Development of albumin monitoring system with hepatic hypoxia-on-a-chip

Hypoxia plays an essential role in the pathogenesis of various liver diseases, and albumin is one of the important biomarkers secreted by the liver. In this study, we developed an albumin monitoring system composed of hepatic hypoxia-on-a-chip and an albumin sensor to study liver function change due to hypoxia. In hepatic hypoxia-on-a-chip, we vertically stack an oxygen-scavenging channel on a liver on a chip with a thin gas-permeable membrane in the middle. This unique design of the hepatic hypoxia-on-a-chip can help to induce hypoxia quickly, attaining <5% within 10 min. An electrochemical albumin sensor was fabricated based on the covalent immobilization of antibodies on the Au electrode to monitor albumin secreting function on the hepatic hypoxia-on-a-chip. Standard albumin samples spiked in PBS, and culture media were measured by the electrochemical impedance spectroscopy using the fabricated immunosensor. The LOD was calculated to be 10 ag/mL in both cases. Using the electrochemical albumin sensor, we measured albumin secretion in normoxia and hypoxia in the chips. The albumin concentration decreased to 27% after 24 h in hypoxia compared to normoxia. This response was consistent with physiological studies. With technical refinements, the present albumin monitoring system can be a powerful tool in studying hepatic hypoxia with real-time liver function monitoring.

Batteryless, Miniaturized Implantable Glucose Sensor Using a Fluorescent Hydrogel

We propose a biomedical sensor system for continuous monitoring of glucose concentration. Despite recent advances in implantable biomedical devices, mm sized devices have yet to be developed due to the power limitation of the device in a tissue. We here present a mm sized wireless system with backscattered frequency-modulation communication that enables a low-power operation to read the glucose level from a fluorescent hydrogel sensor. The configuration of the reader structure is optimized for an efficient wireless power transfer and data communication, miniaturizing the entire implantable device to 3 × 6 mm 2 size. The operation distance between the reader and the implantable device reaches 2 mm with a transmission power of 33 dBm. We demonstrate that the frequency of backscattered signals changes according to the light intensity of the fluorescent glucose sensor. We envision that the present wireless interface can be applied to other fluorescence-based biosensors to make them highly comfortable, biocompatible, and stable within a body.

Thermal activation between Landau levels in the organic superconductor beta(")-(BEDT-TTF)2SF5CH2CF2SO3

We show that Shubnikov-de Haas oscillations in the interlayer resistivity of the organic superconductor beta(")-(BEDT-TTF)2SF5CH2CF2SO3 become very pronounced in magnetic fields approximately 60 T. The conductivity minima exhibit thermally activated behavior that can be explained simply by the presence of a Landau gap, with the quasi-one-dimensional Fermi surface sheets contributing negligibly to the conductivity. This observation, together with complete suppression of chemical potential oscillations, is consistent with an incommensurate nesting instability of the quasi-one-dimensional sheets.

Endoscopic transsphenoidal approach through a widened nasal cavity for pituitary lesions

We operated upon 12 patients with macroadenoma and two with Rathke's cleft cyst using an endoscope through a nasal speculum. Pure endoscopic endonasal transsphenoiolal approach (TSA) was performed in nine patients and endoscope-assisted microscopic endo nasal TSA in five. A thin-bladed nasal speculum was used to achieve a wide, almost midline, pathway without an incision at the septal mucosa. This made it possible to convert from the endoscopic to the microscopic approach and vice versa at any time during operation as the occasion demanded. In 10 of the 12 patients with macroadenoma, adenomas were removed totally and did not recur during the mean follow-up period of 24 months. Two adenomas could not be removed totally due to their invasiveness. In two of five patients who underwent endoscope-assisted microscopic TSA for macroadenoma, the endoscope could visualise residual tumour at blind corners after microscopic tumor removal. Two patients with Rathke's cleft cyst did not show recurrence. No patient showed sinonasal or endocrinological complications. Versatile use of the endoscope through a widened nasal cavity using a nasal speculum is a promising tool for the treatment of pituitary lesions.

Overexpression of membrane-type matrix metalloproteinase-1 gene induces mammary gland abnormalities and adenocarcinoma in transgenic mice

To investigate the role of membrane-type matrix metalloproteinase-1 (MT1-MMP) in mammary gland development and tumorigenesis, transgenic mice overexpressing MT1-MMP in mammary gland under the control of the mouse mammary tumor virus long terminal repeat-promoter were generated. The mouse mammary tumor virus/MT1-MMP transgenic mice displayed abnormalities in 82% of female mammary glands. The abnormalities were verified as lymphocytic infiltration, fibrosis, hyperplasia, alveolar structure disruption, dysplasia, and adenocarcinoma. Northern and reverse transcription-PCR analyses demonstrated that MT1-MMP mRNA was overexpressed in mammary glands exhibiting abnormalities. Western blot analysis and immunohistochemical studies have revealed that the protein expression level was also increased in these glands. In addition, the beta-casein gene as a functional epithelial cell marker was poorly expressed in the mammary glands of transgenic mice exhibiting abnormalities. Gelatin zymography showed significantly increased MMP-2 activation in these mammary glands. These results showed that overexpression of MT1-MMP induced remodeling of the extracellular matrix and tumor formation in the mammary glands of transgenic mice. Therefore, we suggest that overexpression of MT1-MMP may play a key role in development and tumorigenesis in mammary glands.

Antimicrobial peptide of korean native goat lactoferrin and identification of the part essential for this activity

The antimicrobial activity of lactoferrin isolated from Korean native goat (KN goat) milk was studied and its antimicrobial domain was identified using synthetic peptides. Antimicrobial activity was assayed by a micro-method using 96-well microplates and a microplate reader. The amino acid sequence of the antimicrobial domain was suggested to be YQWQRRMRKLGAPSIT and this sequence corresponds to amino acid residues 20 to 35 of KN goat lactoferrin. Five peptides with certain amino acid residues deleted were synthesized in an effort to identify the residues essential for antimicrobial activity and it was found that the part with the sequence RRMRK (24-28) is the region most important for this activity. On the other hand, the conformation of the peptides did not influence the antimicrobial activity.

Characterization of Korean native goat lactoferrin

We purified lactoferrin from the colostrum of the Korean native goat (Capra hircus) by ion-exchange chromatography using CM-Toyopearl 650M followed by affinity chromatography on AF-Heparin Toyopearl 650M. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blot analysis suggested the molecular mass of Korean native goat lactoferrin is 82 kDa with an iron saturation of 30% as estimated by spectroscopic analysis. Circular dichroism analysis shows goat lactoferrin molecule contains 24.5%, alpha-helix; 36.0%, beta-structure; 13.5%, beta-turn and 26.0%, unordered structure. Heparin binding affinity is the same as that of bovine lactoferrin, but lower than that of human lactoferrin. An analysis using synthetic peptides shows that the peptide from residue 22 to 31--WQRRMRKLGA--exerts a positive heparin-binding ability.

[Five human cases of Diphyllobothrium latum infection through eating raw flesh of redlip mullet, Liza haematocheila]

A total of 32 human diphyllobothriasis cases have been reported so far in Korea, excluding 21 egg-positive cases from stool examinations. Authors experienced five more human cases of Diphyllobothrium latum infection, especially infected due to eating raw flesh of redlip mullet, Liza haematocheila. Five cases were neighbors residing in the Puchon area, Kyonggi-do, who ate raw mullets (L. haematocheila) in a party in February 1996. The mullets were purchased at the Noryangjin fisheries market in Seoul. All of cases (2 males and 3 females) were 35 to 43 years old and healthy with the body weight range of 56-62 kg. They complained about gastrointestinal trouble and abdominal discomfort, but were in normal ranges of their hematology and urinalysis data. None revealed any sign of anemia. The patients experienced natural discharge of a chain of segments before, and showed diphyllobothriid eggs in their stool specimens when they visited our laboratory. They were administered with praziquantel (15 mg/kg of body weight) and 30 g of magnesium sulfate as a purgative. Two whole worms with the scolices (310-340 cm in length; 8-13 mm in width) were expelled each from two out of five cases after anthelmintic treatment, and the others expelled the parts of strobilae without scolex. The worms were identified as D. latum, based on the following biological characters: external morphologies, coiling of uterus, the number of uterine loops, position of genital opening, morphologies of cirrus, cirrus sac and seminal vesicle on the histological sections, position of vagina and uterine pore, and microscopical and SEM morphologies of the eggs.

Polymorphic sequence of Korean Native goat lactoferrin exhibiting greater antibacterial activity

Lactoferrin, which exhibits antibacterial activity to protect infants from infectious disease, is a major component of colostrum and milk. Lactoferrin was purified from the colostrum of Korean Native goat, and the cDNA from the mammary gland mRNA of the animal was cloned and sequenced. The nucleotide sequence of the lactoferrin gene of Korean Native goat was found to differ in 15 sites from that of the goat lactoferrin gene reported earlier. This difference in nucleotide sequence resulted in six amino acid substitutions: five in the N-lobe and one in the C-lobe. The antibacterial activity of Korean Native goat lactoferrin was found to be greater than that of Sannen goat lactoferrin.

Monoclonal antibody against bovine Lactoferricin and its epitopic site

Bovine lactoferricin (LFcin B) is a strong antimicrobial peptide derived from N-lobe of lactoferrin. To study the immunochemical and structural properties of LFcin B, monoclonal antibody (mAb) was prepared and the amino acid sequence concerning with the binding to mAb has been identified. Mice injected with LFcin B showed no production of antibody specific to this peptide, whereas those with LFcin B-KLH conjugate produced anti-LFcin B antibodies. None of the mAb reacted with bovine lactoferrin C-lobe, human lactoferrin or LFcin H. By the reactivity of the mAb against the peptides synthesized on cellulose membranes using SPOTs and against chemically modified derivatives of LFcin B, the antigenic determinant of LFcin B was identified to be the sequence of "QWR".

Long-term administration of acipimox potentiates growth hormone response to growth hormone-releasing hormone by decreasing serum free fatty acid in obesity

Obesity is associated with an impairment of normal growth hormone (GH) secretion and blunted responses to all stimuli. A high plasma free fatty acid (FFA) level is frequently observed in obesity. FFA participates in the regulation of pituitary GH secretion. To determine whether the derangement of GH secretion in obesity is associated with high plasma FFA levels, tests with GH-releasing hormone (GHRH) and acipimox (ACX), an antilipolytic agent able to decrease FFA, were undertaken in six obese subjects and seven normal control subjects. In addition, the effect of prolonged suppression of FFA level on GH response to GHRH after administration of ACX for 1 month was also examined in each of the obese subjects. The GH response in obese subjects (median, 9.1 microg/L) to GHRH (1-29) (1 microg/kg intravenously [IV]) was significantly blunted as compared with normal control subjects (23.5 microg / L, P < .05). Basal FFA levels were higher in obese subjects (855.2 microEq / L than in normal control subjects (514.6 microEq / L, P < .05). One-dose ACX (500 mg) decreased FFA levels in both obese and normal subjects: the lowest FFA levels in obese subjects (158.3 microEq/L 2 to 2.5 hours after ACX were similar to those of normal control subjects (108.7 microEq/L). One-dose ACX potentiated GHRH-stimulated GH response in both obese and normal subjects. GH responses potentiated by ACX in obese subjects (27.1 microg/L) were similar to GH responses to GHRH in normal control subjects, but lower than in normal subjects treated with ACX plus GHRH (58.5 microg / L, P < .05). Thereafter, all of the obese subjects were treated with ACX for 1 month, after which the ACX plus GHRH tests were repeated. After 1 month of acipimox administration in the obese subjects, GH responses (38.8 microg/L) were significantly higher than those of obese subjects treated with GHRH and one-dose ACX plus GHRH (P < .05). They were similar to GH responses of normal control subjects receiving the one-dose ACX plus GHRH test. In conclusion, in obesity the prolonged suppression of FFA levels induced by long-term administration of ACX potentiated somatotrope responsiveness, likely acting at the pituitary level, suggesting that the duration of FFA suppression had an important relation to the magnitude of GH response.

Acipimox potentiates growth hormone response to growth hormone-releasing hormone by decreasing serum free fatty acid levels in hyperthyroidism

Hyperthyroidism is associated with an impairment of growth hormone (GH) responses to secretagogues. The aim of this study was to evaluate the effect of acipimox, an antilipolytic agent able to decrease free fatty acids (FFA), on GH response to GH-releasing hormone (GHRH) in hyperthyroid and normal control subjects. We studied six men with hyperthyroidism; seven normal men served as control subjects. Each subject underwent treatment with (1) 2 tablets of placebo orally or (2) 500 mg acipimox orally, 120 minutes before intravenous (IV) injection of 1 microgram/kg GHRH-(1-29)NH2. GH response to GHRH in hyperthyroid patients was markedly reduced; the mean peak GH response (9.6 +/- 1.0 microgram/L) and the area under the GH response curve (12.9 +/- 1.3 micrograms/L x 2 h) were lower than those of control subjects (25.7 +/- 1.8 micrograms/L, P < .05; 28.7 +/- 2.1 micrograms/L x 2 h, P < .05). Hyperthyroid patients had higher baseline levels of plasma FFA than control subjects (998.0 +/- 38.9 v 498.0 +/- 36.0 muEq/L, P < .01). Acipimox decreased FFA levels in both hyperthyroid and control subjects; the lowest FFA levels of hyperthyroid subjects induced by acipimox were similar to those of control subjects. After acipimox pretreatment, GH responses to GHRH increased significantly (P < .05); the mean peak plasma GH level (25.9 +/- 4.6 micrograms/L) was similar to the peak GH levels of control subjects during the GHRH test, and the area under the GH response curve (41.1 +/- 6.7 micrograms/L x 2 h) was even higher than that of control subjects with the GHRH test.(ABSTRACT TRUNCATED AT 250 WORDS)

Acipimox potentiates growth hormone (GH) response to GH-releasing hormone with or without pyridostigmine by lowering serum free fatty acid in normal and obese subjects

Obesity is associated with an impairment of normal GH secretion and blunted responses to all stimuli. Recent reports suggest that increased somatostatinergic activity is the basis for the GH derangement of obesity. However, the basic mechanism of this alteration is still being debated. The high plasma free fatty acid (FFA) is frequently observed in obesity. FFA participates in the regulation of pituitary GH secretion. To determine whether the derangement of GH secretion in obesity is associated with high plasma FFA levels, several tests with GHRH with or without pyridostigmine (PYR) and acipimox (ACX), antilipolytic agents able to decrease FFA, were undertaken in six obese and seven normal control subjects. In obese subjects, the GH response (mean peak +/- SEM: 8.9 +/- 1.1 ug/L) to GHRH-(1-29) (1 ug/kg, i.v.) was significantly blunted when compared with the response in normal control subjects (25.7 +/- 1.8 ug/L; P < 0.05). After PYR (120 mg), the response to GHRH was enhanced in the obese subjects (21.4 +/- 4.9 ug/L; P < 0.05) and was similar to that of the controls with GHRH only, but remained significantly reduced compared with controls treated with PYR plus GHRH (43.2 +/- 6.0 ug/L; P < 0.05). Basal FFA levels were higher than those of normal controls (P < 0.05). ACX (500 mg) decreased FFA levels in both obese and normal subjects; the lowest FFA levels of obese subjects at 15 min were similar to those of normal controls. ACX also potentiated GHRH-stimulated GH response in both obese and normal subjects. The GH responses potentiated by ACX in obesity (22.7 +/- 5.5 ug/L) were similar to those of PYR plus GHRH in obese subjects and GHRH in normal controls, but they were lower than those of control treated with ACX plus GHRH (50.8 +/- 6.7 ug/L; P < 0.05). After the combined pretreatment with ACX and PYR, GH responses in obesity (44.1 +/- 6.0 ug/L) were significantly higher than those in GHRH test, PYR plus GHRH, and ACX plus GHRH in obese subjects (P < 0.05), and they were similar to PYR plus GHRH or ACX plus GHRH in normal controls. However their enhanced GH responses were reduced compared with the control with ACX plus PYR plus GHRH (64.9 +/- 4.5 ug/L; P < 0.05). Our results are in agreement with the hypothalamic hypothesis: an increase in somatostatinergic tone is responsible for the blunted GH response to GHRH in obesity.(ABSTRACT TRUNCATED AT 250 WORDS)

Relationships among 64k autoantibodies, pancreatic beta-cell function, HLA-DR antigens and HLA-DQ genes in patients with insulin-dependent diabetes mellitus in Korea

OBJECTIVES

Among autoantibodies detected in patients with insulin-dependent diabetes mellitus (IDDM), antibodies to 64,000(Mr) islet protein(64k), now recognized as glutamic acid decarboxylase(GAD), appear to be an even more predictive marker of IDDM than islet cytoplasmic antibody (ICA) or insulin autoantibody (IAA). We examined the relationships among 64k autoantibodies, pancreatic beta-cell function, HLA-DR antigens and HLA-DQ genes in patients with IDDM in Korea.

METHODS

To identify the 64k autoantibody, the immunoprecipitation method was performed for 35 patients with IDDM and 10 normal controls. In patients with IDDM, serum C-peptide levels were measured and HLA-DR typings and HLA-DQA1 and DQB1 gene typings were performed.

RESULTS

12 of 35 (34%) patients with IDDM were positive for 64k autoantibody in contrast to none of 10(0%) normal controls. There were no differences in residual pancreatic beta-cell function between 64k autoantibody positive and negative groups. 64k autoantibody was detected more frequently in patients with recent (duration < 6 months, 10/25[40%]) and young -aged(aged < 15 years, 7/18[39%]) onset of IDDM. All of 3(100%) patients with HLA-DR3/DR4 heterotypes were positive in 64k autoantibody, in contrast to 1 of 7(14%) patients without HLA-DR3 nor DR4. The frequencies of HLA-DQA1*0301, HLA-DQB1*0201, DQB1* 0302 and DQB1*0303 gene types were higher in patients with 64k autoantibody (12/12 [100%]) vs. without 64k autoantibody 18/22[81%], 5/11[45%] vs. without 64k autoantibody 5/22[23%], 5/11[45%] vs. without 64k autoantibody 8/22[36%] and 6/11 [55%] vs. without 64k autoantibody 9/22[41%].

CONCLUSIONS

There results suggest that 64k autoantibodies have some relationship with HLA-DR, DQA1 and DQB1 genes, but not with residual pancreatic beta-cell function in Korean patients with IDDM.