Esther Berger

Bone remodelling induced by physical stress is prostaglandin E2 mediated

Abstract In vitro cultured bone cells were found to be responsive to hormones and physical forces. A simple device has been developed which enables the direct application of physical forces to tissue culture dishes to which cells are firmly attached. The physical forces created a deformation of the dish. It was found that prostaglandin E2 synthesis underwent a rapid increase, reaching a maximum after 20 min and then declined. Concurrent with the increase in prostaglandin E2 was an increase in cyclic AMP production, having a maximum around 15 min. The increase in cyclic AMP was blocked by indomethacin, the prostaglandin E2 synthesis inhibitor, indicating the dependence of cyclic AMP production on the de novo synthesis of prostaglandin E2. Prostaglandin E2 added to cells mimicked the effect of physical forces on the production of cyclic AMP. The increase in cyclic AMP resulted from an early rise in adenyl cyclase activity (within 5 min) and a later (10 min) increase in phosphodiesterase activity. The same physical forces also stimulatedthe incorporation of thymidine into DNA after 24 h. On addition of prostaglandin E2 the increase in DNA synthesis was also mimicked. Pretreatment of the cells with indomethacin abolished the effect of physical forces on DNA synthesis. The results suggest a stimulus receptor mechanism for physical forces which, like hormonal effectors, are mediated by prostaglandins and stimulate cyclic AMP and DNA synthesis. We believe that physical forces stimulate bone remodelling through such a stimulus receptor system, mediated by prostaglandins.

Calvaria Derived Osteogenic Cells: Phenotypic Expression in Culture

The osteoblast phenotype is characterized by its ability to (a) synthesize a well defined mineralized collagenous matrix, (b) regulate the remodeling process by synthesizing local hormones (PGE2) and specific molecules (osteocalcin) and enzymes (alkaline phosphatase and collagenase), (c) respond to a variety of hormones (PTH, PGs, vitamin-D metabolites, steroids and growth factors), (d) respond to mechanical stimulation. Most of osteoblast culture systems meet many of the above qualifications though most fail to show the PTH effect on DNA synthesis, (c), and mechanical stimulation (d). Here we show that by using trypsin digestion and serum-containing low calcium medium (0.25 mM), all the above listed osteoblast phenotypic characteristics are demonstrated including their responsiveness to mechanical stimulation and the PTH effect on DNA synthesis.

Effect of atorvastatin on IgA nephropathy in the rat.

BACKGROUND IgA nephropathy (IgAN) is the most common chronic glomerulonephritis in humans and is a major cause of end-stage kidney disease worldwide. There is no agreement on the exact underlying mechanism or therapeutic intervention for this disorder. Mesangial proliferation typifies the renal histopathology in IgAN. Statin drugs, as prenylationinhibitors, have been shown to have an antiproliferative effect on renal mesangial cells and to reduce IgAN-associated glomerulusclerosis and proteinuria. The aim of this study is to examine the effect of atorvastatin on kidney function, proteinuria and kidney histology changes in IgANinduced rats. METHODS IgAN was induced in Wistar-Kyoto rats by bovine γ-globulin (BGG). Four groups of rats were treated in metabolic cages: 1) control; 2) atorvastatin (2 mg/kg body weight/day through nasogastric tube) - treated rats; 3) IgAN-rats; 4) IgAN-rats treated with atorvastatin. Urine volume, urine protein excretion, blood urea and creatinine concentrations in addition to creatinine clearance were examined every 14 days, throughout the duration of the study (56 days). All kidneys from sacrificed rats were examined for histology including glomerular cell nuclei count and immunofluorescence. RESULTS There were no differences in blood creatinine concentrations between the groups. Creatinine clearance was lower on the 42nd day and proteinuria was higher on Days 14, 42 and 56, in rats in Group 3 compared to all others; additionally, histology examination revealed a higher glomerular cell nuclei count in this group. Immunofluorescence was equally positive for IgA in mesangial cells in the kidneys from rats of Groups 2, 3 and 4. CONCLUSIONS Atorvastatin attenuates kidney-function impairment, proteinuria and mesangial cell proliferation in BGG model of IgANinduced rats.

The effect of poly (ADP-ribose) polymerase inhibition on aminoglycoside-induced acute tubular necrosis in rats.

INTRODUCTION Aminoglycosides (AG) cause nephrotoxicity in 10 - 20% of patients. One of the mechanisms is by generating reactive oxygen species (ROS), leading to DNA destruction and activation of poly(ADPribose) polymerase (PARP) causing necrotic tubular cell death. PARP inhibition on gentamicin-induced nephrotoxicity was studied. METHODS 19 female Wistar-Kyoto rats divided into 3 groups: control (3 rats receiving no treatment); gentamicin-treated group (8 rats); and 8 rats treated with gentamicin combined with 3-aminobenzamide (3 AB). Kidney functions, protein, and gentamicin levels as well as urinary trypsin inhibitory activity (TIA) were measured. Tissue microscopic examination and immunohistochemical study for proliferative cell nuclear antigen (PCNA) were determined. The effect of PARP inhibitor on the bactericidal activity of gentamicin was also assessed. RESULTS The following results were statistically significant: urea (mg/dL) 39.9 ± 5.86, 88.3 ± 50.3, and 48.5 ± 12.7 (p = 0.048); serum creatinine (mg/dL): 0.6 ± 0.26, 1.05 ± 0.7, 0.6 ± 0.06 (p = 0.043); proteinuria (mg/24-hours): 7.27 ± 3.65, 41.2 ± 18.1, and 17.6 ± 13.9 (p = 0.050); the number of tubular macronuclei (per 10 mm2): 18.33 ± 16.07, 218 ± 101.8, 41.7 ± 36.2 (p = 0.012); the number of dilated tubes (per 10 mm2): 61.67 ± 12.58, 276.3 ± 112.7, 140.0 ± 90.9 (p = 0.04); and the number of PCNA positive nuclei (per 10 mm2): 223.3 ± 95.69, 3,585 ± 2,215.3, 626.7 ± 236.9 (p = 0.034) in the control, gentamicin, and gentamicin+3AB-treated groups, respectively. The following biochemical and histologic parameters were also examined, however, they showed no statistically significant difference: TIA (p = 0.055), mitoses (p = 0.14), mononuclear infiltrate (p = 0.188), and intratubular cast formation (p = 0.084). No effect on bactericidal activity was observed. CONCLUSION This study illustrates that PARP inhibitor significantly attenuates gentamicin-induced nephrotoxicity in rats with no effect on the bactericidal activity.

Expression of CA125 in Tissue and Serum of Uterine Serous Carcinoma Patients

Uterine serous carcinoma (USC) represents only about 10% of endometrial cancer cases. It is an aggressive tumor with a poor prognosis that is diagnosed in advanced stages in about 40% of the cases and it accounts for a disproportionate number of uterine cancer-related deaths. Even in apparent clinical early stage disease, USC is found to have unfavorable pathological prognostic factors such as lymphovascular space invasion, lymph node involvement, and microscopic intraperitoneal spread [1,2].

The Effect of Cyclooxygenase-2 Expression in Uterine Carcinosarcoma on Survival: A Reassessment Based on Mature Data.

Objective To reassess the effect cyclooxygenase-2 (COX-2) expression in carcinosarcoma on survival based on mature 5-year survival data. Method A comparison of 5-year survival of 27 patients with carcinosarcoma according to the presence of COX-2 immunohistochemical staining and staining score was performed. Results The 5-year survival of those with positive and negative COX-2 staining was statistically not different. However, there was a clear trend for more favorable 5-year survival in patients with a high staining score than in those with a low score, and the difference was of borderline significance (38.5% vs 7.1%; P = 0.06). Conclusion In view of the role of COX-2 in carcinogenesis, our finding that COX-2 expression may confer a better survival in patients with carcinosarcoma is intriguing. Larger studies are indicated to elucidate the effect of COX-2 expression on survival in patients with carcinosarcoma because this may have therapeutic implications.

COX-2 Expression in Nonepithelial Ovarian Malignancies

The aim of the study was to assess the expression of cyclooxygenases (COX)-2 in nonepithelial ovarian malignancies.COX-2 immunohistochemical staining was performed on newly prepared deparaffinized slides from formalin-fixed, paraffin-embedded archival tissue blocks of unselected nonepithelial ovarian malignancies diagnosed between January 1993 and October 2009 after reconfirmation of the diagnosis. Staining was assessed according to intensity of staining and the proportion of stained cells. Staining of more than 10% of the cells was considered positive.During the study period, 26 histologically proven nonepithelial ovarian malignancies were diagnosed. Of them, 16 were granulosa cell tumors and 10 were germ cell tumors (4 dysgerminomas and 6 immature teratomas). Five (31.2%) granulosa cell tumors had positive immunohistochemical COX-2 staining. Positive staining was observed only in 1 immature teratoma and in none of the dysgerminomas.Our data seem to indicate that COX-2 expression by immunohistochemical methods is not frequent in nonepithelial ovarian malignancies.