Kwangwoo Lee

Intranasal Delivery of PEGylated Salmon Calcitonins: Hypocalcemic Effects in Rats

To evaluate the hypocalcemic effect of polyethylene gtycol-conjugated salmon calcitonins (PEG-sCT) in rats, mono-PEGylated sCTs (mono-PEG-sCTs) and unmodified sCT were administered via the intranasal route and serum calcium levels were measured by colorimetric assay using o-cresolphthalein. Mono-PEG-sCTs were prepared with different sizes of succinimidyl succinate monomethoxy PEG molecules (PEG2K, PEG5K, PEG12K) and characterized by HPLC and MALDI-TOF mass spectrometry. Nasal instillation of mono-PEG2K-sCT at a dose of 2 IU/kg resulted in sustained reduction in serum calcium levels over 8 hr, with a maximum reduction (% maxd) of 13% after 6 hr of application. Whereas unmodified sCT showed a transient decrease in serum calcium levels with the maximum reduction (5%) observed after 30 min of administration. The overall reductions in serum calcium levels expressed as the net change in AUC relative to control in 8 hr were 11.9 ± 0.2, 4.6 ± 0.7, and 2.6 ± 0.7% for mono-PEG2K-, mono-PEG5K-, and mono-PEG12K-sCT, respectively, compared to 3.2 ± 0.6% for unmodified sCT. The relative bioavailability of nasally administered 2 IU/kg of mono-PEG2K-sCT was approximately 4-fold higher than nasally administrated unmodified sCT, and the absolute bioavailability was approximately 91% of intravenously injected sCT in 8 hr. It can be concluded that the intranasal absorption of mono-PEG-sCTs was inversely related to the molecular weights of the PEG attached. Of the PEGylated sCTs examined, mono-PEG2K-sCT showed the most pronounced hypocalcemic effect. Therefore the intranasal application would probably be an alternative route of administration for mono-PEG-sCTs in achieving sustained calcium-lowering effects.

Cryptanalysis and improvement of a biometrics-based multi-server authentication with key agreement scheme

In 1981, Lamport proposed a password authentication scheme to provide authentication between single user and single remote server. In a smart card based password authentication scheme, the smart card takes password as input, makes a login message and sends it to the server. Many smart card based password authentication schemes with a single server have already been constructed. However it is impossible to apply the authentication methods in single server environment to multi-server environment. Therefore, some smart card based password authentication schemes for the multi-server environment are proposed. In 2010, Yoon et al. proposed a robust biometrics-based multi-server authentication with key agreement scheme for smart cards on elliptic curve cryptosystem. In this paper, however, we show that scheme of Yoon et al. is vulnerable to off-line password guessing attack and propose an improved scheme to prevent the attack.

PEGylation improves the hypoglycaemic efficacy of intranasally administered glucagon‐like peptide‐1 in type 2 diabetic db/db mice

Aims:  PEGylation – covalent modification of therapeutic peptides with polyethylene glycol (PEG) – is viewed as an effective way of prolonging the short lifetime of glucagon‐like peptide‐1 (GLP‐1). In this study, we investigated the hypoglycaemic efficacies of PEGylated GLP‐1s administered intranasally in type 2 diabetic db/db mice.

Protection profile for secure e-voting systems

In this paper, we propose a protection profile for e-voting systems. Currently, there are three protection profiles for e-voting systems, BSI-PP-0031 in Germany, PP-CIVIS in France, and IEEE P1583 in USA. Although these protection profiles consider the overall security requirements for e-voting systems, they did not consider the voter verifiable audit trail. The voter verifiable audit trail allows voters to verify that their votes were captured correctly. Moreover, it provides a means to audit the stored electronic results, and to detect possible election fraud. Today, several voter verifiable audit trail e-voting systems already exist in the market, and used in public elections. However, a protection profile does not reflect this situation. Therefore, it is required that a protection profile for e-voting systems should consider the voter verifiability. To accomplish this, we propose a protection profile considering the voter verifiability with the existing protection profiles, and then discuss voter verifiability issues related to the electoral process. The proposed protection profile can be used to increase reliability of the entire e-voting process and tabulation result.

Determination of salmon calcitonin in formulations by high-performance liquid chromatography with electrochemical detection

SummaryA novel HPLC method with electrochemical detection has been developed for the determination of salmon calcitonin (sCT). sCT was separated from other components in its formulations on a narrow-bore reversed-phase C18 column with 33% acetonitrile in 0.05m phosphate buffer (pH 6.5) at a flow rate of 0.2 mL min−1. Electrochemical oxidation of sCT at a glassy carbon electrode occurred at 0.87 V relative to the Ag/AgCl reference electrode. The limit of quantitation was 0.1 ng and the calibration curve was linear in the concentration range 0.5–20 ng; the correlation coefficient was 0.998. The method was successfully applied for the quantitation of sCT in commercial injection and nasal spray formulations.

An attack on an RFID authentication protocol conforming to EPC class 1 generation 2 standard

A packet based policing method and apparatus is disclosed which increases the throughput of a network by avoiding the waste of resources. The invention receives cells for a first packet at a node in a network, determines whether a non-conforming cell may be passed according to a running credit value, identifies whether a cell is conforming or non-conforming, passes the cell if the running credit value indicates that a non-conforming cell may be passed or if the cell is a conforming cell, borrows a cell credit if the credit value indicates that a non-conforming cell cannot be passed, wherein the borrowing of the cell credit allows the running credit value to be decremented until reaching a predetermined negative number and decrements the running credit value. All cells in the next packet are discarded and the credit value is incremented for each conforming cell in the next packet, which results in the credit value having a bonus credit value added thereon if the number of conforming cells discarded in the next packet exceeds the number of borrowed cells required to pass the first packet. All cells of all subsequent packets are discarded until the borrowed cell credits have been accounted for. Whether the cell is the last cell of the first frame is ascertained and the last cell is processes so that cells of the first packet are not merged with cells passed next.

Enhanced code-signing scheme for smartphone applications

Recently, the number of incidents by malicious codes designed to suspend services and abuse personal information has grown rapidly, and the installation of applications on smart phones has emerged as one of the most common ways by which such malicious codes are spread. Anti-virus programs can be used to curb the spread of such codes, but these have limitations in terms of speed and efficiency. Accordingly, we need to strengthen the safety of application distribution and verification procedures in order to prevent the spread of malicious codes. To this end, this paper examines the problems of existing application distribution procedures, and suggests an enhanced code-signing scheme using the public key infrastructure (PKI) certificate for an application distribution method. It offers improved reliability and security by using code signing technology to secure the integrity of software and developer authentication functions.

A method for deciding quantization steps in QIM watermarking schemes

In this paper, we propose a method for enlarging quantization steps of a QIM watermarking scheme which determines the perceptual quality and robustness of the watermarked images. In general, increasing the quantization steps leads to good robustness but poor perceptual quality of watermarked images and vice versa. However, if we choose the quantization steps considering the expected quantization results as well as the original images, we can increase both robustness and perceptual quality of the watermarked images.

Sensitive micro-sample analysis of bisphenol A in serum by high-performance liquid chromatography with fluorescence detection

SummaryA rapid and sensitive HPLC method with fluorescence detection has been developed for the micro-sample analysis of bisphenol A in rat serum. Compounds were separated on a Spherisorb C18 analytical column with acetonitrile-0.1% triethylamine in deionized water, 54:46 (v/v), as mobile phase. Bisphenol A was isolated by one-step extraction with dichloromethane. The calibration plot was linear (r=0.999) over the concentration range 1–1000 ng mL−1. The limits of detection and quantitation were 0.2 ng mL−1 and 1 ng mL−1, respectively, for 100-μL serum samples. The assay was successfully used for a pharmacokinetic study after intravenous administration of a low dose (0.1 mg kg−1) of bisphenol A to rats.

Direct Analysis of Clomipramine in Human Plasma by Microbore High Performance Liquid Chromatography with Column-Switching

SummaryAn automated microbore, liquid chromatographic method with column-switching was developed for the determination of clomipramine from human plasma samples. After direct injection of samples (60 μL), plasma proteins and clomipramine were separated in size-exclusion mode using 20% acetonitrile in 20 mM phosphate buffer (pH 7.0) on Capcell Pak MF Ph-1 precolumn (10×4 mm I.D.). By valve switching, a fraction containing clomipramine was directed to an intermediate column for subsequent main separation on a microbore C18 column (250×1.5 mm I.D.) using 50% acetonitrile in 20 mM phosphate buffer (pH 2.5) at 0.1 mL min−1. The method was advantageous for rapidity (total analysis time: 15 min), reproducibility (C.V.<4.8%), and increased sensitivity (1 ng mL−1). The linearity of response was good (r2≥0.999) over the concentration range 1–250 ng mL−1.