Unexpected requirement for ELMO1 in clearance of apoptotic germ cells in vivo.

Apoptosis and the subsequent clearance of dying cells occurs throughout development and adult life in many tissues. Failure to promptly clear apoptotic cells has been linked to many diseases. ELMO1 is an evolutionarily conserved cytoplasmic engulfment protein that functions downstream of the phosphatidylserine receptor BAI1, and, along with DOCK1 and the GTPase RAC1, promotes internalization of the dying cells. Here we report the generation of ELMO1-deficient mice, which we found to be unexpectedly viable and grossly normal. However, they had a striking testicular pathology, with disrupted seminiferous epithelium, multinucleated giant cells, uncleared apoptotic germ cells and decreased sperm output. Subsequent in vitro and in vivo analyses revealed a crucial role for ELMO1 in the phagocytic clearance of apoptotic germ cells by Sertoli cells lining the seminiferous epithelium. The engulfment receptor BAI1 and RAC1 (upstream and downstream of ELMO1, respectively) were also important for Sertoli-cell-mediated engulfment. Collectively, these findings uncover a selective requirement for ELMO1 in Sertoli-cell-mediated removal of apoptotic germ cells and make a compelling case for a relationship between engulfment and tissue homeostasis in vivo.

Intraprocedural cortisol levels in the evaluation of proper catheter placement in adrenal venous sampling.

PURPOSE: Adrenal venous sampling (AVS) is limited by technical failures that result from incorrect catheter placement or failure to catheterize the right adrenal vein. The existence of an inadequate sample may not be recognized at the time of the procedure, which can lead to nondiagnostic results. Rapid assay of serum cortisol levels allows for intraprocedural evaluation of the ratio of adrenal and peripheral cortisol concentrations and confirmation of adequate sampling. MATERIALS AND METHODS: Retrospective review was performed of 64 AVS procedures, 36 performed with digital subtraction venography (DSV) guidance alone and 28 performed with DSV guidance plus intraprocedural quantitative determinations of plasma cortisol levels. RESULTS: Technical success was achieved in 26 of 28 procedures (93%) that included intraprocedural cortisol measurements in addition to DSV. Analysis of cortisol ratios (adrenal vein cortisol level divided by inferior vena cava cortisol level) revealed technical success in 29 of 36 procedures (81%) that used DSV alone (P = .16). Procedure note indication of successful/unsuccessful sampling coincided with cortisol ratios in 28 of 28 cases (100%) that included cortisol measurement and 29 of 36 cases (81%) that did not (P = .01).The feedback provided by the measurement of cortisol levels allowed the operator to salvage three of five inadequate AVS procedures (60%), increasing the overall technical success rate from 82% to 93%. CONCLUSIONS: Intraprocedural measurement of cortisol with rapid results allows for prediction of successful adrenal vein catheterization, which may increase the technical success rate of AVS.

Fiberoptic imaging of cavernous nerves in vivo.

PURPOSE: A critical intraoperative variable for the return of tumescence following radical prostatectomy is preservation of the cavernous nerves. We developed a nontoxic technique that would allow high resolution, in vivo real-time imaging specifically of the cavernous nerves. MATERIALS AND METHODS: The cavernous nerves were labeled by injecting a fluorescent retrograde nerve tracer into the corpus cavernosum of male rats. Nerves were subsequently imaged in vivo using fiberoptic confocal fluorescent microscopy. Initial screening trials were performed to decide on a nerve tracer capable of axonal labeling, optimize injection concentration and characterize retrograde transport time. Toxicity studies included intracavernous pressure monitoring following electrical nerve stimulation, apoptotic staining of injected cavernous tissue and measurement of lipid peroxidation in nerves exposed to laser emissions during imaging. RESULTS: In vivo real-time video sequences of fluorescently labeled cavernous nerves were recorded. The screening trial indicated that the B subunit of cholera toxin conjugated to AlexaFluor 488 (Invitrogen) provided optimal imaging after 9 days of retrograde transport. Toxicity studies showed that maximal intracavernous pressure responses did not differ between labeled and unlabeled nerves (p = 0.9671). Tracer injection did not increase apoptosis in cavernous tissue and laser exposure did not increase lipid peroxidation in nerves. CONCLUSIONS: In vivo real-time imaging of the cavernous nerves is possible with no measurable toxicity, allowing the maintenance of erection. This novel imaging modality may allow urologists to identify cavernous nerves during pelvic surgery.

Venous Abnormalities Leading to Tinnitus: Imaging Evaluation.

Venous anomalies are the most commonly identified abnormality by imaging in the work-up for pulse synchronous tinnitus. Potential diagnoses include idiopathic intracranial hypertension, sigmoid sinus wall anomalies, transverse and sigmoid sinus stenosis, jugular bulb anomalies, and prominent posterior fossa emissary veins. These causes are discussed in detail along with the association between sigmoid sinus wall anomalies and idiopathic intracranial hypertension.

Prevalence of dural venous sinus stenosis and hypoplasia in a generalized population.

BACKGROUND AND PURPOSE: While recent literature has described the prevalence of transverse sinus stenosis in patients with idiopathic intracranial hypertension, tinnitus, and refractory headaches, it is unclear what the prevalence is in the general population. This study evaluates the prevalence of venous sinus stenosis and hypoplasia in the general patient population. MATERIALS AND METHODS: 355 of 600 consecutive patients who underwent CT angiography of the head met the inclusion criteria. The diameters of the dural venous sinuses were recorded. Each study was evaluated by a neuroradiologist for the presence of stenoses. Univariate and multivariate statistical analyses were performed by a statistician. RESULTS: The prevalence of unilateral transverse sinus stenosis or hypoplasia in a sample of patients representing the general population was 33%, the prevalence of bilateral transverse sinus stenosis was 5%, and the prevalence of unilateral stenosis with contralateral hypoplasia was 1%. A multivariate analysis identified arachnoid granulations as a predictor of stenosis (p<0.001). Gender trended toward significance (p=0.094). Race was not a significant predictor of stenosis (p=0.745). CONCLUSIONS: The prevalence of bilateral transverse sinus stenosis in the general population is not trivial. These data may be used as a reference for understanding the mechanistic role of stenoses in idiopathic intracranial hypertension, tinnitus, and refractory headaches.

The predictive value of magnetic resonance imaging in evaluating intracranial arteriovenous malformation obliteration after stereotactic radiosurgery.

OBJECT: The current gold standard for diagnosing arteriovenous malformation (AVM) and assessing its obliteration after stereotactic radiosurgery (SRS) is digital subtraction angiography (DSA). Recently, MRI and MR angiography (MRA) have become increasingly popular imaging modalities for the follow-up of patients with an AVM because of their convenient setup and noninvasiveness. In this study, the authors assessed the sensitivity and specificity of MRI/MRA in evaluating AVM nidus obliteration as assessed by DSA. METHODS: The authors study a consecutive series of 136 patients who underwent SRS between January 2000 and December 2012 and who underwent regular clinical examinations, several MRI studies, and at least 1 post-SRS DSA follow- up evaluation at the University of Virginia. The average follow-up time was 47.3 months (range 10.1-165.2 months). Two blinded observers were enrolled to interpret the results of MRI/MRA compared with those of DSA. The sensitivity, specificity, positive predictive value, and negative predictive value for the obliteration of AVM were reported. RESULTS: On the basis of DSA, 73 patients (53.7%) achieved final angiographic obliteration in a median of 28.8 months. The sensitivity (the probability of finding obliteration on MRI/MRA among those for whom complete obliteration was shown on DSA) was 84.9% for one observer (Observer 1) and 76.7% for the other (Observer 2). The specificity was 88.9% and 95.2%, respectively. The false-negative interpretations were significantly related to the presence of draining veins, perinidal edema on T2-weighted images, and the interval between the MRI/MRA and DSA studies. CONCLUSIONS: MRI/MRA predicted AVM obliteration after SRS in most patients and can be used in their follow-up. However, because the specificity of MRI/MRA is not perfect, DSA should still be performed to confirm AVM nidus obliteration after SRS.

A comparative analysis of 3D conformal deep inspiratory-breath hold and free-breathing intensity-modulated radiation therapy for left-sided breast cancer.

Patients undergoing radiation for left-sided breast cancer have increased rates of coronary artery disease. Free-breathing intensity-modulated radiation therapy (FB-IMRT) and 3-dimensional conformal deep inspiratory-breath hold (3D-DIBH) reduce cardiac irradiation. The purpose of this study is to compare the dose to organs at risk in FB-IMRT vs 3D-DIBH for patients with left-sided breast cancer. Ten patients with left-sided breast cancer had 2 computed tomography scans: free breathing and voluntary DIBH. Optimization of the IMRT plan was performed on the free-breathing scan using 6 noncoplanar tangential beams. The 3D-DIBH plan was optimized on the DIBH scan and used standard tangents. Mean volumes of the heart, the left anterior descending coronary artery (LAD), the total lung, and the right breast receiving 5% to 95% (5% increments) of the prescription dose were calculated. Mean volumes of the heart and the LAD were lower (p<0.05) in 3D-DIBH for volumes receiving 5% to 80% of the prescription dose for the heart and 5% for the LAD. Mean dose to the LAD and heart were lower in 3D-DIBH (p≤0.01). Mean volumes of the total lung were lower in FB-IMRT for dose levels 20% to 75% (p<0.05), but mean dose was not different. Mean volumes of the right breast were not different for any dose; however, mean dose was lower for 3D-DIBH (p = 0.04). 3D-DIBH is an alternative approach to FB-IMRT that provides a clinically equivalent treatment for patients with left-sided breast cancer while sparing organs at risk with increased ease of implementation.

Primary pericardial malignant mesothelioma and response to radiation therapy.

We report a case of a primary pericardial malignant mesothelioma. A 59-year-old male presented with episodic chest pain and dyspnea on exertion. Cardiac magnetic resonance imaging revealed a large mass in the pericardium attached to the right ventricle. Partial resection of the mass was undertaken revealing malignant mesothelioma, byphasic type. The patient was treated with chemotherapy intermittently over a period of 3 years, but his disease continued to progress. The patient was then treated with definitive radiation therapy to 64 Gy to the primary tumor using a six field 3D conformal technique. The patient remains free of progressive disease 86 months from the time of diagnosis and 50 months from the completion of his radiotherapy.

Hypoxia-inducible factor-1alpha is constitutively expressed in murine Leydig cells and regulates 3beta-hydroxysteroid dehydrogenase type 1 promoter activity.

Hypoxia-inducible factor-1alpha (HIF-1alpha) is a transcription factor that plays an essential role in oxygen homeostasis. HIF-1alpha is constitutively made in cells; however, it is ubiquitinated and degraded under normoxic conditions. Hypoxia prevents the ubiquitination of HIF-1alpha, resulting in stabilization of the protein and activation of target genes. Because of its vascular arrangement and the high metabolic demand of spermatogenesis, the testis has been described previously as functioning on the brink of hypoxia; thus, we have hypothesized that HIF-1alpha is constitutively expressed and stabilized in the testis, where it could play a role in testicular homeostasis. Western blot analysis using nuclear proteins from liver, kidney, and testis revealed the presence of HIF-1alpha only in the testis. Immunohistochemistry confirmed this result and revealed that HIF-1alpha was specifically located in interstitial Leydig cells. Electromobility shift assays employing nuclear extracts from the TM3 Leydig cell line revealed that these cells express HIF-1alpha that is capable of binding DNA under normoxic conditions. Furthermore, we found that protein levels can be increased further when the TM3 cells are cultured under hypoxic conditions. Finally, transient transfections of TM3 Leydig cells revealed that the promoter of the mouse 3beta-hydroxysteroid dehydrogenase type 1 (Hsd3b1) gene, which encodes a key enzyme in testosterone production, is a potential target of HIF-1alpha. In conclusion, HIF-1alpha is constitutively present in the Leydig cells of the murine testis, where it potentially regulates Hsd3b1 transcription, and thus male reproductive function.