بایگانی برچسب برای: endocrine

Endocrine.and.Neuroendocrine.Surgery.[taliem.ir]

Endocrine and Neuroendocrine Surgery

Surgery is the only curative treatment for primary hyperparathyroidism. Several intraoperative adjuncts have been developed to facilitate parathyroidectomy to achieve a successful outcome. These include sestamibi-SPECT scanning, cervical ultrasound, 4D-CT scans, and intraoperative parathyroid hormone monitoring. One technology often overlooked is radioguided parathyroidectomy. Radioguided parathyroidectomy is closely related to other radioguided techniques already in use for breast cancer, malignant melanoma, thyroid cancer, and colon cancer. A radiotracer is administered, which accumulates preferentially in the targeted tissue. Radioguided techniques localize specifc tissue through the use of radioactivity, theoretically minimizing dissection and decreasing overall operative time. The radiotracer utilized for radioguided parathyroidectomy is technetium 99mTc–sestamibi, which is the same compound used for preoperative parathyroid imaging. Its use is based upon the principle that enlarged, hypercellular parathyroid glands contain an increased number of mitochondria, and these mitochondria take up and retain 99mTc– sestamibi longer than surrounding tissues. Thus, the abnormal parathyroid becomes “hot” relative to surrounding structures. A hand-held gamma probe can then be utilized to detect the enlarged parathyroid gland. Once resected, the parathyroid gland can be assessed ex vivo for its radioguided counts. The counts are then used to determine if the gland is abnormal.
Principles.of.Endocrinology.and.Hormone.Action.[taliem.ir]

The Endocrine System

The endocrine system allows for the communication between the multiple cells and organs and is comprised of complex network of hormones, hormone receptors, carrier molecules, and signaling pathways. Characteristic of this system is that hormones generally act on cells that are physically separated from the secretory cell/gland, often traveling through the circulatory system to reach target tissues. Hormonal regulation is achieved by the ability of hormones to have specific biologic activity at their target tissues, important for energy production and metabolism, somatic growth and development, reproduction, and ability for the body to respond to internal and external stimuli. These complex interactions utilize controlled mechanisms of hormone synthesis and secretion and communication with other signaling molecules. Hormone deficiency or excess can each result from glandular or extraglandular processes and can be assessed clinically by laboratory testing that may include provocative testing if indicated.
Endocrine.Surgery.in.Children.[taliem.ir]

Endocrine Surgery in Children

This chapter reviews the embryology, anatomy, and physiology of the thyroid gland with special emphasis on how these topics relate to surgical conditions and surgical decision-making. First, thyroid development is reviewed since it is the essential foundation to understand thyroid anatomy. Next, the anatomy of the thyroid, its blood supply and its relationship to nearby nerves are reviewed to understand the conduct of thyroid operations and the risks and complications of those operations. Finally, the details of the thyroid gland’s principle function—the synthesis and secretion of thyroid hormones—are considered. Understanding these normal physiologic functions and their control provides insight into the diagnostic evaluation and treatment of thyroid diseases. Parathyroid gland embryology, anatomy, and function are reviewed in Chap. 5.
Neurogenin3 cooperates with Foxa2 to autoactivate its own expression[taliem.ir]

Neurogenin3 cooperates with Foxa2 to autoactivate its own expression

The transcription factor Neurogenin3 functions as a master regulator of endocrine pancreas formation, and its deficiency leads to the development of diabetes in humans and mice. In the embryonic pancreas, Neurogenin3 is transiently expressed at high levels for a narrow time window to initiate endocrine differentiation in scattered progenitor cells. The mechanisms controlling these rapid and robust changes in Neurogenin3 expression are poorly understood. In this study we characterize a Neurogenin3 positive autoregulatory loop whereby this factor may rapidly induce its own levels. We show that Neurogenin3 binds to a conserved upstream fragment of its own gene, inducing deposition of active chromatin marks and the activation of Neurog3 transcription. Additionally, we show that the broadly expressed endodermal forkhead factors Foxa1 and Foxa2 can cooperate synergistically to amplify Neurogenin3 autoregulation in vitro. However, only Foxa2 colocalizes with Neurogenin3 in pancreatic progenitors, thus indicating a primary role for this factor in regulating Neurogenin3 expression in vivo. Furthermore, in addition to decreasing Neurog3 autoregulation, inhibition of Foxa2 by RNA interference attenuates Neurogenin3-dependent activation of the endocrine developmental program in cultured duct mPAC cells. Hence, these data uncover the potential functional cooperation between the endocrine lineage-determining factor Neurogenin3 and the widespread endoderm progenitor factor Foxa2 in the implementation of the endocrine developmental program in the pancreas