Rapid gastric emptying during pregnancy in a rat model.

BACKGROUND/AIMS: The effect of pregnancy on gastric emptying has not been established, although the predominant clinical assumption is that gastric emptying is delayed during pregnancy. We hypothesized that the rate of emptying of nutrients during pregnancy is not delayed, but is actually more rapid when compared to the non-pregnant state. The rate of gastric emptying is a major determinant of postprandial glucose elevations. MATERIALS AND METHODS: 24 female and 4 male Spague-Dawley rats were used. Female rats were randomly divided into two groups: eight rats for the control group and sixteen rats for the pregnant group. Using physiologic, non-traumatic nuclear medicine scintigraphy imaging methodology, the authors studied gastric emptying of a liquid mixed meal in pregnant rats and non-pregnant controls. Body weights, daily food ingestion, and the rate of nutrient gastric emptying were recorded in both groups at pre-pregnancy, early pregnancy, and late pregnancy. RESULTS: The authors found that pregnancy in this rat model is associated with a 37-43% increased rate of nutrient gastric emptying from the stomach in late pregnancy as compared to non-pregnant control rats and pre-pregnancy rats. CONCLUSION: These findings contradict the current clinical assumption that gastric emptying is delayed in pregnancy. If further studies confirm a more rapid gastric emptying rate during human pregnancy, new therapies aimed at slowing the rate of nutrient absorption should be considered for the prevention and treatment of pregnancy-associated nausea, gestational diabetes, and other insulin-resistant pregnancy-associated states such as pre-eclampsia.

Pancreatic Neuroendocrine Neoplasms: 2020 Update on Pathologic and Imaging Findings and Classification.

Pancreatic neuroendocrine neoplasms (panNENs) are heterogeneous neoplasms with neuroendocrine differentiation that show characteristic clinical, histomorphologic, and prognostic features; genetic alterations; and biologic behavior. Up to 10% of panNENs develop in patients with syndromes that predispose them to cancer, such as multiple endocrine neoplasia type 1, von Hippel-Lindau disease, tuberous sclerosis complex, neurofibromatosis type 1, and glucagon cell adenomatosis. PanNENs are classified as either functioning tumors, which manifest early because of clinical symptoms related to increased hormone production, or nonfunctioning tumors, which often manifest late because of mass effect. PanNENs are histopathologically classified as well-differentiated pancreatic neuroendocrine tumors (panNETs) or poorly differentiated pancreatic neuroendocrine carcinomas (panNECs) according to the 2010 World Health Organization (WHO) classification system. Recent advances in cytogenetics and molecular biology have shown substantial heterogeneity in panNECs, and a new tumor subtype, well-differentiated, high-grade panNET, has been introduced. High-grade panNETs and panNECs are two distinct entities with different pathogenesis, clinical features, imaging findings, treatment options, and prognoses. The 2017 WHO classification system and the eighth edition of the American Joint Committee on Cancer staging system include substantial changes. Multidetector CT, MRI, and endoscopic US help in anatomic localization of the primary tumor, local-regional spread, and metastases. Somatostatin receptor scintigraphy and fluorine 18-fluorodeoxyglucose PET/CT are helpful for functional and metabolic assessment. Knowledge of recent updates in the pathogenesis, classification, and staging of panNENs and familiarity with their imaging findings allow optimal patient treatment. ©RSNA, 2020.

Genetics and imaging of pheochromocytomas and paragangliomas: current update.

Pheochromocytomas (PCCs) and paragangliomas (PGLs) are rare, heterogeneous neuroendocrine neoplasms of the autonomous nervous system of chromaffin cell origin that may arise within the adrenal medulla (PCCs) or the sympathetic and parasympathetic paraganglia (PGLs). Currently referred to by the umbrella term pheochromocytomas-paragangliomas (PPGLs), these distinct tumors are characterized by specific histopathology as well as biological and clinical profiles. PPGLs may occur as part of hereditary syndromes (40% of cases) or as sporadic tumors. Currently, there are 12 different hereditary syndromes with characteristic genetic abnormalities, at least 15 well-characterized driver genes and distinct tumor metabolic pathways. Based on the Cancer Genome Atlas (TCGA) taxonomic schemata, PPGLs have been classified into three main clusters of specific genetic mutations and tumor pathways with clinical, biochemical, and prognostic implications. Imaging plays a pivotal role in the initial diagnosis, tumor characterization, evaluation of treatment response, and long-term surveillance. While MDCT and MRI help in the anatomic localization, SPECT, and PET using different radiotracers are crucial in the functional assessment of these tumors. Surgery, chemotherapy, and radiotherapy are currently available treatment options for PPGLs; antiangiogenic drugs are also being used in treating metastatic disease. Evolving knowledge regarding the different genetic abnormalities involved in the pathogenesis of PPGLs has identified potential therapeutic targets that may be utilized in the discovery of novel drugs.

Current controversies in the initial post-surgical radioactive iodine therapy for thyroid cancer: a narrative review.

Differentiated thyroid cancer (DTC) is the most common endocrine malignancy and the fifth most common cancer in women. DTC therapy requires a multimodal approach, including surgery, which is beyond the scope of this paper. However, for over 50 years, the post-operative management of the DTC post-thyroidectomy patient has included radioactive iodine (RAI) ablation and/or therapy. Before 2000, a typical RAI post-operative dose recommendation was 100 mCi for remnant ablation, 150 mCi for locoregional nodal disease, and 175-200 mCi for distant metastases. Recent recommendations have been made to decrease the dose in order to limit the perceived adverse effects of RAI including salivary gland dysfunction and inducing secondary primary malignancies. A significant controversy has thus arisen regarding the use of RAI, particularly in the management of the low-risk DTC patient. This debate includes the definition of the low-risk patient, RAI dose selection, and whether or not RAI is needed in all patients. To allow the reader to form an opinion regarding post-operative RAI therapy in DTC, a literature review of the risks and benefits is presented.

Ocular silicone oil in the lateral cerebral ventricle.

Silicone oil used for endotamponade of retinal detachment may migrate into the subarachnoid space of the brain, including the cerebral ventricles, presumably by extension through silicone oil-filled spaces in the optic nerve. Silicone oil has characteristic appearances on CT scans and MRI, which can be utilized to distinguish it from more ominous entities. We describe a case of intraventricular silicone in a patient who presented with seizures.

Positron emission tomography (PET): expanding the horizons of oncology drug development.

Positron emission tomography (PET) allows three-dimensional quantitative determination of the distribution of radioactivity permitting measurement of physiological, biochemical, and pharmacological functions at the molecular level. Until recently, no method existed to directly and noninvasively assess transport and metabolism of neoplastic agents as a function of time in various organs as well as in the tumor. Standard preclinical evaluation of potential anticancer agents entails radiolabeling the agent, usually with tritium or 14C, sacrifice experiments, and high-performance liquid chromatography (HPLC) analysis to determine the biodistribution and metabolism in animals. Radiolabeling agents with positron-emitting radionuclides allows the same information to be obtained as well as in vivo pharmacokinetic (PK) data by animal tissue and plasma sampling in combination with PET scanning. In phase I/II human studies, classic PK measurements can be coupled with imaging measurements to define an optimal dosing schedule and help formulate the design of phase III studies that are essential for drug licensure [1]. Many of the novel agents currently in development are cytostatic rather than cytotoxic and therefore, the traditional standard endpoints in phase I and II studies may no longer be relevant. The use of a specialized imaging modality that allows PK and pharmacodynamic (PD) evaluation of a drug of interest has been proposed to permit rapid and sensitive assessment of the biological effects of novel anticancer agents. The progress to date and the challenges of incorporating PET technology into oncology drug development from the preclinical to clinical setting are reviewed in this article.