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AIM: To study the effects of estrogen on the expression of matrix metalloproteinases-1(MMP-1)and tissue inhibitor of matrix metalloproteinase-1(TIMP-1)in lacrimal gland of ovariectomized rat. METHODS:A total of 60 female rats were examined for the expression of MMP-1 and TIMP-1 protein in lacrimal gland through SⅠt measurement together with Western- blot and RT-PCR methods.RESULTS:There was significant reduction in SⅠt and increase in the protein expression of MMP1, TIMP1 and mRNA after ovariectomy conducted on rats(PPCONCLUSION: Estrogen must be applied cautiously to treat xerophthalmia following menopause because estrogen can up regulate the expressions of MMP-1 and TIMP-1 and can aggravate the decrease of lacrimal secretion.

The cytochrome P450 epoxygenase-dependent arachidonic acid metabolites, epoxyeicosatrienoic acids (EETs), are potent survival factors and mitogens for renal epithelial cells, but the molecular identity in the cells that initiates the mitogenic signaling of EETs has remained elusive. We screened kidney cell lines for the expression of G-protein-coupled receptor 40 (GPR40) and found that the porcine renal tubular epithelial cell line LLCPKcl4, which has been previously demonstrated to be sensitive to the mitogenic effect of EETs, expresses higher levels of GPR40 mRNA and protein than the human embryonic kidney cell line HEK293. EETs induced only a weak mitogenic EGFR signaling and mild cell proliferation in HEK293 cells. To determine whether GPR40 expression level is what mediates the mitogenic sensitivity of cells to EETs, we created a human GPR40 (hGPR40) cDNA construct and transfected it into HEK293 cells and picked up a number of stable transfectants. We found that GPR40 overexpression in HEK293 cells indeed significantly enhanced EET-induced cell proliferation and markedly augmented EGFR phosphorylation ERK activation, which were inhibited by the EGFR tyrosine kinase inhibitor, AG1478, or the HB-EGF inhibitor, CRM197. EETs significantly enhanced release of soluble HB-EGF, a natural ligand of EGFR, into the culture medium of hGPR40-transfected HEK293 cells, compared to empty vector-transfected cells. In mouse kidneys, markedly higher level of GPR40 protein was found in the cortex and outer stripe of outer medulla compared to the inner stripe of outer medulla and inner medulla. In situ hybridization confirmed that GPR40 mRNA was localized to a subset of renal tubules in the kidney, including the cortical collecting duct. Thus, this study provides the first demonstration that upregulation of GPR40 expression enhances the mitogenic response to EETs and a relatively high expression level of GPR40 is detected in a subset of tubules including cortical collecting ducts in the mammalian kidney.

The aim of this study was to evaluate the cardiovascular and renal activities of a newly designed natriuretic peptide (NP). Here, we engineered a novel 28-amino acid chimeric peptide, termed AC-NP that combined the 17-amino acid ring of C type natriuretic peptide (CNP) with the 6-amino acid N-terminus and 5-amino acid C-terminus of atrial natriuretic peptide (ANP). Both in vitro and in vivo experiments were performed to determine the actions of AC-NP. In normal rats, AC-NP proved to be more potentially diuretic, natriuretic and hypotensive compared with other NPs, such as ANP, CNP and vasonatrin peptide (VNP), which is another man-made NP. In relaxation of isolated abdominal aorta from rat, AC-NP was equally effective to ANP, CNP and VNP. Elevated levels of 3',5'-guanosine monophosphate (cGMP) in plasma and urine cGMP excretion indicated the participation of cGMP in the functions of AC-NP. Taken together, innovative designed AD-NP might be a new candidate therapeutic peptide against cardiorenal disorders.

The class 3 phosphatidylinositol 3-kinase (Pik3c3) plays critical roles in regulating autophagy, endocytosis, and nutrient sensing, but its expression profile in the kidney remains undefined. Recently, we validated a Pik3c3 antibody through immunofluorescence staining of kidney tissues from cell type-specific Pik3c3 knockout mice. Immunohistochemistry unveiled significant disparities in Pik3c3 expression levels across various kidney cell types. Notably, renal interstitial cells exhibit minimal Pik3c3 expression. Further, coimmunofluorescence staining, utilizing nephron segment- or cell type-specific markers, revealed nearly undetectable levels of Pik3c3 expression in glomerular mesangial cells and endothelial cells. Intriguingly, although podocytes exhibit the highest Pik3c3 expression levels among all kidney cell types, the renal proximal tubule cells (RPTCs) express the highest level of Pik3c3 among all renal tubules. RPTCs are known to express the highest level of the epidermal growth factor receptor (EGFR) in adult kidneys; however, the role of Pik3c3 in EGFR signaling within RPTCs remains unexplored. Therefore, we conducted additional cell culture studies. The results demonstrated that Pik3c3 inhibition significantly delayed EGF-stimulated EGFR degradation and the termination of EGFR signaling in RPTCs. Mechanistically, Pik3c3 inhibition surprisingly did not affect the initial endocytosis process but instead impeded the lysosomal degradation of EGFR. In summary, this study defines, for the first time, the expression profile of Pik3c3 in the mouse kidney and also highlights a pivotal role of Pik3c3 in the proximal tubule cells. These findings shed light on the intricate mechanisms underlying Pik3c3-mediated regulation of EGFR signaling, providing valuable insights into the role of Pik3c3 in renal cell physiology. [ABSTRACT FROM AUTHOR]

Excessive compensatory nephron hypertrophy (CNH) has been implicated in setting the stage for progressive nephron damage. Lack of a class III phosphatidylinositol 3-kinase (Pik3c3) inhibitor suitable for using in animals and lack of a Pik3c3-deficient animal model preclude the possibility of conclusively defining a role for Pik3c3 in CNH in previous studies. Here, we report that insertion of an Frt-flanked PGK-Neo cassette into intron 19 of the mouse Pik3c3 gene resulted in a hypomorphic allele. This allowed us to create a unique mouse model and provide the first definitive genetic evidence demonstrating whether Pik3c3 is essential for the regulation of CNH. Our results indicate that homozygous Pik3c3 hypomorphic (Pik3c3Hypo/Hypo) mice express significantly low levels of Pik3c3 than heterozygous Pik3c3 hypomorphic (Pik3c3Hypo/WT) littermates, which already express a lower level of Pik3c3 than wild-type (Pik3c3WT/WT) littermates. Interestingly, after unilateral nephrectomy (UNX), Pik3c3Hypo/Hypo mice develop a significantly lower degree of CNH than Pik3c3WT/WT mice and Pik3c3Hypo/WT mice, as revealed by measurement of kidney weight, kidney-to-body weight ratio, renal protein-to-DNA ratio, and morphometric analysis of proximal tubular and glomerular size. Mechanistically, UNX-induced mammalian target of rapamycin complex 1 (mTORC1) signaling to phosphorylation of ribosomal protein S6 (rpS6) in the remaining kidney was markedly inhibited in Pik3c3 hypomorphic mice. In conclusion, the present study reports a Pik3c3 hypomorphic mouse model and provides the first definitive evidence that Pik3c3 controls the degree of compensatory nephron hypertrophy. In addition, our signaling data provide the first definitive in vivo proof that Pik3c3 functions upstream of the mTORC1-S6 kinase 1-rpS6 pathway in the regulation of compensatory nephron hypertrophy. [ABSTRACT FROM AUTHOR]

A polymer-bonded explosive substitute material (PBX) composed of sugar granules and polymer binder was fabricated with a weight proportion of 90:10. Static Brazilian tests accompanied by high-speed photography, digital image correlation (DIC) technology, and dynamic mechanical analysis (DMA) were carried out. The tensile stress-strain relation is quasi-linear until failure with a tensile strength of about 0.89 MPa, elastic modulus of 35 MPa, and Poisson's ratio of 0.392. Microscopically, interfacial debonding and intergranular fractures are the main mechanisms of damage. By DMA, the storage modulus and tan d show a strong dependence on temperature and less dependence on frequency; the glass transition temperature is found to be about 50°C. These results are helpful for understanding the behavior of PBX under tensile and dynamic loading. [ABSTRACT FROM AUTHOR]

Renal fibrosis is a common pathological feature in chronic kidney disease (CKD), including diabetic kidney disease (DKD) and obstructive nephropathy. Multiple microRNAs have been implicated in the pathogenesis of both DKD and obstructive nephropathy, although the overall role of microRNAs in tubular injury and renal fibrosis in CKD is unclear. Dicer (a key RNase III enzyme for microRNA biogenesis) was specifically ablated from kidney proximal tubules in mice via the Cre-lox system to deplete micoRNAs. Proximal tubular Dicer knockout (PT- Dicer KO) mice and wild-type (WT) littermates were subjected to streptozotocin (STZ) treatment to induce DKD or unilateral ureteral obstruction (UUO) to induce obstructive nephropathy. Renal hypertrophy, renal tubular apoptosis, kidney inflammation, and tubulointerstitial fibrosis were examined. Compared with WT mice, PT- Dicer KO mice showed more severe tubular injury and renal inflammation following STZ treatment. These mice also developed higher levels of tubolointerstitial fibrosis. Meanwhile, PT- Dicer KO mice had a significantly higher Smad2/3 expression in kidneys than WT mice (at 6 mo of age) in both control and STZ-treated mice. Similarly, UUO induced more severe renal injury, inflammation, and interstitial fibrosis in PT- Dicer KO mice than WT. Although we did not detect obvious Smad2/3 expression in sham-operated mice (2-3 mo old), significantly more Smad2/3 was induced in obstructed PT- Dicer KO kidneys. These results supported a protective role of Dicer-dependent microRNA synthesis in renal injury and fibrosis development in CKD, specifically in DKD and obstructive nephropathy. Depletion of Dicer and microRNAs may upregulate Smad2/3-related signaling pathway to enhance the progression of CKD. [ABSTRACT FROM AUTHOR]

A polymer-bonded explosive, also called PBX or plastic-bonded explosive, is an explosive material in which explosive powder is bound together in a matrix using small quantities (typically 5%-10% by weight) of a synthetic polymer. A PBX substitute material was made from sugar granules and polymer binder. Its compressive creep properties were investigated at room temperature. The creep deformation was found to depend strongly on the applied stress amplitude. Under an applied stress near the strength, creep deformation developed and reached the final rupture very quickly. A power law relationship, ε= 4.14 × 10-8 σ2.5 , was established between steady creep rate and applied stress. Microscopic observations show that the damage mechanism processes include mainly the intergranular and transgranular fractures, binder fracture, and peeling. Both porosity and granule size decrease almost linearly with increasing applied stress. [ABSTRACT FROM AUTHOR]

Hyperinsulinemia has been hypothesized to cause hypertension in obesity, type 2 diabetes, and metabolic syndrome through a renal mechanism. However, it has been challenging to isolate renal mechanisms in chronic experimental models due, in part, to technical difficulties. In this study, we tested the hypothesis that a renal mechanism underlies insulin hypertension. We developed a novel technique to permit continuous insulin infusion through the renal artery in conscious rats for 7 days. Mean arterial pressure increased by ~10 mmHg in rats that were infused intravenously (IV) with insulin and glucose. Renal artery doses were 20% of the intravenous doses and did not raise systemic insulin levels or cause differences in blood glucose. The increase in blood pressure was not different from the IV group. Mean arterial pressure did not change in vehicle-infused rats, and there were no differences in renal injury scoring due to the renal artery catheter. Glomerular filtration rate, plasma renin activity, and urinary sodium excretion did not differ between groups at baseline and did not change significantly with insulin infusion. Thus, by developing a novel approach for chronic, continuous renal artery insulin infusion, we provided new evidence that insulin causes hypertension in rats through actions initiated within the kidney. [ABSTRACT FROM AUTHOR]

Podocytes are highly differentiated epithelial cells wrapping glomerular capillaries to form the filtration barrier in kidneys. As such, podocyte injury or dysfunction is a critical pathogenic event in glomerular disease. Autophagy plays an important role in the maintenance of the homeostasis and function of podocytes. However, it is less clear whether and how autophagy contributes to podocyte injury in glomerular disease. Here, we have examined the role of autophagy in adriamycin-induced nephropathy, a classic model of glomerular disease. We show that autophagy was induced by adriamycin in cultured podocytes in vitro and in podocytes in mice. In cultured podocytes, activation of autophagy with rapamycin led to the suppression of adriamycin-induced apoptosis, whereas inhibition of autophagy with chloroquine enhanced podocyte apoptosis during adriamycin treatment. To determine the role of autophagy in vivo, we established an inducible podocyte-specific autophagy-related gene 7 knockout mouse model (Podo-Atg7-KO). Compared with wild-type littermates, Podo-Atg7-KO mice showed higher levels of podocyte injury, glomerulopathy, and proteinuria during adriamycin treatment. Together, these observations support an important role of autophagy in protecting podocytes under the pathological conditions of glomerular disease, suggesting the therapeutic potential of autophagy induction. [ABSTRACT FROM AUTHOR]

Kidney repair following injury involves the reconstitution of a structurally and functionally intact tubular epithelium. Growth factors and their receptors, such as EGFR, are important in the repair of renal tubules. Exosomes are cell-produced small (~100 nm in diameter) vesicles that contain and transfer proteins, lipids, RNAs, and DNAs between cells. In this study, we examined the relationship between exosome production and EGFR activation and the potential role of exosome in wound healing. EGFR activation occurred shortly after scratch wounding in renal tubular cells. Wound repair after scratching was significantly promoted by EGF and suppressed by EGFR inhibitor gefitinib. Interestingly, scratch wounding induced a significant increase of exosome production. The exosome production was decreased by EGF and increased by gefitinib, suggesting a suppressive role of EGFR signaling in exosome production. Conversely, inhibition of exosome release by GW4869 and manumycin A markedly increased EGFR activation and promoted wound healing. Moreover, exosomes derived from scratch-wounding cells could inhibit wound healing. Collectively, the results indicate that wound healing in renal tubular cells is associated with EGFR activation and exosome production. Although EGFR activation promotes wound healing, released exosomes may antagonize EGFR activation and wound healing. [ABSTRACT FROM AUTHOR]

Kidney size adaptively increases as mammals grow and in response to the loss of 1 kidney. It is not clear how kidneys size themselves or if the processes that adapt kidney mass to lean body mass also mediate renal hypertrophy following unilateral nephrectomy (UNX). Here, we demonstrated that mice harboring a proximal tubule-specific deletion of Pten (PtenptKO) have greatly enlarged kidneys as the result of persistent activation of the class I PI3K/mTORC2/AKT pathway and an increase of the antiproliferative signals p21 Cip1/WAF and p27 Kip1. Administration of rapamycin to PtenptKO mice diminished hypertrophy. Proximal tubule-specific deletion of Egfr in PtenptKO mice also attenuated class I PI3K/mTORC2/AKT signaling and reduced the size of enlarged kidneys. In PtenptKO mice, UNX further increased mTORC1 activation and hypertrophy in the remaining kidney; however, mTORC2-dependent AKT phosphorylation did not increase further in the remaining kidney of PtenptKO mice, nor was it induced in the remaining kidney of WT mice. After UNX, renal blood flow and amino acid delivery to the remaining kidney rose abruptly, followed by increased amino acid content and activation of a class III PI3K/mTORC1/S6K1 pathway. Thus, our findings demonstrate context-dependent roles for EGFR-modulated class I PI3K/mTORC2/AKT signaling in the normal adaptation of kidney size and PTEN-independent, nutrient-dependent class III PI3K/mTORC1/S6K1 signaling in the compensatory enlargement of the remaining kidney following UNX. [ABSTRACT FROM AUTHOR]

In order to detect the variation of electro-conductive property of short steel fiber (SSF) filled polyamide-6 (PA6) under impact loading, a modified split Hopkinson pressure bar (M-SHPB) is suggested. Such M-SHPB is constructed by designing a new test electrocircuit, and connecting it to the specimen and oscillograph. On the other hand, a copper foil cover is designed and placed on the whole SHPB equipment for avoiding interference of electromagnetic wave existing in the testing environment. By means of M-SHPB, the relation between the resistance and dynamic stress or dynamic strain is effectively detected. The experimental results indicate that the resistance of the material decreases with the increase of strain or stress. The sensitive variation of the resistance appears at the beginning of the deformation of the material. [ABSTRACT FROM AUTHOR]

Arachidonic acid is an essential constituent of cell membranes that is esterified to the sn-2-position of glycerophospholipids and is released from selected lipid pools by phospholipase cleavage. The released arachidonic acid can be metabolized by three enzymatic pathways: the cyclooxygenase pathway forming prostaglandins and thromboxanes, the lipoxygenase pathway generating leukotrienes and lipoxins, and the cytochrome P450 (cP450) pathway producing epoxyeicosatrienoic acids and hydroxyeicosatetraenoic acids. The present study describes a novel group of cP450 epoxygenase-dependent metabolites of arachidonic acid, termed 2-epoxyeicosatrienoylglycerols (2-EG), including two regioisomers, 2-(11,12-epoxyeicosatrienoyl)glycerol (2-1 1,12-EG) and 2-(14,15-epoxyeicosatrienoyl)- glycerol (2-14,15-EG), which are both produced in the kidney and spleen, whereas 2-11,12-EG is also detected in the brain. Both 2-11,12-EG and 2-14,15-EG activated the two cannabinoid (CB) receptor subtypes, CB1 and CB2, with high affinity and elicited biological responses in cultured cells expressing CB receptors and in intact animals. In contrast, the parental arachidonic acid and epoxyeicosatrienoic acids failed to activate CB1 or CB2 receptors. Thus, these cP450 epoxygenase-dependent metabolites are a novel class of endogenously produced, biologically active lipid mediators with the characteristics of endocannabinoids. This is the first evidence of a cytochrome P450-dependent arachidonate metabolite that can activate G-protein-coupled cell membrane receptors and suggests a functional link between the cytochrome P450 enzyme system and the endocannabinoid system. [ABSTRACT FROM AUTHOR]

Examines the role of heparin-binding epidermal growth factor on the biological effects of arachidonate epoxygenase metabolites. Activation of phospholipases; Inhibition of the vascular cell molecules; Formation of the lymphoma cell lines.

Focuses on a study which discussed the role of angiotensin IV in inducing tyrosine phosphorylation of focal adhesion kinase and paxillin in proximal tubule cells. Effects of angiotensin IV on cell growth; Materials and methods used; Results; Limitations of the study.

Arachidonic acid is an essential constituent of cell membranes that is esterified to the sn-2 position of glycerophospholipids and is released from selected phospholipid pools by tightly regulated phospholipase cleavage. Metabolism of the released arachidonic acid by the cytochrome P450 enzyme system (cP450) generates biologically active compounds, including epoxyeicosatrienoic acids (EETs) and hydroxyeicosatetraenoic acids. Here we report that 2-(14,15-epoxyeicosatrienoyl)glycerol (2-14,15-EG), a novel cP450 arachidonate metabolite produced in the kidney, is a potent mitogen for renal proximal tubule cells. This effect is mediated by activation of tumor necrosis factor alpha-converting enzyme (ADAM17), which cleaves membrane-bound transforming growth factor α (proTGF-α) and releases soluble TGF-α as a ligand that binds and activates epidermal growth factor receptor (EGFR). The present studies additionally demonstrate that the structurally related 14,15-EET stimulates release of soluble heparin-binding EGF-like growth factor as an EGFR ligand by activation of ADAM9, another member of the ADAM family. Thus, in addition to the characterization of 2-14,15-EG's mitogenic activity and signaling mechanism, our study provides the first example that two structurally related biologically active lipid mediators can activate different metalloproteinases and release different EGFR ligands in the same cell type to activate EGFR and stimulate cell proliferation. [ABSTRACT FROM AUTHOR]

Analyzes nonlinear viscoelastic constitutive relations based on rate sensitive relaxation time under condition of uniaxial stress. Tension test on viscoelastic materials polypropylene and high density polyethylene at different strain rate; Effect of strain rate change on relaxation time of materials.