Accuracy of Evaluation of Fatty Liver with Third-Generation Unenhanced Dual-Energy CT and MRI: Prospective Comparison with MR Spectroscopy

Background and Objectives The purpose of this study is to evaluate and establish the accuracy of noninvasive methods, including third-generation dual-source dual-energy computed tomography (DECT) and proton density fat (PDF) fraction on magnetic resonance imaging (MRI) using three-dimensional multiecho multipoint chemical shift-encoded spoiled gradient echo (q-Dixon) sequence in the quantification of hepatic steatosis; with H1-MR spectroscopy (MRS) as the reference standard.

Materials and Methods A total of 47 patients were included in this prospective study. We studied the accuracy of fatty liver detection using third-generation DECT using mixed set images (MSIs), virtual monochromatic images (VMIs), and MRI q-Dixon. The results were compared with H1-MRS. Data were analyzed using linear regression for each technique compared with MRS.

Results Our study's correlation and linear regression analysis showed a good correlation between PDF values obtained by H1-MRS and MR q-Dixon methods (r = 0.821, r 2 = 0.674, p < 0.001). On MSI, H1-MRS showed a low correlation with average liver attenuation (r 2 = 0.379, p < 0.001) and a moderate correlation with liver attenuation index (r 2 = 0.508, p < 0.001) noted. There was a moderate correlation between H1-MRS and average liver attenuation and liver attenuation index on VMI at 80 to 120 keV with r 2 = 0.434, p < 0.001, and r 2 = 0.485, p < 0.001, respectively.

Conclusion MRI q-Dixon is the method of choice for evaluating fat quantification in the absence of H1 MRS. Among DECT images, VMI is valuable in the evaluation of hepatic fat as compared with the mixed set of images.

Scoring system for predicting ovarian necrosis in adnexal torsion using an ultra-short optimized MRI protocol

PURPOSE

To evaluate a MRI scoring system predicting haemorrhagic necrosis in adnexal torsion with intraoperative and/or histopathological correlation using an abbreviated and optimized MRI protocol.

METHODS

This retrospective observational study includes patients with adnexal torsion who underwent Magnetic Resonance Imaging(MRI) and surgery. T2 sequences were evaluated by three observers of varying experience for following findings: Hypo-intensity of ovarian stroma, around the follicle, cyst wall or ovarian capsule and the twisted pedicle. Hypo-intensities in the above and a thick cyst wall were considered as predictors of necrosis. A scoring system was created based on the number of positive findings. MRI was correlated with intraoperative and histopathological findings. Lesions showing haemorrhagic necrosis were considered true positives.

RESULTS

43 women with torsion were included. 74.4% were secondary to a lead point and 25.4% were without one. Hypointensity score of 2 or more had the highest diagnostic accuracy and inter-reader agreement in predicting necrosis (R1-sensitivity: 92%, specificity: 89%, positive predictive value (PPV): 92% and negative predictive value (NPV): 89%, R2-sensitivity: 92%, specificity: 94%, PPV: 96% and NPV: 90% and R3-sensitivity: 92%, specificity: 83%, PPV: 89% and NPV: 89%).

CONCLUSION

In patients with suspected adnexal torsion, optimized MRI using T2 weighted sequences will serve as a rapid and effective single imaging modality for diagnosing adnexal torsion and accurately predicting necrosis thereby triaging the patients for appropriate management.

Imaging Recommendations for Diagnosis, Staging, and Management of Cervical Cancer

Cervical cancer is the fourth most common cancer in women globally and the second most common cancer in Indian women, more common in lower socioeconomic strata. Improvement in survival and decrease in morbidity reflect the earlier detection with screening and imaging, as well as multifactorial multimodality therapy integrating surgery, and concurrent chemoradiation therapy providing superior therapeutic benefits. Imaging plays a vital role in assessing the extent of disease and staging of cervical cancer. The appropriateness criteria of a modality are different from its availability based on infrastructure, medical facilities, and resource status. Although in an ideal situation, magnetic resonance imaging (MRI) would be of greatest value in locoregional assessment of extent of disease and fluorodeoxyglucose positron emission tomography-computed tomography for distant staging; often, an ultrasonography, chest radiograph, and bone scans are utilized, with contrast-enhanced computed tomography representing a fair superior diagnostic accuracy, and can be reported as per the RECIST 1.1 criteria. MRI is also of good utility in the assessment of residual disease, predicting response and detecting small volume recurrence. MRI offers the highest diagnostic accuracy in determining parametrial invasion and hence surgical planning; so also, MRI-guided radiation planning helps in more accurate graded radiation dose planning in radiation therapy. Stage and therapy-based surveillance imaging should be encouraged and recommended.

Imaging Recommendations for Diagnosis, Staging, and Management of Uterine Cancer

Uterine cancers are classified into cancers of the corpus uteri (uterine carcinomas and carcinosarcoma) and corpus uteri (sarcomas) by the AJCC staging system (eighth edition). Endometrial carcinoma is the most common amongst these with prolonged estrogen exposure being a well-known risk factor. The FIGO staging system for endometrial carcinoma is primarily surgical and includes total hysterectomy, bilateral salpingo-oophorectomy, and lymphadenectomy. Imaging is useful in the preoperative evaluation of tumor stage, especially assessment of myometrial invasion and cervical stromal extension. Dynamic contrast enhanced MRI with DWI has a high staging accuracy and is the preferred imaging modality for primary evaluation with contrast-enhanced CT abdomen being indicated for recurrent disease. PET/CT is considered superior in evaluation of lymph nodes and extra pelvic metastases.

Review of Mammographic and Sonographic Features of an Uncommon Inflammatory Breast Disease - Granulomatous Lobular Mastitis

Background: Granulomatous lobular mastitis (GLM) is a rare inflammatory disease of the breast. Its clinical features and imaging findings often mimic malignancy. The aim of this study is to review the mammographic and ultrasound features of granulomatous lobular mastitis to help differentiate it from other diagnoses. Methods: In our study, imaging data of 51 patients were reviewed retrospectively, who were diagnosed with granulomatous lobular mastitis by core needle biopsy and culture analysis.  Results: The mammographic findings of granulomatous lobular mastitis observed in our study group were focal or global asymmetry (52.6%), oval or round lesions with obscured margins (15.7%), irregular mass with indistinct margins (15.7%) and associated skin thickening (26.3%) with no specific pointers to differentiate from malignancy.The most common morphological abnormality on ultrasound was single or multiple collections with or without tracts (72.5%). Other morphological abnormalities were non-mass areas with tracts (25.5%), dilated ducts with debris (13.7%) and mass (3.9%). The common associated abnormalities were perilesional increased echogenicity (86.3%), increased peripheral vascularity (88.2%), intercommunicating tracts (76.5%) and axillary adenopathy (68.6%) and these ultrasound features were pointers to differentiate granulomatous mastitis from malignancy. Conclusion: Granulomatous lobular mastitis has non-specific clinical and imaging features. Imaging, especially ultrasound as in our study, is found to be indispensable in diagnosing GLM and excluding other causes such as infective mastitis and malignancy.  

Radiological Spectrum of Pseudoangiomatous Stromal Hyperplasia of Breast—A Case Series

Pseudoangiomatous stromal hyperplasia (PASH) is a benign mesenchymal tumor-like lesion of the breast. It is commonly seen as incidental background changes of the intralobular stroma in biopsy specimens performed for other breast lesions. Less frequently, it presents as a nodular form that has a benign morphology on imaging, mimicking fibroadenoma or as a diffuse form causing progressive massive gigantomastia. Diagnosis is established by biopsy. Knowledge of the imaging appearance of PASH not only facilitates proper assessment of radiopathological correlation but also helps in deciding further management of these lesions. Occasionally, nodular PASH may have a suspicious appearance on imaging wherein excision biopsy is indicated to exclude a coexisting carcinoma.

Presence of peritumoral edema on T2w MRI: a poor non-invasive prognostic marker in breast cancer patients

Background

The purpose of the study was to assess the correlation between peritumoral edema (PE) seen on magnetic resonance imaging (MRI) in breast cancer and the established pathological prognostic factors like tumor histology and molecular subtype, grade, Ki67 index, lymphovascular invasion (LVI) and nodal stage. The breast MRI and pathological data of post-surgery specimen of 126 breast cancer patients over a period of 18 months were retrospectively studied. Those who received neoadjuvant therapy, had non-invasive, locally advanced, inflammatory and bilateral breast cancers were excluded. Patients were divided into two groups based on finding of peritumoral edema on T2w MRI images: Group A with PE (n = 88) and Group B without PE (n = 38). Pathological results for the two groups were analyzed and compared using Chi square test. p values of < .05 were considered as significant.

Results

Statistically significant correlation was found between the PE and molecular subtype (p value of < .01), high grade (p value of .001) and High Ki-67 index (p value of .001). No significant correlation was present for the histological type and LVI pathological nodal stage (pN).

Conclusions

We concluded that presence of PE on MRI is associated with poor pathological prognostic factors in breast cancer. It can serve as an additional non-invasive marker to assess prognosis in breast cancer patients especially in those receiving neoadjuvant therapy where the whole tumor may not be available for pathological analysis post-therapy.

Comparison of Turbo Flash and dual-energy modes of third-generation dual-source CT in pre-transplant renal angiography: a prospective observational study

Background

The purpose of this study was to compare the Image Quality, Contrast Medium Volume, and Radiation dose in renal angiography performed using Turbo Flash mode and dual-energy (DE) mode in the third-generation dual-source dual-energy CT.

This prospective observational study was performed on renal donors who underwent CTA imaging as a pre-transplant workup. The study population was divided into two groups. Group A underwent DECT renal angiography. Group B underwent Turbo Flash Mode CT renal angiography. For group A, a contrast volume of 1 ml/kg and for group B at 0.5 ml/kg was administered. Image Quality was evaluated objectively by calculating CNR and SNR and subjectively by a 5-point scale. Radiation Dose analysis was done by noting CTDIvol and DLP on the scanner system and calculating effective radiation dose (ED).

Results

The subjective image quality scores for the Turbo Flash group were comparable with the DE group in qualitative image analysis. Additionally, in the Turbo Flash group, there was a reduction in contrast media and effective radiation dose by 47.5% and 32.7%, respectively. Nevertheless, mean attenuation of the abdominal arteries, CNR, SNR, and Noise (S.D) showed statistical significance between the two groups (p value < 0.01).

Conclusions

To our knowledge, no previous study compared Turboflash mode with DE protocol in CT renal angiography in a donor group of patients. Turbo Flash CT is an excellent modality that is faster and has an added advantage of decreased radiation dose and contrast media volume reduction, which can be recommended for screening of voluntary kidney donors but needs further clinical studies, validation, and standardization with tailored protocols.

Evaluation of Hypervascular Focal Liver Lesions Utilizing Virtual Monoenergetic Images from Third-Generation Dual-Source Dual-Energy Computed Tomography

Objectives The purpose of our study was to evaluate the virtual monochromatic imaging in detecting hypervascular focal liver lesions in the late arterial phase with third-generation dual-source dual-energy computed tomography and to assess its image quality.

Materials and Methods In our study, 80 patients were included. Contrast-enhanced images in the late arterial phase (in the dual-energy mode) were acquired and were post-processed in Syngo, via workstation, using Monoenergetic + software. Five sets of images, one polychromatic energy image (corresponding to 120 kVp single-energy image) and four virtual monoenergetic image (VMI) sets at 40, 50, 60, and 70 keV levels, were generated. All these images were analyzed both objectively and subjectively. The attenuation values were measured, and the contrast-to-noise ratio (CNR) of liver and tumor were measured and compared objectively in each dataset. Image noise, image contrast, and diagnostic confidence for liver lesion detection were analyzed subjectively using a five-point scale system. Statistical analysis was performed using Kolmogorov–Smirnov, analysis of variance, and Kruskal–Wallis tests.

Results Among the VMI, maximum image noise was observed in the 40 keV image, with a gradual reduction in the image noise being noted with an increase in the VMI energy. The CNR of the hepatic parenchyma and the tumor gradually increased with a reduction in VMI energy from 70 to 40 keV. On subjective analysis, image contrast and image noise were observed to be more in low VMI datasets. In lesion detection, diagnostic confidence with an excellent confidence level was observed with a decrease in VMI energy.

Conclusion VMI datasets of 40 to 70 keV from third-generation dual-source DECT provide superior diagnostic accuracy for detecting hypervascular liver lesions. Considering the image noise and lesion detection rate among the VMI datasets, 60 keV VMI is the most helpful dataset for increased liver lesion detection with good image quality.

Comparison of T2 relaxometry and PET CT in the evaluation of patients with mesial temporal lobe epilepsy using video EEG as the reference standard

PURPOSE

Our study aimed to compare the sensitivity of T2 relaxometry and positron emission tomography - computed tomography (PET/CT) in patients with a history suggestive of mesial temporal lobe epilepsy using video electroencephalography (EEG) as the reference standard.

MATERIAL AND METHODS

In our study, 35 patients with a history suggestive of mesial temporal lobe epilepsy were subjected to conventional magnetic resonance imaging (MRI), T2 relaxometry, and PET/CT. The results of each of the studies were compared with video EEG findings. Analyses were performed by using statistical software (SPSS version 20.0 for windows), and the sensitivity of conventional MRI, T2 relaxometry, and PET/CT were calculated.

RESULTS

The sensitivity of qualitative MRI (atrophy and T2 hyperintensity), quantitative MRI (T2 relaxometry), and PET/CT in lateralizing the seizure focus were 68.6% (n = 24), 85.7% (n = 30), and 88.6% (n = 31), respectively.

CONCLUSIONS

The sensitivity of MRI in lateralization and localization of seizure focus in temporal lobe epilepsy can be increased by adding the quantitative parameter (T2 relaxometry) with the conventional sequences. T2 Relaxometry is comparable to PET/CT for localization and lateralization of seizure focus and is a useful tool in the workup of TLE patients.

Comparison between Conventional Unenhanced and Virtual Unenhanced Imaging of Hepatopancreaticobiliary System with Third-Generation Dual-Source Dual-Energy CT—An Observational Study

Objectives The aims of our study were to assess the comparability of conventional unenhanced images (CUIs) of hepatopancreaticobiliary system with virtual unenhanced images (VUIs) derived from arterial and portal venous phases acquired in a third-generation, dual-source, dual-energy CT (DECT), and also to assess the best dataset among these VUIs. We also calculated the radiation effective dose (ED) reduction by eliminating noncontrast acquisition.

Materials and Methods 60 patients were included in our study. Unenhanced images in single energy and contrast-enhanced images in dual-energy mode were acquired. Arterial virtual unenhanced (AVU) and portal virtual unenhanced (PVU) images were generated and compared with CUI, using both objective and subjective methods. The ED was calculated separately for each phase. Statistical significance between difference in mean attenuation values were analyzed using ANOVA and unpaired student t-test.

Results In our study, the difference in mean attenuation of liver, spleen, and pancreas between the three phases—CU, AVU, and PVU—were insignificant with p-value > 0.05. This indicates that the values were comparable. Among the VUI, AVU images were statistically superior in image quality. Elimination of noncontrast CT from triple phase abdominal imaging can achieve an average ED reduction of 39%.

Conclusions We conclude that VUI generated in third-generation, dual-source DECT has diagnostic image quality and can replace the CUI in triple-phase studies, with a mean ED reduction by 39%. The VUI obtained from arterial phase is superior to those obtained from portal venous phase.

Estimation of Accuracy of B-Mode Sonography and Elastography in Differentiation of Benign and Malignant Lymph Nodes With Cytology as Reference Standard: A Prospective Study

Purpose: To prospectively estimate the reliability of B-mode ultrasonography and sonoelastography in differentiating benign and malignant cervical lymph nodes with cytological findings as to the reference standard.

Materials and Methods: A total of 50 patients referred for sonography for enlarged cervical lymph nodes were included in the study. They were subjected initially to B-mode ultrasonography and sonoelastography and later underwent fine-needle aspiration cytology (FNAC) in the same sitting. Sensitivity, specificity, and accuracy were compared.

Results: Out of 50 cases, 33 were males, and 17 were females. On B-mode ultrasonography, 15 enlarged cervical lymph nodes were benign-looking and 35 were malignant-looking. When studied on elastography, 12 were benign-looking and 38 showed features of malignancy. However, when studied histopathologically, 18 were benign and 32 were malignant. The sensitivity, specificity, and diagnostic accuracy were compared, and the results were better in sonoelastography than B-mode ultrasonography. When both B-mode and sonoelastography were combined, an increase in the sensitivity for differentiation was achieved. However, a decrease in specificity was noted when both modalities were combined in our study, probably due to a significant number of patients with tuberculous cervical lymphadenopathy.

Conclusion: In countries like India, where granulomatous infection like tuberculosis is prevalent, the combination of sonoelastography with B-mode ultrasonography has decreased specificity in the differentiation of benign and malignant cervical lymph nodes, and histopathology is always needed for the final confirmation of diagnosis. The decreased specificity on elastography is attributed to simultaneous coexisting inflammation and fibrosis in chronic granulomatous lymphadenopathy.

Spontaneous Perinephric Urinoma Secondary to Drug Induced Acute Interstitial Nephritis: A Case Report

Urinoma is defined as the extravasation of urine from any part of the urinary collecting system, which causes lipolysis of the surrounding fat, resulting in an encapsulated collection. The most common cause of urinoma is the direct obstruction of the urinary system. The other etiologies include trauma and postinstrumentation/surgery. Parenchymal cause for spontaneous urinoma is exceedingly rare. We present a case of a 30-year-old gentleman who presented with lower abdominal pain and was treated with a Diclofenac injection. The pain got better temporarily, but he presented again with right loin pain after 3 days. His computed tomography scan images revealed bilateral perinephric urinoma. As there was significant deterioration of renal function, he underwent a renal biopsy. The histopathology was reported as acute interstitial nephritis (AIN). Drug-induced AIN is very rarely presented with acute loin or abdominal pain due to spontaneous perinephric urinoma, as it was seen in our case.

Renal Lymphangiectasia: An Unusual Mimicker of Cystic Renal Disease - A Case Series and Literature Review

Cystic renal lesions are commonly seen on a daily basis in abdominal imaging. Even though most cystic renal lesions are benign simple cysts, complex and multifocal cystic renal diseases are also common with a vast number of differentials. One of the rare mimickers of this condition is renal lymphangiectasia, and the disease can be diagnosed if radiologists are aware of the imaging findings, and this can help the physician to offer the appropriate treatment. We report a case series of five cases in our hospital and also review the literature on renal lymphangiectasia, including its pathophysiology, clinical presentation, imaging appearances, complications, treatment, and differentials.

Extra Pancreatic Necrotic Volume: Can It Prognosticate Acute Necrotising Pancreatitis— A Prospective Study

Background Acute necrotizing pancreatitis (ANP) is associated with higher mortality and morbidity. We need a method which is accurate in predicting the prognosis, and when applied early in the disease process, can help in closer monitoring and early initiation of treatment for at-risk patients.

Objectives The aim of this prospective study was to assess the extra pancreatic necrosis (EPN) volume in patients with ANP and compare it with outcome variables such as organ failure, death and need for intervention as well as to compare the predictive power of EPN volume with modified CT severity index (CTSI).

Materials and Methods The study had 48 patients with clinical diagnosis of acute pancreatitis, who underwent Contrast enhanced CT (CECT) between 3–6 days of onset. In all these patients, EPN volume (in cubic centimetre) and modified CTSI score were calculated and compared with the patient outcome parameters such as duration of hospital/ICU stay, need for percutaneous/surgical intervention, evidence of infection and organ failure. The results were compared with assess the predictive power of EPN volume.

Statistical analysis The analysis was done in SPSS version 16.0 for windows. Pearson Correlation was used to assess the significant relationship between selected objective variables.

Results EPN volume (>/= to 360 cc) had a statistically significant correlation with outcome parameters as well as in predicting overall organ failure. In our study, Modified CTSI had no significant correlation with the above mentioned factors.

Conclusions The volume of EPN calculated between 3rd and 6th day of onset of symptoms showed a significant correlation with the outcome in patients with ANP.

Spectroscopic investigation and computational studies on the interaction of Acriflavine with various estrogens

The fluorescence quenching of Acriflavine (AFN) by certain estrogens was examined in aqueous media by employing steady state and time-resolved fluorescence measurements. The absorption spectra of AFN change with significant bathochromic shift in presence of quencher molecules. The quenching behavior was examined by correlating the bimolecular quenching rate constant (k_q) with the free energy change (ΔG). The decrease in quenching rate constant depends on the increase in oxidation potential of quencher molecules. The fluorescence quenching experiments were carried out in different solvents of varying polarities and reveals the possibility of charge transfer quenching mechanism. Lifetime measurements indicate static quenching. The quenching behavior is addressed from bond dissociation enthalpy (BDE) calculations. The antioxidant activity of estrogen compounds were evaluated by deoxyribose oxidation assay.

Synthesis, characterization and binding interactions of amino acids coupled perylene diimides with colloidal doped and undoped TiO₂

Two sensitizers based on amino acids coupled with perylene moiety having absorption in the visible region have been designed and their interaction with doped and undoped TiO2 for the application of dye sensitized solar cells (DSSCs) has been studied. The synthesized compounds PDI-PA and PDI-AA were characterized using (1)H and (13)C NMR, Mass and FT-IR spectroscopic techniques. The optical properties and lifetime measurements of the sensitizers were analyzed using various solvents with different polarity. The solvatochromism effect was studied using Lippert-Mataga plot. The electrochemical studies of both dyes were investigated in DMF with various scan rate ranging from 200 to 1000 mV s(-1). Colloidal doped and undoped TiO2 was prepared and characterized by using absorption measurements. Binding ability of the sensitizers with the nanoparticles was studied through absorption, fluorescence quenching, cyclic voltammetry and FT-IR measurements. Results obtained from all the above analysis suggest the mode of quenching may be static. The binding constant values were calculated using Kamat-Fox equation indicates the binding behavior of the sensitizers with the nanoparticles. The fluorescence quenching was mainly attributed to electron transfer from the excited state of PDI's to the conduction band of colloidal semiconductors. The electron transfer mechanism was explained based on the Rehm-Weller equation as well as the energy level diagram.

Investigation on the inclusion and toxicity of acriflavine with cyclodextrins: a spectroscopic approach

Acriflavine hydrochloride (AFN) is a prospective drug worn in the eradication of HIV1 infection. The toxicity and adverse side effects renders the potent drug to limits its usage. However, to overcome the dilemma we have aimed to select carriers with great complexation efficiencies in different cyclodextrins (CDs) of varying cavity size. The interaction of AFN with α, β and γ-CDs were investigated using absorption and steady state as well as lifetime measurements. From the obtained data it was found that AFN fits in the cavity of α and β-CDs but unable to form inclusion complex with γ-CD. The effect of quencher molecules during the inclusion phenomena of AFN with CDs was explored via steady state measurements. The nature of binding forces responsible for the inclusion of AFN with CDs was discussed by using thermodynamic parameters. Using Benesi-Hildebrand equation the stoichiometry of AFN with CDs was predominantly found to be 1:1. To get deeper in situ, the in vitro toxicity of AFN and its complexation product were probed by Artemia salina sp. The toxicity of AFN was reduced when complexed with α and β-CDs.

CdTe quantum dot as a fluorescence probe for vitamin B(12) in dosage form

We here report the CdTe quantum dot (CdTe QDs)-based sensor for probing vitamin B12 derivatives in aqueous solution. In this paper, simple and sensitive fluorescence quenching measurements has been employed. The Stern-Volmer constant (KSV), quenching rate constant (kq) and binding constant (K) were rationalized from fluorescence quenching measurement. Furthermore, the fluorescence resonance energy transfer (FRET) mechanism was discussed. This method was applicable over the concentration ranging from 1 to 14μg/mL (VB12) with correlation coefficient of 0.993. The limit of detection (LOD) of VB12 was found to be 0.15μg/mL. Moreover, the present approach opens a simple pathway for developing cost-effective, sensitive and selective QD-based fluorescence sensors/probes for biologically significant VB12 in pharmaceutical sample with mean recoveries in the range of 100-102.1%.

Interaction of acriflavine with pyrimidines: a spectroscopic approach

The interaction of acriflavine with uracils was investigated by using spectroscopic tools viz., UV-Vis absorption, steady state and time resolved fluorescence measurements. The spectroscopic data were analyzed using Stern-Volmer equation to determine the quenching process. The bimolecular quenching rate constant (k(q)), binding constant (K) and number of binding sites (n) were calculated at different temperature from the relevant fluorescence data. The experimental results obtained from life-time measurement indicate that the quenching mechanism was static via the formation of ground state complex. The free energy change (ΔGet) for electron transfer process was calculated by Rehm-Weller equation. The existence of binding forces and the interactions of acriflavine with uracils were examined.

Studies on the inclusion behavior of 9-Aminoacridine into cyclodextrins: spectroscopic and theoretical evidences

9-Aminoacridine (9-AA) is an important attractive pharmaceutical drug employed as chemotheraptic agent for wound dressings. However, 9-AA possesses limited solubility and rapid metabolic decomposition renders this potential drug to limit its applications. Here we propose cyclodextrins (CDs) as a drug carrier to improve the bioavailability, solubility of 9-AA. The interaction between 9-AA and CDs (α-CD and β-CD) has been studied using UV-Vis absorption, steady state time resolved fluorescence, (1)H NMR and FT-IR spectroscopy techniques. The spectroscopic measurements show that 9-AA does not form stable complex with α-CD and also confirmed by DFT calculations. On the other hand, 9-AA forms inclusion complex with β-CD in a 1:1 stoichiometry ratio. Our DFT results suggest that 9-AA stabilizes inside the CD environment through hydrogen bonding that has unambiguously confirmed by AIM analysis. Thus our studies provide a useful insights in the development of Aminoacridine based drugs & its delivery through a suitable carrier like CDs.

Spectroscopic investigation on the interaction of 9-aminoacridine with certain dyes

The fluorescence quenching of 9-Aminoacridine (9-AA) by various dyes were probed in aqueous medium using steady state and time resolved fluorescence spectroscopic techniques. From these techniques, we had rationalized the interaction of 9-AA with various dyes via ground state complex formation. The binding constant (K) and number of binding sites (n) were calculated from the relevant fluorescence quenching data. The fluorescence emission of 9-Aminoacridine was quenched by the dyes through static quenching followed by the mechanism of energy transfer. The static quenching mechanism was confirmed by lifetime measurements. The thermodynamic parameters such as free energy change (ΔG), enthalpy change (ΔH) and entropy change (ΔS), were calculated by thermodynamic equations. The results showed that Van der Waals interaction or hydrogen bond formation played a major role in the binding of 9-AA with these dyes.

Influence of terminal substitution on structural, DNA, protein binding, anticancer and antibacterial activities of palladium(II) complexes containing 3-methoxy salicylaldehyde-4(N) substituted thiosemicarbazones

The variable chelating behavior of 3-methoxysalicylaldehyde-4(N)-substituted thiosemicarbazones was observed in equimolar reactions with [PdCl(2)(PPh(3))(2)]. The new complexes were characterized by various analytical, spectroscopic techniques (mass, (1)H-NMR, absorption, IR). All the new complexes were structurally characterized by single crystal X-ray diffraction. Crystallographic results showed that the ligands H(2)L(1) and H(2)L(4) are coordinated as binegative tridentate ONS donor ligands in the complexes 1 and 4 by forming six and five member rings. However, the ligands H(2)L(2) and H(2)L(3) bound to palladium in 2 and 3 as uninegative bidentate NS donors by forming a five member chelate ring. From this study, it was found that the substitution on terminal 4(N)-nitrogen may have an influence on the chelating ability of thiosemicarbazone. The presence of hydrogen bonding in 2 and 3 might be responsible for preventing the coordination of phenolic oxygen to the metal ion. The interaction of the complexes with calf-thymus DNA (CT-DNA) has been explored by absorption and emission titration methods. Based on the observations, an electrostatic binding mode of DNA has been proposed. The protein binding studies were monitored by quenching of tryptophan and tyrosine residues in the presence of complexes using Lysozyme as model protein. Antibacterial activity studies of the complexes have been screened against pathogenic bacteria such as Enterococcus faecalis, Staphylococcus aureus, Escherichia coli, Klebsiella pneumonia and Pseudomonas aeruginosa. MIC50 values of the complexes showed that they exhibited significant activity against the pathogens and among them, 3 exhibited higher activity. Further, anticancer activity of the complexes on the lung cancer cell line A549 has also been studied.

An investigation on the fluorescence quenching of 9-aminoacridine by certain pyrimidines

The fluorescence quenching of 9-aminoacridine by certain substituted uracils in water was studied using absorption, steady state and time resolved measurements. The bimolecular quenching rate constants (k(q)), binding constant K and number of binding sites (n) were calculated based on the fluorescence quenching data. The free energy change (ΔG(et)) for electron transfer process was calculated by Rehm-Weller equation. From lifetime measurement we observed that the quenching was mainly due to static mechanism involving ground state complex formation.

Fluorescence Quenching of Phycoerythrin by Anthraquinone Dyes

Fluorescence quenching of phycoerythrin (PE) by a series of anthraquinone dyes has been investigated using steady state fluorescence technique in water medium. The dyes used were Uniblue, Acid blue 129, Alizarin and Alizarin red S. The quenching of PE was found to obey the Stern-Volmer equation and the corresponding Stern-Volmer plots were linear indicating the dynamic quenching. The quenching rate constants (k q) were calculated by using fluorescence data. The mechanism of quenching is discussed on the basis of quenching rate constants as well as the reduction potential of dyes. The electron transfer mechanism has been proved by the calculation of free energy change (ΔGet) by applying Rehm-Weller equation.

Interaction of anthraquinone dyes with lysozyme: evidences from spectroscopic and docking studies

The interaction between lysozyme and anthraquinone dyes such as Alizarin Red S, Acid blue 129 and Uniblue was studied using steady state, time resolved fluorescence measurements and docking studies. Addition of anthraquinone dyes effectively quenched the intrinsic fluorescence of lysozyme. Fluorescence quenching of lysozyme by dyes has revealed the formation of complex. The number of binding sites (n) and binding constant (K) for all the three dyes was calculated by relevant fluorescence quenching data. Based on Förster's non-radiative energy transfer theory, distance (r(0)) between the donor (lysozyme) and acceptor (dyes) as well as the critical energy transfer distance (R(0)) has also been calculated. The interaction between dyes and lysozyme occurs through static quenching mechanism as confirmed by time resolved spectroscopy. The conformational change of lysozyme has been analyzed using synchronous fluorescence measurement. Finally, docking studies revealed that specific interactions were observed with the residue of Trp 62.

Investigations on the photoinduced interaction of water soluble thioglycolic acid (TGA) capped CdTe quantum dots with certain porphyrins

The photoinduced interaction of TGA capped CdTe quantum dots (QDs) with porphyrins such as meso-tetrakis(4-sulfonatophenyl)porphyrin [TSPP], meso-tetrakis(4-carboxyphenyl)porphyrin [TCPP], meso-tetrakis (4-N-methylpyridyl)porphyrin [TMPyP] and meso-tetraphenylporphyrin [TPP] has been studied by using absorption, steady state and time resolved fluorescence spectroscopy. The QD surface was negatively charged due to thiol capping agent containing carboxylic group. Positively charged TMPyP interacts with QDs through charge transfer mechanism, negatively charged porphyrins (TCPP and TSPP) interacted through energy transfer mechanism and the neutral one (TPP) does not have any interaction. The Stern-Volmer constant, quenching rate constant, association constants, rate of electron transfer and energy transfer parameters were calculated from the fluorescence data. Effect of molecular structure has also been studied.

Fluorescence Quenching Study on Electron Transfer from Certain Amines to Excited State Triphenylpyrylium Ion (TPP+)

The fluorescence quenching of excited singlet state of 2,4,6-triphenylpyrylium tetrafluoroborate (TPPBF4 or TPP+), a very good electron acceptor by amines were investigated in a acetonitrile solution using steady state technique. The bimolecular quenching rate constants lie in the range 2.11–10.26 × 1010 M-1 s-1. The driving force (ΔGet) for electron transfer process was calculated from the oxidation potential of amines and the reduction potential of TPP+. The observed k q values correlated well with the driving force for the electron transfer reactions. Aromatic amines show higher k q than aliphatic amines. From the oxidation potential of amines and the quenching rate constant values, a mechanism involving photoinduced electron transfer from amines to excited state TPP is suggested.