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1.
IEEE J Biomed Health Inform ; 27(5): 2288-2295, 2023 05.
Article in English | MEDLINE | ID: mdl-34665750

ABSTRACT

Restrictive public health measures such as isolation and quarantine have been used to reduce the pandemic virus's transmission. With no proper treatment, older adults have been specifically advised to stay home, given their vulnerability to COVID-19. This pandemic has created an increasing need for new and innovative assistive technologies capable of easing the lives of people with special needs. Smart home systems have become widely popular in providing such assistive services to isolated older adults. These systems can provide better services to assist older people if it anticipates what activities inhabitants will perform ahead of time. For example, a smart home can prompt inhabitants to initiate essential activities like taking medicine using activity prediction. This paper proposes a multi-task activity prediction system that jointly predicts labels, locations, and starting times of future activities. The observed sequence of previous activities characterizes future activities. We use body activity information from wearable sensors and motion information from passive environmental sensors to sense activities of daily living of older adults. The activity prediction system consists of recurrent neural networks to capture temporal dependencies. This work also carries out several experiments on collected and existing real datasets to evaluate the system's performance.


Subject(s)
COVID-19 , Self-Help Devices , Humans , Aged , Activities of Daily Living
2.
IEEE J Biomed Health Inform ; 26(11): 5494-5505, 2022 11.
Article in English | MEDLINE | ID: mdl-36048978

ABSTRACT

Epilepsy is a severe threat to society due to the treatment time, cost, and unpredictable nature of the disease, thereby imposing an urgent need for intelligent analysis. Electroencephalogram (EEG) is a commonly deployed test for detecting epilepsy that analyses the electrical activity of an individual's brain. This work proposes an optimized deep sequential model to improve the seizure classification performance based on a hybrid feature set derived from EEG signals. A novel hybridized Battle Royale Search and Rescue optimization (BRRO) algorithm is proposed for optimizing a deep learning (DL) model. Also, the proposed hybrid feature set utilizes empirical mode decomposition, variational mode decomposition, and empirical wavelet transform to capture the temporal property of the data set. The proposed method is validated using publicly available data sets. The results manifest that the proposed optimized algorithm provides better results than the other alternatives.


Subject(s)
Epilepsy , Rescue Work , Humans , Seizures/diagnostic imaging , Epilepsy/diagnostic imaging , Electroencephalography/methods , Wavelet Analysis , Algorithms , Signal Processing, Computer-Assisted
3.
Neural Process Lett ; 53(6): 3981-4010, 2021.
Article in English | MEDLINE | ID: mdl-34305439

ABSTRACT

Training a machine learning model on the data sets with missing labels is a challenging task. Not all models can handle the problem of missing labels. However, if these data sets are further corrupted with label noise, it becomes even more challenging to train a machine learning model on such data sets. We propose to use a transductive support vector machine (TSVM) for semi-supervised learning in this situation. We make this model robust to label noise by using a truncated pinball loss function with it. We name our approach, pin ¯ -TSVM. We provide both the primal and the dual formulations of the obtained robust TSVM for linear and non-linear kernels. We also perform experiments on synthetic and real-world data sets to prove the superior robustness of our model as compared to the existing approaches. To this end, we use small as well as large-scale data sets to perform the experiments. We show that the model is capable of training in the presence of label noise and finding the missing labels of the data samples. We use this property of pin ¯ -TSVM to detect the coronavirus patients based on their chest X-ray images.

4.
Aust Dent J ; 66(1): 105-111, 2021 03.
Article in English | MEDLINE | ID: mdl-33616961

ABSTRACT

Dental extractions are a common part of general dental practice. While dentists routinely screen for medical contraindications during the preoperative assessment, undiagnosed coagulopathies have the potential to severely complicate a seemingly routine extraction. We report a case of surgical removal of a mandibular third molar in a patient with undiagnosed Von Willebrand Disease.


Subject(s)
von Willebrand Diseases , Humans , Tooth Extraction , von Willebrand Diseases/complications , von Willebrand Diseases/diagnosis
5.
Sci Rep ; 10(1): 21445, 2020 Dec 08.
Article in English | MEDLINE | ID: mdl-33293584

ABSTRACT

Growth of polycrystalline CdMnTe ternary compound thin films has been carried out using cathodic electrodeposition technique at different cathodic potentials. The range of the cathodic potentials used in this work has been chosen according to the cyclic voltammogram results. The CdMnTe thin films were electroplated from electrolyte containing CdSO4, TeO2 and MnSO4 in an acidic aqueous medium. Glass/fluorine-doped tin oxide (FTO) substrates have been used to electrodeposit the semiconductor layers. The structural, compositional, morphological, optical and electrical properties of the CdMnTe thin films were studied using X-ray diffraction (XRD), Sputtered neutral-mass spectroscopy (SNMS), Scanning electron microscopy (SEM), UV-Vis spectroscopy and Photo-electro-chemical (PEC) cell measurements respectively. The primarily grown as-deposited (AD) layers went through two different post-growth surface treatment conditions- heat-treated in air in the presence of CdCl2 (CCT) and heat-treated in air in the presence of GaCl3 (GCT). Results from the XRD indicated the polycrystalline nature of the electrodeposited films. The electroplated films have cubic crystal structures and the preferred orientation was found to be along the (111) plane of CdMnTe. Inclusion of Mn has been qualitatively observed using SNMS measurement. The optical energy bandgaps of the thin films were found to be varying between ~ 1.90 and ~ 2.20 eV. Though all the layers after post-treatment showed p-type electrical conduction, both p and n-type conductivity were obtained at different cathodic potentials for as-deposited materials. Comparison of the deposited layers to other electrodeposited ternary compounds has also been discussed.

6.
J Postgrad Med ; 63(1): 4-10, 2017.
Article in English | MEDLINE | ID: mdl-27779152

ABSTRACT

BACKGROUND: Considering a huge working population in health sector faced with stressful work life, limited autonomy in work and declining work contentment calls for an overemphasis on evaluating and monitoring their satisfaction associated with work-related quality of life (WRQoL). This study evaluates WRQoL of hospital employees and validates the bilingual (English and Marathi) version of WRQoL scale. METHODS: The study was conducted during March-April'2014 on employees of a corporate hospital of Pune, India after ethical approval and informed consent from employees. The bilingual WRQoL scale has been tested for reliability and validity, and WRQoL scores have been reported. RESULTS: A total of 132 hospital employees (mean age 31 [±8] years, 55% males) who participated in the study reported overall moderate WRQoL scores. The scale showed high internal consistency (Cronbach's alpha = 0.82, P < 0.0001) and moderate to high validity. WRQoL did not significantly vary across marital status, family size, and gender. "Stress at work" score of WRQoL increased with age of employees. Higher work experience, employment at higher positions and those working in clinical and diagnostic departments reported a higher WRQoL. CONCLUSION: WRQoL scale is a reliable and valid instrument. Better WRQoL in employees placed in higher organizational positions indicates a need for focused measures to enhance WRQoL of employees in lower hierarchical levels, especially in control at work and home life interface domains. WRQoL needs regular monitoring for employees in lower positions and aging employees.


Subject(s)
Health Personnel/psychology , Occupational Stress , Personal Satisfaction , Psychometrics/instrumentation , Quality of Life/psychology , Stress, Psychological/psychology , Surveys and Questionnaires , Workplace/psychology , Adult , Cross-Sectional Studies , Female , Humans , India , Male , Middle Aged , Reproducibility of Results
7.
Environ Sci Pollut Res Int ; 24(1): 164-179, 2017 Jan.
Article in English | MEDLINE | ID: mdl-27704381

ABSTRACT

Ozone dynamics in two urban background atmospheres over middle Indo-Gangetic Plain (IGP) were studied in two contexts: total columnar and ground-level ozone. In terms of total columnar ozone (TCO), emphases were made to compare satellite-based retrieval with ground-based observation and existing trend in decadal and seasonal variation was also identified. Both satellite-retrieved (Aura Ozone Monitoring Instrument-Differential Optical Absorption Spectroscopy (OMI-DOAS)) and ground-based observations (IMD-O3) revealed satisfying agreement with OMI-DOAS observation over predicting TCO with a positive bias of 7.24 % under all-sky conditions. Minor variation between daily daytime (r = 0.54; R 2 = 29 %; n = 275) and satellite overpass time-averaged TCO (r = 0.58; R 2 = 34 %; n = 208) was also recognized. A consistent and clear seasonal trend in columnar ozone (2005-2015) was noted with summertime (March-June) maxima (Varanasi, 290.9 ± 8.8; Lucknow, 295.6 ± 9.5 DU) and wintertime (December-February) minima (Varanasi, 257.4 ± 10.1; Lucknow, 258.8 ± 8.8 DU). Seasonal trend decomposition based on locally weighted regression smoothing technique identified marginally decreasing trend (Varanasi, 0.0084; Lucknow, 0.0096 DU year-1) especially due to reduction in monsoon time minima and summertime maxima. In continuation to TCO, variation in ground-level ozone in terms of seasonality and precursor gases were also analysed from September 2014 to August 2015. Both stations registered similar pattern of variation with Lucknow representing slightly higher annual mean (44.3 ± 30.6; range, 1.5-309.1 µg/m3) over Varanasi (38.5 ± 17.7; range, 4.9-104.2 µg/m3). Variation in ground-level ozone was further explained in terms water vapour, atmospheric boundary layer height and solar radiation. Ambient water vapour content was found to associate negatively (r = -0.28, n = 284) with ground-level ozone with considerable seasonal variation in Varanasi. Implication of solar radiation on formation of ground-level ozone was overall positive (Varanasi, 0.60; Lucknow, 0.26), while season-specific association was recorded in case of atmospheric boundary layer.


Subject(s)
Ozone/analysis , Air Pollutants/analysis , Air Pollutants/chemistry , Atmosphere/analysis , Climate , Environmental Monitoring/methods , India , Ozone/chemistry , Seasons
8.
J Phys Condens Matter ; 28(37): 376001, 2016 09 21.
Article in English | MEDLINE | ID: mdl-27419361

ABSTRACT

Magnetoresistance (MR), thermo power, magnetization and Hall effect measurements have been performed on Co-doped Bi2Se3 topological insulators. The undoped sample shows that the maximum MR as a destructive interference due to a π-Berry phase leads to a decrease of MR. As the Co is doped, the linearity in MR is increased. The observed MR of Bi2Se3 can be explained with the classical model. The low temperature MR behavior of Co doped samples cannot be explained with the same model, but can be explained with the quantum linear MR model. Magnetization behavior indicates the establishment of ferromagnetic ordering with Co doping. Hall effect data also supports the establishment of ferromagnetic ordering in Co-doped Bi2Se3 samples by showing the anomalous Hall effect. Furthermore, when spectral weight suppression is insignificant, Bi2Se3 behaves as a dilute magnetic semiconductor. Moreover, the maximum power factor is observed when time reversal symmetry (TRS) is maintained. As the TRS is broken the power factor value is decreased, which indicates that with the rise of Dirac cone above the Fermi level the anomalous Hall effect and linearity in MR increase and the power factor decreases.

9.
Andrology ; 2(6): 809-18, 2014 Nov.
Article in English | MEDLINE | ID: mdl-25269421

ABSTRACT

The aim of this review was to provide current scenario linking obesity and male fertility. Obesity has been linked to male fertility because of lifestyle changes, internal hormonal environment alterations, and sperm genetic factors. A few studies assessing the impact of obesity on sperm genetic factor have been published, but they did not lead to a strong consensus. Our objective was to explore further the relationship between sperm genetic factor and obesity. There are emerging facts that obesity negatively affects male reproductive potential not only by reducing sperm quality, but in particular it alters the physical and molecular structure of germ cells in the testes and ultimately affects the maturity and function of sperm cells. Inhibition of microRNA in the male pronucleus of fertilized zygotes produces offspring of phenotypes of variable severity depending on miRNAs ratios. Hence, these RNAs have a role in the oocyte development during fertilization and in embryo development, fetal survival, and offspring phenotype. It has been reported that the miRNA profile is altered in spermatozoa of obese males, however, the impact of these changes in fertilization and embryo health remains as yet not known.


Subject(s)
Infertility, Male/complications , Obesity/complications , Adipokines/physiology , Cytokines/physiology , Humans , Infertility, Male/physiopathology , Life Style , Male , Obesity/genetics , Obesity/physiopathology
10.
Curr Med Chem ; 19(9): 1282-94, 2012.
Article in English | MEDLINE | ID: mdl-22304717

ABSTRACT

Glutamate carboxypeptidase II (GCPII, EC 3.4.17.21) is a zinc metallopeptidase that hydrolyzes N-acetylaspartylglutamate (NAAG) into N-acetylaspartate (NAA) and glutamate in the nervous system. Inhibition of GCPII has the potential to reduce extracellular glutamate and represents an opportune target for treating neurological disorders in which excess glutamate is considered pathogenic. Furthermore, GCPII was found to be identical to a tumor marker, prostate-specific membrane antigen (PSMA), and has drawn significant interest as a diagnostic and/or therapeutic target in oncology. Over the past 15 years, tremendous efforts have been made in the discovery of potent GCPII inhibitors, particularly those with phosphorus-, urea- and thiol-based zinc binding groups. In addition, significant progress has been made in understanding the three-dimensional structural characteristics of GCPII in complex with various ligands. The purpose of this review article is to analyze the structure-activity relationships (SAR) of GCPII inhibitors reported to date, which are classified on the basis of their zinc-binding group. SAR and crystallographic data are evaluated in detail for each of these series to highlight the future challenges and opportunities to identify clinically viable GCPII inhibitors.


Subject(s)
Enzyme Inhibitors/chemistry , Enzyme Inhibitors/pharmacology , Glutamate Carboxypeptidase II/antagonists & inhibitors , Glutamate Carboxypeptidase II/metabolism , Structure-Activity Relationship , Animals , Dipeptides/metabolism , Glutamate Carboxypeptidase II/chemistry , Humans , Models, Molecular
11.
Work ; 41 Suppl 1: 4302-14, 2012.
Article in English | MEDLINE | ID: mdl-22317381

ABSTRACT

Abstract : There is good evidence that shift work has negative effects on workers health, safety and performance. It is quite appropriate that attention is paid to this very important feature of socio-technical systems, which may adversely affect mental and physical health, social life and safety of shift workers. Research into the impact of shift work on professionals has consistently identified a range of negative outcomes in physical, psychological, and social domains (Akerstedt, 1988; Costa, Lievore, Casaletti, Gaffuri, & Folkard, 1989; Kogi, 2005; Paley & Tepas, 1994). Hospitals, the biggest employer in the health care field, employ more night shift workers than any other industry. It can therefore be inferred that in medical domain high percentage of workforce may be affected by problems related to shift work. Thus the present study will provide knowledge base for the problems faced by the female nurses. The present study was undertaken with an objective of getting an insight into the problems faced by female nurses in shift work. . It was found that the female nurses in India worked on roaster pattern of change in shift every seven days. They did not have a say in the change of duties, it could only be done on mutual grounds. Partners of younger group did not much adjust to their shift pattern this created stress among the nurses.The results showed that the female nurses in both the age groups i.e. 30-45 years and 45-60 years faced many problems related to health and well being, fatigue, social and domestic situations. They could not give much time to their children in particular. Travelling in nights was risky for them. Common problem was the insufficient sleep during night shifts. The nurses had to cater to the needs of the family, children in particular along with the adjustments to be made due to shift work. They had to sometimes do the night duties and attend social functions as a part of their duty. Children and husband in some cases did not cooperate this lead to frustration. When asked as to whether they would could shift job if they get regular one more than 50 % said yes this means that there need to be come training and intervention for the shift workers and their family so that the problems faced and their impact on personal health of the female nurses could be reduced.


Subject(s)
Family Relations , Interpersonal Relations , Nursing , Work Schedule Tolerance/physiology , Work Schedule Tolerance/psychology , Adaptation, Psychological , Adult , Dyssomnias/etiology , Fatigue/etiology , Female , Humans , India , Job Satisfaction , Middle Aged , Nursing/organization & administration , Personnel Staffing and Scheduling , Quality of Life , Sleep
12.
J Indian Assoc Pediatr Surg ; 14(2): 78, 2009 Apr.
Article in English | MEDLINE | ID: mdl-20671854
13.
J Med Phys ; 33(3): 119-26, 2008 Jul.
Article in English | MEDLINE | ID: mdl-19893702

ABSTRACT

The objective of developing this software is to achieve auto-segmentation and tissue characterization. Therefore, the present algorithm has been designed and developed for analysis of medical images based on hybridization of syntactic and statistical approaches, using artificial neural network (ANN). This algorithm performs segmentation and classification as is done in human vision system, which recognizes objects; perceives depth; identifies different textures, curved surfaces, or a surface inclination by texture information and brightness. The analysis of medical image is directly based on four steps: 1) image filtering, 2) segmentation, 3) feature extraction, and 4) analysis of extracted features by pattern recognition system or classifier. In this paper, an attempt has been made to present an approach for soft tissue characterization utilizing texture-primitive features with ANN as segmentation and classifier tool. The present approach directly combines second, third, and fourth steps into one algorithm. This is a semisupervised approach in which supervision is involved only at the level of defining texture-primitive cell; afterwards, algorithm itself scans the whole image and performs the segmentation and classification in unsupervised mode. The algorithm was first tested on Markov textures, and the success rate achieved in classification was 100%; further, the algorithm was able to give results on the test images impregnated with distorted Markov texture cell. In addition to this, the output also indicated the level of distortion in distorted Markov texture cell as compared to standard Markov texture cell. Finally, algorithm was applied to selected medical images for segmentation and classification. Results were in agreement with those with manual segmentation and were clinically correlated.

14.
Int J Gynecol Cancer ; 17(1): 141-6, 2007.
Article in English | MEDLINE | ID: mdl-17291245

ABSTRACT

The aim of this study was to describe the features of patients with brain metastasis from cervical cancer. Twelve patients with brain metastasis from cervical cancer were identified. Information regarding symptoms, treatment, and survival was analyzed. The incidence of brain metastasis in our population was 0.77%. Median patient age at initial diagnosis of cervical cancer was 43.5 years (range 29-57 years) compared with 44.5 years (range 31-58 years) at identification of brain metastasis. Six patients had FIGO stage IB disease; three had stage IIB disease; and one each had stage IIIA, IIIB, and IVB disease. The median interval from diagnosis of cervical cancer to identification of brain metastasis was 17.5 months (range 1.1-96.1 months). All but one patient presented with neurologic symptoms. Eight patients received whole-brain irradiation and steroids, three received steroids alone, and one underwent surgery, followed by irradiation. All the patients who received whole-brain irradiation experienced improvement in their symptoms. Median survival from diagnosis of brain metastasis to death was 2.3 months (range 0.3-7.9 months). Five patients who received chemotherapy after brain irradiation had a median survival of 4.4 months compared to 0.9 months for those who received no additional treatment after brain irradiation (P= .016). Most patients with brain metastasis from cervical cancer presented with neurologic sequelae. Brain irradiation improved these symptoms. Survival after diagnosis of brain metastasis was poor; however, patients who received chemotherapy after brain irradiation appeared to have improved survival.


Subject(s)
Brain Neoplasms/secondary , Brain Neoplasms/therapy , Uterine Cervical Neoplasms/pathology , Uterine Cervical Neoplasms/therapy , Adult , Female , Humans , Middle Aged , Neoplasm Staging , Survival Rate
15.
Article in English | MEDLINE | ID: mdl-16307903

ABSTRACT

Ternary copper(II) complexes involving polypyridyl ligands in the coordination sphere of composition [Cu(tpy)(phen)](ClO4)2 (1), [Cu(tpy)(bipy)](ClO4)2 (2), [Cu(tptz)(phen)](ClO4)2 (3) and [Cu(tptz)(bipy)](BF4)2 (4) where tpy = 2,2':6',2''-terpyridine, tptz = 2,4,6-tri(2-pyridyl)-1,3,5-triazine, phen = 1,10-phenanthroline and bipy = 2,2'-bipyridine have been synthesized and characterized by elemental analysis, magnetic susceptibility, X-band e.p.r. spectroscopy and electronic spectroscopy. Single crystal X-ray of (1) has revealed the presence of a distorted square pyramidal geometry in the complex. Magnetic susceptibility measurements at room temperature were in the range of 1.77-1.81 BM. SOD and antimicrobial activities of these complexes were also measured. Crystal data of (1): P-1, a = 9.3010(7) A, b = 9.7900(6) A, c = 16.4620(6) A, Vc = 1342.73(14) A3, Z = 4. The bond distance of CuN in square base is 2+/-0.04 A.


Subject(s)
Anti-Bacterial Agents/chemistry , Antifungal Agents/chemistry , Copper/chemistry , Organometallic Compounds/chemistry , Anti-Bacterial Agents/chemical synthesis , Anti-Bacterial Agents/pharmacology , Antifungal Agents/chemical synthesis , Antifungal Agents/pharmacology , Bacteria/drug effects , Crystallography, X-Ray , Fungi/drug effects , Ligands , Microscopy, Electron , Molecular Structure , Organometallic Compounds/chemical synthesis , Organometallic Compounds/pharmacology , Superoxide Dismutase/chemistry
16.
Spectrochim Acta A Mol Biomol Spectrosc ; 62(1-3): 261-8, 2005 Nov.
Article in English | MEDLINE | ID: mdl-16257723

ABSTRACT

Two new mixed ligand copper(II) complexes with diethylenetriamine, 2,2'-bipyridine and 1,10-phenanthroline have been synthesized. The crystal and molecular structures of [Cu(dien)(phen)](ClO(4))(2) and [Cu(dien)(bipy)](BF(4))(2) (dien=diethylenetriamine, phen=1,10-phenanthroline, bipy=2,2'-bipyridine) were determined by X-ray crystallography from single crystal data. These two complexes have similar structures. The EPR spectral data also suggest that these complexes have distorted square pyramidal geometry about copper(II). Anti-microbial and superoxide dismutase activities of these complexes have also been measured. They show the higher SOD activity than the corresponding simple Cu(II)-dien/Cu(II)-PMDT (PMDT=N,N,N',N',N''-pentamethyldiethylenetriamine) complexes because of a strong axial bond of one of the nitrogen atoms of the alpha-diimine. Both the complexes have been found to cleave plasmid DNA in the presence of co-reductants such as ascorbic acid and glutathione.


Subject(s)
Copper/chemistry , Phenanthrolines/chemistry , Polyamines/chemistry , Anti-Bacterial Agents/pharmacology , Copper/pharmacology , Crystallography, X-Ray , Electron Spin Resonance Spectroscopy , Escherichia coli/drug effects , Kinetics , Ligands , Microbial Sensitivity Tests , Models, Molecular , Molecular Conformation , Phenanthrolines/pharmacology , Plasmids/metabolism , Polyamines/pharmacology , Proteus/drug effects , Pseudomonas/drug effects , Salmonella/drug effects , Staphylococcus/drug effects , Superoxide Dismutase/metabolism
17.
Spectrochim Acta A Mol Biomol Spectrosc ; 61(11-12): 2603-10, 2005 Sep.
Article in English | MEDLINE | ID: mdl-16043054

ABSTRACT

X-band electron spin resonance (ESR) and UV-vis spectra of a homobinuclear [(Bipy)2Cu-E-Im-Cu(Bipy)2](BF4)3 and a heterobinuclear [(Bipy)2Cu-E-Im-Zn(Bipy)2](BF4)3 complexes, E-Im=2-ethylimidazolate ion have been described as possible models for superoxide dismutase (SOD). Magnetic moment and ESR spectral measurements of the homobinuclear complex have shown an antiferromagnetic exchange interaction. From pH-dependent ESR and UV-vis spectral measurements studies, these complexes have been found to be stable over 8.5-10.5 pH range. These complexes catalyze the dismutation of superoxide (O2-) at biological pH. All the observations indicate that these complexes act as good possible models for superoxide dismutase.


Subject(s)
Biomimetic Materials/chemical synthesis , Biomimetic Materials/pharmacology , Copper/chemistry , Organometallic Compounds/chemistry , Zinc/chemistry , Anti-Bacterial Agents/chemical synthesis , Anti-Bacterial Agents/chemistry , Anti-Bacterial Agents/pharmacology , Biomimetic Materials/chemistry , Color , Dimethyl Sulfoxide , Electron Spin Resonance Spectroscopy , Hydrogen-Ion Concentration , Magnetics , Molecular Structure , Proteus vulgaris/drug effects , Solutions/chemistry , Spectrophotometry , Superoxide Dismutase/metabolism , Superoxides/chemistry , Superoxides/metabolism
18.
Article in English | MEDLINE | ID: mdl-15863062

ABSTRACT

X-band E.S.R., magnetic and electronic spectra of some imidazolate-bridged homometallic complexes [(en)2Cu-R-Im-Cu(en)2](ClO4)3 where en, ethylenediamine; R-ImH, R = H imidazole (ImH); if R = CH3, 2-methylimidazole (M-ImH) and if R = C2H5, 2-ethylimidazole (E-ImH), and mononuclear complexes [(en)Cu-dien](ClO4)2 and [(en)Cu-PMDT](ClO4)2 where dien, diethylenetriamine; PMDT, pentamethyldiethylenetriamine have been described. Superoxide dismutase (SOD) activity has also been measured and compared with earlier reported complexes. In frozen solution at 77 K, the spectra show axial symmetry with a d(x2-y2) ground state. Difference in lambda(max) between mononuclear and binuclear complexes was found to be approximately 65-75 nm. Magnetic susceptibility and E.S.R. spectral measurements for all these binuclear complexes revealed that the copper(II) ions are involved in antiferromagnetic exchange interactions propagated by the imidazolate bridge.


Subject(s)
Copper/chemistry , Electron Spin Resonance Spectroscopy/methods , Ethylenediamines/chemistry , Imidazoles/chemistry , Organometallic Compounds/chemistry , Superoxide Dismutase/chemistry , Binding Sites , Electromagnetic Fields , Electrons , Hydrogen-Ion Concentration , Inhibitory Concentration 50 , Ligands , Magnetics , Models, Chemical , Molecular Conformation , Spectrophotometry , Superoxides/chemistry , Temperature
19.
J Inorg Biochem ; 99(2): 651-63, 2005 Feb.
Article in English | MEDLINE | ID: mdl-15621300

ABSTRACT

Four imidazolate-bridged binuclear copper(II)-copper(II) and copper(II)-zinc(II) complexes viz., [(Bipy)(2)Cu-Im-Cu(Bipy)(2)](ClO(4))(3).CH(3)OH, [(Phen)(2)Cu-Im-Cu(Phen)(2)](BF(4))(3).2CH(3)OH, [(Bipy)(2)Cu-Im-Zn(Bipy)(2)](BF(4))(3), and [(Phen)(2)Cu-Im-Zn(Phen)(2)](BF(4))(3), (Bipy=2,2'-Bipyridyl, Phen=1-10-Phenanthroline and Im=imidazolate ion) were synthesized as a possible models for superoxide dismutase (SOD). Complex [(Bipy)(2)Cu-Im-Cu(Bipy)(2)](ClO(4))(3).CH(3)OH has been structurally characterized. This complex crystallizes in the triclinic space group P1, with the unit parameters a=8.88(5) A, b=13.79(17) A, c=20.18(18) A, alpha=76.424(8)(o), beta=85.888(6)(o), gamma=82.213(7). The metal-nitrogen bond length from 1.972-2.273 A and the distance Cu-Cu is 5.92 A. The five-coordinate geometry about the copper(II) ion is square pyramidal. Magnetic moment and electron paramagnetic resonance (e.p.r.) spectral measurements of the homobinuclear complexes have shown an antiferromagnetic exchange interaction. From the e.p.r. and UV-Vis spectral measurement studies, these complexes have been found to be stable (pH 8.5-10.5 for 1, 10.5 for 2,3 and 8.5 for 4). These complexes catalyse the dismutation of superoxide radical (O(2)(-)) at biological pH. All the observations indicate that these complexes act as good possible models for superoxide dismutase.


Subject(s)
Copper/chemistry , Organometallic Compounds/chemistry , Organometallic Compounds/chemical synthesis , Superoxide Dismutase/chemistry , Zinc/chemistry , Animals , Anti-Bacterial Agents/chemical synthesis , Anti-Bacterial Agents/chemistry , Anti-Bacterial Agents/pharmacology , Catalytic Domain , Cattle , Crystallography, X-Ray , Electron Spin Resonance Spectroscopy , In Vitro Techniques , Models, Chemical , Molecular Structure , Organometallic Compounds/pharmacology , Spectrometry, Mass, Fast Atom Bombardment , Spectrophotometry
20.
Spectrochim Acta A Mol Biomol Spectrosc ; 61(1-2): 287-97, 2005 Jan 01.
Article in English | MEDLINE | ID: mdl-15556452

ABSTRACT

The imidazolate-bridged binuclear copper(II)-copper(II) complex [(dien)Cu(mu-im)Cu(dien)](ClO(4))(3) and related mononuclear complexes [Cu(dien)(H(2)O)](ClO(4))(2), [Cu(dien)(Him)](ClO(4))(2) were synthesized with diethylenetriamine (dien) as capping ligand. The crystal structure of mononuclear [Cu(dien)(Him)](ClO(4))(2) and binuclear complex [(dien)Cu(mu-im)Cu(dien)](ClO(4))(3) have been determined by single crystal X-ray diffraction methods. The mononuclear complex [Cu(dien)(Him)](ClO(4))(2) crystallizes in the orthorhombic, Pca2(1) with a = 9.3420(9) A, b = 12.3750(9) A, c = 14.0830(9) A, beta = 90.000(7)(o) and Z = 4 and binuclear complex [(dien)Cu(mu-im)Cu(dien)](ClO(4))(3) crystallizes in the monoclinic space group P2(1)/a, with a = 15.017(7) A, b = 11.938(6) A, c = 15.386(6) A, beta = 110.30(4)(o) and Z = 4. The molecular structures show that copper(II) ions in an asymmetrically elongated octahedral coordination (type 4 + 1 + 1) and in binuclear complex Cu(1) atom has a asymmetrically elongated octahedral coordination (type type 4 + 1 + 1) and Cu(2) atom exhibits a square base pyramidal coordination (type 4 + 1). The bridging ligand (imidazolate ion, im) lies nearly on a straight line between two Cu(2+), which are separated by 5.812 A, slightly shorter than the value in copper-copper superoxide dismutase (Cu(2)-Cu(2)SOD). Magnetic measurements and electron spin resonance (ESR) spectroscopy of the binuclear complex have shown an antiferromagnetic exchange interaction. From pH-dependent cyclic voltametry (CV) and electronic spectroscopic studies the complex has been found to be stable over a wide pH range (7.75-12.50).


Subject(s)
Copper/chemistry , Models, Chemical , Organometallic Compounds/chemistry , Superoxide Dismutase/chemistry , Absorption , Anti-Bacterial Agents/pharmacology , Carbon/chemistry , Crystallography, X-Ray , Electrochemistry , Electrodes , Electron Spin Resonance Spectroscopy , Glass , Hydrogen-Ion Concentration , Magnetics , Molecular Conformation , Molecular Structure , Organometallic Compounds/chemical synthesis , Organometallic Compounds/pharmacology , Solutions , Superoxide Dismutase/metabolism
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