Deletion of Genes Encoding Arginase Improves Use of "Heavy" Isotope-Labeled Arginine for Mass Spectrometry in Fission Yeast

<div><p>The use of “heavy” isotope-labeled arginine for stable isotope labeling by amino acids in cell culture (SILAC) mass spectrometry in the fission yeast <i>Schizosaccharomyces pombe</i> is hindered by the fact that under normal conditions, arginine is extensively catabolized <i>in vivo</i>, resulting in the appearance of “heavy”-isotope label in several other amino acids, most notably proline, but also glutamate, glutamine and lysine. This “arginine conversion problem” significantly impairs quantification of mass spectra. Previously, we developed a method to prevent arginine conversion in fission yeast SILAC, based on deletion of genes involved in arginine catabolism. Here we show that although this method is indeed successful when ¹³C₆-arginine (Arg-6) is used for labeling, it is less successful when ¹³C₆¹⁵N₄-arginine (Arg-10), a theoretically preferable label, is used. In particular, we find that with this method, “heavy”-isotope label derived from Arg-10 is observed in amino acids other than arginine, indicating metabolic conversion of Arg-10. Arg-10 conversion, which severely complicates both MS and MS/MS analysis, is further confirmed by the presence of ¹³C₅¹⁵N₂-arginine (Arg-7) in arginine-containing peptides from Arg-10-labeled cells. We describe how all of the problems associated with the use of Arg-10 can be overcome by a simple modification of our original method. We show that simultaneous deletion of the fission yeast arginase genes <i>car1+</i> and <i>aru1+</i> prevents virtually all of the arginine conversion that would otherwise result from the use of Arg-10. This solution should enable a wider use of heavy isotope-labeled amino acids in fission yeast SILAC.</p></div

Adrenal-sparing surgery: current concepts on a theme from the past

Adrenal insufficiency represents a debilitating condition which mandates lifelong steroid replacement and which is associated with significant long-term morbidity, due to either inadequate or excessive replacement. The concept of preserving healthy cortical tissue by means of partial adrenalectomy has evolved as a means of avoiding the detrimental consequences of adrenal insufficiency. The advent of advanced technology in adrenal surgery has greatly facilitated the performance of partial adrenalectomy, enabling utilization of this method in an increasing number of endocrine diseases. Hereditary pheochromocytoma, Conn’s syndrome, Cushing’s syndrome, and non-functional adrenal masses represent the current indications for partial adrenalectomy, although the specific circumstances under which adrenal-sparing surgery should be proposed are still debatable. Partial adrenalectomy can be achieved by all types of minimally invasive surgery. In the absence of randomized, prospective, controlled studies designed to compare laparoscopic, retroperitoneoscopic, and robot-assisted partial adrenalectomy, none of these techniques has as yet been proven to be the gold standard for adrenal-sparing surgery. Apart from indications for surgery, results of surgery, and different types of partial adrenalectomy, controversial topics addressed in this review article include technical aspects such as the volume of residual adrenal tissue needed, ligation of adrenal vein, and means of tumor identification. Discussion of these controversial topics represents an attempt to define the role of partial adrenalectomy in modern adrenal surgery. © 2020, Hellenic Endocrine Society

Neoadjuvant therapy for advanced pancreatic neuroendocrine tumors: An emerging treatment modality?

OBJECTIVE: Complete surgical resection is the only potentially curative treatment of localized pancreatic neuroendocrine tumors. Unfortunately, a significant proportion of these patients present with unresectable locally advanced tumors or massive metastatic disease. Recently, a new therapeutic approach for this subset of patients has emerged consisting of neoadjuvant therapy followed by surgical exploration in responders. DESIGN: We searched MEDLINE for the purpose of identifying reports regarding neoadjuvant treatment modalities for advanced pancreatic neuroendocrine tumors. RESULTS: We identified 12 studies, the vast majority of which were either case reports or small case series. Treatment options included chemotherapy, radiotherapy, peptide receptor radionuclide therapy, biological agents or various combinations of them. CONCLUSIONS: Increasing evidence supports the application of neoadjuvant protocols in advanced pancreatic neuroendocrine tumors aiming at tumor downsizing, thus rendering curative resection feasible. Given that prospective and controlled randomized clinical trials from high-volume institutions are not feasible, expert panel consensus is needed to define the optimal treatment algorithm. © 2016, Hellenic Endocrine Society. All rights reserved

Surgical treatment of potentially primary malignant adrenal tumors: An unresolved issue

Although the great majority of incidentalomas are adrenocortical adenomas, a number of them, depending on the size and radiological characteristics of the lesions, will turn out to be carcinomas. These tumors may present as suspicious on initial evaluation and potentially malignant or malignant on histology. Adrenocortical carcinoma is a rare and aggressive malignancy with evolving diagnostic and therapeutic approaches. Laparoscopic surgery has become the gold standard for surgery of benign adrenal tumors. Despite the extensive experience gained in laparoscopic adrenalectomy, controversy still remains in the management of adrenal tumors with high suspicion or evidence of malignancy. The aim of this review is to update the existing information regarding the diagnostic approach and surgical management of suspicious and potentially malignant primary adrenal tumors. The interpretation of radiologic characteristics is a cornerstone in pre-operative assessment of large adrenal masses, since open surgery remains the preferred procedure when malignancy is suspected in large tumors with possible local invasion. Despite the improvement of imaging techniques, they lack sufficient accuracy to exclude primary malignancy in tumors from 4 cm to 10 cm in size. An initial laparoscopic approach can be used in this group of patients, but early conversion to open technique is mandatory if curative resection cannot be performed. Adrenal tumors &gt;10 cm of malignant potential should be treated by the open approach from the start. Solitary adrenal metastasis from another primary malignancy is usually amenable to laparoscopic surgery. Patients with suspected adrenal cancer should be referred to tertiary centers that perform laparoscopic and open adrenal surgery with minimal morbidity and mortality. © 2015, Hellenic Endocrine Society. All rights reserved