A highly magnified star at redshift 6.2.

Galaxy clusters magnify background objects through strong gravitational lensing. Typical magnifications for lensed galaxies are factors of a few but can also be as high as tens or hundreds, stretching galaxies into giant arcs1,2. Individual stars can attain even higher magnifications given fortuitous alignment with the lensing cluster. Recently, several individual stars at redshifts between approximately 1 and 1.5 have been discovered, magnified by factors of thousands, temporarily boosted by microlensing3-6. Here we report observations of a more distant and persistent magnified star at a redshift of 6.2 ± 0.1, 900 million years after the Big Bang. This star is magnified by a factor of thousands by the foreground galaxy cluster lens WHL0137-08 (redshift 0.566), as estimated by four independent lens models. Unlike previous lensed stars, the magnification and observed brightness (AB magnitude, 27.2) have remained roughly constant over 3.5 years of imaging and follow-up. The delensed absolute UV magnitude, -10 ± 2, is consistent with a star of mass greater than 50 times the mass of the Sun. Confirmation and spectral classification are forthcoming from approved observations with the James Webb Space Telescope.

Genotype MTBDR plus assay for molecular detection of rifampicin and isoniazid resistance in Mycobacterium tuberculosis.

AIM: This study was performed for the rapid identification of Mycobacterium tuberculosis complex and its resistance to rifampicin and isoniazid, directly from the sputum samples of pulmonary tuberculosis patients. MATERIALS AND METHODS: A commercially available genotype MTBDR plus assay was used for the identification and detection of mutations in Mycobacterial isolates. A total of 100 sputum samples of pulmonary tuberculosis patients were analyzed by using the genotype MTBDR plus assay. The MTBDR plus assay is designed to detect the mutations in the hotspot region of rpoB gene, katG and regulatory region of inhA gene. RESULTS: The genotype MTBDR plus assay detected 22% multidrug resistant (MDR), 2% rifampicin (RMP) monoresistant and 1% isoniazid (INH) monoresistant isolates. In 22 MDR isolates, the codons most frequently involved in RMP-associated mutations were codon 531 (54.55%), 516 (31.82%) and 526 (13.63%), and 90.90% of MDR isolates showed KatG S315T mutations and 9.1% showed inhA C-15T mutations associated with INH resistance. CONCLUSION: The new genotype MTBDR plus assay represents a rapid, reliable tool for the detection of MDR-TB, wherein results are obtained in 5 h allowing early and appropriate treatment, which is essential to cut the transmission path and reduce the spread of MDR-TB. The genotype MTBDR plus assay can readily be included in a routine laboratory work for the early diagnosis and control of MDR-TB.

Immunohistochemical expression of PTTG in brain tumors.

BACKGROUND: Pituitary tumor-transforming gene (PTTG1) has been implicated in several oncogenic processes. The aim of this study was to determine PTTG expression in brain tumors. MATERIALS AND METHODS: We investigated 88 benign and malignant brain tumors. PTTG immunoexpression was evaluated using a scale of 0 to 3. PTTG immunoexpression was nuclear and cytoplasmic in most tumors, except for medulloblastomas and hemangiopericytomas. Expression was highest in medulloblastomas. Higher grade gliomas including glioblastoma multiforme (GBM) IV and astrocytoma III had the highest level of PTTG expression, whereas low-grade gliomas had the lowest levels of PTTG expression. Hemangiopericytomas had the lowest levels of PTTG immunoreactivity, with meningiomas and schwannomas exhibiting similarly low PTTG levels. Nuclear PTTG immunoreactivity was higher than cytoplasmic in higher-grade tumors. CONCLUSION: Our results indicate that PTTG immunoexpression is higher in aggressive brain tumors including medulloblastomas, GBM IV, and astrocytoma III, whereas in more benign tumors, PTTG immunoexpression is lower.

O-6-methylguanine-DNA methyltransferase (MGMT) immunohistochemical expression in pituitary corticotroph adenomas.

BACKGROUND: O-6-methylguanine-DNA methyltransferase (MGMT) is a DNA repair enzyme that counteracts chemotherapeutic cytotoxicity of alkylating agents such as temozolomide. Low levels of MGMT expression have been shown to correlate with longer survival in glioma patients treated with temozolomide. The same is true in pituitary adenomas. OBJECTIVE: We investigated the immunohistochemical expression of MGMT in a variety of corticotroph adenoma subtypes to determine the potential utility of temozolomide as a therapeutic agent. METHODS: The tumors consisted of 40 cases of adrenocorticotropin-secreting pituitary tumors in Cushing disease, 12 Crooke cell adenomas, and 7 subtype I silent corticotroph adenomas. Staining for MGMT was assessed by light microscopy; nuclear reactivity was estimated semiquantitatively as present in < 10%, 10% to 25%, 25% to 50%, 50% to 75%, and > 75% of cells. RESULTS: Immunoexpression showed no correlation with patient age, sex, tumor size, invasiveness, or recurrence in patients with Cushing disease. Among adrenocorticotropin-secreting adenomas associated with Cushing disease, most invasive (60%) and recurrent (86%) tumors showed low MGMT immunopositivity, defined as < 25%. Most (75%) Crooke cell adenomas exhibited an MGMT immunoreactivity of ≤ 50%. All subtype I silent corticotroph adenomas showed < 10% MGMT staining. CONCLUSION: Our descriptive findings of low MGMT expression in adrenocorticotropin-producing pituitary adenomas, particularly aggressive tumors, suggest that they may be suitable candidates for temozolomide therapy.

Low immunohistochemical expression of MGMT in ACTH secreting pituitary tumors of patients with Nelson syndrome.

MGMT expression in tumors has been correlated with response to treatment with temozolomide therapy. Few medical therapies are available for Nelson syndrome, and the efficacy of such therapeutics remains limited. The aim of the present study was to assess immunohistochemical expression of MGMT in ACTH-secreting pituitary adenomas of patients with Nelson syndrome. Our material consisted of eight specimens from ACTH-secreting pituitary adenomas of patients with Nelson syndrome. Immunohistochemical staining for MGMT was performed using the streptavidin-biotin-peroxidase complex method. MGMT immunoreactivity was assessed microscopically and recorded as an estimated percentage of nuclear MGMT immunostaining (0 = none, 1=<10%, 2=<25%, 3=<50%, 4=>50%). Five of the eight specimens (65%) exhibited no MGMT immunoreactivity, with two out of eight cases (25%) showing slight MGMT staining (<10%) and one out of eight cases (12%) demonstrating moderate MGMT positivity (<25%). Patient male/female ratio was 3:5, with average patient age being 62.4 (range 57­66). Our findings suggest that temozolomide therapy may be of potential use in patients with Nelson syndrome, as these tumors express absent/low levels of MGMT. Absent or low MGMT staining in brain and other neoplasms has been shown to correlate with successful treatment with temozolomide, and recent reports of aggressive pituitary adenomas suggest similar outcomes.

Role of MGMT in tumor development, progression, diagnosis, treatment and prognosis.

O(6)-Methylguanine-DNA-methyltransferase (MGMT) is a unique protein, which both repairs O(6)-alkylguanine lesions stoichiometrically without a multi-enzymatic pathway and self-inactivates. It has recently been linked to the therapeutic success of alkylating agent chemotherapy, specifically temozolomide treatment. This drug affects the MGMT pathway to induce cell death in tumor tissue. Low levels of functional MGMT have been correlated with success of treatment, while high levels bring about failure of therapy. Expression of MGMT protein varies in normal and tumoral tissue. Furthermore, its epigenetic silencing due to promoter methylation has been linked to its lack of expression in many types of tumor, including gliomas. Great enthusiasm surrounds the utility of this protein in cancer treatment. Not only has there been success in manipulating MGMT levels to enhance alkylating agent therapy, but studies also suggest a possible role of MGMT in protecting hematopoietic cells from the myelosuppressive effects of high-dose chemotherapy. Innovative research into this protein will no doubt be rewarding. This review presents a summary of what is known about this unique protein, including its structure, function in its pathway, polymorphisms, expression in normal and tumoral tissue, relation to alkylating agent therapy, and possible future applications.