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1.
Eur Radiol ; 29(8): 4303-4314, 2019 Aug.
Article in English | MEDLINE | ID: mdl-30350166

ABSTRACT

OBJECTIVE: To investigate the incidence of thoracic recurrence and the diagnostic value of chest CT for postoperative surveillance in curatively-resected colorectal cancer (CRC) patients. METHODS: This retrospective study consisted of 648 CRC patients (M:F, 393:255; mean age, 66.2 years) treated with curative surgery between January 2010 and December 2012. The presence of CRC recurrence over follow-ups was analysed and recurrence-free survival and risk factors of recurrence were assessed using Kaplan-Meier analysis with log-rank test and Cox-regression analysis, respectively. RESULTS: Over a median follow-up of 57 months, thoracic recurrence occurred in 8.0% (52/648) of patients with a median recurrence-free survival rate of 19.5 months. Among the 52 patients with thoracic recurrence, 18 (2.7%) had isolated thoracic recurrence, and only five (0.8%) were diagnosed through chest CT. Risk factors of overall thoracic recurrence included age, positive resection margin, presence of venous invasion, positive pathologic N-class, and presence of abdominal recurrence (odds ratio [OR] = 1.78, 19.691, 2.993, 2.502, and 31.137; p = 0.045, 0.004, 0.001, 0.005, and p < 0.001, respectively). As for isolated thoracic recurrence, serum carcinoembryonic antigen level ≥ 5 ng/mL during postoperative follow-up (OR = 9.112; p < 0.001) was demonstrated to be the only predictive factor. There were no thoracic recurrences in patients with CRC stages 0 and I. CONCLUSION: In patients with curatively-resected CRCs, routine surveillance using chest CT may be of limited value, particularly in those with CRC stages 0 or I, as recurrence only detectable through chest CT was shown to be rare. KEY POINTS: • Postoperative thoracic recurrence only detectable through chest CT was shown to be rare. • There were no thoracic recurrences in colorectal cancers stage 0 and I. • Postoperative surveillance chest CT is of limited value in patients with curatively resected colorectal cancers.


Subject(s)
Colectomy , Colorectal Neoplasms/diagnosis , Neoplasm Recurrence, Local/diagnosis , Thoracic Neoplasms/epidemiology , Tomography, X-Ray Computed/methods , Aged , Biomarkers, Tumor/blood , Carcinoembryonic Antigen/blood , Colorectal Neoplasms/secondary , Colorectal Neoplasms/surgery , Female , Humans , Incidence , Male , Postoperative Period , Republic of Korea/epidemiology , Retrospective Studies , Risk Factors , Thoracic Neoplasms/diagnosis
2.
Obes Sci Pract ; 3(1): 25-35, 2017 Mar.
Article in English | MEDLINE | ID: mdl-28392929

ABSTRACT

OBJECTIVE: Pervasive weight stigma and discrimination have led to ongoing calls for efforts to reduce this bias. Despite increasing research on stigma-reduction strategies, perspectives of individuals who have experienced weight stigma have rarely been included to inform this research. The present study conducted a systematic examination of women with high body weight to assess their perspectives about a broad range of strategies to reduce weight-based stigma. METHODS: Women with overweight or obesity (N = 461) completed an online survey in which they evaluated the importance, feasibility and potential impact of 35 stigma-reduction strategies in diverse settings. Participants (91.5% who reported experiencing weight stigma) also completed self-report measures assessing experienced and internalized weight stigma. RESULTS: Most participants assigned high importance to all stigma-reduction strategies, with school-based and healthcare approaches accruing the highest ratings. Adding weight stigma to existing anti-harassment workplace training was rated as the most impactful and feasible strategy. The family environment was viewed as an important intervention target, regardless of participants' experienced or internalized stigma. CONCLUSION: These findings underscore the importance of including people with stigmatized identities in stigma-reduction research; their insights provide a necessary and valuable contribution that can inform ways to reduce weight-based inequities and prioritize such efforts.

3.
Br J Radiol ; 85(1016): e349-56, 2012 Aug.
Article in English | MEDLINE | ID: mdl-22422382

ABSTRACT

OBJECTIVE: The objective of this study was to compare the underestimation rate of invasive carcinoma in cases with ductal carcinoma in situ (DCIS) at percutaneous ultrasound-guided core biopsies of breast lesions between 14-gauge automated core-needle biopsy (ACNB) and 8- or 11-gauge vacuum-assisted biopsy (VAB), and to determine the relationship between the lesion type (mass or microcalcification on radiological findings) and the DCIS underestimation rate. METHODS: We retrospectively reviewed imaging-guided biopsies of breast lesions performed from February 2003 to August 2008. 194 lesions were diagnosed as DCIS at ultrasound-guided core biopsy: 138 lesions in 132 patients by 14-gauge ACNB, and 56 lesions in 56 patients by 8- or 11-gauge VAB. The histological results of the core biopsy samples were correlated with surgical specimens. The clinical and radiological findings were also reviewed. The histological DCIS underestimation rates were compared between the two groups and were analysed for differences according to the clinical and radiological characteristics of the lesions. RESULTS: The DCIS underestimation rate was 47.8% (66/138) for 14-gauge ACNB and 16.1% (9/56) for VAB (p<0.001). According to the lesion type on sonography, DCIS underestimation was 43.4% (63/145) in masses (47.6% using ACNB and 15.8% using VAB; p=0.012) and 24.5% (12/49) in microcalcifications (50.0% using ACNB and 16.2% using VAB; p=0.047). CONCLUSION: The underestimation rate of invasive carcinoma in cases with DCIS at ultrasound-guided core biopsies was significantly higher for ACNB than for VAB. Furthermore, this difference does not change according to the lesion type on ultrasound. Therefore, ultrasound-guided VAB can be a useful method for the diagnosis of DCIS lesions presented as either mass or microcalcification.


Subject(s)
Biopsy, Needle/methods , Breast Neoplasms/pathology , Breast/pathology , Carcinoma, Ductal, Breast/pathology , Carcinoma, Intraductal, Noninfiltrating/pathology , Adult , Biopsy, Needle/instrumentation , Calcinosis/pathology , Delayed Diagnosis , Female , Humans , Middle Aged , Prognosis , Sensitivity and Specificity , Ultrasonography, Interventional/methods , Vacuum
4.
J Nanosci Nanotechnol ; 11(1): 661-5, 2011 Jan.
Article in English | MEDLINE | ID: mdl-21446519

ABSTRACT

Natural halloysite nanotubes with a 15-nm internal lumen and a 50 nm outer diameter were investigated as a nanocontainer for the loading and extended release of glycerol for cosmetic applications. Cytotoxicity testing of the halloysite was conducted on 3T3 and MCF-7 cells, and the tubules showed no toxic effect on the cells for over 48 h. The capability of halloysite for loading glycerol was higher with the USA halloysite than with the New Zealand's, being approximately 20% and 2.3% by weight, respectively. The total elapsed time for releasing glycerol from the nanotubes exceeded 20 h. To further retard the glycerol release rate, the halloysite samples filled with glycerol were coated with several alternate layers of polyethyleneimine and polyacrylic acid. The release rate remained at the same level, however, probably due to the low molecular weight of the polyelectrolytes and the high solubility of glycerol in water.


Subject(s)
Aluminum Silicates/chemistry , Cosmetics/chemistry , Drug Delivery Systems/methods , Glycerol/administration & dosage , Glycerol/chemistry , Nanotubes/chemistry , 3T3 Cells , Aluminum Silicates/administration & dosage , Animals , Biocompatible Materials/administration & dosage , Biocompatible Materials/chemistry , Biocompatible Materials/pharmacokinetics , Cell Line, Tumor , Cell Survival/drug effects , Clay , Cosmetics/administration & dosage , Delayed-Action Preparations , Glycerol/pharmacokinetics , Humans , Materials Testing , Mice , Microscopy, Electron, Scanning
5.
J Pathol ; 209(3): 392-9, 2006 Jul.
Article in English | MEDLINE | ID: mdl-16583357

ABSTRACT

In aspirin-intolerant subjects, adverse bronchial and nasal reactions to cyclooxygenase (COX) inhibitors are associated with over-production of cysteinyl-leukotrienes (cys-LTs) generated by the 5-lipoxygenase (5-LO) pathway. In the bronchi of patients with aspirin-intolerant asthma, we previously linked cys-LT over-production and aspirin hyper-reactivity with elevated immunoexpression in eosinophils of the terminal enzyme for cys-LT production, LTC4 synthase. We investigated whether this anomaly also occurs in the nasal airways of these patients. Immunohistochemical expression of 5-LO and COX pathway proteins was quantified in nasal polyps from 12 patients with aspirin-intolerant asthma and 13 with aspirin-tolerant asthma. In the mucosa of polyps from aspirin-intolerant asthmatic patients, cells immunopositive for LTC4 synthase were four-fold more numerous than in aspirin-tolerant asthmatic patients (p=0.04). There were also three-fold more cells expressing 5-LO (p=0.037), with no differences in 5-LO activating protein (FLAP), COX-1 or COX-2. LTC4 synthase-positive cell counts correlated exclusively with mucosal eosinophils (r=0.94, p<0.001, n=25). Co-localisation confirmed that five-fold higher eosinophil counts (p=0.007) accounted for the increased LTC4 synthase expression in polyps from aspirin-intolerant asthmatic patients, with no alterations in mast cells or macrophages. Within the epithelium, increased counts of eosinophils (p=0.006), macrophages (p=0.097), and mast cells (p=0.034) in aspirin-intolerant asthmatic polyps were associated only with 2.5-fold increased 5-LO-positive cells (p<0.05), while the other enzymes were not different. Our results indicate that a marked over-representation of LTC4 synthase in mucosal eosinophils is closely linked to aspirin intolerance in the nasal airway, as in the bronchial airways.


Subject(s)
Arachidonate 5-Lipoxygenase/metabolism , Aspirin/adverse effects , Asthma/enzymology , Nasal Polyps/enzymology , Prostaglandin-Endoperoxide Synthases/metabolism , Adolescent , Adult , Aged , Asthma/complications , Asthma/immunology , Cyclooxygenase Inhibitors/adverse effects , Eosinophilia/enzymology , Female , Glutathione Transferase/metabolism , Humans , Leukocyte Count , Male , Middle Aged , Nasal Mucosa/enzymology , Nasal Mucosa/immunology , Nasal Polyps/complications , Nasal Polyps/immunology
6.
Dement Geriatr Cogn Disord ; 19(5-6): 324-30, 2005.
Article in English | MEDLINE | ID: mdl-15785033

ABSTRACT

To compare the diagnostic accuracies of the Revised Hasegawa Dementia Scale (HDS-R) and Mini-Mental Status Examination (MMSE) for Alzheimer's diseases (AD), we administered them simultaneously to 82 AD patients and 82 age- and sex-matched nondemented control subjects. The area under the receiver operator curve (AUC) for AD of the HDS-R (AUC(HDS-R)) and MMSE (AUC(MMSE)) were bigger than 0.90 indicating that both tests are useful for detecting AD. However, AUC(HDS-R) (0.952) was significantly larger than that of the AUC(MMSE )(0.902) regardless of the educational level of the subjects, indicating that the HDS-R is more accurate than MMSE in diagnosing AD. Moreover, the superiority of the HDS-R (AUC(HDS-R) = 0.894) to the MMSE (AUC(MMSE) = 0.704) remained significant in mild AD patients alone, who are the focus of screening. In conclusion, the HDS-R is better than the MMSE as a screening instrument for AD.


Subject(s)
Alzheimer Disease/diagnosis , Mass Screening/standards , Mental Status Schedule/standards , Severity of Illness Index , Aged , Aged, 80 and over , Alzheimer Disease/psychology , Female , Humans , Male , Middle Aged , Neuropsychological Tests/standards , ROC Curve
7.
Clin Exp Allergy ; 34(8): 1270-5, 2004 Aug.
Article in English | MEDLINE | ID: mdl-15298569

ABSTRACT

BACKGROUND: Nasal polyps infiltrated with eosinophils are commonly found in chronic asthmatic patients, more frequently in those with aspirin-intolerant asthma (AIA) than aspirin-tolerant asthma (ATA). Some studies have suggested a contribution of superantigens derived from Staphylococcus sp to nasal polyposis and eosinophilia, but their relative importance in AIA and ATA subjects is unknown. OBJECTIVE: We investigated whether local production of specific IgE to staphylococcal enterotoxins A and B (SEA and SEB) and relationships with markers of eosinophilic inflammation differ in the nasal polyps of AIA and ATA subjects. METHODS: Fifteen AIA subjects with positive responses to lysine-aspirin bronchoprovocation and 15 ATA subjects underwent polypectomy. Immunoassays were used to quantify eosinophil cationic protein (ECP), IL-5, mast cell tryptase, soluble IL-2 receptors (sIL-2R), total IgE, and specific IgE for SEA and SEB. RESULTS: ECP levels in nasal polyp homogenates were higher in AIA subjects than in ATA subjects (P < 0.02), with no significant differences in tryptase, IL-5 or sIL-2R. Total IgE, and specific IgE to both SEA and SEB, were detectable in some nasal polyps from both subject groups, but median levels were markedly higher in AIA subjects than in ATA subjects (P = 0.04, 0.01, 0.05, respectively). Levels of specific IgE to SEA and SEB correlated significantly with levels of ECP and IL-5, but not those of tryptase or sIL-2R. CONCLUSION: These findings suggest that staphylococcal superantigens may drive local eosinophilic inflammation in nasal polyp tissue, and that this is exacerbated in subjects with AIA.


Subject(s)
Asthma/immunology , Enterotoxins/immunology , Immunoglobulin E/analysis , Nasal Mucosa/immunology , Nasal Polyps/immunology , Staphylococcus/metabolism , Adult , Anti-Inflammatory Agents, Non-Steroidal/adverse effects , Aspirin/adverse effects , Asthma/chemically induced , Asthma/microbiology , Biomarkers/analysis , Eosinophil Cationic Protein/analysis , Eosinophilia , Female , Humans , Interleukin-5/analysis , Male , Middle Aged , Nasal Mucosa/microbiology , Nasal Polyps/microbiology , Receptors, Fc/immunology , Staphylococcal Protein A/immunology
10.
Ann Allergy Asthma Immunol ; 86(4): 444-8, 2001 Apr.
Article in English | MEDLINE | ID: mdl-11345290

ABSTRACT

BACKGROUND AND OBJECTIVE: Hop Japanese (Hop J) pollen has been reported as one of the major causative pollen allergens in the autumn season. There have been no published data regarding the clinical and immunologic effects of Hop J pollen immunotherapy in sensitized patients. In this study, we evaluated clinical and immunologic effects of Hop J immunotherapy. PATIENTS AND METHODS: Pollens were collected in our area, and "Depo-Hop J" was prepared in the laboratory of Allergopharma (Reinbek, Germany). Fifteen asthmatic patients who had Hop J immunotherapy for > 1 year were enrolled. Their clinical parameters, such as asthma symptom scores, were monitored. Skin reactivity to Hop J and degree of airway hyperresponsiveness to methacholine were measured before and 1 year after the immunotherapy. Sera were collected before the immunotherapy, at the end of initial therapy, and 1 year after the therapy. Serum total IgE levels were compared by radioimmunoassay. Serum-specific IgE, IgG1, and IgG4 levels to Hop J were compared by ELISA. To evaluate the changes of cellular mechanisms, soluble CD30 (sCD30), soluble interleukin (IL)-2 receptor (sIL-2R), soluble CD23 (sCD23), and IL-10 levels were measured by ELISA. RESULTS: Specific IgG1 and IgG4 levels began to increase at the end of the initial therapy (P < 0.05) with significant decreases in symptom scores (P < 0.05), whereas total and specific IgE levels showed variable responses during the immunotherapy with no statistical significance (P > 0.05). Serum sIL-2R and sCD30 levels decreased significantly (P < 0.05) 1 year after immunotherapy. No significant changes were noted in sCD23, IL-10, skin reactivity to Hop J, or airway responsiveness to methacholine (P > 0.05). CONCLUSIONS: We are certain that Hop J allergen immunotherapy, if carried out properly according to suitable indications, can favorably influence asthma. Thus, an increase in specific IgG4 and IgG1 antibodies and reduction of a possible Th2 lymphocyte marker (sCD30) may be associated with symptomatic improvements.


Subject(s)
Desensitization, Immunologic , Pollen/immunology , Rhinitis, Allergic, Seasonal/drug therapy , Rhinitis, Allergic, Seasonal/immunology , Adolescent , Adult , Allergens/therapeutic use , Bronchial Hyperreactivity/diagnosis , Female , Humans , Immunoglobulin E/blood , Immunoglobulin G/blood , Interleukin-10/blood , Ki-1 Antigen/blood , Male , Methacholine Chloride , Middle Aged , Receptors, IgE/blood , Receptors, Interleukin-2/blood , Skin Tests
11.
Genet Epidemiol ; 21 Suppl 1: S706-11, 2001.
Article in English | MEDLINE | ID: mdl-11793765

ABSTRACT

We explore an approach that allows us to consider a trait for which we wish to determine the optimal subset of markers out of a set of p > or = 3 candidate markers being considered in a linkage analysis. The most effective analysis would find the model that only includes the q markers closest to the q major genes which determine the trait. Finding this optimal model using classical "frequentist" multiple regression techniques would require consideration of all 2p possible subsets. We apply the work of George and McCulloch [J Am Stat Assoc 88:881-9, 1993], who have developed a Bayesian approach to optimal subset selection regression, to a modification of the Haseman-Elston linkage statistic [Elston et al., Genet Epidemiol 19:1-17, 2000] in the analysis of the two quantitative traits simulated in Problem 2. The results obtained using this Bayesian method are compared to those obtained using (1) multiple regression and (2) the modified Haseman-Elston method (single variable regression analysis). We note upon doing this that for both Q1 and Q2, (1) we have extremely low power with all methods using the samples as given and have to resort to combining several simulated samples in order to have power of 50%, (2) the multivariate analysis does not have greater power than the univariate analysis for these traits, and (3) the Bayesian approach identifies the correct model more frequently than the frequentist approaches but shows no clear advantage over the multivariate approach.


Subject(s)
Chromosome Mapping/statistics & numerical data , Models, Genetic , Quantitative Trait, Heritable , Bayes Theorem , Genetic Markers/genetics , Humans , Multivariate Analysis , Regression Analysis
12.
J Biol Chem ; 271(41): 25213-9, 1996 Oct 11.
Article in English | MEDLINE | ID: mdl-8810281

ABSTRACT

A specific protein inhibitor of partially purified bovine brain phospholipase D (PLD) was identified from bovine brain cytosol. The PLD inhibitor has been enriched through several chromatographic steps and characterized with respect to size and mechanism of inhibition. The inhibitor showed an apparent molecular mass of 30 kDa by Superose 12 gel exclusion chromatography and inhibited PLD activity with an IC50 of 7 nM. The inhibitor had neither proteolytic activity nor phospholipid-hydrolyzing activity. Because phosphatidylinositol 4,5-bisphosphate (PIP2), which is included in substrate vesicles, is an essential cofactor for PLD, we examined whether the inhibition might be mediated by sequestration of PIP2. PIP2 hydrolysis by phospholipase C (PLC)-beta1 was not affected by the inhibitor and the inhibitor did not bind to substrate vesicles containing PIP2. In contrast, a PH domain derived from PLC-delta1, which could bind to PIP2, showed a nearly identical inhibition of both PLC-beta1 and PLD activities. Thus, the PLD inhibition by the inhibitor is due to the specific interaction with not PIP2 but PLD. The suppression of PLD activity by the inhibitor was largely eliminated by the addition of ADP-ribosylation factor (ARF) and GTPgammaS. We propose that the inhibitor plays a negative role in regulation of PLD activity by PIP2 and ARF.


Subject(s)
Brain/physiology , Enzyme Inhibitors/pharmacology , Nerve Tissue Proteins/pharmacology , Phospholipase D/isolation & purification , Animals , Brain/enzymology , Brain Chemistry , Cattle , Chromatography, Gel , Chromatography, Ion Exchange , Cytosol/physiology , Enzyme Inhibitors/isolation & purification , Isoenzymes/metabolism , Kinetics , Molecular Weight , Nerve Tissue Proteins/isolation & purification , Phosphatidylinositol 4,5-Diphosphate/metabolism , Phosphatidylinositol 4,5-Diphosphate/pharmacology , Phospholipase C beta , Type C Phospholipases/metabolism
13.
Surg Endosc ; 10(2): 137-42, 1996 Feb.
Article in English | MEDLINE | ID: mdl-8932615

ABSTRACT

BACKGROUND: The aim of this study was to retrospectively assess the usefulness of the preoperative oral cholecystogram (OCG) as an index to the feasibility of laparoscopic cholecystectomy (LC) and the operative pathologic findings. Laparoscopic cholecystectomy has become the standard treatment for symptomatic gallbladder (GB) disease. However, no definite diagnostic modality that can predict the feasibility of LC and severity of pathologic anatomy has been proposed. METHODS: Retrospective data were collected on 240 consecutive patients undergoing LC at St. Vincent Hospital, Catholic University Medical College, from October 1991 until December 1993. Radiologic interpretations of OCG were standardized according to the method of Koehler and Kyaw--from grade 0 to 4. And the operative findings--pericholecystic adhesion, color of GB, and thickness of the GB wall--were evaluated simultaneously. RESULTS: The analysis showed that preoperative OCG can predict intraoperative GB perforation (p = 0.022), intraoperative controllable bleeding (p = 0.034), and operating time (p = 0.0001) according to the grade of visualization of GB. Grade 2- or -better visualized groups had more patients who had blue-colored GB (p = 0.000) and who had thin GB wall (p = 0.000). CONCLUSIONS: Preoperative oral cholecystogram may be an accurate index of the feasibility of laparoscopic cholecystectomy--represented by operating time and important intraoperative minor complications related to the operative pathological findings.


Subject(s)
Cholecystectomy, Laparoscopic , Cholecystography , Gallbladder Diseases/diagnostic imaging , Gallbladder Diseases/surgery , Adolescent , Adult , Aged , Aged, 80 and over , Analysis of Variance , Cholecystectomy, Laparoscopic/methods , Cholecystography/methods , Female , Gallbladder Diseases/pathology , Humans , Male , Middle Aged , Multivariate Analysis , Predictive Value of Tests , Preoperative Care , Prognosis , Retrospective Studies
14.
J Biol Chem ; 269(6): 4668-74, 1994 Feb 11.
Article in English | MEDLINE | ID: mdl-8308038

ABSTRACT

Recent studies suggest that epithelial cells and neurons employ similar mechanisms to target proteins to the distinct subdomains of their polarized cell surface membranes. We have examined the sorting behavior of the neuronal gamma-aminobutyric acid (GABA) transporter GAT-1 expressed by transfection in the polarized epithelial Madin-Darby canine kidney (MDCK) cell line. We find that the GABA transporters endogenously expressed by polarized hippocampal neurons in culture are restricted to axonal plasma membranes. In transfected MDCK cells, the GABA transporter is found to be localized primarily to the apical cell surface when examined by immunocytochemistry, cell surface biotinylation, and transport assay. MDCK cells exposed to hyperosmotic stress express a close relative of GAT-1, the betaine transporter (BGT-1). We find that BGT-1 expressed by transfection in MDCK cells accumulates predominantly at the basolateral cell surface. These observations suggest that the sorting information required for axonal targeting may be similar to that which mediates apical localization in epithelia. Furthermore, it would appear that despite their high degree of homology, the BGT-1 and GAT-1 transporters manifest sorting signals which specify their targeting to distinct cell surface domains.


Subject(s)
Carrier Proteins/metabolism , Cell Membrane/metabolism , Cell Polarity , Membrane Proteins/metabolism , Membrane Transport Proteins , Nerve Tissue Proteins/metabolism , Organic Anion Transporters , Animals , Axons/metabolism , Betaine/metabolism , Cell Compartmentation , Cell Line , Cell Membrane/ultrastructure , Cells, Cultured , Dogs , Epithelium/ultrastructure , Fluorescent Antibody Technique , GABA Plasma Membrane Transport Proteins , In Vitro Techniques , gamma-Aminobutyric Acid/metabolism
15.
Biochemistry ; 31(7): 1974-9, 1992 Feb 25.
Article in English | MEDLINE | ID: mdl-1536839

ABSTRACT

The cDNA clone GAT-1, which encodes a Na(+)- and Cl(-)-coupled GABA transporter from rat brain, has been expressed in mammalian cells using three different systems: (1) transient expression upon transfection of mouse Ltk- cells with a eukaryotic expression vector containing GAT-1; (2) stable expression in L-cells transfected with the same vector; (3) transfection of HeLa cells infected with a recombinant vaccinia virus expressing T7 RNA polymerase. Similar results both qualitatively and quantitatively were obtained with all systems. The GABA transporter expressed in HeLa and L-cells retains all the properties described previously for GABA transport into synaptosomes and synaptic plasma membrane vesicles. It was fully inhibited by cis-3-aminocyclohexanecarboxylic acid (ACHC) and not by beta-alanine. The KM for GABA transport and the IC50 for ACHC inhibition were similar to the presynaptic transporter. Accumulated [3H]GABA was released from transfected cells by dissipating the transmembrane Na+ gradient with nigericin or by exchange with unlabeled external GABA. Accumulation was stimulated by both Na+ and Cl- in the external medium. However, in the absence of external Cl-, a small amount of GABA transport remained which was dependent on GAT-1 transfection. Functional expression of the GABA transporter was abolished by tunicamycin. An antitransporter antibody specifically immunoprecipitates a polypeptide with an apparent molecular mass of about 70 kDa from GAT-1-transfected cells. When cells were grown in the presence of tunicamycin, only a faint band of apparent mass of about 60 kDa was observed.(ABSTRACT TRUNCATED AT 250 WORDS)


Subject(s)
Carrier Proteins , Membrane Proteins , Membrane Transport Proteins , Nerve Tissue Proteins/genetics , Organic Anion Transporters , Animals , Biological Transport/drug effects , Chlorides/metabolism , Cloning, Molecular , DNA/genetics , GABA Plasma Membrane Transport Proteins , Gene Expression , Genetic Vectors , HeLa Cells , Humans , Kinetics , L Cells , Mice , Nerve Tissue Proteins/metabolism , Plasmids , Precipitin Tests , Rats , Sodium/metabolism , Transfection , Tunicamycin/pharmacology , Xenopus , gamma-Aminobutyric Acid/metabolism
16.
J Biol Chem ; 266(33): 22102-9, 1991 Nov 25.
Article in English | MEDLINE | ID: mdl-1939231

ABSTRACT

Previous studies on the chlorination reaction catalyzed by horseradish peroxidase using chlorite as the source of chlorine detected the formation of a chlorinating intermediate that was termed Compound X (Shahangian, S., and Hager, L.P. (1982) J. Biol. Chem. 257, 11529-11533). These studies indicated that at pH 10.7, the optical absorption spectrum of Compound X was similar to the spectrum of horseradish peroxidase Compound II. Compound X was shown to be quite stable at alkaline pH values. This study was undertaken to examine the relationship between the oxidation state of the iron protoporphyrin IX heme prosthetic group in Compound X and the chemistry of the halogenating intermediate. The experimental results show that the optical absorption properties and the oxidation state of the heme prosthetic group in horseradish peroxidase are not directly related to the presence of the activated chlorine atom in the intermediate. The oxyferryl porphyrin heme group in alkaline Compound X can be reduced to a ferric heme species that still retains the activated chlorine atom. Furthermore, the reaction of chlorite with horseradish peroxidase at acidic pH leads to the secondary formation of a green intermediate that has the spectral properties of horseradish peroxidase Compound I (Theorell, H. (1941) Enzymologia 10, 250-252). The green intermediate also retains the activated chlorine atom. By analogy to peroxidase Compound I chemistry, the heme prosthetic group in the green chlorinating intermediate must be an oxyferryl porphyrin pi-cation radical species (Roberts, J. E., Hoffman, B. M., Rutter, R. J., and Hager, L. P. (1981) J. Am. Chem. Soc. 103, 7654-7656). To be consistent with traditional peroxidase nomenclature, the red alkaline form of Compound X has been renamed Compound XII, and the green acidic form has been named Compound XI. The transfer of chlorine from the chlorinating intermediate to an acceptor molecule follows an electrophilic (rather than a free radical) path. A mechanism for the reaction is proposed in which the activated chlorine atom is bonded to a heteroatom on an active-site amino acid side chain. Transient state kinetic studies show that the initial intermediate, Compound XII, is formed in a very fast reaction. The second-order rate constant for the formation of Compound XII is approximately 1.1 x 10(7) M-1 s-1. The rate of formation of Compound XII is strongly pH-dependent. At pH 9, the second-order rate constant for the formation of Compound XII drops to 1.5 M-1 s-1. At acidic pH values, Compound XII undergoes a spontaneous first-order decay to yield Compound XI.(ABSTRACT TRUNCATED AT 400 WORDS)


Subject(s)
Horseradish Peroxidase/metabolism , Binding Sites , Chlorides/metabolism , Horseradish Peroxidase/chemistry , Hydrogen-Ion Concentration , Kinetics , Spectrophotometry
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