Biomedical subjects

Ann Chen

Publications and source records attributed to Ann Chen.

At least 19 recordsLinked to original sources

PubMed2026

iModMix: integrative module analysis for multi-omics data.

SUMMARY: Integrative Module Analysis for Multi-omics Data (iModMix) is a biology-agnostic framework that enables the discovery of novel associations across any type of quantitative abundance data, including but not limited to transcriptomics, proteomics, and metabolomics. Instead of relying on pathway annotations or prior biological knowledge, iModMix constructs data-driven modules using graphical lasso to estimate sparse networks from omics features. These modules are summarized into eigenfeatures and correlated across datasets for horizontal integration, while preserving the distinct feature sets and interpretability of each omics type. iModMix operates directly on matrices containing expression or abundances for a wide range of features, including but not limited to genes, proteins, and metabolites. Because it does not rely on annotations (e.g., KEGG identifiers), it can seamlessly incorporate both identified and unidentified metabolites, addressing a key limitation of many existing metabolomics tools. iModMix is available as a user-friendly R Shiny application requiring no programming expertise (https://imodmix.moffitt.org), and as a Bioconductor R package for advanced users (https://bioconductor.org/packages/release/bioc/html/iModMix.html). The tool includes several public and in-house datasets to illustrate its utility in identifying novel multi-omics relationships in diverse biological contexts. AVAILABILITY AND IMPLEMENTATION: iModMix is freely available from Bioconductor (https://bioconductor.org/packages/release/bioc/html/iModMix.html), and the example dataset package (iModMixData) is also available from Bioconductor (https://bioconductor.org/packages/release/ data/experiment/html/iModMixData.html). The R package source code and Docker are available from GitHub: https://github.com/biodatalab/iModMix. Shiny application can be accessed at: https://imodmix.moffitt.org.

Multiomics↗

PubMed2007

STI571 sensitizes nasopharyngeal carcinoma cells to cisplatin: sustained activation of ERK with improved growth inhibition.

Previously, we demonstrated that c-kit and stem cell factors (SCF) commonly co-expressed in primary and metastatic nasopharyngeal carcinomas (NPC), and in HONE-1 NPC cells with tyrosine autophosphorylation of c-kit. These findings suggest that the SCF/c-kit signaling may contribute to pathogenesis of NPC. Therefore, the efficacy of STI571 treatment alone and when combined with cisplatin on HONE-1 cells were evaluated. STI571 induced growth inhibition at the IC50 concentration (14.9 microM). When the concentration was at or higher than 30 microM, the induction of cell apoptosis was observed. The effects of STI571 were shown to be mediated by the sustained activation of ERK but did not involve the inhibition of c-kit signal activity. When the STI571 (5 microM) and cisplatin (5 microg/ml) treatments were combined, there were further inductions of ERK activation resulting in obviously enhanced growth inhibition and induction of cell apoptosis. In a xenograft model, STI571 (50 mg/kg/day) showed only a limited ability to inhibit HONE-1 cell growth, but when combined with cisplatin (3 mg/kg/twice a week) treatment, there was a significant improvement in growth inhibition compared with STI571 or cisplatin treatment alone. Our results provide experimental support for the advanced NPC therapeutic trials using the combined STI571 and cisplatin treatment.

Animals↗

PubMed2006

Association of EMMPRIN and fascin expression in renal cell carcinoma: correlation with clinicopathological parameters.

EMMPRIN and fascin are important factors in tumor invasion and progression. We tested the hypothesis that expression of EMMPRIN and fascin correlate with clinicopathological parameters of renal cell carcinoma (RCC). Immunohistochemical analysis of EMMPRIN and fascin were performed in tissue microarrays of 100 surgical specimens, including 35 clear-cell RCC (CRCC), 21 clear-cell RCC with granular differentiation (GRCC), 12 chromophobe RCC (ChRCC), 8 papillary RCC (PRCC), 9 carcinoma of the collecting duct of Bellini (CDC), 10 clear-cell RCC with sarcomatoid differentiation (SRCC), and 6 metastatic RCC. Average immunoscores of EMMPRIN were 100.8 in CRCC, 195.2 in GRCC, 298.4 in ChRCC, 219.2 in PRCC, 186.1 in CDC, 226.9 in SRCC, and 151.7 in metastatic RCC. Among all included cases, average EMMPRIN immunoscores were 84.6 in grade I, 130.4 in grade II, 184.3 in grade III, and 223.5 in grade IV. Additionally, average immunostaining scores of fascin were 53.6 in CRCC, 289.3 in GRCC, 193.3 in ChRCC, 151.8 in PRCC, 181.3 in CDC, 275.4 in SRCC, and 131.7 in metastatic RCC. Average fascin immunoscores were 59.3 in grade I, 91.6 in grade II, 130.2 in grade III, and 194.7 in grade IV. Higher EMMPRIN and fascin immunoscores also correlated significantly with TNM stages and survival rates in RCC. Significant correlation was found between EMMPRIN and fascin expression. In conclusion, higher expression of EMMPRIN and fascin correlate significantly with histological grades, clinical stages, and survival rates of RCC.

Basigin↗

PubMed2006

Fibronectin in blood invokes the development of focal segmental glomerulosclerosis in mouse model.

BACKGROUND: Focal segmental glomerulosclerosis (FSGS) is caused by gradual deposition of extracellular matrix proteins, one of which, fibronectin (FN) is critical for sclerosis development. The origin of the FN deposited at an early stage of FSGS is still unclear. METHODS: For investigating the origin of FN, the onset of increases in FN levels in the serum, glomeruli and urine were studied in a mouse model induced by adriamycin and compared with the time-course of development of glomerulosclerosis and expression of FN mRNA. RESULTS: In the FSGS mice, serum FN levels were significantly increased as early as the onset of proteinuria on day 4 (7.26 +/- 0.37 mg/ml compared with 5.58 +/- 0.76 mg/ml in normal controls, P < 0.05). This was followed by an increase in glomerular deposition of FN protein on day 7 (FN/actin ratio, 0.216 +/- 0.003 compared with 0.039 +/- 0.009 in normal controls, P < 0.05). Glomerular m-RNA expression was also significantly elevated on day 7, but the locally synthesized FN did not show any increase until day 15. A significant increase in urinary FN protein and focal glomerulosclerosis was seen on day 11. CONCLUSIONS: We infer that FN in blood acts as an initiator of the development of FSGS in this mouse model. In addition, serum and urine FN proteins could serve as useful biomarkers for monitoring the progression of FSGS.

Animals↗

PubMed2006

What is the learning curve associated with double-balloon enteroscopy? Technical details and early experience in 6 U.S. tertiary care centers.

BACKGROUND: Performance parameters for double-balloon enteroscopy (DBE) have not been described. OBJECTIVE: To determine the learning curve for DBE. DESIGN: Prospective cohort study. SETTING: Six U.S. tertiary centers. PATIENTS: A total of 188 subjects undergoing 237 DBE procedures; 130 (69%) with obscure GI bleeding. INTERVENTIONS: Performance parameters from each center's initial 10 cases were compared to the subsequent examinations. MAIN OUTCOME MEASUREMENTS: Exam duration, depth of insertion, and findings on DBE examination. RESULTS: DBE was introduced by mouth in 149 (63%) cases, by rectum in 77 (33%) cases, and through a stoma in 6 (2.5%) patients. The mean (+/-SD) duration was 109.1 +/- 44.6 minutes for the first 10 cases and 92.4 +/- 37.6 minutes for subsequent cases (P = .005) but did not change for rectal DBE procedures. There was no change in mean depth of insertion, but the mean fluoroscopy time declined significantly (P = .025). Diagnostic or therapeutic maneuvers were performed in 64% of cases; DBE led to a diagnosis in 81 (43%) patients. A total of 78% of patients had prior capsule endoscopy (CE) with significant agreement between DBE and CE (kappa = 0.74). One perforation occurred (0.4%). Per-rectal cases failed to reach the small bowel in 24 (31%) cases. LIMITATIONS: All patients did not undergo initial CE. The therapeutic DBE scope was not available for the initial 8 months of the study. CONCLUSIONS: There was a significant decline in overall procedural time and fluoroscopy time after the initial 10 DBE cases. There was no improvement in performance parameters when DBE was performed via the rectal approach despite increased, but limited, operator experience.

Adolescent↗

PubMed2006

Increasing expression of serine protease matriptase in ovarian tumors: tissue microarray analysis of immunostaining score with clinicopathological parameters.

Matriptase is a type II transmembrane serine protease expressed by cells of surface epithelial origin, including epithelial ovarian tumor cells. Matriptase cleaves and activates proteins implicated in the progression of cancer and represents a potential prognostic and therapeutic target. The aim of this study was to examine the expression of matriptase in ovarian tumors and to assign clinicopathological correlations. Immunohistochemical analysis of matriptase was performed in tissue microarrays of 164 ovarian neoplasms including 84 serous adenocarcinomas, 23 mucinous adenocarcinomas, 10 endometrioid adenocarcinomas, six yolk sac tumors, 12 clear cell carcinomas, six dysgerminomas, eight granulosa cell tumors, four transitional cell carcinomas, five fibromas, and six Brenner tumors. All ovarian tumors except the fibromas and Brenner tumors showed significant expression of matriptase. The matriptase scores were significantly higher in the tumors than in their nontumor counterparts (304+/-26 for serous adenocarcinoma; 361+/-28 for mucinous adenocarcinoma; 254+/-17 for endometrioid adenocarcinoma; 205+/-19 for yolk sac tumor; 162+/-16 for clear cell carcinoma; 109+/-11 for dysgerminoma; 105+/-9 for granulosa cell tumor; and 226+/-18 for transitional cell carcinoma). Matriptase scores in serous adenocarcinoma were correlated with TNM stage and FIGO stage. Our findings demonstrate for the first time that matriptase is overexpressed in many malignant ovarian tumors. It may be a novel biomarker for diagnosis and treatment of malignant ovarian tumors.

Adenocarcinoma, Clear Cell↗

PubMed2006

Biological inhibitory effects of the Chinese herb danggui on brain astrocytoma.

OBJECTIVE: Previous studies have demonstrated the utility of the traditional Chinese herb danggui in the treatment of chronic myelogenous leukemia. Our aim was to examine whether it might similarly be used to treat glioblastoma multiforme. METHODS: The lipid-soluble active ingredients of danggui were extracted with acetone (AS-AC) or chlorophenol (AS-CH) and their antiproliferative and proapoptotic effects were studiedin vitro on cultured GBM 8401 cells and in vivoon tumors in nude mice. RESULTS: After a 24-hour treatment, either AS-AC or AS-CH at a lower (50 micro g/ml) and a higher concentration (100 micro g/ml) significantly inhibited the proliferative activity of GBM 8401 cultured cells by 30-50%, as well as the expression of cathepsin B and vascular endothelial growth factor (VEGF). In nude mice, the growth of the tumor was inhibited by 30% by AS-CH or AS-AC (20 mg/kg; p < 0.05) and by 60% by AS-CH or AS-AC (60 mg/kg; p < 0.05). AS-AC and AS-CH also significantly inhibited microvessel formation in the tumors of nude mice. CONCLUSIONS: Danggui may inhibit tumor growth by reducing the level of VEGF and the proapoptotic protein, cathepsin B. Thus, danggui may be useful in the treatment of high-grade astrocytomas.

Adult↗

PubMed2006

Expression of serine protease matriptase in renal cell carcinoma: correlation of tissue microarray immunohistochemical expression analysis results with clinicopathological parameters.

Serine protease matriptase (matriptase) cleaves and activates proteins implicated in the progression of cancer and represents a potential therapeutic target. Immunohistochemical analysis of matriptase was performed in tissue microarrays of 168 renal cell carcinomas (RCCs). All subtypes of RCC showed significant immunohistochemical expression of matriptase. In contrast, no expression occurred in areas of RCC with sarcomatous differentiation (SRCC) and in normal collecting tubules. The matriptase scores were significantly higher in papillary RCC (341+/-28) and clear cell RCC with granular cell differentiation (GRCC; 324+/-27) than in other histologic subtypes of RCC. In GRCC, matriptase scores were correlated with TNM staging and nuclear grading. Matriptase was overexpressed in all subtypes of RCC, and matriptase scores could distinguish between conventional clear cell RCC, GRCC, and SRCC.

Aged↗

PubMed2005

Characterization of neutralizing monoclonal antibodies recognizing a 15-residues epitope on the spike protein HR2 region of severe acute respiratory syndrome coronavirus (SARS-CoV).

The spike (S) glycoprotein is thought to play a complex and central role in the biology and pathogenesis of SARS coronavirus infection. In this study, a recombinant protein (rS268, corresponding to residues 268-1255 of SARS-CoV S protein) was expressed in Escherichia coli and was purified to near homogeneity. After immunization with rS268, S protein-specific BALB/c antisera and mAbs were induced and confirmed using ELISA, Western blot and IFA. Several BALB/c mAbs were found to be effectively to neutralize the infection of Vero E6 cells by SARS-CoV in a dose-dependent manner. Systematic epitope mapping showed that all these neutralizing mAbs recognized a 15-residues peptide (CB-119) corresponding to residues 1143-1157 (SPDVDLGDISGINAS) that was located to the second heptad repeat (HR2) region of the SARS-CoV spike protein. The peptide CB-119 could specifically inhibit the interaction of neutralizing mAbs and spike protein in a dose-dependent manner. Further, neutralizing mAbs, but not control mAbs, could specifically interact with CB-119 in a dose-dependent manner. Results implicated that the second heptad repeat region of spike protein could be a good target for vaccine development against SARS-CoV.

Amino Acid Sequence↗

PubMed2005

Glomerular crescent-related biomarkers in a murine model of chronic graft versus host disease.

BACKGROUND: We examined the alterations in gene expression associated with the development of crescentic glomerulonephritis in murine chronic graft-versus-host disease, a model for human systemic lupus erythematosus. METHODS: The disease was induced in (C57BL/6 x DBA/2) F(1) hybrids by injection of DBA/2 lymphocytes leading to deposition of auto-antibodies in the glomeruli, and a lupus type of nephritis morphologically. After extensive crescent formation at week 9 of disease, cDNA microarray analysis was performed and highly expressed genes were evaluated as molecular markers by real-time reverse transcription-polymerase chain reaction (RT-PCR), in situ hybridization, immunohistochemistry and immunoassay of urine proteins. RESULTS: Six genes, secreted acidic cysteine-rich glycoprotein (Sparc), thymosin beta 10 (Tmsb10), S100 calcium-binding protein A6 (S100a6), annexin A2 (Anxa2), osteopontin (OPN) and lipocalin 2 (Lcn2), were quantified by real-time RT-PCR in laser microdissected glomeruli in a time course manner. Sparc was detected early before the onset of proteinuria and continued to increase throughout the course of the disease. The expression of Tmsb10, S100a6 and Anxa2 coincided with heavy proteinuria. By week 9, OPN and Lcn2 were highly expressed. The expression of proteins encoded by these genes was predominant in the glomerular crescent. The protein levels of Sparc, OPN and Lcn2 in urine were significantly elevated. CONCLUSIONS: These findings implicate these six genes in the development of glomerular crescents. More importantly, detection of Sparc, OPN and Lcn2 in urine may mean that these molecules could serve as important biomarkers for non-invasive diagnosis of glomerular crescents.

Animals↗

PubMed2005

Rapid and sensitive detection of multiple genes from the SARS-coronavirus using quantitative RT-PCR with dual systems.

The outbreak of severe acute respiratory syndrome (SARS) was caused by a newly identified coronavirus (SARS-CoV) in 2003. To detect early SARS-CoV infection, a one-step, real-time quantitative reverse transcription-polymerase chain reaction (RT-PCR) assay was developed that could simultaneously detect nucleocapsid (N), membrane (M), and spike (S) genes of SARS-CoV with the same PCR condition using either Applied Biosystems (ABI) Prism 7700 Sequence Detection System or Roche LightCycler. The sensitivity of this assay was evaluated using cell culture-derived viruses, in vitro transcribed viral RNA, and clinical specimens. The SARS-S, -M, and -N primer/probe sets described in this paper could detect one to ten copies of in vitro transcribed S, M, and N RNA per test using both the ABI and Roche assay systems. The relative sensitivities for detecting cell culture-derived SARS-CoV were 0.01, 0.01, and 0.001 PFU/test, respectively. It showed that SARS-N has comparable detection efficiencies to SARS2 and SARS3 which are primers sets designed by Centers for Disease Control and Prevention. In addition, SARS-S and SARS-M also demonstrated equivalent sensitivity to the commercially available RealArt HPA-Coronavirus reagents (Artus). The relative sensitivity of these primer/probe sets was also examined using human sera spiked viruses and clinical specimens from four confirmed SARS patients. Similar results as above were obtained. Specificity tests and sequence alignment showed that these primer/probe sets annealed perfectly to 31 isolates of SARS-CoV; and there was no cross detection with other coronaviruses and human respiratory tract-associated viruses. Therefore, not only is it compatible with the ABI and Roche systems, this multiple-gene detection assay also has the merit of being a rapid, safe, sensitive, and specific tool for accurate diagnosis of SARS-CoV infection.

Genes, Viral↗

PubMed2005

Co-expression of c-kit and stem cell factor in primary and metastatic nasopharyngeal carcinomas and nasopharyngeal epithelium.

Expression of c-kit has been demonstrated in 33% of adult nasopharyngeal carcinomas (NPCs) and in 88% of paediatric NPCs. Patients with tumours expressing c-kit tend to exhibit better survival, but a paracrine/autocrine function for the stem cell factor (SCF)/c-kit system in nasopharyngeal carcinomas has not been reported. This study evaluated the expression of c-kit and SCF by immunohistochemical staining of nasopharyngeal epithelium (NPE) and of primary and metastatic NPCs. In addition, c-kit and SCF expression were studied in HONE-1 NPC cells by immunoprecipitation and western blotting. Expression of c-kit and SCF was detected in 75% and 57% of NPE, respectively, and there was 48% co-expression. In primary NPCs, 86% expressed c-kit, 69% had SCF expression, and there was 67% co-expression. In metastatic NPCs, 76% expressed c-kit, 72% expressed SCF and there was 68% co-expression. Co-expression of c-kit and SCF with tyrosine autophosphorylation of p145(c - kit) was demonstrated in HONE-1 NPC cells. In addition, the expression level of c-kit and its autophosphorylation status was not obviously influenced by the transient co-expression of Epstein-Barr nuclear antigen 1 (EBNA1) and latent membrane protein 1 (LMP1). Co-expression of c-kit and SCF is therefore commonly found in nasopharyngeal epithelium and NPCs, and in HONE-1 NPC cells with autoactivation possibly independent of the co-expression of EBNA1 and LMP1. All of these findings suggest that autoactivation of SCF/c-kit signalling may be a potent regulator of the nasopharyngeal epithelial barrier and of immune function at the nasopharyngeal mucosa surface, and may contribute to the carcinogenesis and progression of NPC. Further molecular analysis is required to evaluate the possibility of treatment with tyrosine kinase inhibitors in NPC, analogous to the treatment of gastrointestinal stromal tumours with STI571.

Adaptor Proteins, Signal Transducing↗

PubMed2005

Effects of a membrane-permeable radical scavenger, Tempol, on intraperitoneal sepsis-induced organ injury in rats.

There is good evidence that endotoxemia, sepsis, and septic shock are associated with the generation and release of reactive oxygen species (ROS) such as superoxide anion (O2), indicating that oxygen-derived free radicals play an important role in the pathogenesis of sepsis/shock. Studies on the application of free oxygen radical scavengers to limit the damage to tissues and organs have been recently attempted. A stable piperidine nitroxide of low molecular weight (Tempol) can permeate biological membranes and scavenge O2 in vitro and in vivo. Thus, we investigated effects of Tempol on the circulatory failure and multiple organ injuries caused by a clinically relevant polymicrobial sepsis model in the rat-cecal ligation and puncture (CLP). CLP not only successfully induced circulatory failure but also substantially increased plasma concentrations of glutamate-oxalate-transferase and glutamate-pyruvate-transferase (indicators of liver injury), creatinine and blood urea nitrogen (indicators of kidney injury), and decreased base excess in arterial blood in the late stage, indicating the development of multiple organ injury in this study. These were also confirmed by a histologic examination showing that the CLP-induced sepsis accompanied increase of polymorphonuclear neutrophil (PMN) infiltration in the lung and sequestration in the liver. Our results demonstrated that Tempol not only ameliorated the deterioration of hemodynamic changes and renal and liver injuries but also attenuated PMN infiltration in the lung and sequestration in the liver (histology). In addition, Tempol improved the survival in CLP-induced septic rats. Moreover, Tempol reduced the plasma NO. and interleukin-1beta and organ O2 levels in CLP-treated rats. In conclusion, Tempol prevented circulatory failure and attenuated organ dysfunction/injury as well as decreased the mortality rate in CLP-treated animals. These beneficial effects of Tempol may be attributed to inhibition of ROS formation (e.g., NO. and O2), suggesting antioxidant (e.g., Tempol) is a potential therapeutic agent in the treatment of intraperitoneal septic shock.

Animals↗

PubMed2005

Calcium-binding proteins annexin A2 and S100A6 are sensors of tubular injury and recovery in acute renal failure.

BACKGROUND: Rise in cellular calcium is associated with acute tubular necrosis, the most common cause of acute renal failure (ARF). The mechanisms that calcium signaling induce in the quiescent tubular cells to proliferate and differentiate during acute tubular necrosis have not been elucidated. METHODS: Acute tubular necrosis induced in mice by single intravenous injection of uranyl nitrate and examined after 1, 3, 7, and 14 days. Renal function was monitored and kidneys were evaluated by histology, immunohistochemistry, Western blotting, in situ hybridization, and real-time reverse transcription-polymerase chain reaction (RT-PCR). Models of folic acid induced-ARF and ischemic/reperfusion (I/R) injury were similarly investigated. RESULTS: Analysis of mRNA expression of intracellular calcium and phospholipid-binding proteins demonstrated selective expression of S100A6 and Annexin A2 (Anxa2) in the renal cortex with marked elevation on day 3, and gradually decline on day 7 and further attenuation on day 14. Similarly, the expression of both proteins, as demonstrated by immunohistochemistry and Western blot analysis, was increased and reached the peak level on day 7 and then gradually declined by day 14. Vimentin, a marker of dedifferentiated cells, was highly expressed during the recovery phase. Combined in situ hybridization immunohistochemistry revealed colocalization of both S100A6 and Anxa2 with proliferating cell nuclear antigen (PCNA). The universality of this phenomenon was confirmed in two other mouse acute tubular necrosis models, the ischemic-reperfusion injury and folic acid-induced ARF. CONCLUSION: Collectively, these findings demonstrate that S100A6 and Anxa2 expression, initiated in response to tubular injury, persist in parallel throughout the recovery process of tubular cells in acute renal failure.

Acute Kidney Injury↗

PubMed2004

Mouse model of membranous nephropathy induced by cationic bovine serum albumin: antigen dose-response relations and strain differences.

BACKGROUND: Few well-characterized animal models have been developed to study the pathogenesis of membranous nephropathy (MN). We have developed a mouse model of MN induced by cationic bovine serum albumin (cBSA), and examined the role of genetic background on disease induction by assessing different mouse strains. METHODS: cBSA in an optimum dose was given intravenously to 8-week-old female ICR, BALB/c and C57BL/6 mice for 4 weeks. The disease state was verified by renal histopathology as well as by serum and urine metabolic profiles. Serum concentrations of anti-cBSA immunoglobulins (Igs) and circulating immune complex (CIC) were assayed to study the mechanisms of initiation and progression. T-helper (Th) cell subsets in peripheral blood were examined using flow cytometry, and the Th1/Th2 subset distribution was determined by comparing the serum concentrations of IgG1 and IgG2a, using quantitative heterologous interpolation enzyme-linked immunosorbent assays. RESULTS: Only ICR and BALB/c mice developed the typical clinical and pathological patterns of MN in response to an optimum dose of cBSA. Disease induction was dose related and strain specific. The serum concentrations of anti-cBSA were significantly higher in the strains that developed MN, but there were no differences in CIC concentrations. This suggests that in situ immune-complex glomerulonephritis may be involved in the development of MN. The Th2 type immune response may predominate in the ICR and BALB/c mice models, as the serum concentration of IgG1 was higher than that of IgG2a; moreover Th2 type strain specificity was necessary for the development of MN. CONCLUSIONS: This improved mouse model of MN induced by cBSA more closely duplicates human MN than the other available models. Disease generation is antigen dose related and strain specific.

Animals↗

PubMed2004

IgA immune complex blunts the contraction of cultured mesangial cells through the inhibition of protein kinase C and intracellular calcium.

The effects of IgA immune complex (IgA-IC) on the contractile function of cultured mesangial cells were measured by the changes in planar surface area in response to treatment with agonists. Incubation of mesangial cells with IgA-IC for 24 hours significantly decreased the contractile responses to angiotensin II (10(-6) M) and phorbol 12-myristate 13-acetate (PMA, 10(-6) M). Pretreatment of mesangial cells with the protein kinase C (PKC) inhibitor, chelerythrine (10(-6) M), eliminated the difference in contractile responses to angiotensin II or PMA between the control and IgA-IC groups indicating IgA-IC may inhibit the activity of PKC. The contractile responses to ionomycin were not significantly different between IgA-IC treated and control mesangial cells, suggesting that the contractile machinery is not impaired by IgA-IC. Intracellular calcium, [Ca2+]i measured by changes in fura-2 level in response to ATP or bradykinin, was significantly inhibited in IgA-IC treated mesangial cells, compared to control cells. In contrast, treatment with thapsigargin did not result in significant differences in [Ca2+]i between IgA-IC and control mesangial cells, suggesting that a negligible role of endoplasmic reticulum in the effects of IgA-IC. Using PKC specific antibodies, IgA-IC significantly increased the particulate fraction of PKC-iota of mesangial cells to 141+/-13% of control, without significantly changing the protein content of PKC-alpha, -delta and -lambda in the cytosolic and particulate fractions. In summary, IgA-IC inhibits the contractile responses of cultured mesangial cells to agonists by inhibiting the activation of PKC and [Ca2+]i.

Alkaloids↗

PubMed2004

Adriamycin impairs the contraction of mesangial cells through the inhibition of protein kinase C and intracellular calcium.

The effects of adriamycin on the contractile function of cultured mesangial cells were measured by the changes in planar surface area in response to treatment with agonists. Incubation of mesangial cells with adriamycin (0.2 microg/ml) for 24 h significantly decreased the contractile responses to the calcium channel activator BAY K 8644 (1 microM) and to the PKC activator PMA (1 microM). Intracellular calcium concentration ([Ca(2+)](i)), measured by changes in fura 2 levels in response to ATP (0.1 mM), was significantly inhibited in adriamycin-treated mesangial cells compared with control cells. In the absence of extracellular calcium, treatment with ionomycin (0.1 mM) or thapsigargin (10 microM) resulted in a significantly smaller increase in [Ca(2+)](i) in adriamycin-treated mesangial cells compared with control, suggesting an important role of the endoplasmic reticulum in the effects of adriamycin. Using PKC-specific antibodies, adriamycin significantly decreased the cytosolic and membranous fractions of PKC-alpha in mesangial cells to 75 +/- 6 and 70 +/- 12% of control, respectively. The PKC activity of mesangial cells was also significantly inhibited after incubation with adriamycin for 24 h. In conclusion, adriamycin induces hypocontractility of mesangial cells, which may mediate this effect by inhibiting PKC-alpha and [Ca(2+)](i).

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗

PubMed2004

Low-dose dexamethasone ameliorates circulatory failure and renal dysfunction in conscious rats with endotoxemia.

Corticosteroids have long been proposed as a therapeutic adjuvant in septic renal dysfunction because of their anti-inflammatory properties and favorable results from animal experiments. However, some reports suggested the potential for harm associated with the administration of early high-dose corticosteroids in patients with severe sepsis and septic shock. Thus, we examined the effects of low-dose dexamethasone (0.01 and 0.1 mg/kg) on hemodynamics and renal function in conscious rats with endotoxemia. Intravenous injection of rats with endotoxin (E. coli lipopolysaccharide, LPS, 1 mg/kg) caused hypotension, vascular hyporeactivity, and tachycardia as well as renal dysfunction. Circulatory failure and renal dysfunction caused by LPS were significantly attenuated in the dexamethasone 0.1 mg/kg-treated group. The nitric oxide (NO) production in plasma and renal tissue and the iNOS protein expression in the kidney were suppressed by cotreatment of LPS rats with dexamethasone, 0.1 mg/kg. Light microscopy showed that 0.1 mg/kg dexamethasone reduced marked infiltration of neutrophils in renal tissues from LPS rats. Moreover, the survival rate at 18 h was significantly increased in the dexamethasone 0.1 mg/kg-treated group when compared with the LPS group. These results suggest that the beneficial effects of low-dose dexamethasone (0.1 mg/kg) in conscious rats with endotoxic shock are associated with amelioration of circulatory failure and renal dysfunction, and this is attributed to inhibition of NO production.

Animals↗