Section 3 Medical Literature 第三部分 医学文献
Part 1.
Most of the endocrine glands remain active for one’s life:they are the socalled perennial1) endocrine glands,such as the pituitary gland,the thyroid and the suprarenal glands2).Others，such as the female glands，function in a limited span，and they are called transient endocrine glands.A faulty functioning of the endocrine glands(the excessive or insufficient production of hormones),along with a natural variation of the endocrine activity，causes visible psychological and physical changes，and often diseases and malfunctions.
Problems caused by a lack of a hormone are much more solvable than others:by in taking an adequate dose of the missing hormone，complications and symptoms are drastically limited.An example of this is diabetes.This is a disease which is becoming more and more diffused in industrialized countries，and is caused by a faulty functioning of the pancreas3)，which produces an amount of insulin insufficient for metabolizing the glucose present in the blood(the sugar found in food).As this substance collects in the food，it can cause many problems:besides coma(only in extreme cases)malaise,nausea,loss of appetite,dehydration of the skin，shrinking of the pupils，and acetone breath are very frequent.With time，many organs can suffer:loss of vision，the kidneys，the heart，but in particular the blood vessels and the nervous system，can alter their functionality:problems such as nephropathies，coronary diseases，gangrene of the lower limbs and alteration of the tactile sensitivity and of the motor ability are quite common.Complications can be avoided or limited with the proper cure，specific for every type of diabetes(there are 5，all with different origins and symptoms).
注释：
1）perennial［pəˈrenjəl］多年生的，常年性的
2）suprarenal gland 肾上腺
3）pancreas 胰腺
Part 2.Endocrine disorders
As a general rule,endocrine disorders are the result of either excessive secretion of a hormone or of insufficient secretion.The terminology used to describe these disorders can be confusing.Too much hormone is indicated by the prefix hyper-，while too little hormone is indicated by the prefix hypo-(from the Greek meaning ‘over’ and ‘below’，respectively).So hypercortisolism1) is the state of excess cortisol production.The suffix can also change to indicate where the excess occurs，so hypercortisolaemia is too much cortisol in the blood.Clycosuria means that there is glucose in the urine.In this case we do not need to use hypo-or hyper-,because glucose is not normally found in urine,so the fact of its presence is all that needs reporting.
The effects of either hormone excess or relative absence of hormone are exaggerations of the normal physiological effects of thr hormone and serve as a very useful illustration of endocrine physiology.Historically，endocrine disease states were used to gain an understanding of the actions of different hormones.The cases used in this book have been chosen to illustrate important points about either the biochemistry of hormone synthesis or the physiology of endocrine regulation.
Fig 8.1 an endocrine axis and negative feedback(https://www.daowen.com)
The endocrine axes described above mean that a deficiency in the final hormone of the cascade may be due to a defect at one of several points in the axis.Looking at the example of an endocrine axis shown in Figure 8.1，a defect in the thyroid failure，a problem with pituitary secretion of TSH would be called secondary thyroid failure,and a deficiency of TRH from the hypothalamus would be called teriary thyroid failure.This categorization of primary，secondary and tertiary defect is generally used in describing disorders of an endocrine axis.Another generalizable feature is that very often the symptoms of the disorder may be similar for each of the primary,secondary and tertiary causes because they all result in abnormal secretion of the final hormone in the axis.
We started the Preface to this book woth Professor John Landon’s quote about clinical endocrinology being about either too much or too little of a hormone.As you may have guessed however，endocrinology is a bit more complicated than that.While most endocrine disorders are the result of either excessive secretion of a hormone or of insufficient secretion,there are also a number of clinical conditions which result fro receptor insensitivity to a hormone.A good example of this is non-insulin dependent diabetes2)，which can be considered to be a condition of insulin resistance.In other words，although there is circulating insulin and there are insulin receptors on the target cells，it does not have the same effectiveness.
注释：
1）hypercortisolism 皮质醇增多症
2）non-insulin dependent diabetes 非胰岛素依赖型糖尿病
Part 3.
Graves’disease1) is an autoimmune disorder with B lymphocytes producing immunoglobulins2)，some of which act like TSH and termed thyroid—stimulating immunoglobulins(TSI).Other antibodies occur in Graves’ and other autoimmune diseases such as Hashimoto’s disease3).Some antibodies bind to the TSH receptor but block TSH action and lead to thyroid atrophy.Specific antibodies directed against non-TSH retro-orbital antigens localized on retro-orbital fibroblasts and muscle cells as well as antibodies directed at TSH-like antigens have been described.Retro-orbital fibroblasts appear to express a TSH receptor-like protein.The simultaneous occurrence of blocking TSH antibodies may prevent hyperthyroidism in such patients.
A genetically mediated antigen-specific defect in T lymphocyte suppressor function would allow T helper cell clones，which mistake part of the TSH receptor as a foreign antigen.Such clones would then stimulate B cells to produce anti-TSH receptor antibodies.Alternatively，thyroid cells stimulated by specific cytokines produced in response to a viral infection may express on their cell surface.Class Ⅱ molecules of specific HLA-DR types that present fragments of the TSH receptor to T lymphocytes；these then would stimulate B lymphocytes to produce TSH receptor antibodies.The autoimmune response may be promoted by poorly defined factors including the following:(1)iodine excess；for example，the incidence of Graves’disease increase after iodine supplementation in deficient areas；(2)viral or bacterial infection；for example，outbreaks of Graves’disease can follow Yersinia enterocolitica infection;(3)glucocorticoid4) withdrawal or stress；(4)parturition；(5)lithium therapy；this may modify immune responses.
注释：
1）Graves’disease格雷夫斯病，弥漫性毒性甲状腺肿
2）immunoglobulins 免疫球蛋白
3）Hashimoto’s disease 桥本氏甲状腺炎，慢性淋巴细胞性甲状腺炎
4）glucocorticoid 糖皮质激素