-2, but has similar bioactivity to rIL-2. Structural analysis through enzymatic cleavage, HPLC peptide mapping, mass spectrometry, sequencing, and amino acid composition revealed that the difference between these two proteins is a C-terminal extension of 11 amino acids. This extension could be the result of a nonstandard translation event.

Amino Acid Sequence↗

PubMedDate not supplied

Equipment acquisition using various forms of leasing.

How best to finance the acquisition of equipment is a major decision. It's important to understand the different kinds of lease structures before selecting one. Any purchase versus lease analysis should include an understanding of lease terms and conditions. Capital and operating leases are two categories under which all leases fall. Capital leases are accounted for much like a loan taken out to finance the purchase of an asset. An operating lease is accounted for differently, having no assets or liabilities booked on the balance sheet. Product acceptance, supply and demand and other less tangible factors play a role in the determination of lease rates. Internal factors must also be considered when making the decision to purchase or lease. It is critical that the method selected for financing be appropriately matched to the intended use of the equipment. An important factor when leasing medical equipment is how it will be disposed of at the end of the lease term. There are a variety of options available, from third-party sources to seeking trade-in credits, good toward the purchase of new equipment. It's important to consider the tax implications associated with leasing or buying assets.

Budgets↗

PubMedDate not supplied

Analyzing lease/purchase options.

The authors' previous article, "Equipment Acquisition Using Various Forms of Leasing," covers information necessary for selecting among the different kinds of leases. This article explains how to reach a proper financial analysis, preferably using two phases. Using a representative example, the article guides the reader through the first phase and introduces the elements needing review in the second phase. Key elements include pretax aftertax and cash flow analyses. Different organizations use different yardsticks to measure the financials of a transaction, but in general, cash is king. Therefore, the most widely used comparison is the purchase versus lease IRR (internal rate of return) produced by measuring the cash flow of the purchase case compared to the cash flow of the lease case.

Capital Expenditures↗