Constraints on cosmic strings from the LIGO-Virgo gravitational-wave detectors

Cosmic strings can give rise to a large variety of interesting astrophysical phenomena. Among them, powerful bursts of gravitational waves (GWs) produced by cusps are a promising observational signature. In this Letter we present a search for GWs from cosmic string cusps in data collected by the LIGO and Virgo gravitational wave detectors between 2005 and 2010, with over 625 days of live time. We find no evidence of GW signals from cosmic strings. From this result, we derive new constraints on cosmic string parameters, which complement and improve existing limits from previous searches for a stochastic background of GWs from cosmic microwave background measurements and pulsar timing data. In particular, if the size of loops is given by the gravitational backreaction scale, we place upper limits on the string tension Gμ below 10(-8) in some regions of the cosmic string parameter space.

[Radiosurgery of the brain at the beginning of the 21st century: gamma knife with C-table]

The goal of stereotactic radiosurgery by definition is "the delivery of a single, high dose of radiation allowing the precise and complete destruction of chosen target structures containing healthy and/or pathological cells, without significant concomitant or late radiation damage to adjacent tissues". This effect is obtained by the precise focusing of multiple low energy radiation beams crossing at the target. Three different techniques can be used for radiosurgery: linear accelerator (LINAC) based radiosurgery, Bragg-peak (proton) therapy and Gamma Knife radiosurgery. Leksell Gamma Knife (LGK) is a dedicated neurosurgical device for brain surgery to destroy predetermined intracranial targets through the intact skull. It operates via the radiobiological effect of stereotactically directed, highly focused ionizing gamma-beams of 201 cobalt-60 sources. The LGK offers the best precision of target during irradiation. The mechanical accuracy is about 0.3 mm, which makes it particularly suitable for highly sophisticated neurosurgical interventions. Radiosurgery was originally developed to treat functional neurological disorders, but soon after its introduction cerebral arteriovenous malformations, and brain tumors became the main targets for the technique. Since the first LGK installation at the Sophiahemmet Hospital, Stockholm, Sweden in 1967, over 150,000 patients have already been treated in more than 150 units worldwide. The accumulated clinical experience with the LGK has established this method as the "golden standard" of radiosurgery. In December 1999, a new development, the LGK Model-C was installed at the Centre Gamma Knife, Université Libre de Bruxelles, Hôpital Académique Erasme, Brussels, Belgium. This was followed by completion of two similar units in Krefeld, Germany, and at the Presbyterian University Hospital, Pittsburgh, Pennsylvania, U.S.A. The major innovation in the design of the LGK Model-C is the robotic Automatic Positioning System, which allows computer-controlled automatic and sequential positioning of multiple shots during treatment. Thus all steps of the procedure are performed through an unbroken digital chain, from stereotactic image acquisition to the control of the irradiation sequence. This represents a significant achievement which increases the accuracy and practicality of the treatment. The technical details of the method are described, and the main treatment indications are reviewed.

Gamma surgery for intracranial metastases from renal cell carcinoma

OBJECT

The goal of this study was to evaluate the effectiveness and limitations of gamma surgery (GS) in the treatment of renal cell carcinoma that has metastasized to the brain.

METHODS

The authors performed a retrospective analysis of a consecutive series of 21 patients with 37 metastatic brain deposits from renal cell carcinoma who were treated with GS at the University of Virginia from 1990 to 1999. Clinical data were available in all patients. No patient died of progression of intracranial disease or deteriorated neurologically following GS. Eight patients clinically improved. Follow-up imaging studies were available for 23 tumors in 12 patients. Nine patients did not undergo follow-up imaging. One patient lived 17 months and succumbed to systemic disease: no brain imaging was performed in this case. Another patient refused further imaging and lived 7 months. Seven patients lived up to 4 months after the procedure; however, their physicians did not require these patients to undergo follow-up imaging examinations because of their general conditions-all had systemic progression of disease. Of the 23 tumors that were observed posttreatment, one remained unchanged in volume, 16 decreased in volume, and six disappeared. No tumor progressed at any time, and there were no radiation-induced changes on follow-up imaging an average of 21 months after GS (range 3-63 months).

CONCLUSIONS

Gamma surgery provides an alternative to surgical resection of metastatic brain deposits from renal cell carcinoma. Neurological side effects were seen in only one case; freedom from progression of disease was achieved in all cases.

[The gamma-knife in stereotaxic surgery. A new era in brain surgery]

The gamma knife is a dedicated neurosurgical equipment for brain surgery to treat predetermined intracranial normal or pathological targets through the intact skull without damaging the surrounding normal brain tissue. The operating method is called radiosurgery and it works with the biological effect of stereotactically directed, highly focused ionizing beams of 201 independent cobalt-60 sources. The treatment is a single day procedure with obvious advantages over the invasive conventional craniotomy-related surgery. It has the benefits of increased biological efficacy of the irradiation along with decreased hospital stay and side effects. The device and radiosurgery was originally developed to treat functional neurological diseases, but very soon arteriovenous malformations and tumours became the main objects for the method, and a new dimension opened in the treatment of brain pathologies with difficult access. The first gamma knife was installed in Stockholm, Sweden in 1968. Since then 85 units have been set up, and more than 70,000 patients were treated with the device worldwide. The simple management technique and high mechanical and beam accuracy made the gamma knife a reliable and effective tool for its intended purpose over 30 years now. This review summarizes the history of the device, the basic radiation physics and biology related to stereotactic radiosurgery, the description of the unit and the possibilities and limits of the treatment modality.

Third ventricle germinoma after total removal of intrasellar teratoma. Case report

A unique case is presented of a third ventricle germinoma developing 3 years after total removal of an intrasellar teratoma. The third ventricle germinoma was not considered to be a recurrence or dissemination of the mature intrasellar teratoma but to have been transformed from multicenter germ cells present in the midline of the brain with different temporal development. The relevant literature is reviewed and the problems of management of patients with germ-cell tumors are discussed.

[Persistent trigeminal artery associated with pituitary adenoma]

The authors report of a case with a pituitary macroadenoma which was associated with a persistent trigeminal artery. The tumour was removed by transsphenoidal microsurgical approach to the sella turcica. To recognise the developmental anomaly is very important to avoid complications during operation.

[Intracystic instillation of yttrium 90 silicate colloid in cystic craniopharyngioma]

The authors evaluate the intracavital treatment with 90 Yttrium silicate colloid given in 31 occasion in 26 patients of cystic craniopharyngioma. The method has been applied since 1975 in the National Institute of Neurosurgery Budapest, using practically the same method as described by Backlund et al. (1972). Although the intracavital treatment was only one among several applied forms of treatment (resection, aspiration, shunting etc.) the effectiveness of the internal irradiation is obvious. The main effect is shrinkage of the cyst. At the 26 patients there was an average of more than 70% volume decrease of the cysts. In 5 cases the cysts totally disappeared and only on two occasions the volume has remained unchanged. Neuroophtalmological data: Preoperatively visual field defects or an impairment of visual activity have been observed in 24 out of the 26 patients studied. After the 90-Yttrium treatment the ophtalmological state of the patients improved 4, worsened in 2 cases. There was no change in 18 cases. The neuroophtalmological prognosis was good only when a relatively intact optic disc was seen; when the disc was atrophic the visual deterioration proved to be irreversible. Pathologically, the fibrotic tissue is responsible for the shrinkage of the cyst.

[Surgical treatment of pituitary apoplexy]

Hypophysis apoplexy is a clinical syndrome characterized by the sudden development of headache, visual disturbance, associated with nausea, vomiting, signs of meningeal irritation and ophthalmoplegia. The symptoms are caused by the hemorrhage of a hypophyseal adenoma. This leads to the swelling of the tumor and compression of the perisellar structures. The authors processed the clinical and pathological characteristics of 28 cases occurring among the patient material of the National Institute of Neurosurgery of the past 10 years. According to the experiences the most important factor of a successful treatment of hypophyseal apoplexy is an early diagnosis and quick admittance to an institute of neurosurgery of satisfactory conditions. Thereafter a steroid hormone therapy of large doses and decompression operation performed by transnasal-transsphenoidal approach leads in the majority of cases to recovery.

Further experiences in the treatment of cystic craniopharyngeomas with yttrium 90 silicate colloid

20 patients suffering from cystic craniopharyngioma were treated with intracavitary irradiation on 25 occasions. The beta emitting radionuclide 90Y silicate colloid was instilled into the cyst or cystic part of the tumour. 17 patients on 22 occasions underwent follow-up CT and ophthalmological examinations 1 to 144 (average: 34) months after the intracavitary radioisotope therapy. An 23 occasions there was an average of 82 to 90% volume decrease of the craniopharyngioma cysts. On two occasions the volume has remained unchanged and the result of the 90Y therapy cannot be evaluated yet. The neuroophthalmological prognosis was good only when a relatively intact optic disc was seen; when the disc was atrophic the visual deterioration proved to be irreversible. Pathologically, it is the fibrotic tissue that is responsible for the shrinkage of the cyst.

Demonstration of light chain monotypia in B cell non-Hodgkin's lymphomas using unfixed freeze-dried and formalin-fixed trypsinised paraffin sections

Immunohistological light chain analysis was carried out in 55 patients with non-Hodgkin's lymphoma of B cell origin. Unfixed freeze-dried paraffin sections were used to detect surface Ig and formaldehyde-fixed trypsinised sections to detect cytoplasmic Ig. Cytoplasmic Ig was seen inconstantly in freeze-dried paraffin sections. There was complete agreement with regard to the type of light chain between freeze-dried and formaldehyde-fixed trypsinised sections. Immunohistology showed the monotypic immunoglobulin light chains in 83% of cases when unfixed freeze-dried paraffin sections were used for sIg demonstration while only in 45% of cases when formaldehyde-fixed material was used for cIg detection. The efficiency of sIg demonstration in unfixed freeze-dried paraffin sections was comparable with that based on unfixed cryostat sections or on cell suspensions when the lymphocytic lymphoma/CLL group was excluded from the evaluation. The relatively low frequency of monotypic sIg positivity obtained in this group (12/19) is due to the low density of surface Ig in CLL lymphocytes.

Sensitivity and specificity of immunohistological methods on freeze-dried paraffin sections

The application of freeze-dried paraffin sections for immunohistology eliminates many of the problems associated with the cryostat technique: the sections are thin sufficiently, the cell morphology is improved, there are no diffusion artifacts and the intensity of immunohistological reactions is superior to that obtained on cryostat sections. The preservation of antogenicity in freeze-dried paraffin sections is sufficient for the demonstration of light chain monotypia in lymphomas of B-cell origin. Indirect immunofluorescence is the method of choice for demonstrating surface Ig in freeze-dried paraffin sections.

Follicular centre cell lymphoma with alpha heavy chain disease. A histopathological and immunohistological study

The first recorded case of a small intestinal lymphoma with alpha heavy chain disease occurring in Hungary is reported. The clinical manifestation of the disease and the focal distribution of mucosal alterations do not fulfill the criteria to make a diagnosis of Mediterranean type lymphoma (MTL) but the lymphomatous segments of the jejunum show the same pathological and immunohistological characteristics as seen in MTL. One of the basic features of MTL, the so called lympho-histiocytic nodules, which have been suspected by previous authors to represent an incipient neoplastic process involving histiocytic cells, is identified as follicular centroblastic/centrocytic malignant lymphoma. The cytogenetical connection between the massive proliferation of abnormal alpha chain producing plasma cells and neoplastic germinal centres is substantiated by direct immunohistological evidence using a combined immunofluorescent and immunoperoxidase technique to detect heavy and light chains within the same cell. The sarcomatous-appearing pleomorphic cell proliferation is interpreted as an anaplastic change in the centroblastic/centrocytic lymphoma. Unequivocal evidence for an abnormal IgA production in this pleomorphic component has not been obtained. Our observations suggest that in alpha heavy chain disease the neoplastic cell population originates in the germinal centres.