Reduced urinary excretion of epidermal growth factor in incipient and overt diabetic nephropathy

To study the relationship between glomerular and tubular function we investigated glomerular filtration rate (GFR), urinary albumin excretion, and urinary excretion of epidermal growth factor (EGF, a mitogenic peptide synthesized in the renal tubular cells) in normal subjects (group I, n = 7) and in Type 1 (insulin-dependent) diabetic patients with normoalbuminuria (group II, n = 11); with incipient nephropathy (microalbuminuria) (group III, n = 9); with nephropathy and normal GFR (group IV, n = 12); and with reduced GFR (group V, n = 8). EGF (nmol 24 h-1) decreased with progressive glomerular involvement, from 7.9 (4.1-10.5) (median and range) in group I, to 6.7 (1.3-9.2) in group II, 5.0 (3.6-7.4) in group III, 4.1 (2.5-9.5) in group IV, and 1.1 (0.1-2.5) in group V. The urinary excretion of EGF was significantly reduced in patients with elevated UAE (group III, IV, and V) compared with normal control subjects (p less than 0.05). A significant correlation between urinary excretion of EGF and GFR (r = 0.71, p less than 0.001) and an inverse correlation between the urinary excretion of EGF and albumin (r = -0.35, p less than 0.05) was demonstrated in the Type 1 diabetic patients with GFR greater than 90 ml min-1. Our study demonstrates that urinary excretion of epidermal growth factor diminishes with increasing nephron impairment, and that renal tubular function as judged by the excretion of EGF is reduced early in the development of diabetic kidney disease.     

双钢板内固定治疗肱骨髁间骨折160例临床观察

目的：探讨双钢板内固定治疗肱骨髁间骨折的临床疗效。方法：选择本院2010年1月-2011年6月收治的160例肱骨髁间骨折患者作为研究对象,采用肱三头肌两侧入路的78例患者为A组,采用尺骨鹰嘴V形入路的82例患者为B组,比较两组患者的临床疗效、恢复时间以及并发症发生情况。结果：A组优良率为91.0%,略低于B组的92.7%,但两组比较差异无统计学意义（P〉0.05）;B组的术中出血量明显少于A组,且早期功能锻炼时间及出院时间均明显早于A组,两组比较差异有统计学意义（P〈0.05）;A组并发症发生率为3.8%,B组为3.7%,两组比较差异无统计学意义（P〉0.05）。结论：双钢板内固定治疗肱骨髁间骨折临床疗效满意且安全性好,尺骨鹰嘴V形入路更利于患者的快速康复,是首选的手术方案之一。     

Tubular epithelial cells have the capacity to transdifferentiate into CD68-positive macrophage-like cells by oxidative stress

Objective:  The present study was intended to assess transdifferentiation from tubular epithelial cells to macrophage- like cells. Methods:  Puromycin aminonucleoside nephrotic rats were sacrificed at days 4, 8, 24 and 112. We immunohistochemically evaluated CD68, CD163, and cytokeratin AE1/AE3, known as markers for macrophages and tubular epithelial cells. Nitrotyrosine, gp91^phox and Rac 1 expressions was also analyzed. CD68 expression in cultured murine proximal tubular epithelial cells (mProx) stimulated by crude and pure BSA was examined by flow cytometry and immunofluorescence. Results:  The tubular CD68-positive cells were observed on day 112. Immunoelectronmicroscopy revealed that some CD68-positive cells showed brush borders on the cell membrane and some of cytokeratin-positive tubular cells also expressed CD163 in mirror sections. The tubular CD68-positive cells were also positive for nitrotyrosine, gp91 ^phox and Rac 1. They contained lipid in their cytoplasm. Crude BSA, containing free fatty acid, induced CD68 expression in a dose- and time-dependent manner in mProx, but not pure BSA. The surface expression of CD68 was increased by high dose and long term stimulation with crude BSA as shown by immunofluorescence. Conclusions:  We confirmed that tubular epithelial cells have the capacity to transdifferentiate to CD68-positive macrophage-like cells, which may be linked to oxidative stress. Received 10 September 2006; returned for revision 4 November 2007; received from final revision 21 July 2008; accepted by M. Katori 8 August 2008     

Slow spontaneous [Ca2+]i oscillations reflect nucleotide release from renal epithelia

Renal epithelia can be provoked mechanically to release nucleotides, which subsequently increases the intracellular Ca²⁺ concentration [Ca²⁺]_i through activation of purinergic (P2) receptors. Cultured cells often show spontaneous [Ca²⁺]_i oscillations, a feature suggested to involve nucleotide signalling. In this study, fluo-4 loaded Madin–Darby canine kidney (MDCK) cells are used as a model for quantification and characterisation of spontaneous [Ca²⁺]_i increases in renal epithelia. Spontaneous [Ca²⁺]_i increases occurred randomly as single cell events. During an observation period of 1 min, 10.9 ± 6.7% (n = 23) of the cells showed spontaneous [Ca²⁺]_i increases. Spontaneous adenosine triphosphate (ATP) release from MDCK cells was detected directly by luciferin/luciferase. Scavenging of ATP by apyrase or hexokinase markedly reduced the [Ca²⁺]_i oscillatory activity, whereas inhibition of ecto-ATPases (ARL67156) enhanced the [Ca²⁺]_i oscillatory activity. The association between spontaneous [Ca²⁺]_i increases and nucleotide signalling was further tested in 132–1N1 cells lacking P2 receptors. These cells hardly showed any spontaneous [Ca²⁺]_i increases. Transfection with either hP2Y₆ or hP2Y₂ receptors revealed a striking degree of oscillations. Similar spontaneous [Ca²⁺]_i increases were observed in freshly isolated, perfused mouse medullary thick ascending limb (mTAL). The oscillatory activity was reduced by basolateral apyrase and substantially lower in mTAL from P2Y₂ knock out mice (0.050 ± 0.020 events per second, n = 8) compared to the wild type (0.147 ± 0.018 events per second, n = 9). These findings indicate that renal epithelia spontaneously release nucleotides leading to P2-receptor-dependent [Ca²⁺]_i oscillations. Thus, tonic nucleotide release is likely to modify steady state renal function. C. S. Geyti and E. Odgaard contributed equally to the publication.     

Molecular biology of multispecific organic anion transporter family (OAT family)

It has been predicted that a variety of organic anions of endogenous and exogenous origin are secreted by the renal proximal tubules via the p-aminohippurate (PAH) transport system. Organic anions are taken up from the peritubular plasma by the basolateral PAH transporter, and subsequently excreted into the urine by distinct organic anion transporter(s) in the luminal membrane. In 1997, we isolated the PAH transporter, organic anion transporter 1 (OAT1), from the rat kidney by the expression cloning method. OAT1 is a 551-amino-acid residue protein with 12 putative membrane spanning domains. It is exclusively expressed in the kidney, and is localized to the basolateral membrane of the cells of the middle portion of the proximal tubule, S2. OAT1 is a sodium-independent, organic anion/dicarboxylateexchanger, and mediates the transport of various organic anions. We have also identified two other isoforms of OAT. Rat OAT2 is predominantly expressed in the liver, while rat OAT3 is expressed in the liver, kidney, brain, and eyes. The isoforms exhibit overlapping but distinct substrate specificities. Interestingly, the members of the OAT family are structurally related to the members of the organic cation transporter (OCT) family. In addition, we have identified a membrane protein showing homology to both OATs and OCTs. This clone (CT1) mediated the transport of carnitine, a zwitterion. In this article, we describe the structure and functions of the members of the OAT family in association with these features in members of the OCT family and the zwitterion transporter. Received: September 27, 1999 / Accepted: October 13, 1999     

Combination of neutrophil gelatinase-associated lipocalin and matrix metalloproteinase-9 are biomarkers for the detection of colon tubular adenocarcinoma

BACKGROUNDTubular adenocarcinoma of the colon, which originates from the epithelium of the glands, is a major health concern worldwide. However, it is difficult to detect at an early stage. The lack of biomarkers is a main barrier to the diagnosis and treatment of tubular adenocarcinoma. Neutrophil gelatinase-associated lipocalin (NGAL) is a secreted protein that induces the expression of matrix metalloproteinase-9 (MMP-9) and is involved in various tumors. NGAL and MMP-9 have been reported to be associated with tumorigenesis and development. They may have potential as biomarkers for diagnosis of tubular adenocarcinoma of the colon.AIMTo determine whether NGAL and MMP-9 can be used as potential biomarkers to indicate the progression of tubular adenocarcinoma of the colon.METHODSSamples were collected from surgically excised tissue from various patients. The content of pro-gastrin-releasing peptide (pro-GRP) in the serum was measured by an electrochemiluminescence immunoassay. The expression patterns of NGAL and MMP-9 and the relationship between NGAL and MMP-9 were examined by quantitative real-time PCR, Western blotting and immunohistochemical analysis.RESULTSIn this study, we found that NGAL and MMP-9 can be used as biomarkers for the detection of tubular adenocarcinoma of the colon and that their combination improved diagnostic accuracy. By analyzing the expression of NGAL in tubular adenocarcinoma at different levels, we found that NGAL expression was significantly upregulated in primary tubular adenocarcinoma tissues compared with normal tissues. The upregulation of NGAL expression was strongly correlated with both the degree of differentiation and the disease stage (I–III), indicating that NGAL could serve as a diagnostic biomarker for tubular adenocarcinoma. When using NGAL as a biomarker for diagnosis, the accuracy was similar to that achieved with the widely used biomarker pro-GRP, suggesting that NGAL is reliable. Moreover, the expression of MMP-9 was also strongly correlated with the differentiation stage, demonstrating that MMP-9 could be used as a biomarker to indicate the progression of tubular adenocarcinoma of the colon. More importantly, the combination of NGAL and MMP-9 produced a more accurate diagnosis of tubular adenocarcinoma, and these results were further confirmed by immunohistochemical analysis of tissue sections.CONCLUSIONOur study demonstrated that both NGAL and MMP-9 can be used as biomarkers for the diagnosis of colon tubular adenocarcinoma and that the results could be further improved by combining them.     

Store-operated calcium entry: From physiology to tubular aggregate myopathy

Store-Operated Ca²⁺ entry (SOCE) is recognized as a key mechanism in muscle physiology necessary to refill intracellular Ca²⁺ stores during sustained muscle activity. For many years the cell structures expected to mediate SOCE in skeletal muscle fibres remained unknown. Recently, the identification of Ca²⁺ Entry Units (CEUs) in exercised muscle fibres opened new insights into the role of extracellular Ca²⁺ in muscle contraction and, more generally, in intracellular Ca²⁺ homeostasis. Accordingly, intracellular Ca²⁺ unbalance due to alterations in SOCE strictly correlates with muscle disfunction and disease. Mutations in proteins involved in SOCE (STIM1, ORAI1, and CASQ1) have been linked to tubular aggregate myopathy (TAM), a disease that causes muscle weakness and myalgia and is characterized by a typical accumulation of highly ordered and packed membrane tubules originated from the sarcoplasmic reticulum (SR). Achieving a full understanding of the molecular pathways activated by alterations in Ca²⁺ entry mechanisms is a necessary step to design effective therapies for human SOCE-related disorders.