Insulin-like growth factor-1 expression in reflux nephropathy

Background Reflux nephropathy (RN) is recognised as a major cause of end-stage renal failure in children and young adults. Insulin-like growth factor-1 (IGF-1), a peptide growth factor produced by collecting ducts, and its receptor, insulin-like growth factor-1 receptor (IGF-1R), are present in the glomeruli and basolateral membrane of renal proximal tubular cells. Exogenous IGF-1 has been shown to enhance proliferation and reduce apoptosis of tubular cells following renal injury.Methods We designed this study to investigate the expression of IGF-1 in RN. The kidney specimens from 15 children with RN were obtained at the time of nephrectomy. Control material included normal kidney specimens obtained from adult patients during partial nephrectomy for an incidentaloma. Single-label immunofluorescence histochemistry was carried out using polyclonal antibodies to IGF-1 and IGF-1R employing laser scanning confocal microscopy. Double-label immunofluorescence histochemistry was carried out using monoclonal antibodies to vimentin and clusterin to assess tubulointerstitial fibrosis. IGF-1 and IGF-1R gene expression were evaluated by in situ hybridisation (ISH). The TUNEL method was utilised to assess tubular apoptosis.Results In the normal kidney there was strong IGF-1 and IGF-1R immunoreactivity in the proximal tubules, whereas IGF-1 and IGF-1R immunoreactivity was markedly reduced in RN specimens. Strong IGF-1 and IGF-1R mRNA expression was observed in the proximal tubules in normal kidneys, whereas IGF-1 and IGF-1R mRNA expression was undetectable in RN. Renal tubulointerstitial expression of vimentin and clusterin was markedly increased in RN kidneys. Decreased IGF-1 and IGF-1R expression in RN strongly correlated with severity of tubular apoptosis in RN compared with controls.Conclusion These data suggest that the downregulation of IGF-1 and IGF-1R may play an important role in the pathogenesis of RN, at least in part by increasing interstitial collagen deposition and tubular apoptosis.     

Cell Proliferation in the Developing Human Kidney

In a previous study, utilizing antibodies to proliferating cell nuclear antigen (PCNA), we determined the proliferation index (PI) (percentage of PCNA-positive cells) of intrinsic renal cell populations in the normal adult and pediatric kidney. We have found that the PI in both adult and pediatric kidneys was very low (below 0.5 in all examined cell populations). In our present study, we investigated cell proliferation in the developing human kidney with an antibody to PCNA. Histologically normal kidneys were collected from 25 fetuses (spontaneous abortions and stillborns) ranging from 10 wk of gestation to term. Immature mesenchyme (blastema), immature early tubules, ampulla of ureteric bud, proximal tubules, Tamm-Horsfall protein (THP)-positive tubules, distal tubules, collecting ducts, and glomeruli were evaluated separately. The PI for each cell population was calculated. The PI of immature early tubules remains high (33–43) throughout embryonic life. The PI of blastemal cells is initially similarly high, but gradually decreases starting from the second trimester. The PI of THP-positive tubules, distal tubules, collecting ducts, and glomeruli starts out relatively high (5.9, 8.6, 6.0, and 12.4, respectively) and decreases gradually as term approaches (1.8, 1.3, 1.2, and 1.4, respectively). Interestingly, as soon as proximal tubules become differentiated (appearance of light microscopic features of proximal tubular epithelium with TP lectin positive brush border), their PI becomes very low (below 1) irrespective of the age of the kidney. This is the first quantitative study to show changes of the PI in various renal cell populations during human nephrogenesis. These changes in the PI relate to the stage of differentiation of the developing nephron segments. Received December 12, 1996; accepted April 24, 1997     

Microdissection demonstration of the lesion of the endocrine kidney in children

Microdissection of nephrons of kidneys of children showing advanced ischemic tubular atrophy, and removed for control of hypertension, demonstrates marked proximal convoluted tubular atrophy, with formation of multiple small proximal tubular diverticula. These diverticula presumably contribute to the microscopic appearance of large numbers of small tubules lined by low epithelial cells with pale or clear cytoplasm, adjacent to glomeruli in the cortices of kidneys showing ischemic tubular atrophy (endocrine kidney). Segmentation of such atrophic tubules leads to formation of blind segments (microcysts), as demonstrated in this study and by Oliver. The distinctive microscopic appearance of the endocrine kidney, a not infrequent finding in kidneys of children with chronic renal insufficiency who require nephrectomy for control of hypertension, has not hitherto been emphasized in the literature on pediatric renal disease.     

Distal renal tubular acidosis with severe hypokalaemia, probably caused by colonic H(+)-K(+)-ATPase deficiency

We describe a 21 month old male infant who presented with failure to thrive associated with severe hypokalaemia and metabolic acidosis, together with hypomagnesaemia. Evaluation revealed marked renal and probable faecal potassium wasting, distal renal tubular acidosis, mild urinary magnesium wasting, and a normal gastric pH (gastric H(+)-K(+)-ATPase). Hypokalaemic forms of metabolic acidosis, such as diabetic ketoacidosis and proximal renal tubular acidosis were ruled out from the clinical picture. The hypokalaemia of distal renal tubular acidosis usually improves with alkali therapy, but this was not observed: despite correction of acidosis with 5 mmol/kg potassium citrate per day, an additional 5 mmol/kg potassium chloride was required to bring serum potassium to 3.5 mmol/l. At 3 years of age potassium was provided in the absence of potential alkali and acidosis ensued; serum bicarbonate fell to 10 mmol/l. Although a specific genetic analysis is not yet possible, the abnormalities are consistent with a novel form of distal renal tubular acidosis. The pathophysiology probably does not stem from defects in the vacuolar H(+)-ATPase but more likely from deficient activity of the colonic isoform of H(+)-K(+)-ATPase that is resident in the medullary collecting duct and mediates potassium absorption and proton secretion.     

Distal renal tubular acidosis with severe hypokalaemia, probably caused by colonic H(+)-K(+)-ATPase deficiency.

We describe a 21 month old male infant who presented with failure to thrive associated with severe hypokalaemia and metabolic acidosis, together with hypomagnesaemia. Evaluation revealed marked renal and probable faecal potassium wasting, distal renal tubular acidosis, mild urinary magnesium wasting, and a normal gastric pH (gastric H(+)-K(+)-ATPase). Hypokalaemic forms of metabolic acidosis, such as diabetic ketoacidosis and proximal renal tubular acidosis were ruled out from the clinical picture. The hypokalaemia of distal renal tubular acidosis usually improves with alkali therapy, but this was not observed: despite correction of acidosis with 5 mmol/kg potassium citrate per day, an additional 5 mmol/kg potassium chloride was required to bring serum potassium to 3.5 mmol/l. At 3 years of age potassium was provided in the absence of potential alkali and acidosis ensued; serum bicarbonate fell to 10 mmol/l. Although a specific genetic analysis is not yet possible, the abnormalities are consistent with a novel form of distal renal tubular acidosis. The pathophysiology probably does not stem from defects in the vacuolar H(+)-ATPase but more likely from deficient activity of the colonic isoform of H(+)-K(+)-ATPase that is resident in the medullary collecting duct and mediates potassium absorption and proton secretion.     

Microdissection Demonstration of the Lesion of the Endocrine Kidney in Children

Microdissection of nephrons of kidneys of children showing advanced ischemic tubular atrophy, and removed for control of hypertension, demonstrates marked proximal convoluted tubular atrophy, with formation of multiple small proximal tubular diverticula. These diverticula presumably contribute to the microscopic appearance of large numbers of small tubules lined by low epithelial cells with pale or clear cytoplasm, adjacent to glomeruli in the cortices of kidneys showing ischemic tubular atrophy (endocrine kidney). Segmentation of such atrophic tubules leads to formation of blind segments (microcysts), as demonstrated in this study and by Oliver.⁸ The distinctive microscopic appearance of the endocrine kidney, a not infrequent finding in kidneys of children with chronic renal insufficiency who require nephrectomy for control of hypertension, has not hitherto been emphasized in the literature on pediatric renal disease.     

成纤维细胞生长因子受体4在人发育肾和病理肾中的表达

目的：观察成纤维细胞生长因子受体4(Fibroblast growth factor receptor4, FGFR4) 在人发育肾组织和儿童常见肾脏疾病中的表达,研究成纤维细胞生长因子（Fibroblast growth factor, FGF）及其受体(FGFR4)在人发育肾和病理肾中的作用,为肾脏病理发生机制研究提供新思路。方法：采用免疫组化法分析FGFR4在18例8~34周龄胎儿肾组织和82例儿科常见肾脏疾病,包括原发性肾病综合征、急性肾炎、紫癜性肾炎、单纯性血尿的表达,并作与肾脏病理积分的相关性分析。结果：①肾发生带内FGFR4表达微弱,肾囊泡和S 型小体的上支和中间支,即原始肾小管上皮细胞部位有微弱表达,间充质、压缩间充质细胞未见表达,输尿管芽及其末端壶腹和C-期足细胞表达不明显。M-期肾小球和近端小管无阳性细胞染色,远端小管和集合管表达较为明显。②所有病理切片均存在FGFR4不同程度阳性的表达,较正常对照组明显增加,其中肾小球区表达微弱,主要在足细胞部位;肾小管区表达较为强烈,主要部位在远端小管,表达密集部位的小管结构明显异常,表现为细胞萎缩、管腔扩大,尤其部分近端小管更为明显。③原发性肾病综合征与其他3种肾脏疾病的各部位FGFR4表达均未见明显差异(P>0.05)。肾近端小管和远端小管各病理类型间FGFR4表达差异无显著性,足细胞FGFR4表达在紫癜性肾炎组明显高于其他各病理类型组( P<0.05)。④相关性分析发现,近端小管FGFR4表达与肾小管病理积分呈正相关,其他各部位表达均与病理积分呈负相关（均P<0.05）。结论：FGF-FGFR4对早期肾单位的形成可能不起关键作用,而是与其后期较成熟阶段肾小管和集合管发育的调控有关。FGFR4可能参与儿童原发性肾病综合征、急性肾炎、紫癜性肾炎、单纯性血尿的病理发生,表达程度增多与肾脏病理损害有一定关系,表达适度增多有利于足细胞和肾小管损伤修复,过表达则可能加重病理损害。［中国当代儿科杂志,2007,9（2）：133-138］     

The role of nitric oxide in reflux nephropathy

Reflux nephropathy (RN) is recognized as a major cause of end-stage renal failure in children and young adults. Inhibition of nitric oxide (NO) exacerbates and enhanced production ameliorates tubulointerstitial fibrosis (TIF) in experimental obstructive uropathy. NO is synthesised by NO synthase (NOS), three distinct isoforms of which have been identified: inducible (iNOS), endothelial (eNOS), and neuronal (nNOS). It has been reported that iNOS induces immunologic injury to glomerular cells and enhances accumulation of extracellular matrix in the glomerulus and tubulointerstitial space. Furthermore, it has been suggested that nNOS and eNOS have beneficial effects in ameliorating TIF. We investigated the expression of different isoforms of NOS in severe refluxing kidneys in order to further understand the pathogenesis of RN in kidney specimens from nine children with severe RN obtained at nephrectomy. Control material included normal kidney specimens from three adult patients undergoing partial nephrectomy for small kidney tumours. Histochemistry for NO was performed using nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase. Single-label immunofluorescence histochemistry was carried out using polyclonal antibodies to nNOS, iNOS, eNOS, and transforming growth factor (TGF)-beta 1 employing laser-scanning confocal microscopy. The TUNEL method was used to assess tubular apoptosis. Strong NADPH staining was observed in the proximal tubules of RN kidneys compared to controls, where there was weak staining. Control kidneys demonstrated weak immunoreactivity for iNOS in the proximal tubules and a lack of immunoreactivity for nNOS and eNOS. RN kidneys demonstrated strong immunoreactivity for nNOS in the tubulointerstitial space, for eNOS in the glomerulus, and for iNOS in the glomerulus and proximal tubules. Strong immunoreactivity for TGF beta 1 was seen in the glomerulus and proximal tubules identical to iNOS. Increased immunoreactivity for iNOS and TGF-beta 1 strongly correlated with the severity of apoptosis in RN. Our data demonstrate that NO derived from nNOS, iNOS, and eNOS is strongly expressed in RN. The selective shunting of NO via iNOS may induce renal fibrosis in RN. The upregulation of nNOS and eNOS in RN appears to be a compensatory mechanism of ameliorating TIF.     

HSP70在缺血再灌注大鼠肾脏中的表达及意义

目的观察大鼠肾脏缺血及缺血再灌注(I/R)诱导热休克蛋白70(HSP70)的表达及意义。方法制作大鼠肾脏缺血及I/R模型,缺血组于缺血5、15和30min,I/R组于再灌注2、5、8、24、48、72h不同时间摘取肾脏,采用免疫组化方法检测肾脏HSP70的表达,同时采用HE染色,观察肾脏病理改变。结果在缺血组各时间点肾脏HSP70的表达无明显差异(P>0·05);肾脏I/R后,随时间延长,HSP70表达明显增强(P<0·05);肾脏病理显示,缺血时肾组织呈现局灶性及弥散性血管周围水肿,I/R后随时间延长肾脏损伤加重,损伤部位主要在肾小管,表现为空泡样变、小管萎缩、上皮细胞脱落及肾小球囊腔扩张等。结论HSP70在I/R后表达增强,但肾脏仍损伤严重,提示HSP70在肾脏I/R过程中没有起到主要的保护作用。     

Renal Tubular Apoptosis in Twin-to-Twin Transfusion Syndrome

Twin-to-twin transfusion syndrome (TTTS) is caused by uneven shunting of blood between monochorionic twins, resulting in polycythemia in the recipient twin and growth restriction, anemia, and oliguria in the donor twin. Recent reports have described loss of proximal convoluted tubules in the kidneys of TTTS donor twins. In order to elucidate the pathogenesis of tubular deficiency in TTTS, we have reviewed the renal pathology in 25 twin pairs with autopsy-proven TTTS. Loss of differentiated proximal tubules, associated with atrophy of medullary tubules, was identified in 12/25 donor twins. In seven of these cases (all > 23-wk gestational age), the kidneys showed diffuse or partial tubular atrophy without evidence of cell death, similar to previously reported patterns. In five cases (all between 18- and 22-wk gestation), proximal and medullary tubules showed active injury characterized by markedly increased apoptosis, cell detachment, and intraluminal cell debris associated with calcifications. Tubular apoptosis tended to be more prevalent in donor fetuses with greater inter-twin body weight discordance, consistent with a more severe degree of TTTS. These results extend the spectrum of tubular alterations in TTTS to include an early stage of active apoptotic injury. The temporal distribution of injury patterns suggests that apoptotic injury of proximal and medullary tubules may be a precursor to partial or diffuse tubular atrophy. We speculate that the risk for development of tubular apoptosis in TTTS depends on the severity and timing of the hemodynamic imbalance, whereby early mid-trimester fetuses may be more vulnerable.     

Glomerular proteinuria induces heme oxygenase-1 gene expression within renal epithelial cells

To clarify the patterns of heme oxygenase-1 (HO-1) production within the human kidney, we examined HO-1 mRNA expression in various renal diseases and compared the patterns with those of HO-1 protein expression and these data with the clinical features. The degrees of hematuria and proteinuria and the levels of urinary N-acetyl-beta-D-glucosaminidase (NAG), beta(2)-microglobulin (beta(2)-mg), and creatinine were determined. In situ hybridization and immunohistochemical studies were performed to evaluate HO-1 expression. HO-1 mRNA was detectable within tubular, glomerular, and Bowman's epithelial cells and infiltrating macrophages. Within the proximal tubuli, there was a correlation between expression of HO-1 protein and mRNA, but the intensity of HO-1 mRNA expression was much less than expected from the levels of protein. In contrast, both HO-1 protein and mRNA were expressed at significant levels within distal tubuli. Furthermore, there was no correlation with both expressions within distal tubuli. HO-1 mRNA expression within tubular, glomerular, and Bowman's epithelial cells tended to be more intense with greater degrees of proteinuria. However, there was little correlation between the intensity of HO-1 mRNA expression and the degree of hematuria, NAG, and beta(2)-mg. HO-1 plays important roles in maintaining renal functions by protecting renal epithelial cells from glomerular proteinuria, which can become a cause of oxidative stress. Furthermore, from the different expression pattern of HO-1 gene between within the proximal tubuli and within the distal tubuli, renal expression of HO-1 is regulated in a segment-specific manner, with HO-1 thereby playing distinct roles in different segments of the nephron to maintain renal functions.     

Effects of maternal subtotal nephrectomy on the development of the fetal kidney: A morphometric study

The present study was designed to explore if maternal subtotal (5/6) nephrectomy affects the development of fetal rat kidneys using morphometric methods and examining whether there are any apoptotic changes in the fetal kidney. To generate 5/6 nephrectomized model rats, animals underwent 2/3 left nephrectomy on gestation day (GD) 5 and total right nephrectomy on GD 12. The fetal kidneys were examined on GDs 16 and 22. A significant decrease in fetal body weight resulting from maternal 5/6 nephrectomy was observed on GD 16, and a significant decrease in fetal renal weight and fetal body weight caused by maternal nephrectomy was observed on GD 22. Maternal 5/6 nephrectomy induced a significant increase in glomerular number, proximal tubular length, and total proximal tubular volume of fetuses on GD 22. Maternal 5/6 nephrectomy resulted in an increase in the number of apoptotic cells in the metanephric mesenchyme of the kidney on GD 16, and in the collecting tubules on GD 22. These findings suggest that maternal 5/6 nephrectomy stimulates the development of the fetal kidney while suppressing fetal growth.     

Gestational changes in renal responsiveness to cortisol in the ovine fetus

The ontogenetic renal responsiveness to exogenous cortisol was examined in the chronically cannulated ovine fetus. The contribution of effects at proximal and distal tubule of the kidney were studied also. Cortisol (81.5 micrograms/h) was infused into immature ovine fetuses (mean gestational age -113.9 days) on five occasions and increased blood cortisol from 0.8 +/- 0.5 to 21.3 +/- 6.2 nmol/liter. This dose of cortisol produced a highly significant diuresis and natriuresis, in part due to an increase in GFR and in part due to a significant decrease in proximal tubular reabsorption of sodium. Cortisol (107.2 +/- 4.7 micrograms/h) was infused into mature fetuses (mean gestational age 133.4 days) and produced an increase in blood cortisol concentration from 11.4 +/- 5.6 to 33.7 +/- 6.8 nmol/liter. No natriuresis or diuresis was seen in the mature fetuses. Cortisol caused a significant depression of proximal tubular sodium reabsorption in mature fetuses, but this extra load was reabsorbed in the distal tubule in these fetuses. The inability of the premature or very low birth wt baby to maintain normal sodium balance on a standard salt intake may be due, at least in part, to a "fetal" renal response to the high plasma cortisol concentrations found in such babies. As the kidney matures it becomes capable of increasing distal tubular sodium reabsorption to compensate for any increased distal tubular fluid delivery.     

Increased expression of fibroblast growth factors in segmental renal dysplasia

 Renal dysplasia (RD) is a disorganized development of renal parenchyma that results in a deficit of functional renal tissue. Dysplastic renal tissue is characterized by primitive tubular epithelium associated with increased mesenchyme. Several polypeptide growth factors (GF), which interact with target cells through a cell-surface membrane receptor, have been reported to be involved in the regulation of urothelial cell growth in normal and neoplastic states. Recent reports have demonstrated that basic fibroblast GF (bFGF, FGF-2) is a mitogen for renal proximal-tubule epithelial cells. Keratinocyte GF (KGF, FGF-7), which belongs to the FGF family, is believed to be a paracrine mediator of epithelial-cell proliferation. The aim of this study was to investigate the immunoactivity of bFGF and KGF and their receptors in the dysplastic kidney in order to further understand the pathogenesis of RD. Specimens of dysplastic upper poles of duplex kidneys were surgically resected from ten patients. Age-matched control material included six kidney specimens taken at autopsy from patients without evidence of urologic disease. Indirect immunohistochemistry was performed using the Strept-ABC method with four antibodies: bFGF, KGF, FGF receptor (flg), and KGF receptor (bek). There was absent or weak bFGF, KGF, flg, and bek immunoreactivity in normal kidneys. In the dysplastic kidneys, there was strong immunoreactivity of bFGF and KGF and their receptors in the epithelium of primitive tubules. Increased local expression of bFGF and KGF and their receptors in primitive tubules suggests that bFGF and KGF may play an important role in the development of RD.     

Labeled Lectin Studies of Renal Tubular Dysgenesis and Renal Tubular Atrophy of Postnatal Renal Ischemia and end-Stage Kidney Disease

Renal tubular dysgenesis (RTD), with hypoplasia especially of renal proximal convoluted tubules and clinical neonatal anuria or oliguria, has been reported as a congenital familial (autosomal recessive) disease, variably with features of oligohydramnios, Potter syndrome, or pulmonary hypoplasia. A similar tubular lesion due to antenatal tubular atrophy has been reported for conjoined twins with twin-twin transfusion syndrome or acardia and in infants of mothers given antihypertensive agents, including angiotensin-converting enzyme (ACE) inhibitors, during pregnancy, and it has been seen as a unilateral lesion in young infants with renal artery stenosis due to arteritis or medial arterial calcinosis. The renal tubular changes in RTD are very like those of the “endocrine kidney” in experimental animals and resemble those of the renal tubular atrophy of end-stage kidney diseases such as glomerulonephritis, tubulointerstitial kidney disease, obstructive uropathy/pyelonephritis, graft rejection of transplanted kidneys, or the renal parenchymal changes seen with protracted dialysis therapy. Labeled lectins that differentially mark proximal convoluted, distal convoluted and connecting, and collecting tubules showed no distinctive differences in stainingpatterns of the hypoplastic renal tubules of infants and children with RTD, postnatal renal artery obstruction, or the various types of end-stage renal disease with the lectins used (PNA, GSL1, UEA, and LTA). The findings suggest that the renal tubular changes in some if not all the conditions studied are the result of renal ischemia. The reported familial RTD with hypernephronic nephromegaly may be a specific disorder, but other forms could reflect renal ischemia acquired in utero or in early or later postnatal life.     

Antioxidant defense mechanisms of endothelial cells and renal tubular epithelial cells in vitro: role of the glutathione redox cycle and catalase.

We recently demonstrated that endothelial cells are more susceptible than renal tubular epithelial cells to oxidant injury and that renal tubular epithelial cells with proximal tubular characteristics including porcine proximal tubular epithelial cells, opossum kidney proximal tubular epithelial cells, and normal human kidney cortical epithelial cells are more susceptible to oxidant injury than the distal nephron-derived Madin Darby canine kidney cell line. To determine the basis of this differential response, we evaluated several antioxidant defenses in the five cell lines. Glutathione levels were not significantly different among the five cell lines, but catalase and glutathione reductase levels were significantly (p less than 0.01) lower in endothelial cells compared to all renal tubular epithelial cells. Among renal tubular epithelial cells, Madin Darby canine kidney cells had significantly (p less than 0.05) higher glutathione peroxidase activity. To further evaluate the role of antioxidant defenses in limiting oxidant injury, we determined two responses to oxidant injury (ATP depletion and 51Cr release) when glutathione was depleted with buthionine sulfoxamine and when catalase was inhibited with aminotriazole. Oxidant-induced ATP depletion was accentuated when catalase was inhibited as well as when glutathione was depleted with buthionine sulfoxamine. In contrast, inhibition of catalase had little or no effect on 51Cr release, whereas glutathione depletion resulted in accentuated 51Cr release. We conclude that the increased susceptibility of endothelial cells to oxidant injury as compared with epithelial cells is associated with lower antioxidant defenses. Disruption of the glutathione redox cycle results in accentuated ATP depletion and lytic injury, whereas inhibition of catalase results in accentuated ATP depletion with little effect on lytic injury.(ABSTRACT TRUNCATED AT 250 WORDS)     

Erythrocyte sodium-potassium transport in cystic fibrosis.

Erythrocytes from 15 patients with cystic fibrosis (CF) aged 8 mo to 22 y (mean age 12.8 y) were analyzed for Na+,K(+)-ATPase activity and sodium, potassium, and ATP concentrations. Sodium concentrations and Na(+)-K+ ratio of erythrocytes were statistically significantly lower in the CF patients [6.6 (SD 1.9) versus 9.2 (SD 1.1) mmol/L (p less than 0.01) and 0.070 (SD 0.023) versus 0.104 (SD 0.016) mmol/L (p less than 0.01), respectively]. The Na+,K(+)-ATPase activity was similar compared with that of reference individuals [536 (SD 100) versus 488 (SD 92) nmol inorganic phosphate/mg protein/h]. Intraerythrocyte sodium concentration and Na(+)-K+ ratio were thus lower in relation to the recorded Na+,K(+)-ATPase activities in controls, indicating a change of the passive transmembrane movements of sodium ions in CF. There was a rise of erythrocyte sodium and Na(+)-K+ ratio despite unchanged Na+,K(+)-ATPase activity after regular infusion of a fat emulsion rich in essential fatty acids, inferring that an altered membrane composition by essential fatty acid deficiency could explain the low intracellular sodium concentration in CF.     

地塞米松对内毒素血症幼年大鼠肾脏细胞凋亡超微结构的影响

目的：探讨内毒素血症幼年大鼠肾脏损害的部分机制及地塞米松对其肾脏的保护作用。方法：健康18日龄Wistar大鼠54只，随机分为健康对照组、内毒素（LPS）组和地塞米松治疗组，每组18只。健康对照组腹腔注射9g／L盐水0．1mL；LPS组腹腔注射LPS4 mg／kg；地塞米松治疗组LPS注射后1h腹腔注射地塞米松5mg／kg。分别于注射后6、24和72h处死取出肾脏，利用透射电镜观察各组大鼠肾脏细胞超微结构的改变。结果：注射LPS 6、24h幼年大鼠肾小球基底膜厚薄不均，局部有增厚和足突融合，近端小管上皮细胞内线粒体嵴溶解，远端小管微绒毛减少；注射LPS72h近端小管出现核染色质浓缩、着边及核破碎的凋亡改变。地塞米松治疗组肾脏结构改变明显减轻，凋亡改变消失。结论：内毒素血症肾损伤时存在肾细胞凋亡，地塞米松通过抑制细胞凋亡对肾脏起保护作用。