Sunyoung Ahn

Pincer nail deformity and pseudo-Kaposi’s sarcoma: complications of an artificial arteriovenous fistula for haemodialysis

Pseudo‐Kaposi’s sarcoma which develops due to arteriovenous fistulae for haemodialysis is relatively well known. In contrast, nail changes associated with pseudo‐Kaposi’s sarcoma or venous hypertension are rare. We report a novel case of pincer nail deformity associated with pseudo‐Kaposi’s sarcoma and venous hypertension, complications of an arteriovenous fistula for haemodialysis, and review eight similar cases reported in the literature. Most of the subjects presented with similar findings, having circulatory disturbance due to an arteriovenous fistula and/or increased venous pressure, and swelling, discoloration and papules/nodules of the skin distal to the shunt. Of the nine patients, three had overcurvature of the nails, in which the lateral edge of the nail pressed deeply into the lateral nail fold. Pincer nail deformity associated with pseudo‐Kaposi’s sarcoma after placement of an arteriovenous fistula may be relatively common and should be recognized as a specific sign of circulatory disturbance due to the arteriovenous fistula.

The effects of topical α-hydroxyacids on the normal skin barrier of hairless mice

Background α‐hydroxyacids (AHA), such as glycolic acid and lactic acid, have recently been used in cosmetic and dermatological formulations. However, the mechanisms of action of these substances have not been well documented.

Imaging of the Inflammatory Response in Reperfusion Injury after Transient Cerebral Ischemia in Rats : Correlation of Superparamagnetic Iron Oxide-Enhanced Magnetic Resonance Imaging with Histopathology

Background: Acute inflammatory responses have been thought to play a central role in ischemia-reperfusion injury after acute ischemic stroke. Superparamagnetic iron oxide (SPIO) particles have been known to enable in-vivo monitoring of macrophage infiltration by magnetic resonance imaging (MRI) in the experimental ischemic rat brain. Purpose: To determine whether the accumulation of macrophages could be seen in vivo in a reperfusion animal model after focal cerebral ischemia using SPIO-enhanced MRI. Material and Methods: Thirty-four adult male rats were enrolled in this study. SPIO particles were injected into the rats at different time points after 1-hour transient occlusion of the middle cerebral artery, and three-dimensional (3D) T2*-weighted magnetic resonance (MR) images with a gradient-echo sequence were performed 24 hours later. Histochemical iron staining was compared with T2* signal abnormalities. Results: At days 3 and 4 post-reperfusion, focal areas of signal loss indicating local accumulation of SPIO particles appeared in a part of the damaged brain. Areas of signal loss corresponded to local accumulation of iron-laden macrophages in histologic sections, and SPIO-induced signal loss indicated active macrophage transmigration into the reperfused brain. Conclusion: SPIO-enhanced MRI demonstrated through in-vivo monitoring that macrophages participate in reperfusion injury at early stages of injury development. SPIO-enhanced MRI could be a useful tool to examine the inflammatory mechanisms involved in reperfusion brain injury.

The skin barrier state of aged hairless mice in a dry environment

Summary Background Many elderly people have chronic xerosis, and frequently experience an exacerbation during winter.

Nodular cystic fat necrosis in a patient with erythema nodosum

Nodular cystic fat necrosis shows a distinctive spectrum of clinical and histological features. Most of the lesions arc mobile subcutaneous nodules in regions vulnerable to trauma, such as the elbows, knees, and shins. There have been no reports of an association with other conditions. The histology is characterized by encapsulated fat necrosis in which multiple, non‐viable adipocytes are surrounded by condensed fibrous tissue.

Stimulation of epidermal calcium gradient loss increases the expression of hyaluronan and CD44 in mouse skin

Background.  Hyaluronan (HA), a major extracellular matrix component in epidermis, has been found to accumulate in the epidermis after disruption of the epidermal barrier; however, the precise mechanisms underlying this process are not yet clear. Alterations in the epidermal calcium gradient are an important signal for permeability‐barrier homeostasis. Thus, we hypothesized that epidermal calcium‐ions might regulate HA expression.

Pleomorphic fibroma on the scalp

We present the eleventh case of benign pleomorphic fibroma arising on the scalp in a young Korean woman. Histopathologically these lesions were characterized by a polypoid or dome-shaped cutaneous fibrous mass with sparse cellularity but striking nuclear atypia and rare mitotic figures. They all showed benign clinical behavior, despite these histopathological findings.

Influence of Vitamin C and Maltose on the Accuracy of Three Models of Glucose Meters

Dear Editor, Glucose meters are increasingly used in hospitals and home settings. These handheld devices provide instant readings and are therefore, beneficial for glucose-level monitoring in patients with diabetes [1]. Nonetheless, there have been concerns regarding the measurement accuracy of glucose meters. Some substances, such as vitamin C and maltose, are considered responsible for errors in glucose measurements using point-of-care testing glucose meters [1,2,3]. Vitamin C is widely used in the treatment of cancer, viral infections, severe burns, and chronic fatigue syndrome because of the antioxidant effects [4]. Maltose can be upregulated in patients undergoing peritoneal dialysis involving icodextrin as an osmotic agent [3]. High concentrations of vitamin C and maltose in blood can lead to false increase in glucose meter readings, resulting in misdiagnosis of hypoglycemia and potential fatalities [1]. Therefore, there is an urgent need for interference-resistant glucose meters [5]. We evaluated the interference of vitamin C and maltose with glucose readings obtained using the following three meters: Accuchek Inform (Roche Diagnostics, Indianapolis, IN, USA), Starstrip (Nova Biomedical, Waltham, MA, USA), and Barozen H plus (i-SENS Inc., Seoul, Korea). These three models are based on the glucose dehydrogenase-pyrroloquinoline quinone (GDH-PQQ), modified glucose oxidase (GOD), and GDH-flavin adenine dinucleotide (FAD) assays, respectively [5,6]. After prior depletion of glucose by overnight storage at room temperature, we prepared three pooled blood specimens [4] from EDTA-treated whole blood samples and added glucose (CAS 50-99-7, Duksan Pure Chemicals Co., Ansan, Korea) at final concentrations of 60, 126, or 300 mg/dL. To study the effect of various concentrations of vitamin C (0, 3, 15, or 30 mg/dL) [7] or maltose (0, 10, 40, 200, or 500 mg/dL) [8], we added 0.15 mL of the vitamin C or maltose stock solutions (control: normal saline) to 3 mL of pooled blood specimens. The stock solutions were prepared from L-ascorbic acid (CAS 50-81-7, Sigma-Aldrich, St. Louis, MO, USA) and D (+) -maltose monohydrate (CAS 6363-53-7, Junsei Chemical Co., Tokyo, Japan). Then, we compared the whole blood glucose readings of the specimens, with and without an interfering substance, using three glucose meters. We also measured the plasma glucose levels in each sample with Hitachi 7600 chemistry analyzer (Hitachi, Tokyo, Japan) for a benchmark comparison. Each sample was tested in duplicate. Assessment of interference and accuracy for each glucose meter was performed according to the criteria of the International Organization for Standardization (ISO) 15197:2013(E) [9]. Accuchek Inform glucose level readings at all concentrations were subject to significant positive interference (>10% deviation from control sample levels) from vitamin C presence at concentrations of 15 and 30 mg/dL, whereas no significant positive interference was observed for Barozen H plus and Starstrip models (Fig. 1). However, Starstrip failed to produce readings in two out of three measurements in specimens, which contained 30 mg/dL vitamin C (Fig. 1). In contrast to the effect of vitamin C, no significant interference at any maltose concentration was noted for all the three models tested (Fig. 1). Owing to interference from high concentrations of vitamin C (15 and 30 mg/dL), Accuchek Inform showed unacceptable accuracy levels (>15% difference from the value obtained by the chemistry analyzer; Table 1). Starstrip generally showed lower readings than those determined by the chemistry analyzer, especially at higher glucose concentrations: a negative bias >15% was detected in four out of nine measurements (Table 1). Fig. 1 Glucose level measurements in different concentrations of interferents. Glucose was added to blood at various concentrations: low (60 mg/dL), medium (126 mg/dL), and high (300 mg/dL). The X-axis represents the level of interferent, and the Y-axis represents ... Table 1 Accuracy of whole-blood glucose concentration readings using three glucose meter models compared with the measurements obtained by using a chemistry analyzer Vitamin C is a strong antioxidant that inactivates free radicals and can be oxidized at the surface of electrochemical strips producing electrons and increasing the current [1]. Icodextrin, an osmotic agent used in peritoneal dialysis, is metabolized in the systemic circulation into various glucose polymers, mainly maltose [10]. It can interfere with readings obtained using GDH-PQQ-based method, because GDH-PQQ catalyzes the oxidation of not only glucose but also other sugars [1]. Thus, vitamin C and maltose can cause positive interference resulting in misdiagnosis of true glucose levels. However, GDH currently used in Accuchek Inform was modified by the manufacturer to increase enzyme specificity for glucose and to diminish probability of incorrect high glucose readings [8]. In this study, all three glucose meters showed reliable results in presence of maltose. However, at higher vitamin C concentrations, Accuchek Inform showed a positive bias, while Starstrip occasionally malfunctioned. In conclusion, high concentrations of vitamin C may affect blood glucose measurements depending on the glucose meter used. Therefore, caution is required while monitoring the glucose level, using a glucose meter, of patients receiving high dose of vitamin C. There is a need for continuous technical improvement and further studies for possible interferents of glucose meters.

Molecular Epidemiology and Characterization of Carbapenemase-Producing Enterobacteriaceae Isolated at a University Hospital in Korea during 4-Year Period

Department of Laboratory Medicine and Research Institute of Bacterial Resistance, Yonsei University College of Medicine, Department of Laboratory Medicine, National Police Hospital, Brain Korea 21 PLUS Project for Medical Science, Yonsei University, Department of Infection Control, Severance Hospital, Division of Infectious Diseases, Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea

Stability of lyophilized pooled sera as quality control materials for tumor marker assays in external quality assessment

BACKGROUND External quality assessment (EQA) requires stable quality control (QC) materials. We evaluated the stability of QC materials made of lyophilized and liquid pooled sera for the tumor markers α-fetoprotein, carcinoembryonic antigen, carbohydrate antigen 125, and carbohydrate antigen 19-9. METHODS Specimens of the 4 tumor markers were collected from the sera of patients and stored at -20°C. After sera collection and pooling, liquid or lyophilized samples were stored at -20°C, 5°C, or room temperature. Tumor markers were quantified on days 0, 1, 4, 7, 14, 30, and 90 of storage. Internal QC results were analyzed, and the effects of heat inactivation and sucrose addition were assessed. RESULTS Heat inactivation lowered tumor marker levels in lyophilized pooled sera, whereas sucrose addition had no effect. The coefficients of variation of the internal QC results were stable, whereas those of lyophilized samples were higher than those of liquid samples. Tumor marker levels were significantly lower in lyophilized samples (p<0.05) and did not significantly differ according to storage temperature. A declining trend over time was observed for all tumor markers. CONCLUSIONS Lyophilized QC materials are insufficiently stable for use in EQA among clinical laboratories.