7,549 research outputs found
Dust in the 55 Cancri planetary system
The presence of debris disks around 1-Gyr-old main sequence stars
suggests that an appreciable amount of dust may persist even in mature
planetary systems. Here we report the detection of dust emission from 55
Cancri, a star with one, or possibly two, planetary companions detected through
radial velocity measurements. Our observations at 850m and 450m imply
a dust mass of 0.0008-0.005 Earth masses, somewhat higher than that in the the
Kuiper Belt of our solar system. The estimated temperature of the dust grains
and a simple model fit both indicate a central disk hole of at least 10 AU in
radius. Thus, the region where the planets are detected is likely to be
significantly depleted of dust. Our results suggest that far-infrared and
sub-millimeter observations are powerful tools for probing the outer regions of
extrasolar planetary systems.Comment: 8 pages and 2 figures, to appear in the Astrophysical Journa
Age as the Second Parameter in NGC 288 / NGC 362? I. Turnoff Ages: a Purely Differential Comparison
We present deep V,I photometry of the globular clusters NGC 288, NGC 362 and
NGC 1851 obtained during a single observational run under strictly homogeneous
conditions. We use the bimodal horizontal branch (HB) of NGC 1851 as a
``bridge'' to obtain the optimum relative match between the HBs of NGC 288 and
NGC 362. In this way we can effectively remove the uncertainties associated
with distance, reddening and inhomogeneities in the absolute calibration, thus
obtaining a very robust, purely differential estimate of the age difference
between these two clusters. According to the bridge test, NGC 288 is found to
be older than NGC 362 by 2 +- 1 Gyr. This result is fully confirmed also by all
classical differential age diagnostics, either based on the luminosity or color
of the main sequence turnoff point.Comment: Accepted by The Astronomical Journal - 30 pages, 6 tables, 14
figures, LaTeX, the emulateapj5.sty macro is used. Fig. 2 and Fig. 3 are
provided in reduced resolution. Full resolution versions available upon
request to the first author ([email protected]). Minor changes due to
modifications in the companion paper (Pap II
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Rare Lymphoid Malignancies of the Breast: A Report of Two Cases Illustrating Potential Diagnostic Pitfalls
Breast involvement by lymphoma is uncommon and poses challenges in diagnosis. Lymphomas may clinically, radiologically, and morphologically mimic both benign and neoplastic conditions. We describe two cases of lymphoid malignancies predominantly involving the breast, both presenting diagnostic dilemmas. The first case, ALK-negative anaplastic large-cell lymphoma involving a seroma associated with a breast implant, is an emerging clinicopathologic entity. Anaplastic large-cell lymphoma has been identified in association with breast implants and seroma formation relatively recently. The second case, hairy cell leukemia involving the breast and ipsilateral axillary sentinel lymph node, is, to our knowledge, the first reported case of hairy cell leukemia involving the breast at the time of diagnosis. While a localized bone lesion was present at time of diagnosis, bone marrow involvement was relatively mild in comparison to that seen in the breast and lymph node. In the first case, lymphoma occurred in a clinical setting where malignancy was unsuspected, highlighting the importance of careful morphologic evaluation of paucicellular samples, as well as awareness of rare clinicopathologic entities, in avoiding a misdiagnosis of a benign inflammatory infiltrate. In the second case, the lymphoid neoplasm exhibited classic morphologic and immunophenotypic features, but presented at an unusual site of involvement. Knowledge of the patient's concurrent diagnosis of hairy cell leukemia involving the bone marrow and bone helped avoid a misdiagnosis of carcinoma rather than lymphoma
Long-Term Survival after Gamma Knife Radiosurgery in a Case of Recurrent Glioblastoma Multiforme: A Case Report and Review of the Literature
The management of recurrent glioblastoma is highly challenging, and treatment outcomes remain uniformly poor. Glioblastoma is a highly infiltrative tumor, and complete surgical resection of all microscopic extensions cannot be achieved at the time of initial diagnosis, and hence local recurrence is observed in most patients. Gamma Knife radiosurgery has been used to treat these tumor recurrences for select cases and has been successful in prolonging the median survival by 8–12 months on average for select cases. We present the unique case of a 63-year-old male with multiple sequential recurrences of glioblastoma after initial standard treatment with surgery followed by concomitant external beam radiation therapy and chemotherapy (temozolomide). The patient was followed clinically as well as with surveillance MRI scans at every 2-3-month intervals. The patient underwent Gamma Knife radiosurgery three times for 3 separate tumor recurrences, and the patient survived for seven years following the initial diagnosis with this aggressive treatment. The median survival in patients with recurrent glioblastoma is usually 8–12 months after recurrence, and this unique case illustrates that aggressive local therapy can lead to long-term survivors in select situations. We advocate that each patient treatment at the time of recurrence should be tailored to each clinical situation and desire for quality of life and improved longevity
Feasibility of Multiple Repeat Gamma Knife Radiosurgeries for Trigeminal Neuralgia: A Case Report and Review of the Literature
Treatment options for trigeminal neuralgia (TN) must be customized for the individual patient, and physicians must be aware of the medical, surgical, and radiation treatment modalities to prescribe optimal treatment courses for specific patients. The following case illustrates the potential for gamma knife radiosurgery (GKRS) to be repeated multiple times for the purpose of achieving facial pain control in cases of TN that have been refractory to other medical and surgical options, as well as prior GKRS. The patient described failed to achieve pain control with initial GKRS, as well as medical and surgical treatments, but experienced significant pain relief for a period of time with a second GKRS procedure and later underwent a third procedure. Only a small subset of patients have reportedly undergone more than two GKRS for TN; thus, further research and long-term clinical followup will be valuable in determining its usefulness in specific clinical situations
Gamma knife radiosurgery for essential tremor: A Case report and review of the literature
Approximately 5 million people in America are affected by essential tremors (ET), which are classified as a type of benign movement disorder. This disease manifests as tremors that usually occur in the hands, but they may also be present in the head, face, tongue, and lower limbs. Radiofrequency thalamotomy (RF) and deep brain stimulation (DBS) are common invasive procedures with proven track records that are used to treat ET. Although these procedures have high success rates, they still put patients at risk of potential side effects and are invasive by nature. Thalamotomy using the gamma knife (GK) also produces favorable outcomes in treating tremors, without the complications associated with invasive neurosurgery procedures. This report describes the presenting symptoms and extended treatment outcome for a patient with an advanced case of ET, who received GK thalamotomy treatment six years ago. Because of this non-invasive treatment, she regained the ability to paint and live with an improved quality of life. We also discuss and review the relevant literature regarding the risks and benefits of this treatment modality. GK thalamotomy is one effective option for the treatment of ET, and due to its noninvasive nature, it has a different risk profile than neurosurgery. We suggest that GK thalamotomy should be presented as one viable treatment option to all ET patients, and should be recommended to those who would be best served by less invasive treatment techniques
Cytological and transcript analyses reveal fat and lazy persister-like bacilli in tuberculous sputum
As nonreplicating tubercle bacilli are tolerant to the cidal action of antibiotics and resistant to multiple stresses, identification of this persister-like population of tubercle bacilli in sputum presents exciting and tractable new opportunities to investigate both responses to chemotherapy and the transmission of tuberculosis
Gamma knife radiosurgery for movement disorders: a concise review of the literature
Medication is the predominant method for the management of patients with movement disorders. However, there is a fraction of patients who experience limited relief from pharmaceuticals or experience bothersome side-effects of the drugs. Deep brain stimulation (DBS) and surgical lesioning of the thalamus and basal ganglia are respected neurosurgical procedures, with valued success rates and a very low incidence of complications. Despite these positive outcomes, DBS and surgical lesioning procedures are contraindicated for some patients. Stereotactic radiosurgery with the Gamma Knife (GK) has been used as a lesioning technique for patients seeking a non-invasive treatment alternative and for medication-intolerable patients, who are unable to undergo DBS or lesioning due to comorbid medical conditions. Tremors of various etiologies are treated using GK thalamotomy, which targets the ventralis intermedius nucleus. GK thalamotomy produces favorable outcomes when treating tremors, with success rates ranging from 80-100%. In contrast, GK pallidotomy targets the internal globus pallidus, and is used in treating bradykinesia, rigidity, and dyskinesia. Although radiosurgery has proven beneficial for tremors, radiosurgical pallidotomy for bradykinesia, rigidity, and dyskinesia remains questionable, with mixed success rates in the literature that ranges from 0-87%. We suggest that GK thalamotomy be offered along with other neurosurgical approaches as a feasible treatment option to patients who prefer the non-invasive nature of radiosurgery and to those who are unqualified candidates for the neurosurgical alternatives. Also, we advise that patients with bradykinesia, rigidity, and dyskinesia be educated about the variability in the literature pertaining to GK pallidotomy before proceeding with treatment
Multimodality treatment of brain metastases: an institutional survival analysis of 275 patients
<p>Abstract</p> <p>Background</p> <p>Whole brain radiation therapy (WBRT), surgical resection, stereotactic radiosurgery (SRS), and combinations of the three modalities are used in the management of patients with metastatic brain tumors. We present the previously unreported survival outcomes of 275 patients treated for newly diagnosed brain metastases at Cancer Care Northwest and Gamma Knife of Spokane between 1998 and 2008.</p> <p>Methods</p> <p>The effects treatment regimen, age, Eastern Cooperative Oncology Group-Performance Status (ECOG-PS), primary tumor histology, number of brain metastases, and total volume of brain metastases have on patient overall survival were analyzed. Statistical analysis was performed using Kaplan-Meier survival curves, Andersen 95% confidence intervals, approximate confidence intervals for log hazard-ratios, and multivariate Cox proportional hazard models.</p> <p>Results</p> <p>The median clinical follow up time was 7.2 months. On multivariate analysis, survival statistically favored patients treated with SRS alone when compared to patients treated with WBRT alone (p < 0.001), patients treated with resection with SRS when compared to patients treated with SRS alone (p = 0.020), patients in ECOG-PS class 0 when compared to patients in ECOG-PS classes 2 (p = 0.04), 3 (p < 0.001), and 4 (p < 0.001), patients in the non-small-cell lung cancer group when compared to patients in the combined melanoma and renal-cell carcinoma group (p < 0.001), and patients with breast cancer when compared to patients with non-small-cell lung cancer (p < 0.001).</p> <p>Conclusions</p> <p>In our analysis, patients benefited from a combined modality treatment approach and physicians must consider patient age, performance status, and primary tumor histology when recommending specific treatments regimens.</p
Clinical Outcomes of Gamma Knife Radiosurgery in the Treatment of Patients with Trigeminal Neuralgia
Since its introduction by Leksell, Gamma Knife radiosurgery (GKRS) has become increasingly popular as a management approach for patients diagnosed with trigeminal neuralgia (TN). For this reason, we performed a modern review of the literature analyzing the efficacy of GKRS in the treatment of patients who suffer from TN. For patients with medically refractory forms of the condition, GKRS has proven to be an effective initial and repeat treatment option. Cumulative research suggests that patients treated a single time with GKRS exhibit similar levels of facial pain control when compared to patients treated multiple times with GKRS. However, patients treated on multiple occasions with GKRS are more likely to experience facial numbness and other facial sensory changes when compared to patients treated once with GKRS. Although numerous articles have reported MVD to be superior to GKRS in achieving facial pain relief, the findings of these comparison studies are weakened by the vast differences in patient age and comorbidities between the two studied groups and cannot be considered conclusive. Questions remain regarding optimal GKRS dosing and targeting strategies, which warrants further investigation into this controversial matter
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