Roy Thomas Daniel

High-throughput and sensitive immunopeptidomics platform reveals profound IFNγ-mediated remodeling of the HLA ligandome

Comprehensive knowledge of the human leukocyte antigen (HLA) class-I and class-II peptides presented to T-cells is crucial for designing innovative therapeutics against cancer and other diseases. However methodologies for their purification for mass-spectrometry analysis have been a major limitation. We designed a novel high-throughput, reproducible and sensitive method for sequential immuno-affinity purification of HLA-I and -II peptides from up to 96 samples in a plate format, suitable for both cell lines and tissues. Our methodology drastically reduces sample-handling and can be completed within five hours. We challenged our methodology by extracting HLA peptides from multiple replicates of tissues (n = 7) and cell lines (n = 21, 108 cells per replicate), which resulted in unprecedented depth, sensitivity and high reproducibility (Pearson correlations up to 0.98 and 0.97 for HLA-I and HLA-II). Because of the methods achieved sensitivity, even single measurements of peptides purified from 107 B-cells resulted in the identification of more than 1700 HLA-I and 2200 HLA-II peptides. We demonstrate the feasibility of performing drug-screening by using ovarian cancer cells treated with interferon gamma (IFNγ). Our analysis revealed an augmented presentation of chymotryptic-like and longer ligands associated with IFNγ induced changes of the antigen processing and presentation machinery. This straightforward method is applicable for basic and clinical applications.

Gangliocytomas of the sellar region: A challenging diagnosis

Gangliocytoma of the sellar region are extremely rare and often coexist with pituitary adenoma. Aim of this review is to collect all the cases reported in literature and to summarize the most recent literature evidences on the subject. A systematic review was performed through PubMed searching for articles describing gangliocytoma of the sellar region in the adult population, up to September 2015. An analysis of epidemiological data, clinical presentation, histochemical and radiological features and follow-up data was performed. A total of 55 articles were included in our analysis, reporting 129 cases of gangliocytoma of the sellar region. One case identified in our institution was also included. 85% of cases presented in association with pituitary adenomas. A female prevalence was evident. Patients presented most frequently with symptoms of hyperprolactinemia (44%) or visual disturbances (47%) when the sellar gangliocytoma was isolated, or with acromegalic manifestations (67%) when the gangliocytoma was associated with a pituitary adenoma. Immunohistochemistry showed a higher prevalence of mixed GH-PRL adenomas in association with sellar gangliocytomas, followed by GH adenomas. A purely intrasellar localization was found in about 25% of cases and a suprasellar extension in 30% of cases. A more extensive infiltration was present in about 40% of cases. A complete resection was obtained in 56% of collision lesions. The follow-up period was variable but endocrine remission was reported in 81% of cases of associated gangliocytoma and pituitary adenoma. Sellar gangliocytomas are rare lesions and an association with pituitary adenomas should always be searched. Mixed GH PRL adenomas are most frequently isolated. Collision lesions seem to have a behavior similar to isolated adenoma but a more important aggressiveness should be excluded at a molecular level. Further studies will allow advancements in clarifying the pathogenesis of this association.

Spinal epidural abscess from group A Streptococcus after varicella infection: a case report and review of the literature

IntroductionSpinal epidural abscess (SEA) is a very rare condition in pediatric patients. Varicella zoster infection could be a predisposing factor, and SEA should be suspected in patients with signs of secondary bacterial infection and even mild neurological signs.Clinical caseWe describe here a case of a 30-month-old girl with a history of remitting varicella infection, diagnosed for a lumbar epidural abscess and sacro-ileitis, secondary to group A Streptococcus (GAS).DiscussionThis is the third case of SEA from GAS reported in the literature in a pediatric population with varicella infection. We discuss here the clinical presentation and the diagnostic challenges for SEA in childhood through a review of the literature.

The length distribution and multiple specificity of naturally presented HLA-I ligands

HLA-I molecules bind short peptides and present them for recognition by CD8+ T cells. The length of HLA-I ligands typically ranges from 8 to 12 amino acids, but high variability is observed across different alleles. Here we used recent in-depth HLA peptidomics data to analyze the peptide length distribution of 85 different HLA-I alleles. Our results revealed clear clustering of HLA-I alleles with distinct peptide length distributions, which enabled us to study the structural basis of peptide length distributions and predict peptide length distributions from HLA-I sequences. We further took advantage of our collection of curated HLA peptidomics studies to investigate multiple specificity of HLA-I molecules and validated these observations with binding assays. Explicitly modeling peptide length distribution and multiple specificity improved predictions of naturally presented HLA-I ligands, as demonstrated in an independent benchmarking based on 10 newly generated HLA peptidomes (27,882 unique peptides) from meningioma samples.

Posterior reversible encephalopathy syndrome (PRES) due to neuroblastoma in a child presenting with acute hydrocephalus

Dear Editor, Posterior reversible encephalopathy syndrome (PRES) is a polyhedral entity, and its diagnosis remains challenging due to the large spectrum of clinical and radiological manifestations. Here, we report the first case of PRES directly related to neuroblastoma in a child who did not have any anticancer treatment and neither surgery and who was admitted with symptoms of acute hydrocephalus. A 2-year-old boy, with no antecedent illnesses, presented with 2 days history of headache and vomiting followed by fever, descreased consciousness (GCS 8/14), and focal motor seizures on the right side. His vital signs included blood pressure of 221/127 mmHg, pulse rate of 200/min, and oxygen saturation of 75%. The physical examination revealed a soft tissue mass in the peri-umblical region. He was sedated and intubated. The systemic hypertension was controlled with intravenous labetalol. Cerebral CT scan showed obstructive hydrocephalus due to compression of the aqueduct secondary to posterior fossa edema (Fig. 1a). The obstructive hydrocephalus was treated by the placement of an external ventricular drain (EVD). The abdominal CT scan showed a retroperitoneal enhancing mass compatible with a neuroblastoma (Fig. 1b). Cerebral MRI showed symmetrical hyperintense areas on T2-weighted sequences located in the midbrain, pons, cerebellum, and deep white matter diffusely (Fig. 1c–d). Diffusion-weighted sequences revealed restriction of signal intensity at the pons and midbrain and in the left sub-cortical parietal white matter and the splenium of the corpus callosum. These features were highly suggestive of PRES. The retroperitoneal mass was biopsied and analysis revealed a neuroblastoma. Oncologic treatment was instituted with vincristine, cyclophosphamide, and doxorubicin. The patient was weaned off progressively of the ventricular drain within 14 days. Followup MRI demonstrated the regression of the inflammatory lesions, posterior fossa edema, and the hydrocephalus (Fig. 2 a– b) confirming the diagnosis of PRES. PRES is a rare neurological condition characterized by headache, seizures, altered mental status, and visual loss associated with vasogenic edema affecting predominantly the occipital and parietal lobes [1]. Posterior fossa involvement, as in our patient, is considered an atypical PRES variant and can be occasionally associated with obstructive hydrocephalus [2]. The physiopathology of PRES remains debatable. Several factors are implicated in the physiopathology of PRES like hypertensive crises, pre-eclampsia, chronic renal failure, dialysis, autoimmune diseases, immunosuppressive, and chemotherapeutic agents [2]. In literature to date, the association of PRES and neuroblastoma has only been described in the contest of antineoplastic treatment, such as the administration of monoclonal antibodies [3], immunosoppressive agents (e.g., tacrolimus and cyclosporine-A), anticancer drugs, and surgery [4]. The mechanism by which antineoplastic treatments can predispose patients to PRES still remains uncertain [3]. In our patient, the neuroblastoma and PRES were diagnosed at the same time, before the child was started on any specific antineoplastic medications. We believe that the PRES was related to the hypertensive crisis that was seen at initial clinical presentation. The hypertensive crisis led to the * V. Aureli viviana.aureli@chuv.ch

Sphenoid mucocele with intracranial extension: An anatomical perspective

BACKGROUND Isolated sphenoid mucoceles are rare, but because of their close proximity to important vasculonervous structures, local extension may result in serious consequences. CASE DESCRIPTION A 47-year-old patient presented with headaches, meningismus, and a left homonymous lateral hemianopia. We report the atypical evolution of a posttraumatic sphenoid mucocele invading the sellar region and extending into the subarachnoid space with compression of the right optic tract, and we describe its surgical management. Further, with the aid of cadaveric specimens, we aim to analyze the precise pathway followed by the expanding collection from an anatomic perspective. CONCLUSIONS Anatomic knowledge of the sellar and parasellar regions is the key to understand the process of how sphenoid mucoceles may extend intracranially. Early endoscopic drainage with a large sphenoidotomy allows favorable outcomes and prevents serious consequences.

An exceptional presentation of pituicytoma apoplexy: A case report

Pituicytomas are a rare form of indolent neoplasms, which typically present with visual disturbance and hypopituitarism. Complete resection by a trans-sphenoidal approach is the optimal treatment. Only 80 cases have been described thus far in the current literature and the present case is the first to describe the development of pituitary apoplexy in the context of a pituicytoma. A 77-year-old man presented with fatigue and clinical signs of hypogonadism and a sellar lesion was diagnosed at cerebral magnetic resonance imaging (MRI). A watch-and-wait management was initially decided and 1 year after the initial diagnosis, he presented with a thunderclap headache with images suggestive of pituitary apoplexy. A pituitary adenoma was suspected and an endoscopic resection was decided upon the development of a visual deficit. Pathological analysis established the correct diagnosis of a pituicytoma. Pituicytomas are characterised by dense vascularisation, thus ischaemic and haemorrhagic events may be common. When confronted with a hypervascularised pituitary lesion demonstrating strong contrast enhancement and no abnormal hormonal secretion, one must maintain a high index of suspicion for a pituicytoma. A wide range of differential diagnoses should thus be considered in the context of pituitary apoplexy.

Neuroendoscopic septostomy: Indications and surgical technique

BACKGROUND Endoscopic septostomy is the treatment of choice for monolateral obstruction of the foramen of Monro. Common causes of this condition include: neoplasms, hemorrages, infections, congenital atresia, idiopathic occlusion. METHOD All the steps for performing a safe endoscopic pellucidotomy are presented. A brief discussion about the most common technical variations and their rationale is added. CONCLUSION Endoscopic pellucidotomy is a safe and effective treatment when a thorough understanding of anatomy is achieved.

Thirty-day outcome in pediatric epilepsy surgery

Dear Editor: We wish to commend Vedantam et al. [1] for their interesting paper dealing with early complications in pediatric epilepsy surgery based on a nationwide sample of 280 patients recorded in the NSQIP-P database. The different surgical procedures were classified into three categories: invasive monitoring/resection, corpus callosotomy, and hemispherectomy. The authors report a significantly higher incidence of complications (approx. 50%) and hospital readmissions after hemispherectomy. However, as underlined also by the authors, data were extracted from a mix of smalland large-volume centers with a heterogeneous practice. An important limitation of this study is the lack of distinction that has been made between the types of procedures that have been performed for hemispheric epilepsy. Considering that this was a nationwide study, the types would have included anatomical hemispherectomy (AH), hemidecortication, and functional procedures like hemispherotomy. These procedures, in fact, vary significantly with respect to their complications. This renders the interpretation of the results of Vedantam’s study [1] difficult. Several techniques of functional hemispherectomy have been described during the last 20 years for the surgical treatment of hemispheric epilepsy [2, 3], with long-term seizure control results similar to AH and a more important reduction in complication rates [4]. In particular, the peri-insular hemispherotomy (PIH) was introduced in the field of hemispheric epilepsy surgery with the primary motive of reducing complications while keeping intact the excellent seizure outcomes associated with hemispheric epilepsy surgery at the same time. The principal complications associated with AH were related to the Bcavity effect,^ namely early and delayed hydrocephalus, with associated frequent shunt dysfunctions [2]. Hemidecortication also fell out of favor due to similar complications. The procedure of a PIH is in effect based on minimal brain removal and maximal preservation of the cerebral vasculature, aiming at disconnecting the affected hemisphere through a minimal exposure. The keys to safely perform PIH are the preservation of the vascularization of the disconnected hemisphere (to avoid swelling and mass effect), the careful drainage of CSF during and after the procedure to limit the risk of remote hemorrhages, and the performance of an attentive hemostasis to limit early and delayed postoperative hydrocephalus. In our surgical series of patients treated with PIH and with a long-term follow-up, hydrocephalus was detected in only 4% of cases [4]. This data differs from the data reported by Vedantam et al. where 6% of patients treated by hemispherectomy required placement or revision of a ventriculo-peritoneal shunt at 30 days of follow-up. Analysis at longer-term follow-up periods should show higher rates of hydrocephalus. This elevated incidence of hydrocephalus within the early follow-up period are likely to be due to the inclusion of AH and hemidecortication in the analysis. The absence of differentiation among the different surgical procedures represents an important bias of the current study [1]. Furthermore, the risk factors for complications in the hemispherectomy group as identified by Vedantam et al. [1] were the extensive surgical resection and the long duration of surgery. These factors have significantly been reduced after the introduction of PIH in this field. The craniotomy for a PIH is much smaller, the manipulation of the cortex is minimal, and the majority of the work is within the white matter which is relatively much less vascularized. This significantly reduces operative times along with a significant reduction of the amount of intra and post-operative bleeding into the ventricular cavities. This translates to lesser cavity complications and a limited need of blood transfusions. Another point to be studied in a large patient cohort as in this study [1] would have been the age at surgery as determining factor for post-operative hydrocephalus. In effect, a younger age at surgery might be a factor that favors the development of delayed postoperative hydrocephalus [5]. * Giulia Cossu giulia.cossu@chuv.ch

Cannabinoid-induced alteration of motor-evoked potentials (MEPs) prior to intradural spinal tumor removal: a nasty surprise

Dear Editor: The morbidity related to intradural spinal tumor resection was reduced in the last years thanks to the recent advances in microsurgical techniques and the addition of intraoperative monitoring (IOM) [1]. Motor-evoked potentials (MEPs) and D-wave are generally coupled with continuous electromyography (EMG) to permit safe resection of spinal tumors [2]. Nevertheless, intraoperative MEPs may be altered due to previous intradural surgeries or concomitant pharmacological interactions [3]. Here, we present an interesting case of early operative MEPs alteration probably secondary to preoperative cannabinoid treatment. A 12-year-old girl with neurofibromatosis type 1 suffered from a multi metastatic, resected posterior fossa ependymoma. She was previously operated for a C3-C6 intramedullary metastasis (WHO grade III ependymoma), followed by craniospinal radiotherapy. Motor-evoked potentials were preserved on upper limbs and present but delayed on both lower limb tibialis anterior at the end of the first surgery, as well as D-wave recorded over C7-D1 spinal cord segments. Despite adjuvant treatment, she required further surgery for the progression of an intradural metastatic lesion at L1-L2 (Fig. 1a). The neurological preoperative evaluation showed no neurological deficit. Due to diffuse neuropathic pain, she was started on Sativex®, an extract of Cannabis sativa containing 3 mg of THC and 3 mg of cannabidiol per push (treatment schedule 7 nasal pushes twice a day). The patient underwent spinal tumor resection through a posterior laminoplasty under IOM with MEPs and EMG (Fig. 2). MEPs were evoked using 75-μs-long biphasic 400-Hz bursts of five stimulations with current intensity from 300 to 500 V. Triggered EMG was also recorded on the same muscles during tumor removal using 200-μs-long monophasic 1-Hz stimulation at 0.5to 1-mA intensities. Subcutaneous needle electrodes were positioned bilaterally in the vastus lateralis, tibialis anterior, gastrocnemius, abductor of the hallux muscles, and anal sphincter. Stimulation electrodes were positioned 2 cm bilaterally to the vertex (Cz) point approximatively at C1-C2 level known to stimulate lower limbs motor response. A recording electrode was also placed in the right hand as internal control. After induction and intubation under sevoflurane and rocuronium, total intravenous anesthesia (TIVA) was performed using propofol (5 mg/kg/h) and fentanyl boluses. Muscle relaxation was tested using the train of four technique (TOF). Mean arterial blood pressure was maintained more than70 mmHg and the patient’s temperature between 35.5 and 37 °C. The depth of anesthesia was monitored during the entire procedure using the Fz-Cz derivation and maintained as stable as possible. Despite the absence of neuromuscular blockade (TOF 4/4), MEP responses were absent in thigh muscles and in the muscles of the right hand at all stimulation intensities. In contrast, MEP responses were present at the abductor of the hallux bilaterally and at the external anal sphincter (Fig. 2a). * Rodolfo Maduri Rodolfo.maduri@gmail.com