Time-resolved emission spectroscopy to elucidate the functional nature of heat-stable transcription factor.

A 22 kDa protein from Thermus thermophilus is characterised as a DNA binding transcription regulator and its function is established using the fluorescence spectroscopy technique. The steady-state fluorescence spectroscopy result shows significant binding of calf thymus DNA and protein molecule. To confirm, the DNA quenching effect in real-time, a time-resolved emission spectroscopy study was performed and the result shows good agreement with steady-state quenching analysis.

Environmental risk appraisement of disinfection by-products (DBPs) in plant model system: Allium cepa.

The organic toxicants formed in chlorinated water cause potential harm to human beings, and it is extensively concentrated all over the world. Various disinfection by-products (DBPs) occur in chlorinated water are genotoxic and carcinogenic. The toxicity is major concern for chlorinated DBPs which has been present more in potable water. The purpose of the work was to evaluate genotoxic properties of DBPs in Allium cepa as a plant model system. The chromosomal aberration and DNA laddering assays were performed to examine the genotoxic effect of trichloroacetic acid (TCAA), trichloromethane (TCM), and tribromomethane (TBM) in a plant system with distinct concentrations, using ethyl methanesulfonate (EMS) as positive control and tap water as negative control. In Allium cepa root growth inhibition test, the inhibition was concentration dependent, and EC50 values for trichloroacetic acid (TCAA), trichloromethane (TCM), and tribromomethane (TBM) were 100 mg/L, 160 mg/L, and 120 mg/L respectively. In the chromosome aberration assay, root tip cells were investigated after 120 h exposure. The bridge formation, sticky chromosomes, vagrant chromosomes, fragmented chromosome, c-anaphase, and multipolarity chromosomal aberrations were seen in anaphase-telophase cells. It was noticed that with enhanced concentrations of DBPs, the total chromosomal aberrations were more frequent. The DNA damage was analyzed in roots of Allium cepa exposed with DBPs (TCAA, TCM, TBM) by DNA laddering. The biochemical assays such as lipid peroxidation, H2O2 content, ascorbate peroxidase, guaiacol peroxidase, and catalase were concentration dependent. The DNA interaction studies were performed to examine binding mode of TCAA, TCM, and TBM with DNAs. The DNA interaction was evaluated by spectrophotometric and spectrofluorometric studies which revealed that TCAA, TCM, and TBM might interact with Calf thymus DNA (CT- DNA) by non-traditional intercalation manner.

A new insight into the interaction of ZnO with calf thymus DNA through surface defects.

Experimental evidences on the binding interaction of ZnO and Calf Thymus (CT) DNA using several biophysical techniques are the centre of interest of the present study. The interaction of ZnO with CT DNA has been investigated in detail by absorption spectral study, fluorescence titration, Raman analysis, zeta potential measurement, viscometric experiment along with thermal melting study and microscopic analysis. Steady-state fluorescence study revealed the quenching (48%) of the surface defect related peak intensity of ZnO on interaction with DNA. The optimized concentration of ZnO and DNA to obtain this level of quenching has been found to be 0.049mM and 1.027µM, respectively. Additional fluorescence study with 8-hydroxy-5-quinoline (HQ) as a fluorescence probe for Zn2+ ruled out the dissolution effect of ZnO under the experimental conditions. DNA conjugation on the surface of ZnO was also supported by Raman study. The quantitative variation in conductivity as well as electrophoretic mobility indicated significant interaction of ZnO with the DNA molecule. Circular dichroism (CD) and viscometry titrations provided clear evidence in support of the conformational retention of the DNA on interaction with ZnO. The binding interaction was found to be predominantly entropy driven in nature. The bio-physical studies presented in this paper exploring ZnO-CT DNA interaction could add a new horizon to understand the interaction between metal oxide and DNA.

Thymic Metastasis in Breast Cancer: A Case Report

A malignant tumor is generally believed to be very unlikely to metastasize to the thymus. Only three cases of thymic metastases have been reported so far in the medical literature. We report here a rare case of metastatic breast cancer to the thymus, which was detected by CT and PET scanning, and the metastasis was also confirmed by video-assisted thoracic surgery biopsy. Recognition of an unusual breast cancer metastasis, such as to the thymus, as well as the usual patterns of breast cancer metastasis will facilitate an accurate, prompt diagnosis and its appropriate treatment.

Multiple Thymoma in a Patient with Myasthenia Gravis: Case Report

A thymoma often occurs in patients with myasthenia gravis, but the development of multiple thymoma is very rare. The authors report the radiologic and pathologic findings of multiple invasive thymoma in a 59-year-old male with myasthenia gravis.

Thymic Epithelial Tumors Classified According to a Newly Established WHO Scheme: CT and MR Findings

Thymic epithelial tumor is a distinctive pathologic entity exhibiting variable histologic features and heterogeneous oncologic behavior. Among the various classification systems, that of the World Health Organization has been adopted because of good correlation between histologic appearance and oncologic behavior. Radiologically, a smooth contour and round shape are most suggestive of a type-A tumor, whereas an irregular contour most strongly suggests type C. Pleural seeding is rare in type-A and AB tumors; calcification is suggestive of type B. Type-C tumors are significantly larger and more commonly associated with lymphadenopathy than type B3. At T2-weighted MR imaging, lobular internal architecture is more prominent in types B1, B2, and B3 tumors than in others. However, imaging findings among the various types overlap to some extent, and the ability of imaging studies to differentiate types AB, B1, B2, and B3 is limited.

Thymic Enlargement in Patients with Hyperthyroidism

PURPOSE: To evaluate the radiologic findings and clinical feasibility of thymic enlargement in patients with hyperthyroidism. MATERIALS AND METHODS: Seven patients with hyperthyroidism and anterior mediastinal bulging revealed by chest radiogaphy were evaluated. The CT findings were analyzed with regard to the shape of the anterior mediastinal mass, surrounding infiltration, and enlargement of mediastinal lymph nodes. Whether or not tumor markers (alpha-fetoprotein, beta-human chorionic gonadotrophin, and chorionic embryonic antigen) showed increased levels was determined, and the size and thickness of the anterior mediastinal mass were measured and compared with previously described age-matched thymus data. In addition, changes in the thyroid gland were evaluated. RESULTS: In all seven patients, anterior mediastinal masses were bi-lobed, with no surrounding infiltration or enlarged mediastinal lymph node, and tumor marker levels showed no increase. The masses were therefore considered to be thymus. In six patients, the size of the thymus exceeded two upper standard deviations of mean value and in one patient, it was smaller than this. In three patients, PCNB (percutaneous needle biopsy) revealed normal thymic tissue and in two, follow-up chest PA demonstrated no interval change. CT showed that in three patients, the thyroid glands were diffusely enlarged. CONCLUSION: In patients with hyperthyroidism, an anterior mediastinal mass seen on chest radiographs was due to thymic enlargement. The recognition of CT findings of thymic enlargement in such patients may avoid unnecessary biopsy.

Thymoma Arising from Aberrant Cervical Thymus

Thymoma is one of the most common neoplasms of the mediastinum, and the most frequent tumor of theanterosuperior compartment. Thymoma developing from arrested undescended thymic cells in the neck is, however,rare. The most common extrathoracic location is the vicinity of the thyroid. Two cases of aberrant cervicalthymoma are presented. Both manifested as mass lesions at the thoracic inlet, with superior displacement of thethyroid. The masses had clinical features similar to those previously reported for cervical thymoma: preponderancein women, and the absence of myasthenic symptoms, but in one case there was malignant transformation.

CT Differentiation of Invasive thymoma and Thymic carcinoma

PURPOSE: In order to determine the differential points between them, we analyzed the CT findings of invasivethymoma and thymic carcinoma. MATERIALS AND METHODS: We retrospectively reviewed the CT scans of 14 patients withinvasive thymoma and 15 with thymic carcinoma, confirmed by surgery(n=19) or percutaneous needle aspiration (n=10)between 1988 and 1996. CT findings were evaluated in each group for intrathoracic spread (posterior, directposterior, and anterolateral), obliteration of the fat plane between the mass and vascular structures, vesselencasement, invasion of adjacent mediastinal structures, pleural implants, mediastinal nodes and distantmetastasis. RESULTS: Direct posterior spread was more common in thymic carcinoma than invasive thymoma ; it wasseen in one case (7%) of invasive thymoma and 12(80%) of thymic carcinoma(p=0.00). Posterior spread was seen insix cases (43%) of invasive thymoma and nine (60%) of thymic carcinoma. Anterolateral spread was seen only in twocases (13%) of thymic carcinoma. Obliteration of the fat plane was seen in nine cases (64%) of invasive thymomaand 14 (93%) of thymic carcinoma, while vessel encasement was seen in two cases (14%) of invasive thymoma and13(87%) of thymic carcinoma(p=0.00). Invasion of adjacent structures was seen in two cases (14%) of invasivethymoma and eight (53%) of thymic carcinoma. Pleural implants were more common in invasive thymoma than thymiccarcinoma, being seen in six cases (43%) of the former and one (7%) of the latter(p=0.04). Mediastinallymphadenopathy was seen in three cases (21%) of invasive thymoma and ten (67%) of thymic carcinoma. Distantmetastases were observed only in six cases (40%) of thymic carcinoma(p=0.02). CONCLUSION: Althoughdifferentiation between invasive thymoma and thymic carcinoma is difficult on the basis of CT findings, there arecertain differential points. Thymic carcinomas showed a higher rate of direct posterior intrathoracic spread,vessel encasement, mediastinal nodes and distant metastases than invasive thymomas. These, however, were morecommonly associated with pleural implants than were thymic carcinoma.

Ultrasonographic and CT findings of Cervical Ectopic Thymus of an Infant

We report a case of ectopic thymus in the left submandibular area of a two-month-old boy. On US and CT scans, a well-marginated, 3 x 2cm-sized solid mass along the left carotid sheath, anteromedial to the sternocleidomastoid muscle and posterior to the submandibular gland, was seen. CT attenuation of the mass showed that it was similar to that of normal thymus in the anterior mediastinum. Although a rare disease, ectopic thymus should be included in the differential diagnosis of cervical masses along the carotid sheath in infants.