Trocar assisted distal shunt tube insertion with intra-operative X-Ray confirmation.

Trocar assisted distal shunt catheter placement could be an alternative to mini-laparotomy or laporoscopy with good results in comparison to other procedures. Objects: We report our experience with trocar assisted distal shunt tube placement with intraoperative x-ray to rule-out misplacement. Methods: Patients having peritoneal distal catheter site placement for ventriculo-peritoneal or lumbo-peritoneal shunts presenting to Dr. Soliman Fakeeh Hospital, Jeddah, Saudi Arabia, over 27 months' period between October 2016 and December 2018. Results: We performed 65 procedures on 58 patients with mean age of 11 years. The main etiology was congenital hydrocephalus with and without meningeocele followed by post hemorrhagic hydrocephalus and idiopathic intracranial hypertension. Two patients developed shunt infection and one case was complicated by bowel injury. No patient showed pre-peritoneal shunt tube malposition. Conclusion: Trocar-assisted distal shunt tube insertion is a good option in shunt procedures for operation time and infection risk. However, we do not recommend usage of trocar in patients with previous abdominal surgery as adhesions may increase the risk of visceral perforation.

Optical valley separation in two-dimensional semimetals with tilted Dirac cones.

Quasiparticles emerging in crystalline materials can possess a binary flavor known as the valley quantum number which can be used as a basis to encode information in an emerging class of valleytronic devices. Here we show that two-dimensional semimetals with tilted Dirac cones in the electronic band structure exhibit spatial separation of carriers belonging to different valleys under illumination. In stark contrast to gapped Dirac materials this optovalleytronic phenomenon occurs in systems with intact inversion and time-reversal symmetry that host gapless Dirac cones in the band structure, thereby retaining the exceptional graphene-like transport properties. We thus demonstrate that optical valley separation is possible at arbitrarily low photon frequencies including the deep infrared and terahertz regimes with full gate tunability via Pauli blocking. As a specific example of our theory, we predict tunable valley separation in the proposed two-dimensional tilted Dirac cone semimetal 8-Pmmn borophene for incident infrared photons at room temperature. This work highlights the potential of two-dimensional tilted Dirac cone materials as a platform for tunable broadband optovalleytronic applications.

Spindle Cell Oncocytoma of the Anterior Pituitary Presenting with an Acute Clinical Course Due To Intraventricular Hemorrhage. A Case Report and Review of Literature.

BACKGROUND Spindle cell oncocytoma (SCO) is a rare nonfunctioning neoplasm of the adenohypophysis, and was first described in 2002. SCO has been categorized as a separate entity by the 2007 World Health Organization (WHO) and is classified as a Grade 1 tumor of the central nervous system (CNS). Review of the literature has shown that 33 cases of SCO have been reported to date, and most of them presented with a mass effect or with panhypopituitarism. However, all reported cases have described the tendency of SCO to be hypervascular on imaging and histology. We detail the first reported case of SCO to present with acute symptoms (pituitary apoplexy) and intraventricular hemorrhage, and review the literature on SCO. CASE REPORT We report the case of 56-year-old man who presented suddenly with a severe headache and an altered level of consciousness. Brain magnetic resonance imaging (MRI) showed a suprasellar mass with hemorrhagic areas within the tumor and bleeding into the lateral ventricle with chiasmal and hypothalamic compression. The patient underwent urgent craniotomy, tumor resection and placement of an external ventricular drain (EVD). Histology and immunohistochemistry supported a diagnosis of SCO. CONCLUSIONS SCO of the adenohypophysis should be considered in patients who present suddenly with symptoms of pituitary apoplexy and intraventricular hemorrhage which may worsen the prognosis.

Novel syn intramolecular pathway in base-catalyzed 1,2-elimination reactions of beta-acetoxy esters.

As part of a comprehensive investigation of electronic effects on the stereochemistry of base-catalyzed 1,2-elimination reactions, we observed a new syn intramolecular pathway in the elimination of acetic acid from beta-acetoxy esters and thioesters. 1H and 2H NMR investigation of reactions using stereospecifically labeled tert-butyl (2R*,3R*)-3-acetoxy-2,3-2H2-butanoate (1) and its (2R*,3S*) diastereomer (2) shows that 23 +/- 2% syn elimination occurs. The elimination reactions were catalyzed with KOH or (CH3)4NOH in ethanol/water under rigorously non-ion-pairing conditions. By contrast, the more sterically hindered beta-trimethylacetoxy ester produces only 6 +/- 1% syn elimination. These data strongly support an intramolecular (Ei) syn path for elimination of acetic acid, most likely through the oxyanion produced by nucleophilic attack at the carbonyl carbon of the beta-acetoxy group. The analogous thioesters, S-tert-butyl (2R*,3R*)-3-acetoxy-2,3-2H2-butanethioate (3) and its (2R*,3S*) diastereomer (4), showed 18 +/- 2% syn elimination, whereas the beta-trimethylacetoxy substrate gave 5 +/- 1% syn elimination. The more acidic thioester substrates do not produce an increased amount of syn stereoselectivity even though their elimination reactions are at the E1cb interface.