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1.
Int J Biol Macromol ; 216: 42-51, 2022 Sep 01.
Article in English | MEDLINE | ID: mdl-35779650

ABSTRACT

Previously, N-acetyl-l-arginine (NALA) suppressed the aggregation of intravenous immunoglobulins (IVIG) more effectively and with a minimum decrease in transition temperature (Tm) than arginine monohydrochloride. In this study, we performed a comparative study with etanercept (commercial product: Enbrel®), where 25 mM arginine monohydrochloride (arginine) was added to the prefilled syringe. The biophysical properties were investigated using differential scanning calorimetry (DSC), dynamic light scattering (DLS), size-exclusion chromatography (SEC), and flow-imaging microscopy (FI). NALA retained the transition temperature of etanercept better than arginine, where arginine significantly reduced the Tm by increasing its concentration. End-over-end rotation was applied to each formulation for 5 days to accelerate protein aggregation and subvisible particle formation. Higher monomeric content was retained with NALA with a decrease in particle level. Higher aggregation onset temperature (Tagg) was detected for etanercept with NALA than arginine. The results of this comparative study were consistent with previous study, suggesting that NALA could be a better excipient for liquid protein formulations. Agitated IVIG and etanercept were injected into C57BL/6J female mice to observe immunogenic response after 24 h. In the presence of silicone oil, NALA dramatically reduced IL-1 expression, implying that decreased aggregation was related to reduced immunogenicity of both etanercept and IVIG.


Subject(s)
Protein Aggregates , Silicone Oils , Animals , Arginine/analogs & derivatives , Arginine/pharmacology , Etanercept/chemistry , Female , Immunity, Innate , Immunoglobulins, Intravenous , Mice , Mice, Inbred C57BL , Silicone Oils/chemistry
2.
Clin Psychopharmacol Neurosci ; 20(1): 143-153, 2022 Feb 28.
Article in English | MEDLINE | ID: mdl-35078957

ABSTRACT

OBJECTIVE: This study aimed to compare the efficacy and safety of atomoxetine (ATX) and OROS methylphenidate (MPH) as adjunctive to selective serotonin reuptake inhibitors (SSRIs) in adults with attention-deficit hyperactivity disorder (ADHD) with comorbid partially responsive major depressive disorder (MDD). METHODS: Sixty Korean adults with ADHD and comorbid partially responsive MDD were recruited in a 12-week, randomized, rater-blinded, active-controlled trial and were evenly randomized to ATX or OROS MPH treatment. RESULTS: Depressive symptoms measured using the Hamilton Depression Rating Scale and Clinically Useful Depression Outcome Scale, and ADHD symptoms measured using the Adult ADHD Self-Report Scale, as well as the Clinical Global Impression-Severity, Clinical Global Impression-Improvement, and the Sheehan Disability Scale scores were significantly improved in both groups during the 12 weeks of treatment. The changes in all outcome measures during the 12-week treatment were not significantly different between the two groups (all p > 0.05). No serious adverse events were reported and there were no significant differences in systolic and diastolic blood pressure, pulse rate, weight, or body mass index between the ATX and MPH groups. CONCLUSION: Our findings suggest that ATX and MPH can be used as adjunctive treatments in adults with ADHD and comorbid partially responsive MDD. The efficacy and tolerability of ATX and MPH in adults with ADHD did not differ significantly. Further studies should be conducted to draw a definitive conclusion.

3.
Clin Psychopharmacol Neurosci ; 20(1): 167-179, 2022 Feb 28.
Article in English | MEDLINE | ID: mdl-35078959

ABSTRACT

OBJECTIVE: Childhood trauma is the most important environmental factor for several psychiatric disorders. Depressed patients with childhood trauma appear to have severe symptoms that frequently recur. This study investigated whether depressed patients with childhood trauma showed attenuated Nogo event-related potentials (ERPs) and source activity during response-inhibition tasks. METHODS: Forty-four patients patients with major depressive disorder (MDD) were instructed to perform a Go/Nogo task during electroencephalography. Sensors and source activities of N2 and P3 of the Nogo ERPs were analyzed. The participants' clinical symptoms were assessed using the Childhood Trauma Questionnaire (CTQ), Beck Depression Inventory, State-Trait Anxiety Inventory, Barratt Impulsivity Scale, and Affective Lability Scale. The participants were divided into two groups (low and high), based on their total CTQ scores. RESULTS: MDD subjects with high CTQ scores showed significantly decreased Nogo P3 amplitudes at the frontal, frontocentral, central, and parietal electrodes than those with low CTQ scores (all p < 0.01). In Nogo P3, the source activities of the right cuneus, right posterior cingulate cortex, right precuneus, left supramarginal gyrus, and left lingual gyrus were significantly lower in the high CTQ group than in the low one (all p < 0.01). There were significant negative correlations between the total CTQ scores and the Nogo P3 amplitudes in the frontocentral (p = 0.03) and parietal regions (p = 0.02), which showed lower source activity in the Nogo P3 condition. CONCLUSION: Depressed patients with severe childhood trauma showed different Nogo-ERP characteristics, which might reflect inhibitory failure and dysfunction in related brain regions.

4.
Clin Psychopharmacol Neurosci ; 19(2): 334-340, 2021 May 31.
Article in English | MEDLINE | ID: mdl-33888662

ABSTRACT

OBJECTIVE: There are animal models associating dopamine dysfunction with behavioral impairments that model attention deficit hyperactivity disorder (ADHD). Erythropoietin (EPO) has trophic effects on dopaminergic neurons. The aim of this study was to examine the EPO plasma levels and determine whether there was any correlation between plasma EPO levels and clinical characteristics of ADHD. METHODS: Plasma EPO levels were measured in 78 drug-naïve children with ADHD and in 81 healthy children. The severity of ADHD symptoms was determined by scores on the Korean ADHD Rating Scale (K-ARS) in ADHD children and healthy controls. RESULTS: The difference between median plasma EPO levels in ADHD children and in healthy controls was not statistically significant. Adjusting for age and sex, a linear regression analysis showed that inattention score was significantly higher in the second highest tertile of plasma EPO compared to those in the lowest tertile. Hyperactivity-impulsivity score was significantly higher in the highest tertile of plasma EPO compared to those in the lowest tertile. Moreover, total K-ARS scores were significantly higher in the second highest tertile of plasma EPO compared to those in the lowest tertile. CONCLUSION: These findings suggest that plasma EPO levels were related to some ADHD symptoms, which could be used in the monitoring of the disorder.

5.
Psychiatry Investig ; 17(10): 996-1005, 2020 Oct.
Article in English | MEDLINE | ID: mdl-33045796

ABSTRACT

OBJECTIVE: Attention-deficit and poor impulse control have frequently been observed in major depressive disorder (MDD) and attention-deficit and hyperactivity disorder (ADHD). Altered event-related potential (ERP) performance, such as GoNogo tasks, has been regarded as a neurocognitive process associated with attention and behavioral inhibition. The aim of this study was to investigate the association between Nogo ERP and adult ADHD in MDD. METHODS: A total of 64 participants with MDD (32 comorbid with ADHD) and 32 healthy controls aged 19-45 years were recruited; they performed GoNogo paradigms during electroencephalogram measurement. Beck Depression Inventory (BDI), State-Trait Anxiety Inventory (STAI), and the Adult ADHD Self-Report Scale (ASRS) were evaluated. Clinical measures and GoNogo ERP were compared between three groups: depression with ADHD, depression without ADHD, and healthy controls. RESULTS: MDD subjects with ADHD showed significantly decreased Nogo P3 amplitude at frontal electrode, compared with those without ADHD and healthy controls. MDD subjects with ADHD showed significantly longer Nogo N2 latency at frontal and frontocentral electrodes, compared with those without ADHD and healthy controls. In MDD subjects with ADHD, the Nogo P3 amplitude at the frontal electrode was negatively correlated with the ASRS score and inattention. The Nogo N2 latency at the frontal electrode was positively correlated with false alarm rate. CONCLUSION: The decreased Nogo P3 amplitude in the frontal area might be a potential biological marker for inattention in depressed patients with ADHD.

6.
Clin Psychopharmacol Neurosci ; 16(1): 95-102, 2018 Feb 28.
Article in English | MEDLINE | ID: mdl-29397671

ABSTRACT

OBJECTIVE: Chronic 'latent' infection by Toxoplasma gondii is common and most of the hosts have minimal symptoms or they are even asymptomatic. However, there are possible mechanisms by which T. gondii may affect human behavior and it may also cause humans to attempt suicide. This article aimed to investigate the potential pathophysiological relationship between suicide attempts and T. gondii infection in Korea. METHODS: One hundred fifty-five psychiatric patients with a history of suicide attempt and 135 healthy control individuals were examined with enzyme-linked immunoassays and fluorescent antibody technique for T. gondii seropositivity and antibody titers. The group of suicide attempters was interviewed regarding the history of suicide attempt during lifetime and evaluated using 17-item Korean version of Hamilton Depression Scale (HAMD), Columbia Suicide Severity Rating Scale (C-SSRS), State-Trait Anxiety Inventory (STAI) and Korean-Barratt Impulsiveness Scale (BIS). RESULTS: Immunoglobulin G antibodies were found in 21 of the 155 suicide attempters and in 8 of the 135 controls (p=0.011). The Toxoplasma-seropositive suicide attempters had a higher HAMD score on the depressed mood and feeling of guilt subscales and a higher total score than the seronegative suicide attempters. T. gondii seropositive status was associated with higher C-SSRS in the severity and lethality subscales. T. gondii IgG seropositivity was significantly associated with higher STAI-X1 scores in the suicide attempters group. CONCLUSION: Suicide attempters showed higher seroprevalence of T. gondii than healthy controls. Among the suicide attempters, the T. gondii seropositive and seronegative groups showed several differences in the aspects of suicide. These results suggested a significant association between T. gondii infection and psychiatric problems in suicidality.

7.
Chem Commun (Camb) ; 53(67): 9352-9355, 2017 Aug 17.
Article in English | MEDLINE | ID: mdl-28786444

ABSTRACT

Direct oxygen atom transfer from a nonheme Mn(iv)-oxo complex, [(Bn-TPEN)MnIV(O)]2+, to triphenylphosphine (Ph3P) derivatives occurs with a significant steric effect resulting from the ortho-substituents on the phenyl group of the Ph3P derivatives, whereas the phosphine oxygenation by a Mn(iv)-oxo complex in the presence of HOTf occurs via an electron transfer mechanism without the substrate-steric effect.

8.
Am J Trop Med Hyg ; 95(5): 1021-1025, 2016 Nov 02.
Article in English | MEDLINE | ID: mdl-27645781

ABSTRACT

Identification of mite and tick bite sites provides important clinical information. The predominant mite species in Korea associated with scrub typhus are Leptotrombidium pallidum and Leptotrombidium scutellare The most abundant tick species is Haemaphysalis longicornis To date, there has been no comparative study on preferred bite sites between mites and ticks in humans. This study included a review of medical records and a field study. For mite bite sites, eschars were checked on 506 patients with scrub typhus, confirmed by indirect immunofluorescence assay or nested polymerase chain reaction on the 56-kDa type-specific antigen gene of Orientia tsutsugamushi Tick bite sites were identified and marked on a diagram for 91 patients who experienced tick bites within the previous year through a field epidemiological investigation. The mite and tick bite sites in Koreans were compared. The most frequently observed mite bite sites were the anterior chest, including the axillae (29.1%) and the abdominal region, including the inguinal area (26.1%). Tick bite sites were most frequent on the lower extremities (33.0%), followed by the abdominal region, including the inguinal area (26.4%), and upper extremities (26.4%). The distribution was significantly different between mite and tick bite sites (P < 0.001). There was a statistically significant difference in the mite bite (P = 0.001), but not tick bite sites (P = 0.985), between men and women. This is the first report on the differences between tick and mite bite sites, and may help clinicians reach a rapid diagnosis of mite- or tick-borne infection.


Subject(s)
Bites and Stings/diagnosis , Mite Infestations/diagnosis , Tick-Borne Diseases/diagnosis , Ticks , Trombiculidae , Animals , Bites and Stings/parasitology , Female , Humans , Male , Orientia tsutsugamushi/isolation & purification , Polymerase Chain Reaction , Prospective Studies , Republic of Korea , Scrub Typhus/parasitology , Scrub Typhus/transmission
9.
Article in English | MEDLINE | ID: mdl-27103462

ABSTRACT

Attention-deficit/hyperactivity disorder (ADHD) is a highly prevalent mental disorder of childhood, which often continues into adolescence and adulthood. Stimulants such as methylphenidate (MPH) and non-stimulants such as atomoxetine are effective medications for the treatment of ADHD. However, about 30% of patients do not respond to these medications. Pharmacological treatment for ADHD, although highly effective, is associated with marked variabilities in clinical response, optimal dosage needed and tolerability. This article provides an overview of up-to-date knowledge regarding the clinical and neurobiological factors which contribute to and help predict treatment-refractory ADHD. Pharmacogenetic, pharmacogenomics and neuroimaging studies are still controversial with respect to determining the associations between response to medication and genetic factors, thereby resulting in hypotheses that differences in the genetic factors and neuroimaging findings contribute to treatment outcome. Much research on the potential role of genotype in pharmacological effects has focused on the catecholaminergic gene related to executive functions. Many neuroimaging studies have also reported a relationship between treatment response and common patterns of brain structure or activity according to various genetic polymorphisms. When children, adolescents and adults with ADHD do not respond to MPH, we should consider additional pharmacological options, including other classes of psychostimulants, the nonstimulant atomoxetine, bupropion, tricyclic antidepressant, clonidine, guanfacine and lisdexamphetamine. Prudent choice of an appropriate medication and active engagement of children, parents, and teachers in daily management may help to ensure long-term adherence. Therefore, additional research might help to optimize the treatment of children, adolescents and adults with ADHD and to find new options for the treatment of patients who do not respond to stimulants and the other medications. Because these findings should be interpreted cautiously, further studies are needed to elucidate these issues more clearly.


Subject(s)
Attention Deficit Disorder with Hyperactivity/physiopathology , Attention Deficit Disorder with Hyperactivity/therapy , Attention Deficit Disorder with Hyperactivity/diagnostic imaging , Attention Deficit Disorder with Hyperactivity/genetics , Drug Resistance/genetics , Drug Resistance/physiology , Humans
10.
Tuberc Respir Dis (Seoul) ; 79(2): 101-3, 2016 Apr.
Article in English | MEDLINE | ID: mdl-27066088

ABSTRACT

Nocardia species are aerobic, gram-positive pathogens found worldwide in soil. Nocardia is considered an opportunistic pathogen, and its infection mostly occurs in immunocompromised patients. We report a case of Nocardia farcinica induced mediastinitis and pneumonia that occurred in a 64-year-old male patient who had no significant medical history except for hypertension. He visited another hospital with a complaint of dyspnea and left chest wall pain. The symptoms arose 7 days ago without any trauma and they worsened. A mediastinal mass was found on computed tomography scan. After being transferred to our hospital for further evaluation, he was diagnosed with mediastinitis and pneumonia. As N. farcinica was found to be the causative organism by 16S rRNA sequencing, proper antibiotic therapy including trimethoprim/sulfamethoxazole was initiated immediately. After this, the patient improved and he was discharged. If an infection has a disseminating course, nocardiosis cannot be excluded even in immunocompetent patients. Once the diagnosis is established, prompt antibiotic therapy should be performed based on the severity.

11.
Am J Infect Control ; 44(2): 189-93, 2016 Feb.
Article in English | MEDLINE | ID: mdl-26518500

ABSTRACT

BACKGROUND: Postexposure prophylaxis for occupational exposure to hepatitis B virus (HBV) plays an important role in the prevention of HBV infections in health care workers (HCWs). We examined data concerning the acceptable duration between occupational exposure and administration of a hepatitis B immunoglobulin (HBIG) injection in an occupational clinical setting. METHODS: A retrospective analysis was conducted with data from 143 cases of HCWs exposed to HBV in 15 secondary and tertiary teaching hospitals between January 2005 and June 2013. Data were taken from the infection control records of each hospital. RESULTS: Active vaccination after HBV exposure was started in 119 cases (83.2%) and postvaccination testing for hepatitis B antibody showed positive seroconversion in 93% of cases. In 98 cases (68.5%), HBIG was administered within 24 hours after HBV exposure; however, 45 HCWs (31.5%) received an HBIG injection more than 24 hours postexposure and 2 among the 45 received an injection after 7 days. Although 31.5% received an HBIG injection more than 24 hours postexposure, no cases of seroconversion to hepatitis b antibody positivity occurred. CONCLUSIONS: For susceptible HCWs, HBIG administered between 24 hours and 7 days postexposure may be as effective as administration within 24 hours in preventing occupational HBV infection.


Subject(s)
Hepatitis B Antibodies/blood , Hepatitis B virus/immunology , Hepatitis B/prevention & control , Immunoglobulins/administration & dosage , Occupational Exposure , Adult , Female , Health Personnel , Humans , Male , Middle Aged , Post-Exposure Prophylaxis , Republic of Korea , Retrospective Studies , Time Factors
12.
Chem Sci ; 6(6): 3624-3632, 2015 Jun 01.
Article in English | MEDLINE | ID: mdl-26146538

ABSTRACT

Triflic acid (HOTf)-bound nonheme Mn(IV)-oxo complexes, [(L)MnIV(O)]2+-(HOTf)2 (L = N4Py and Bn-TPEN; N4Py = N,N-bis(2-pyridylmethyl)-N-bis(2-pyridyl)methylamine) and Bn-TPEN = N-benzyl-N,N',N'-tris(2-pyridylmethyl)ethane-1,2-diamine), were synthesized by adding HOTf to the solutions of the [(L)MnIV(O)]2+ complexes and were characterized by various spectroscopies. The one-electron reduction potentials of the MnIV(O) complexes exhibited a significant positive shift upon binding of HOTf. The driving force dependence of electron transfer (ET) from electron donors to the MnIV(O) and MnIV(O)-(HOTf)2 complexes were examined and evaluated in light of the Marcus theory of ET to determine the reorganization energies of ET. The smaller reorganization energies and much more positive reduction potentials of the [(L)MnIV(O)]2+-(HOTf)2 complexes resulted in much enhanced oxidation capacity towards one-electron reductants and para-X-substituted-thioanisoles. The reactivities of the Mn(IV)-oxo complexes were markedly enhanced by binding of HOTf, such as a 6.4 × 105-fold increase in the oxygen atom transfer (OAT) reaction (i.e., sulfoxidation). Such a remarkable acceleration in the OAT reaction results from the enhancement of ET from para-X-substituted-thioanisoles to the MnIV(O) complexes as revealed by the unified ET driving force dependence of the rate constants of OAT and ET reactions of [(L)MnIV(O)]2+-(HOTf)2. In contrast, deceleration was observed in the rate of H-atom transfer (HAT) reaction of [(L)MnIV(O)]2+-(HOTf)2 complexes with 1,4-cyclohexadiene as compared with those of the [(L)MnIV(O)]2+ complexes. Thus, the binding of two HOTf molecules to the MnIV(O) moiety resulted in remarkable acceleration of the ET rate when the ET is thermodynamically feasible. When the ET reaction is highly endergonic, the rate of the HAT reaction is decelerated due to the steric effect of the counter anion of HOTf.

13.
Chemistry ; 21(30): 10676-80, 2015 Jul 20.
Article in English | MEDLINE | ID: mdl-26096281

ABSTRACT

Redox-inactive metal ions play important roles in tuning chemical properties of metal-oxygen intermediates. Herein we report the effect of water molecules on the redox properties of a nonheme iron(III)-peroxo complex binding redox-inactive metal ions. The coordination of two water molecules to a Zn(2+) ion in (TMC)Fe(III) -(O2 )-Zn(CF3 SO3 )2 (1-Zn(2+) ) decreases the Lewis acidity of the Zn(2+) ion, resulting in the decrease of the one-electron oxidation and reduction potentials of 1-Zn(2+) . This further changes the reactivities of 1-Zn(2+) in oxidation and reduction reactions; no reaction occurred upon addition of an oxidant (e.g., cerium(IV) ammonium nitrate (CAN)) to 1-Zn(2+) , whereas 1-Zn(2+) coordinating two water molecules, (TMC)Fe(III) -(O2 )-Zn(CF3 SO3 )2 -(OH2 )2 [1-Zn(2+) -(OH2 )2 ], releases the O2 unit in the oxidation reaction. In the reduction reactions, 1-Zn(2+) was converted to its corresponding iron(IV)-oxo species upon addition of a reductant (e.g., a ferrocene derivative), whereas such a reaction occurred at a much slower rate in the case of 1-Zn(2+) -(OH2 )2 . The present results provide the first biomimetic example showing that water molecules at the active sites of metalloenzymes may participate in tuning the redox properties of metal-oxygen intermediates.


Subject(s)
Ferric Compounds/chemistry , Water/chemistry , Zinc/chemistry , Cations, Divalent/chemistry , Cerium/chemistry , Nitrates/chemistry , Oxidation-Reduction , Oxygen/chemistry
14.
Nord J Psychiatry ; 69(7): 546-51, 2015.
Article in English | MEDLINE | ID: mdl-25753832

ABSTRACT

BACKGROUND: Recent evidence suggests that neurotrophic growth factor systems, including brain-derived neurotrophic factor, might be involved in the pathophysiology of attention deficit hyperactivity disorder (ADHD). Glial cell line-derived neurotrophic factor (GDNF) is from the transforming growth factor-ß family and is abundantly expressed in the central nervous system, where it plays a role in the development and function of hippocampal cells. To date, no association studies have been done between ADHD and GDNF. Thus, here we investigate the hypothesis that there are differences in plasma GDNF levels between children with ADHD and healthy controls. METHODS: Plasma GDNF levels were measured in 86 drug-naïve children with ADHD and 128 healthy children. The severity of ADHD symptoms was determined by scores on the Korean ADHD Rating Scale (K-ARS) in patients and healthy controls. RESULTS: The median plasma GDNF levels in ADHD patients was 74.0 (IQR: 23.4-280.1) pg/ml versus 24.6 (IQR: 14.5-87.3) pg/ml in healthy controls; thus the median plasma GDNF levels in ADHD patients were significantly higher than in healthy controls (Mann-Whitney U-test, P < 0.01). Plasma GDNF levels were correlated positively with K-ARS subscale scores (inattention, hyperactivity-impulsivity and total), determined by Spearman's correlation test in ADHD patients and healthy controls (r = 0.371, P < 0.01; r = 0.331, P < 0.01; and r = 0.379, P < 0.01, respectively). CONCLUSIONS: These findings suggest increased plasma GDNF levels in untreated ADHD patients. In addition, plasma GDNF levels had a significant positive correlation with inattention, hyperactivity-impulsivity and K-ARS total scores in ADHD patients and healthy controls. Further studies are required to determine the source and role of circulating GDNF in ADHD.


Subject(s)
Attention Deficit Disorder with Hyperactivity/blood , Attention Deficit Disorder with Hyperactivity/diagnosis , Glial Cell Line-Derived Neurotrophic Factor/blood , Adolescent , Biomarkers/blood , Brain-Derived Neurotrophic Factor/blood , Child , Female , Humans , Impulsive Behavior , Male
15.
Chem Commun (Camb) ; 50(85): 12944-6, 2014 Nov 04.
Article in English | MEDLINE | ID: mdl-25220234

ABSTRACT

Hydride transfer from NADH analogues to a nonheme Mn(iv)-oxo complex, [(Bn-TPEN)Mn(IV)(O)](2+), proceeds via a rate-determining electron transfer step with no deuterium kinetic isotope effect (KIE = 1.0 ± 0.1); a charge-transfer complex formed between the Mn(IV)(O) complex and NADH analogues is involved in the hydride transfer reaction.


Subject(s)
Coordination Complexes/chemistry , Manganese/chemistry , NAD/analogs & derivatives , Electron Transport , Kinetics , Models, Molecular
16.
J Am Chem Soc ; 135(24): 9186-94, 2013 Jun 19.
Article in English | MEDLINE | ID: mdl-23742163

ABSTRACT

One and two scandium ions (Sc(3+)) are bound strongly to nonheme manganese(IV)-oxo complexes, [(N4Py)Mn(IV)(O)](2+) (N4Py = N,N-bis(2-pyridylmethyl)-N-bis(2-pyridyl)methylamine) and [(Bn-TPEN)Mn(IV)(O)](2+) (Bn-TPEN = N-benzyl-N,N',N'-tris(2-pyridylmethyl)-1,2-diaminoethane), to form Mn(IV)(O)-(Sc(3+))1 and Mn(IV)(O)-(Sc(3+))2 complexes, respectively. The binding of Sc(3+) ions to the Mn(IV)(O) complexes was examined by spectroscopic methods as well as by DFT calculations. The one-electron reduction potentials of the Mn(IV)(O) complexes were markedly shifted to a positive direction by binding of Sc(3+) ions. Accordingly, rates of the electron transfer reactions of the Mn(IV)(O) complexes were enhanced as much as 10(7)-fold by binding of two Sc(3+) ions. The driving force dependence of electron transfer from various electron donors to the Mn(IV)(O) and Mn(IV)(O)-(Sc(3+))2 complexes was examined and analyzed in light of the Marcus theory of electron transfer to determine the reorganization energies of electron transfer. The smaller reorganization energies and much more positive reduction potentials of the Mn(IV)(O)-(Sc(3+))2 complexes resulted in remarkable enhancement of the electron-transfer reactivity of the Mn(IV)(O) complexes. Such a dramatic enhancement of the electron-transfer reactivity of the Mn(IV)(O) complexes by binding of Sc(3+) ions resulted in the change of mechanism in the sulfoxidation of thioanisoles by Mn(IV)(O) complexes from a direct oxygen atom transfer pathway without metal ion binding to an electron-transfer pathway with binding of Sc(3+) ions.


Subject(s)
Coordination Complexes/chemistry , Manganese/chemistry , Oxygen/chemistry , Scandium/chemistry , Binding Sites , Cations/chemistry , Electron Transport , Ethylenediamines/chemistry , Methylamines/chemistry , Models, Molecular , Pyridines/chemistry
17.
Dalton Trans ; 42(22): 7842-5, 2013 Jun 14.
Article in English | MEDLINE | ID: mdl-23588673

ABSTRACT

The ring size effect of macrocyclic TMC ligands in nonheme iron(IV)-oxo complexes has been examined in hydrogen atom transfer (HAT) and oxygen atom transfer (OAT) reactions; an iron(IV)-oxo complex bearing a smaller TMC ligand is more reactive in both HAT and OAT reactions, resulting from its high Fe(IV/III) redox potential.


Subject(s)
Heterocyclic Compounds/chemistry , Iron Compounds/chemistry , Iron/chemistry , Oxygen/chemistry , Hydrogen/chemistry , Ligands , Methylation , Models, Molecular
18.
J Am Chem Soc ; 135(17): 6388-91, 2013 May 01.
Article in English | MEDLINE | ID: mdl-23324100

ABSTRACT

Redox-inactive metal ions play pivotal roles in regulating the reactivities of high-valent metal-oxo species in a variety of enzymatic and chemical reactions. A mononuclear non-heme Mn(IV)-oxo complex bearing a pentadentate N5 ligand has been synthesized and used in the synthesis of a Mn(IV)-oxo complex binding scandium ions. The Mn(IV)-oxo complexes were characterized with various spectroscopic methods. The reactivities of the Mn(IV)-oxo complex are markedly influenced by binding of Sc(3+) ions in oxidation reactions, such as a ~2200-fold increase in the rate of oxidation of thioanisole (i.e., oxygen atom transfer) but a ~180-fold decrease in the rate of C-H bond activation of 1,4-cyclohexadiene (i.e., hydrogen atom transfer). The present results provide the first example of a non-heme Mn(IV)-oxo complex binding redox-inactive metal ions that shows a contrasting effect of the redox-inactive metal ions on the reactivities of metal-oxo species in the oxygen atom transfer and hydrogen atom transfer reactions.


Subject(s)
Manganese/chemistry , Metals/chemistry , Electron Spin Resonance Spectroscopy , Electrons , Indicators and Reagents , Models, Molecular , Molecular Conformation , Oxidation-Reduction , Oxygen/chemistry , Protons , Scandium/chemistry , Spectrometry, Mass, Electrospray Ionization , Spectrophotometry, Ultraviolet , X-Ray Diffraction
19.
Chem Commun (Camb) ; 48(91): 11187-9, 2012 Nov 25.
Article in English | MEDLINE | ID: mdl-23042153

ABSTRACT

Electron-transfer properties of a nonheme Mn(IV)-oxo complex, [(Bn-TPEN)Mn(IV)(O)](2+), reveals that Mn(IV)-oxo complex acts as a stronger one-electron oxidant than the Fe(IV)-oxo analogue. As a result, an electron transfer process in N-dealkylation has been detected by a transient radical cation intermediate, para-Me-DMA˙(+), in the oxidation of para-Me-DMA by [(Bn-TPEN)Mn(IV)(O)](2+).


Subject(s)
Coordination Complexes/chemistry , Iron/chemistry , Manganese/chemistry , Electron Transport , Ethylamines/chemistry , Oxidation-Reduction , Porphyrins/chemistry , Pyridines/chemistry
20.
Clin Psychopharmacol Neurosci ; 10(2): 117-23, 2012 Aug.
Article in English | MEDLINE | ID: mdl-23430959

ABSTRACT

OBJECTIVE: A number of studies have reported association between Toxoplasma gondii (T. gondii) and Chlamydia infection and the risk of schizophrenia. The aim of the present study was to compare the prevalence of T. gondii and Chlamydia infection between the schizophrenia and normal control subjects and to compare the clinical features between seropositive and seronegative schizophrenia patients. METHODS: The rate of serum reactivity to T. gondii, Chlamydia trachomatis (C. trachomatis), Chlamydia pneumonia in 96 schizophrenia and 50 control subjects was investigated using enzyme-linked immunosorbent assay and indirect fluorescent antibody technique. The clinical symptoms of the schizophrenia patients were scored with Positive and Negative Syndrome Scale and a comparative analysis was carried out. RESULTS: A significant positive association between immunoglobulin G (IgG) antibodies to T. gondii and C. trachomatis in schizophrenia was found, and the odds ratio of schizophrenia associated with IgG antibody was found to be 3.22 and 2.86, respectively. The Toxoplasma-seropositive schizophrenia patient had higher score on the negative subscale N1 and N7 and general psychopathology subscale G13, while C. trachomatis-seropositive schizophrenia patient had higher score on the general psychopathology subscale G10. CONCLUSION: The results from the present study suggest significant association between T. gondii, C. trachomatis infection and schizophrenia. In future, further studies are needed to elucidate the correlation between the two types of infection and schizophrenia.

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