Drosophila melanogaster as a function-based high-throughput screening model for antinephrolithiasis agents in kidney stone patients

Kidney stone disease involves the aggregation of stone-forming salts consequent to solute supersaturation in urine. The development of novel therapeutic agents for this predominantly metabolic and biochemical disorder have been hampered by the lack of a practical pre-clinical model amenable to drug screening. Here, Drosophila melanogaster, an emerging model for kidney stone disease research, was adapted as a high-throughput functional drug screening platform independent of the multifactorial nature of mammalian nephrolithiasis. Through functional screening, the therapeutic potential of a novel compound commonly known as arbutin that specifically binds to oxalate, a key component of kidney calculi, was identified. Through isothermal titration calorimetry, high-performance liquid chromatography and atomic force microscopy, arbutin was determined to interact with calcium and oxalate in both free and bound states, disrupting crystal lattice structure, growth and crystallization. When used to treat patient urine samples, arbutin significantly abrogated calculus formation in vivo and outperformed potassium citrate in low pH urine conditions, owing to its oxalate-centric mode of action. The discovery of this novel antilithogenic compound via D. melanogaster, independent of a mammalian model, brings greater recognition to this platform, for which metabolic features are primary outcomes, underscoring the power of D. melanogaster as a high-throughput drug screening platform in similar disorders. This is the first description of the use of D. melanogaster as the model system for a high-throughput chemical library screen. This article has an associated First Person interview with the first authors of the paper.

Comparative effectiveness of management options for patients with small renal masses: a prospective cohort study

OBJECTIVES

To explore the comparative effectiveness of partial nephrectomy (PN), radical nephrectomy (RN), ablative therapies (ablation) and active surveillance (AS) for small renal masses (SRMs; tumour diameter ≤4.0 cm) in the domains of survival, renal function and quality of life (QoL) using the prospectively maintained Delayed Intervention and Surveillance for Small Renal Masses (DISSRM) Registry.

PATIENTS AND METHODS

Estimated glomerular filtration rate (eGFR) was calculated from creatinine values to determine renal function. QoL was measured using the Short Form 12 (SF-12) questionnaire. The Kaplan-Meier method and Cox proportional hazards regression were used for survival analysis. The mixed-effects model was used for renal function and QoL analysis.

RESULTS

Of 638 patients, 231 (36.2%) chose PN, 41 (6.4%) RN, 27 (4.2%) ablation and 339 (53.1%) AS. Cancer-specific survival at 7 years was 98.8% in PN patients and 100% in all other groups. Overall survival (OS) at 7 years was 87.9%, 90.2%, 83.5% and 66.1% in PN, RN, ablation and AS patients, respectively. The OS rate was significantly worse in the AS group than other groups and likely attributable to older age and increased comorbidities. The eGFR was lowest in RN patients but comparable in all other groups. QoL was lowest in AS patients due to lower physical health scores, but mental health scores were similar in all groups.

CONCLUSIONS

With excellent oncological outcomes in all groups, nephron-sparing approaches, like PN and ablation, are preferred over RN when intervention is indicated for SRMs. AS is a reasonable option for select patients, given the comparable oncological and mental health outcomes.

A Direct Aspiration First Pass Technique for Mechanical Thrombectomy in the Setting of a Suspected Cerebral Aneurysm

There is little guidance in the literature on which thrombectomy technique is preferred in patients with acute ischemic stroke and concomitant aneurysms. Here, we present the case of a 58-year-old female with an acute ischemic stroke requiring emergent thrombectomy that was complicated by the presence of multiple, nonruptured intracranial aneurysms. Imaging confirmed an occlusion of the right middle cerebral artery and multiple nonruptured intracranial aneurysms. The patient was administered intravenous recombinant tissue plasminogen activator and the thrombus was aspirated via a direct aspiration first pass technique (ADAPT). Her symptoms improved significantly postoperatively with a consequent National Institutes of Health Stroke Scale (NIHSS) score of 0. The purpose of this case report is to give an overview and compare various techniques that can help guide the physician for safe, early revascularization while reducing recanalization time in patients having an ischemic stroke who also harbor intracranial aneurysms.

Preoperative Embolization in Tandem with Surgical Resection for Cerebral Arteriovenous Malformations

A number of treatment options are available for cerebral arteriovenous malformations (AVMs) including surgical resection, stereotactic radiosurgery, and endovascular embolization. Endovascular embolization may be used pre-operatively to reduce the size of large AVMs and thus reduce surgical complications. Here we present two patients who successfully underwent preoperative embolization of their AVMs and subsequent surgery. Preoperative embolization is a viable option for AVMs to reduce complications and improve patient outcomes.

Coil Now, Pipe Later: Two-stage Treatment for Acute Intracranial Aneurysm Rupture

The two main treatment modalities of acute intracranial aneurysm rupture are endovascular embolization and surgical clipping, each with its own benefits and risks. Endovascular treatment is associated with better outcomes compared to surgical clipping, but is also associated with high recurrence rates. We present the case of a patient with an acutely ruptured intracranial aneurysm, who subsequently underwent partial endovascular coiling acutely, and later underwent flow diversion therapy with the Pipeline Embolization Device. We also review the literature on this topic for further recommendations on treatment options of acute intracranial aneurysm rupture.

Intracranial Ischemic Infarct Due to Blunt Force Trauma in a High School Football Player

Ischemic stroke is an uncommon cause of death among teenagers and young adults; however, the etiologies differ when compared to ischemic strokes in older individuals. Large-vessel atherosclerosis and small-vessel disease causing ischemic stroke are rare for the teenage population, while cervicocerebral arterial dissections account for up to 20% of ischemic strokes. Here, we present the case of a 16-year-old male who developed internal carotid artery dissection (ICAD) after a head injury and subsequently developed ischemic stroke and seizures.

Superior Ophthalmic Vein Access for Embolization of an Indirect Carotid Cavernous Fistula

Carotid cavernous fistulae (CCF) are defined as abnormal connections between the carotid circulation and cavernous sinus. CCFs can be categorized as being direct or indirect. Direct CCFs are usually associated with trauma, whereas indirect CCFs are associated with revascularization following cavernous sinus thrombosis. We present a case of a 53-year-old male who presented with tinnitus, proptosis, conjunctivitis, and blurry vision. The patient had a recent endovascular transvenous embolization that was only partially successful, with a residual carotid cavernous fistula draining to the left superior ophthalmic vein and multiple cortical veins. A physical examination of the patient showed elevated intraocular pressures bilaterally. The patient had a high-flow indirect carotid cavernous fistula with bilateral superior ophthalmic vein (SOV) and retrograde cortical vein drainage. The SOV was punctured with a micropuncture needle and was used to successfully gain access to the cavernous sinus. Multiple coils were placed in the posterior aspect of the sinus until there was complete occlusion of venous flow. Coils were packed up to the posterior aspect of the orbit near the junction of the cavernous sinus with the SOV, and the embolization was successful. Indirect CCFs have gradual onset and are usually low-flow. Low-flow CCFs might improve with medical management.Some CCFs may cause ocular manifestations and can be symptomatically managed with prism therapy or ocular patching for diplopia, lubrication for keratopathy, or topical agents for elevated intraocular pressures. However, patients presenting with persistent ocular morbidity may require surgical or endovascular intervention.

Percutaneous Vertebral Artery Access for Embolization of Cerebrovascular Disease: Illustrative Case and Operative Technique

Intracranial arteriovenous malformations can be further complicated by the development of aneurysms, which themselves carry the risk of rupture and hemorrhage. New endovascular techniques allow for more treatment options for these lesions in the setting of arteriovenous malformations. Here we present the case of a patient who developed an aneurysm in the setting of an arteriovenous malformation and subsequently underwent successful endovascular treatment via percutaneous access of the vertebral artery along with reviewing the literature on further treatment options and developments.

To Stent or Not to Stent: A Tale of Two Occlusions

Stenting and balloon angioplasty, along with mechanical thrombectomy, have gained notability as adjunctive treatment options to intravenous tissue plasminogen activator (IV-tPA) for tandem internal carotid artery (ICA) and middle cerebral artery (MCA) occlusions (TIM occlusions). Acute ischemic strokes (AISs) secondary to TIM occlusions are associated with poor patient outcomes primarily due to low recanalization rates following intravenous thrombolysis, consequently prompting the need for more invasive recanalization efforts. Often, the treatment algorithm is based on the success of the initial angioplasty, suspected volume of completed infarction, and whether or not thrombolytics are utilized. Here, we present two patients with AIS due to TIM occlusions where two different treatment modalities were implemented for recanalization efforts. Patient 1 did not receive IV-tPA and was successfully managed with balloon angioplasty and subsequent carotid stenting followed by direct oral anticoagulant (DOAC) administration. Patient 2 received IV-tPA and balloon angioplasty without carotid stenting followed by intracranial mechanical thrombectomy. Complete recanalization was attained in both cases. Administration of IV-tPA can make subsequent carotid stenting a potentially higher-risk treatment option for patients with TIM due to potential hemorrhagic complications in the setting of requisite antiplatelet agents. Each case of AIS resulting from a TIM must be considered unique, and the use of IV thrombolytics, balloon angioplasty, carotid stenting, and mechanical thrombectomy alone or in combination must be tailored to the individual clinical parameters.

Delayed Endovascular Stenting for Severe Vertebral Artery Stenosis with Precarious Thrombosis

A significant but less recognized cause of ischemic stroke and transient ischemic attack (TIA) is atherosclerosis of the vertebrobasilar system, which accounts for 20% of ischemic strokes. Pathology of the vertebrobasilar system can present significant challenges in determining the course of treatment. Due to the complexity of the vertebrobasilar system, there is slight disagreement about how to approach patients with atherosclerotic pathology of the posterior circulation. Two such approaches are either stenting of the vertebral or basilar artery or aggressive medical management. Here, we present the case of a 63-year-old male who presented with lightheadedness, diaphoresis, two episodes of loss of consciousness, and the abrupt onset of unilateral right-sided paresis. A computed tomography angiogram (CTA) of the head and neck demonstrated complex posterior circulation vertebrobasilar vascular stenosis and occlusions. There was an unstable clot located at the junction of the vertebral and basilar arteries requiring a carefully nuanced approach. The patient was started on dual antiplatelet therapy and heparin in an effort to resolve the clot. Repeat CTA after five days revealed resolution of the unstable clot; however, the distal intradural right vertebral artery remained occluded and the left vertebral artery remained stenosed. The patient was then treated with a balloon-mounted coronary stent to eliminate the stenosis, which ultimately restored normal posterior fossa flow dynamics. This case serves as a testament to the variability and complexity of vertebrobasilar arteriopathies as well as the benefit of experienced neurointerventionalists in the successful management of these cases. 

Large Transcalvarial Meningioma: Surgical Resection Aided by Preoperative Embolization

Meningiomas are the most common type of primary brain tumors, accounting for about 30% of all brain tumors. Meningiomas originate from the meninges and can be associated with any part of the skull. Classification of meningiomas is based upon the World Health Organization (WHO) classification system and prognosis of meningiomas can be determined via histologic grading. Surgery is the gold standard treatment option for all types of meningiomas. Due to the high vascularity of some meningiomas, surgical resection can lead to certain complications including intraoperative blood loss and hemorrhage. Strategies for complication avoidance include preoperative embolization of the meningioma vascular supply. Preoperative embolization has been shown to assist in surgical resection of selected tumors and decrease intraoperative blood loss. We present a case of successful preoperative embolization for a large, complex, transcalvarial meningioma along with a literature review on this topic.

A Nonoperative Approach for Neurosurgical Management of a Sylvian Fissure Dermoid Cyst

The nonoperative management of sylvian fissure dermoid/epidermoid cysts presents a risk that is difficult to quantify. With rupture, potentially fatal complications such as chemical meningitis, hydrocephalus, fever, seizure, or meningeal irritation may occur. In this paper, we present an asymptomatic case of such a cyst with imaging evidence of prior rupture, and we review the literature for the likelihood of future complications. We use for illustration a case of a 68-year-old woman with imaging features of a sylvian fissure epithelial inclusion cyst who refused surgical intervention and review the literature for further investigation. Conservative management of our patient has not resulted in a complication in over five years, with the continued offer of surgical resection rejected by the patient. This article suggests the possibility of a safe, non-operative management of dermoid/epidermoid cysts of the sylvian fissure; however, the paucity of literature calls for larger studies yielding reliable data regarding the comparative risk of nonoperative management, including the rate of spontaneous rupture, versus the risk and complication incidence of surgical intervention.