Section 3 Medical Literature 第三部分 医学文献
Part 1.
They are solid concretions，which form inside the lumen of the renal calyces or toward the exit of the renal pelvis:the calculi that form directly inside the ureter，are extremely rare.The calculi are a combination of inorganic salts(such as calcium，phosphorus，ammonia，etc.)or organic salt(such as the uric acid).We still do not know exactly how they form，even if in some cases we know the exact cause of their formation.One of these causes is gout1):this metabolic disease，in which there is an incorrect catabolism of the purines，with a consequent increase in the concentration of uric acid inside the blood and in the tissues(with resulting leg pain)，was very common in well-to-do families，during the 18th century，due to a diet too rich in animal proteins.In people affected by gout，the concentration of uric acid increases dramatically even in the renal secretion:as the urine concentrates in the terminal parts of the urinary pathways，this salt precipitates2)，forming the calculi.A similar mechanism intervenes in the formation of precipitating calculi caused by metabolic dysfunctions:these are the calcium3) calculi.
However，the possible(and theoretically valid)causes for the onset of the renal calculi are numerous:a poor diet or a poor vitamin intake；an imbalance in the chemical composition of the urine due to alterations of the renal processes,to infections or to a poor drainage of one or more renal pathways；endocrine complications(mostly at the expenses of the parotid glands).It is also possible that the onset of a calculus could be due to a set of joint causes:the fact that it occurs primarily in men and not women，that the onset occurs between the ages of 40 and 60 and not among young people,and that single calculi are more common than multiple ones，strengthen this hypothesis.
Usually，the presence of these foreign bodies inside the kidney causes excruciating pains4)(renal colic)and determines the presence of blood or pus in the urine，compromising the renal activity.Often they move into the ureter，causing worse pains，until they are naturally expelled.However，when the calculus is too big to get expelled naturally，or when it blocks a renal pathway，or when it causes an infection or recurring acute attacks，it is often necessary to surgically intervene.While in the past，special tools were used to grab and pull out these calculi(very painful procedures)，today we rely on endoscopic lithotripsy,on Shock Wave Extracorporeal Lithotripsy5)(ESWL)or on laser lithotripsy，all techniques which reduce a surgical intervention to a minimum.In some cases we can also rely on specific drugs:if the calculus is made up of only salts from the uric acid，a specific drug therapy can dissolve them.
注释：
1）gout 痛风（症）
2）precipitates 沉淀（物）
3）calcium 钙（离子）
4）excruciating pains 剧痛
5）shock wave extracorporeal lithotripsy 冲击波体外碎石术
Part 2.
The urinary tract is made up of the kidneys，ureters，bladder and urethra(Fig.9.1).The kidneys are normally considered to be the upper urinary tract，whereas the remaining structures may be considered to be the lower urinary tract.There are normally two kidneys，each placed retroperitoneally in the posterior abdominal wall on either side of the spine at the level of the upper lumbar vertebrae.Each kidney is 10-14 cm in length in adults and is surrounded by a fibrous capsule within perirenal fat1).The renal hilus2) on the entry for the arteries，veins and nerves，and exit for the urine drainage system.The urine formed by the kidney initially drains into the renal pelvis，which may be considered as the dilated portion of the ureter which links the kidney to the bladder.The urine in the renal pelvis is propelled by peristaltic action along the length of the ureter into the bladder.The ureters run medially and insert into the posterior base of the bladder，with the terminal end of the ureter tunneled submucosally to form the vesicoureteric junction.The normal intrinsic musculature of the bladder surrounding the oblique course of the intravesical segment of the ureter is thought to be responsible for ureteric competence during bladder emptying，thus preventing the reflux of urine from the bladder back into the ureter.Abnormalities in the development of this intravesical segment are thought to predispose to the development of vesicoureteric reflux3).
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Fig.9.1 principal anatomical components of the urinary tract
The bladder is an elastic organ consisting of connective tissue and smooth muscle known as detrusor，loosely arranged in outer longitudinal，middle circular and inner longitudinal layers.This muscle arrangement results in the bladder’s ability to empty during contraction.The dome of the bladder is covered by parietal peritoneum and is in apposition to other organs in the pelvis.The proximal urethra lies between the bladder neck and the pelvic diaphragm，and functionally consists of two sphincter mechanisms composed of both and striated muscle.In women，the pelvic diaphragm is responsible for most of the sphincter mechanism.In men，the sphincter mechanism is largely incorporated into the prostrate，with minimal sphincteric function incorporated into the bulbar and penile urethra.
Thus the kidneys and ureters are bilateral and paired，whereas the bladder and urethra are centrally placed and form a single structure.As a general principle，damage to a single kidney has minimal impact on overall renal excretory function provided the remaining kidney is normal.However，structural abnormalities of a single kidney or ureter may still predispose to infection，and may be relevant to Tommy’s presentation，as will be discussed later in the chapter.
注释：
1）perirenal fat 肾周脂肪
2）renal hilus 肾门
3）vesicoureteric reflux 膀胱输尿管回流
Part 3.
Diabetic nephropathy1)(DN)is one of the most serious complications and a major cause of death in diabetes.Frequencies of nephropathy of type 1 and type 2 diabetes mellitus2)(DM)are 30% and 20% respectively.Indeed，the excess mortality of diabetes occurs mainly in proteinuria type 1 and type 2 DM patients and results not only from end-stage renal disease(ESRD)but also from cardiovascular disease,particularly cardiovascular disease in type 2 diabetes mellitus patients.So it isn’t true that frequencies of nephropathy in type 1 DM is lower than in type 2 DM.Diabetic nephropathy is the single most common cause of ESRD in western countries and Japan，diabetic patients accounting for 30%-50% of all patients enrolled in the ESRD.Hypertension hyperperfusion and hyperfiltration in glomerulus3)，are present in early stage of DN.Further，the basement membrane(BM)in the capillary walls is thicker than normal.The dominating change is augmentation of the extracellular material.In the end，glomerular sclerosis is present.Clinical feature in early stage is the increase of glomerular filtration rate4)(GFR).Further microalbuminuria5) appear.Once overt proteinuria is present，disease will progress till renal failure.In early stage of DN,intensified blood glucose control and improvement of hypertension in glomeruli can delay or prevent the progress of DN.Prognosis of renal failure in DN patients is conspicuously worse than ones in other causes.
注释：
1）diabetic nephropathy 糖尿病肾病
2）diabetes mellitus 糖尿病
3）glomerulus 肾小球（复数形式为glomeruli）
4）glomerular filtration rate 肾小球滤过率
5）microalbuminuria 微量白蛋白尿