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Hormon Steroid dan Asas Fisiologi Penyakit
ISBN 983-996-553-0  RM15.00
Khalid Abdul Kadir

Abstrak
Dalam jangkamasa selama 15 tahun yang lepas, fungsi hormon- hormon steroid dan peranan hormon-hormon ini mengawal homeostasis dan fungsi tubuh telah dapat difahami dengan lebih jelas. Kefahaman terkini ialah hormon steroid memberi kesan pada tisu badan melalui reseptor-reseptor tertentu. Jika ada keganjilan reseptor tersebut, akibatnya ialah penyakit ada berkaitan dengan keperluan steroid tersebut. Umpamanya, steroid testosteron memberi kesan kelelakian, tetapi pada pesakit "Testicular Feminization Syndrome" kekurangan atau keganjilan reseptor androgen menyebabkan pesakit lelaki itu menjadi wanita. Kekurangan steroid pun boleh menyebabkan penyakit seperti Addison's Disease dan kelebihan steroid pula boleh menyebabkan penyakit seperti Cushing's Disease. Untuk mengesan penyakit-penyakit tersebut, tatakaedah sendiri telah dibangunkan untuk penentuan paras hormon-hormon streroid mengguna cara asai radioreseptor, atau asai radioimum (RIA) atau asai enzim bergabung imun (ELISA). Kajian klinikal mengguna asai-asai tersebut telah berjaya mendapat beberapa penemuan baru, termasuk peningkatan hormon progesteron pada kalangan pesakit diabetes yang hamil dan tidak terkawal keadaan diabetesnya dan paras hormon steroid aldosteron yang rendah pada pesakit tirotoksikosis. Dalam keadaan tekanan stres, steroid glukokortikoid seperti kortisol dikeluarkan hingga ke paras yang tinggi. Dalam masa yang sama, hormon peptida opioid seperti endorfin juga meningkat dalam saluran darah dan cecair badan. Peranan steroid kortisol merencat kesan stres seperti hipotensi telah dikaji dan dipercayai steroid mengurangkan reseptor opioid. Kesan hormon-hormon steroid pada tisu-tisu lain seperti otot bronkus, peparu, otot ileum, limfosit, kelenjar timus, pituitari, hipotalamus dan hipokampus otak telah juga diselidik termasuk peranan steroid seks mengurangkan atau meningkatkan kesan karsinogen pada sel-sel hepar yang teraruh barah. Banyak penemuan baru telah didapati dan akan dibentangkan.

Abstract
Over the last 15 years, there has been a tremendous increase in the understanding of the mechanisms of action of steroid hormones and how they can cause disease. Steroid hormones exert their effect via specific cellular receptors in the target tissues and organs. Abnormalities in the steroid receptors will result in specific diseases depending on the type of steroid concerned. For example, testosterone will give rise to male characteristics but in patients with Testicular Feminization Syndrome, lack of a abnormalities in the androgen receptor which binds testosterone results in the patient, although genetically males, having female features externally. Deficiency of steroids will also cause disease, such as Addison's Disease, whilst excess steroids will also cause diseases such as Cushing's Syndrome. Deficiencty of cortisol with secondary increase in adrenal gland androgens results in congenital adrenal hyperplasia. To diagnose these hormonal disorders, in-house assays for measuring the levels of steroid and related hormones were set up, using radioreceptor assays, radioimmunoassays (RIA) and enzyme linked immunosorbent assays (ELISA). Clinical studies using the above assays have resulted in more accurate diagnoses, and also many new findings. Amongst others, it was found that progesterone, a hormone of pregnancy, was increased in poorly controlled pregnant diabetic patients, and the the salt controlling hormone aldosterone was very low in patients with thyrotoxicosis. During stress, there is increased secretion of the steroid cortisol from the adrenal glands. At the same time, the peptide opioid hormone `endorphin' is also secreted with resultant increased levels in blood and tissue fluids. The mechanism by which cortisol inhibits the effects of stress such as hypotension was investigated. It was found that steroids inhibit the synthesis and block the secretion of these opioids, as well as reduce the number of receptors for these steroids. The effects of various types of steroid hormones on other tissues such as the bronchus, lungs, gut, lymphocytes, thymus gland, pituitary gland, hypothalamus and gippocampus of the brain were also investigated, including the role of sex steroids in reducing or increasing the effects of carcinogens on liver cells. Many interesting new findings were obtained and will be presented, such as the effect of steroids in reducing the sensitivity of the bronchus to bronchospasm and female sex steroids in reducing the effects of carcinogens in liver cells