Objective Narcolepsy type 1 （NT1） is known to be associated with low levels of hypocretin-1 （Hcrt-1） in cerebrospinal fluid （CSF）. The standard method for Hcrt-1 measurement is radioimmunoassay （RIA） with imported reagents， but this antibody-dependent method is limited to radiation safety-certified lab， gradual radioactivity degradation， and slow turn-around time. The purpose of this study is to explore a non-radioactive， faster， and antibody independent domestic method in China for Hcrt-1 detection. Methods Repeated testing of cerebrospinal fluid from 14 clinically diagnosed NT1 patients and 10 non-narcolepsy patients was performed using liquid chromatography-tandem mass spectrometry （LC-MS/MS）technology，including the establishment and optimization of fundamental methodological procedures. The main steps involved the addition of non-radioactive isotope-labeled internal standards to the cerebrospinal fluid， followed by solid-phase extraction， mass spectrometry signal acquisition， and quantitative analysis. The results were then compared with the corresponding radioimmunoassay（RIA） findings. Results The LC-MS/MS method showed faster speed， and good linearity across a wider range of synthesized standard（5~2 500 pg/ml）， and good repeatability. Although this absolute-quantitation-based LC-MS/MS method and RIA method have different reading values in Hcrt-1 quantitation， they both can segregate NT1 group from non-NT1 group well. Conclusion Although larger cohorts are needed to set up a standard method in China，LC-MS/MS method is proved to be an easier， safer， faster， and possibly more accurate method for Hcrt-1 quantitation and detection for NT1 diagnosis.
Narcolepsy ; Radioimmunoassay

BACKGROUND: In both developed and developing countries, noise is regarded as the most common occupational hazard in various industries. The present study aimed to examine the effect of sound pressure level (SPL) on serum cortisol concentration in three different times during the night shift. METHODS: This case–control study was conducted among 75 workers of an industrial and mining firm in 2017. The participants were assigned to one of the three groups (one control and two case groups), with an equal number of workers (25 participants) in each group. Following the ISO 9612 standard, dosimetry was adopted to evaluate equivalent SPL using a TES-1345 dosimeter. The influence of SPL on serum cortisol concentration was measured during the night shift. The serum cortisol concentration was measured using a radioimmunoassay (RIA) test in the laboratory. Repeated measure analysis of variance and linear mixed models were used with α = 0.05. RESULTS: The results indicated a downward trend in the serum cortisol concentration of the three groups during the night shift. Both SPL and exposure time significantly affected cortisol concentration (p < 0.0001, p < 0.0001). Conversely, age and body mass index had no significant influence on cortisol concentration (p = 0.360, p = 0.62). CONCLUSION: Based on the obtained results, increasing SPL will lead to enhancement of serum cortisol concentration. Given that cortisol concentration varies while workers are exposed to different SPLs, this hormone can be used as a biomarker to study the effect of noise-induced stress.
Body Mass Index ; Developing Countries ; Hydrocortisone ; Mining ; Noise ; Noise, Occupational ; Radioimmunoassay

BACKGROUND/AIMS: The aim of this study was to determine the risk factors of multiple gastric polyps according to the histological classification of gastric polyps. METHODS: Subjects with multiple gastric polyps (at least three) during endoscopy were enrolled prospectively. They were assigned to a fundic gland polyp (FGP) group and hyperplastic polyp (HP) group based on a histological classification of gastric polyps. Helicobacter pylori (H. pylori) was confirmed by its histology. Serum gastrin was measured using the radioimmunoassay method. A questionnaire was taken regarding the intake of proton pump inhibitor and nonsteroidal anti-inflammatory drugs, alcohol, smoking history, and diet. RESULTS: Among the 60 subjects enrolled from 2015 to 2018 at Seoul National University Bungdang Hospital, 47 and 13 subjects were assigned to the FGP and HP groups, respectively. The H. pylori infection rate was 12.8% in the FGP group, which is lower than that in the HP group (69.2%, p<0.001). The gastrin level was higher in the HP group (194.7 pg/dL, range 50.6–387.8 pg/dL) than in the FGP group (57.4 pg/dL, range 24.8–79.0 pg/dL) (p=0.007). Histologically, neutrophil infiltration in the antrum and body of the stomach were higher in the HP group than in the FGP group (p=0.022 and p=0.030, respectively). In contrast, monocyte infiltration in the antrum and body of the stomach were higher in the FGP group than in the HP group (p=0.018 and p<0.001, respectively). CONCLUSIONS: HPs arise from inflammation caused by H. pylori. On the other hand, the FGP was not associated with H. pylori or environmental factors.
Classification ; Cohort Studies ; Diet ; Endoscopy ; Gastrins ; Hand ; Helicobacter pylori ; Inflammation ; Methods ; Monocytes ; Neutrophil Infiltration ; Polyps ; Prospective Studies ; Proton Pump Inhibitors ; Proton Pumps ; Radioimmunoassay ; Risk Factors ; Seoul ; Smoke ; Smoking ; Stomach

BACKGROUND/AIMS: Infliximab (IFX) often loses its therapeutic effect in initial responders with inflammatory bowel disease (IBD) over time. Low serum IFX trough levels (TLs) are linked to poor clinical response and outcomes. Maintenance of optimal therapeutic IFX concentrations is important for sustaining response and achieving good clinical outcomes. Measurement of serum IFX TLs is helpful for determining a further proper therapeutic plan. However, adequate therapeutic IFX TLs in pediatric IBD is uncertain. We aimed to identify the cutoff values for IFX TLs associated with laboratory response to IFX maintenance therapy. METHODS: Patients with pediatric IBD who had received IFX infusions between December 2008 and March 2015 at Samsung Medical Center were retrospectively investigated. We analyzed 239 blood samples that were collected from 103 pediatric patients. We measured IFX TLs at induction (6 and 14 weeks) and during maintenance therapy (>22 weeks, 8 weeks interval) by fluid-phase radioimmunoassays. RESULTS: A significant association was found between the erythrocyte sedimentation rate (ESR) and IFX TLs during maintenance (correlation coefficient, −0.11; p=0.0005). A cutoff value of 18 mm/hr for ESR was used to define higher levels. Receiver operating characteristic analysis identified optimal cutoff values: IFX TL >1.58 μg/mL (sensitivity 82% and specificity 73%). CONCLUSIONS: Cutoff values are considered a prerequisite for further investigating the clinical usefulness of measurements of IFX in patients maintained with IFX treatment.
Blood Sedimentation ; Drug Monitoring ; Humans ; Inflammatory Bowel Diseases ; Infliximab ; Radioimmunoassay ; Retrospective Studies ; ROC Curve ; Sensitivity and Specificity

BACKGROUND/AIMS: The aim of this study was to determine the risk factors of multiple gastric polyps according to the histological classification of gastric polyps.METHODS: Subjects with multiple gastric polyps (at least three) during endoscopy were enrolled prospectively. They were assigned to a fundic gland polyp (FGP) group and hyperplastic polyp (HP) group based on a histological classification of gastric polyps. Helicobacter pylori (H. pylori) was confirmed by its histology. Serum gastrin was measured using the radioimmunoassay method. A questionnaire was taken regarding the intake of proton pump inhibitor and nonsteroidal anti-inflammatory drugs, alcohol, smoking history, and diet.RESULTS: Among the 60 subjects enrolled from 2015 to 2018 at Seoul National University Bungdang Hospital, 47 and 13 subjects were assigned to the FGP and HP groups, respectively. The H. pylori infection rate was 12.8% in the FGP group, which is lower than that in the HP group (69.2%, p<0.001). The gastrin level was higher in the HP group (194.7 pg/dL, range 50.6–387.8 pg/dL) than in the FGP group (57.4 pg/dL, range 24.8–79.0 pg/dL) (p=0.007). Histologically, neutrophil infiltration in the antrum and body of the stomach were higher in the HP group than in the FGP group (p=0.022 and p=0.030, respectively). In contrast, monocyte infiltration in the antrum and body of the stomach were higher in the FGP group than in the HP group (p=0.018 and p<0.001, respectively).CONCLUSIONS: HPs arise from inflammation caused by H. pylori. On the other hand, the FGP was not associated with H. pylori or environmental factors.
Classification ; Cohort Studies ; Diet ; Endoscopy ; Gastrins ; Hand ; Helicobacter pylori ; Inflammation ; Methods ; Monocytes ; Neutrophil Infiltration ; Polyps ; Prospective Studies ; Proton Pump Inhibitors ; Proton Pumps ; Radioimmunoassay ; Risk Factors ; Seoul ; Smoke ; Smoking ; Stomach

BACKGROUND/OBJECTIVES: This study evaluated the effects and molecular mechanisms of the Schisandra chinensis fruit extract (SC) and its major compound gomisin A (GA), on the contractility of rabbit penile corpus cavernosum smooth muscle (PCCSM). MATERIALS/METHODS: PCCSM was exposed to SC or GA after appropriate pretreatment with nitric oxide synthase (NOS) blocker, guanylate cyclase blocker, adenylyl cyclase blocker or protein kinase A blocker. Subsequently, we evaluated the cyclic nucleotide in the perfusate by radioimmunoassay, protein expression level of neuronal NOS (nNOS) and endothelial NOS (eNOS) by western blot, and the interaction of SC or GA with udenafil and rolipram. RESULTS: Both SC and GA induce PCCSM relaxations in a concentration-dependent manner. Pretreatment with NOS blocker, guanylate cyclase blocker, adenylyl cyclase blocker or protein kinase A blocker result in significantly decreased relaxation. SC and GA also induce the levels of cyclic nucleotide in the perfusate in a concentration-dependent manner. Perfusion with GA also showed significantly higher levels of eNOS protein. Furthermore, the udenafil and rolipram induced relaxations of PCCSM were enhanced after exposure to SC and GA. Our results indicate that SC and GA induce the relaxation of PCCSM via the nitric oxide (NO)-cGMP and cAMP signaling pathways. CONCLUSIONS: The SC and GA are potential alternative treatments for men who want to consume natural products to ameliorate erectile function, or who do not respond to the commercially available medicines.
Adenylyl Cyclases ; Biological Products ; Blotting, Western ; Cyclic AMP-Dependent Protein Kinases ; Erectile Dysfunction ; Fruit* ; Guanosine Monophosphate* ; Guanosine* ; Guanylate Cyclase ; Humans ; Lignans ; Male ; Muscle, Smooth* ; Neurons ; Nitric Oxide Synthase ; Nitric Oxide* ; Perfusion ; Phosphodiesterase 5 Inhibitors ; Radioimmunoassay ; Relaxation ; Rolipram ; Schisandra*

PURPOSE: In radioimmunoassay (RIA), the gamma counter is the important instrument for the accurate measurement. To manage quality assurance of RIA, the counting efficiency of gamma counter is one of the important parameters. The aimof this study was to evaluate the counting efficiency of gamma counters in multiple institutes on the base of traceability by using the certified reference materials (CRMs).METHODS: Twenty-three institutes that perform RIA were enrolled in this study. I-125 CRMs that were certified by National Institute of Standards and Technology (NIST) were used. Each institute was asked to count the activity of I-125 CRMs at most twice on all gamma counters in use. The counting efficiency of each well of counter was calculated on the base of NIST-certified information, corrected for I-125 decay for date of testing.RESULTS: From 23 institutes, 44 gamma counters were evaluated. The average counting efficiency of all wells was 85.9% and the standard deviation was 13.5%. As a mean value of each gamma counter, three gamma counters showed poor counting efficiency (less than 70%). The poorest counting efficiency was 7%. The counting efficiency of seven gamma counters was between 70 and 75%. Eight counters had the counting efficiency between 75 and 90%. More than half of counter (26 gamma counters) showed excellent counting efficiency (more than 90%). The standard deviation variation range of inter-well efficiency was from 0 to 11.2.CONCLUSION: The first survey on the counting efficiency of gamma counter was performed in South Korea. Most of the RIA laboratories have well managed the quality assurance of gamma counter.
Academies and Institutes ; Immunoradiometric Assay ; Korea ; Quality Control ; Radioimmunoassay

BACKGROUND: Psoriasis is a chronic inflammatory skin disorder histopathologically characterized by epidermal hyperplasia, vascular proliferation, and inflammatory infiltrates. It runs a less severe course in women than in men. The role of estrogen in the pathogenesis of psoriasis remains unclear. OBJECTIVE: We investigated the clinicohistopathological differences between men and women with psoriasis and examined whether serum estrogen levels and immunohistochemical findings correlate with gender and disease severity. METHODS: We retrospectively reviewed the medical records of 500 patients with psoriasis. Among these patients, 60 who consented to participate in the study were classified into four groups as follows: 10 men showing psoriasis on < 10% of their body surface area (BSA) with psoriasis area severity index (PASI) < 10; 20 men showing psoriasis on ≥10% of their BSA with PASI≥10; 10 women showing psoriasis on < 10% of their BSA with PASI < 10; and 20 women showing psoriasis on ≥10% of their BSA with PASI ≥10. Serum estrogen levels were measured using radioimmunoassay. Immunohistochemical staining of skin biopsy tissues was performed using ERα, ERβ, and CCL5. RESULTS: Men diagnosed with psoriasis showed higher BSA and PASI scores than women. Women aged ≥60 years showed higher BSA and PASI scores than women aged < 60 years. There were no histological differences between the four groups. Serum estrogen levels were higher in the patients presenting with mild psoriasis, as well as in women. ERα, ERβ, and CCL5 showed a stronger staining tendency in patients with more severe psoriasis. CONCLUSION: Gender influences the severity of psoriasis, and estrogen plays an important role. This finding is explained by the fact that estrogen decreases inflammation in psoriasis possibly via its action on estrogen receptors in epidermal keratinocytes.
Biopsy ; Body Surface Area ; Estrogens* ; Female ; Humans ; Hyperplasia ; Immunohistochemistry ; Inflammation ; Keratinocytes ; Male ; Medical Records ; Psoriasis* ; Radioimmunoassay ; Receptors, Estrogen ; Retrospective Studies ; Skin

BACKGROUND: There are growing concerns about the role of vitamin D deficiency in cardiovascular diseases. Therefore, we investigated the correlation between serum 25-hydroxy-vitamin D (25[OH]D) and arterial stiffness among Korean adults. METHODS: We retrospectively reviewed the medical charts of 302 people (115 women and 187 men) who visited a tertiary hospital from January 2015 to December 2016. Serum 25(OH)D was measured using the radioimmunoassay technique, and brachial-ankle pulse wave velocity (baPWV) was measured using an automatic wave analyzer. We obtained the doctor's report on the medical history of the participants, their alcohol consumption and smoking habits, and their exercise status. Metabolic syndrome was diagnosed based on guidelines from the National Cholesterol Education Program (NCEP)-Adult Treatment Panel (ATP III) and the International Diabetes Federation (IDF). Results of basic blood tests and physical assessment were also collected. RESULTS: In the Pearson correlation analysis, serum 25(OH)D and baPWV showed a statistically significant inverse relationship (r=-0.279, P<0.001). Using multiple regression analysis, and after adjusting for possible confounders, serum 25(OH)D concentration was found to be significantly associated with baPWV (β=-0.121, P=0.011). CONCLUSIONS: We observed an association between serum 25(OH)D concentration and arterial stiffness. Further studies involving larger sample sizes will be needed to confirm this associations.
Adult* ; Alcohol Drinking ; Calcifediol ; Cardiovascular Diseases ; Cholesterol ; Education ; Female ; Hematologic Tests ; Humans ; Pulse Wave Analysis ; Radioimmunoassay ; Retrospective Studies ; Sample Size ; Smoke ; Smoking ; Tertiary Care Centers ; Vascular Stiffness* ; Vitamin D Deficiency

BACKGROUND: Although the exact mechanism of insulin resistance (IR) has not yet been established, IR is the hallmark characteristic of type 2 diabetes mellitus (T2DM). The aim of this study was to examine the relationship between plasma ghrelin levels and IR in Saudi subjects with T2DM. METHODS: Patients with T2DM (n=107, cases) and non-diabetic apparently healthy subjects (n=101, controls) from Saudi Arabia were included in this study. The biochemical profiles and plasma insulin levels of all subjects were analyzed, and IR was estimated using the homeostatic model assessment of insulin resistance (HOMA-IR) index. Active ghrelin levels in plasma were measured using the radioimmunoassay technique. RESULTS: Only 46.7% (50 of 107) of the T2DM subjects had IR, including 26% (28 of 107) with severe IR (HOMA-IR ≥5), while 5.9% (six of 101) of the controls had moderate IR (3 ≤HOMA-IR <5). HOMA-IR values were not associated with age, disease duration, or gender. Importantly, T2DM itself and the co-occurrence of IR with T2DM were significantly associated with low plasma ghrelin levels. However, ghrelin levels were inversely correlated with the HOMA-IR index, body weight, and fasting plasma insulin levels, mainly in the control subjects, which was indicative of the breakdown of metabolic homeostasis in T2DM. CONCLUSION: The prevalence of IR was relatively low, and IR may be inversely associated with plasma ghrelin levels among Saudi patients with T2DM.
Body Weight ; Diabetes Mellitus ; Diabetes Mellitus, Type 2* ; Fasting ; Ghrelin* ; Healthy Volunteers ; Homeostasis ; Humans ; Insulin Resistance* ; Insulin* ; Plasma* ; Prevalence ; Radioimmunoassay ; Saudi Arabia