Evaluation of mediastinal masses by endoscopic ultrasound and endoscopic ultrasound-guided fine needle aspiration

OBJECTIVE: Interest has been growing in using endoscopic ultrasound and endoscopic ultrasound-guided fine needle aspiration in the evaluation of mediastinal masses. The purpose of this study was to review the spectrum of mediastinal masses encountered using endoscopic ultrasound. METHODS: We reviewed all cases of mediastinal masses examined by endoscopic ultrasound, with or without endoscopic ultrasound-guided fine needle aspiration, prospectively gathered from our electronic database from April 1995 to July 2000. RESULTS: Of 1447 upper endoscopic ultrasound examinations, 33 (2.3%) involved a mediastinal mass. Sixty-one percent of the patients were male and the average age was 65 yr. Fifty-five percent of patients had dysphagia, 48 percent experienced weight loss, and only 12 percent were totally asymptomatic. Seventy-three percent had masses by chest CT. Sixty-seven percent were ultimately found to be malignant, 21 percent were solid benign lesions, and four were cystic. Only two lesions were resected. Endoscopic ultrasound-guided fine needle aspiration was used in 76 percent of all patients. The median survival of patients with malignant lesions was only 87 days. CONCLUSIONS: Lesions of the deep mediastinum are often difficult to conclusively diagnose with nonendoscopic studies. Endoscopic ultrasound and endoscopic ultrasound-guided fine needle aspiration can easily access this region to aid in the diagnosis and management of these lesions.     

Gonadotropin-releasing hormone induces classical meiotic maturation in subpopulations of atretic preantral follicles

GnRH has been shown to induce premature meiotic maturation in preantral follicles of the immature estrogen-primed hypophysectomized rat. As these animals are free of circulating gonadotropins and contain large numbers of full-grown oocytes in preantral follicles, we have investigated this model to determine its usefulness in studying meiotic maturation. We show that a maximum dose of the agonist D-Trp6,Pro9,Net-LRF (GnRH-a) induces approximately 25% of full grown oocytes to resume meiosis within a 12-h period. This response is dose dependent (ED50 = 0.24 microgram/rat) and specific for GnRH-a. GnRH-a stimulates germinal vesicle breakdown and first polar body formation within 2 and 8 h, respectively. More than 75% of those oocytes that initiate meiotic maturation reach metaphase II by 15 h. This effect of GnRH parallels the time course of physiological meiotic maturation triggered by LH as well as that of oocytes maturing spontaneously in vitro. Oocytes in primordial and primary follicles do not respond to GnRH. The majority of affected follicles are small tertiary follicles (200-400 micron in diameter) and show signs of atresia. This atresia is not caused by GnRH-a and does not, in itself, result in meiotic maturation, but appears to confer susceptibility to GnRH-a-induced meiotic maturation. Our studies indicate that this animal model will be useful to elucidate further the mechanisms and requirements for meiotic maturation. It will also facilitate investigation of the role of atresia in the GnRH response of tertiary follicles and the issue of follicle heterogeneity within these animals.     

A specific FSH receptor in rat granulosa cells: properties of binding in vitro.

The specific binding of [125I]iodoFSH to granulosa cells collected from immature, hypophysectomized, DES-treated rats, was studied in vitro. Specific binding occurred after 5 min and reached maximum after 3 h of incubation at 37 C. Non specific binding was very low (less than 10% of the total binding). The [25I]iodoFSH remained tightly associated with the receptor at pH 7.5, but was rapidly dissociated at pH 5. Unlabeled hFSH competitively inhibited [125I]iodoFSH binding. Kinetic analyses of equilibrium binding experiments gave an apparent association constant (Ka) of 1.34 (+/- 0.31) x 10(10)M-1 [mean (+/- SE)] and a number of binding sites per cell of (NB) 1, 130 +/- 70 (mean +/- SE). Rat prolactin, wheat germ agglutinin, and concanavalin-A did not compete with [125I]iodoFSH, but hLH, hCG, and rTSH competed at doses 300- to 900-fold higher than those of hFSH. Granulosa cells isolated from adult DES-treated rats, as well as cells collected from medium and preovulatory follicles of proestrous rats, gave Ka and NB values similar to those described above. A comparative study of rabbit granulosa cells indicated a much lower binding affinity compared with those from the rat.     

Automated Algorithm for GI Spike Burst Detection and Demonstration of Efficacy in Ischemic Small Intestine

We present a novel, fully-automated gastrointestinal spike burst detection algorithm. Following pre-processing with SALPA (Wagenaar and Potter, J. Neurosci. Methods 120:113–120, 2002) and a Savitzky–Golay filter to remove unwanted low and high frequency components, candidate spike waveforms are detected utilizing the non-linear energy operator. Candidate waveforms are classified as spikes or artifact by a support vector machine. The new method achieves highly satisfactory performance with >90% sensitivity and positive prediction value. We also demonstrate an application of the new method to detect changes in spike rate and spatial propagation patterns upon induction of mesenteric ischemia in the small intestine. Spike rates were observed to transiently increase 10–20 fold for a duration of ≈600 s, relative to baseline conditions. In ischemic conditions, spike activity propagation patterns included retrograde-longitudinal wavefronts with occasional spontaneous conduction blocks, as well as self-terminating concentric-circumferential wavefronts. Longitudinal and circumferential velocities were 6.8–8.0 cm/s and 18.7 cm/s, respectively.     

Radiotherapy for benign disease; assessing the risk of radiation-induced cancer following exposure to intermediate dose radiation

Most radiotherapy (RT) involves the use of high doses (>50 Gy) to treat malignant disease. However, low to intermediate doses (approximately 3–50 Gy) can provide effective control of a number of benign conditions, ranging from inflammatory/proliferative disorders (e.g. Dupuytren''s disease, heterotopic ossification, keloid scarring, pigmented villonodular synovitis) to benign tumours (e.g. glomus tumours or juvenile nasopharyngeal angiofibromas). Current use in UK RT departments is very variable. This review identifies those benign diseases for which RT provides good control of symptoms with, for the most part, minimal side effects. However, exposure to radiation has the potential to cause a radiation-induced cancer (RIC) many years after treatment. The evidence for the magnitude of this risk comes from many disparate sources and is constrained by the small number of long-term studies in relevant clinical cohorts. This review considers the types of evidence available, i.e. theoretical models, phantom studies, epidemiological studies, long-term follow-up of cancer patients and those treated for benign disease, although many of the latter data pertain to treatments that are no longer used. Informative studies are summarized and considered in relation to the potential for development of a RIC in a range of key tissues (skin, brain etc.). Overall, the evidence suggests that the risks of cancer following RT for benign disease for currently advised protocols are small, especially in older patients. However, the balance of risk vs benefit needs to be considered in younger adults and especially if RT is being considered in adolescents or children.