A Simple and Rapid Method Based on Liquid Chromatography-Tandem Mass Spectrometry for the Measurement of alpha-L-Iduronidase Activity in Dried Blood Spots: An Application to Mucopolysaccharidosis I (Hurler) Screening

BACKGROUND: We developed an analytical method to measure alpha-L-iduronidase (IDUA) activity in dried blood spots. This was achieved by using liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) with electrospray ionization in the positive ion mode. METHODS: Chromatographic separation was completed using mobile phase involving water-formic acid and acetonitrile-formic acid over 2.8 min of run time on a column with a Kinetex XB-C18 (Phenomenex, USA). The detection of column effluent was performed using a Xevo TQ-S triple quadrupole mass spectrometer (Waters, USA) in the multiple-reaction monitoring mode. This method was verified with blank and control samples at four activity levels: base, low, medium, and high. Control materials were provided from Centers for Disease Control and Prevention (CDC). RESULTS: Intra- and inter-day precisions were between 2.6% and 16.5% and between 7.9% and 17.0%, respectively. A correlative regression study on the IDUA activity in CDC-control samples performed to assess the validity of the developed method showed a highly significant linear association (r2=0.9976) between the calculated and CDC-reported values and an obvious difference in activity among the four levels. This reliable analytical method was applied to mucopolysaccharidosis I (Hurler) screening of patients under treatment (n=4) and in normal controls (n=129). IDUA activity ranged from 8.98 to 77.12 micromol/hr/L) in normal controls, and patients undergoing medical treatment showed low IDUA activity. CONCLUSIONS: This method had advantages of simplicity, rapid sample preparation, and liquid chromatographic separation, which efficiently inhibited ionization suppression induced by matrix effects in mass spectrometric detection.

A Novel Simultaneous Determination of Sarpogrelate and its Active Metabolite (M-1) in Human Plasma, Using Liquid Chromatography-Tandem Mass Spectrometry: Clinical Application

BACKGROUND: This study describes a novel analytical method for simultaneously determining sarpogrelate and its metabolite (M-1) in human plasma, using liquid chromatography coupled with tandem mass spectrometry, with electrospray ionization in the positive ion mode. METHODS: Sarpogrelate, M-1, and labeled internal standard (d3-sarpogrelate) were extracted from 50 microL of human plasma by simple protein precipitation. Chromatographic separation was performed by using a linear gradient elution of a mobile phase involving water-formic acid (99.9:0.1, v/v) and acetonitrile-formic acid (99.9:0.1, v/v) over 4 min of run time on a column, with a core-shell-type stationary phase (Kinetex C18, 50 mm x 2.1 mm i.d., 2.6-microm particle size, Phenomenex, USA). Detection of the column effluent was performed by using a triple-quadruple mass spectrometer in the multiple-reaction monitoring mode. RESULTS: The developed method was validated in human plasma, with lower limits of quantification of 10 ng/mL for sarpogrelate and 2 ng/mL for M-1. The calibration curves of sarpogrelate and M-1 were linear over the concentration ranges of 10-2,000 and 2-400 ng/mL, respectively (R2>0.99). The carry-over effect, precision, accuracy, and stability of the method met the criteria for acceptance. CONCLUSIONS: A simple, fast, robust, and reliable analytical method was successfully developed and applied to the high-throughput determination of sarpogrelate and its metabolite in real plasma samples in a pharmacokinetic study of healthy subjects.

Primary Pneumococcal Peritonitis in a Healthy Child / 대한소아소화기영양학회지

Primary peritonitis usually refers to a bacterial infection of the peritoneal cavity without a demonstrable intra-abdominal source. Most cases occur in children with ascites resulting from nephrotic syndrome or cirrhosis. Rarely, it may occur in previously healthy children less than 7 years of age, usually a girl. Distinguishing primary peritonitis from appendicitis may be impossible in patients without a history of nephrotic syndrome or cirrhosis. Accordingly, the diagnosis of primary peritonitis is made only at laparotomy. We report one case of primary pneumococcal peritonitis in a 27-month-old female who underwent explorative laparotomy to discover the cause of suspicious intestinal perforation and mechanical ileus. Later, pneumococci were cultured in blood and gram-positive diplococci were isolated from the pus of peritoneal cavity.

Epidemiological Study of Kawasaki Disease in Kyung Nam Area

PURPOSE: The aim of this study was to determine the epidemiology of Kawasaki disease in the Kyung Nam area and to evaluate whether the results of this epidemiological study could support infectious etiology. METHODS: We sent a questionnaire to three training hospitals in the Kyung Nam area and retrospectively reviewed their medical records of Kawasaki disease from Jun. 1995 to Dec. 1999. RESULTS: The total number of patients was 717 cases, with little differences of annual prevalence during the five years. In all cases, the monthly prevalence of Kawasaki disease was high in Apr. and Jul. At the eastern of Kyung Nam, the monthly prevalence was high in Apr. and Jul. in 1995 and 1996, Jul. in 1997, Apr. in 1998 and Apr. and Jul. in 1999. In the central area of Kyung Nam, the monthly prevalence was high in Apr. in 1995 and 1996, Apr. and Jul. in 1997 and Jul. in 1998 and 1999. In the western Kyung Nam, the monthly prevalence was high in Nov. in 1995, Aug. in 1996, Oct. in 1997, Dec. in 1998 and Nov. in 1999. CONCLUSION: In the eastern and central areas of Kyung Nam, the monthly prevalence of Kawasaki disease was similarly high in Apr. and Jul. However, in the western district, the prevalence was high in late fall and winter. We could not prove the hypothesis that Kawasaki disease occurred with the spread of single infectious agent, but the a nnually similar prevalence in eastern and central Kyung Nam supported the infection theory for the etiology of the disease.