Internalization of extraintestinal Escherichia coli O18 strains by epithelial cells is modulated by EGF, insulin, and effectors of transmembrane signal transduction

Adhesion to and internalization into host cells is an essential step in the pathogenesis of various bacterial infections. Here we investigated the effects of growth factors on the internalization of Escherichia coli O18 strains isolated from patients with urinary tract infection (UTI) by human epithelial cells. A dramatic increase in the uptake of Escherichia coli was observed after treatment of epithelial cells with epidermal growth factor (EGF) and to a lower extent with insulin. EGF-dependent internalization can be suppressed by tyrosine kinase inhibitors suggesting an involvement of the receptor tyrosine kinases in the regulation of the endocytotic process. Inhibitors of phospholipase A2, lipoxygenase, and cyclooxygenase significantly decreased internalization of bacteria induced by EGF. Finally, the specific inhibitor of PI 3-kinases Wortmannin was shown to suppress completely the EGF-independent internalization. The data of this analysis indicate the involvement of several signaling paths in bacterial internalization of uropathogenic Escherichia coli O18 strains and contribute to the comprehension of the pathogenesis of recurrent UTI.     

CD8+T-bet+ cells as a predominant biomarker for inclusion body myositis

Background

Myositis is a heterogeneous group of muscular auto-immune diseases with clinical and pathological criteria that allow the classification of patients into different sub-groups. Inclusion body myositis is the most frequent myositis above fifty years of age. Diagnosing inclusion body myositis requires expertise and is challenging. Little is known concerning the pathogenic mechanisms of this disease in which conventional suppressive-immune therapies are inefficacious.

Reduced protein tyrosine phosphatase (PTPase) activity of CD45 on peripheral blood lymphocytes in patients with systemic lupus erythematosus (SLE)

To disclose the mechanism of aberrant function of peripheral blood lymphocytes (PBL) in SLE, we focused on the catalytic function of CD45, and determined the CD45 PTPase activity in SLE patients. The sample population consisted of 32 SLE patients with different disease activity. PTPase activity of cell lysates immunoprecipitated by anti-CD45 MoAb was assayed against phosphotyrosine analogue PNPP, followed by measuring the release of para-nitro phenol at 410 nm. CD45 PTPase activity of PBL was significantly decreased in SLE patients, compared with that of normal controls and patients with systemic sclerosis (964 ± 265, 1202 ± 172, 1210 ± 125, respectively; SLE versus normal, P < 0.05). It was correlated with SLE Disease Activity Index (SLEDAI) score (r = 0.597, P = 0.0006), but not with the dose of prednisolone (r = 0.214, P = 0.2657), indicating that CD45 PTPase activity became reduced when the disease was active, but it was not affected by prednisolone. Moreover, it was not corrected by in vitro culture with or without stimulation. The expression of CD45 on PBL was comparable between normal and SLE, raising a possibility that it may be due to aberrant regulation of catalytic function of CD45 in SLE. Given the evidence that tyrosine phosphorylation of cellular proteins by tyrosine kinases and phosphatases is one of the key biochemical events in the signal transduction pathway, the decreased CD45 PTPase activity in SLE may account for the defective signal transduction via TCR/CD3, leading to dysregulated effector function of the lymphocytes.     

Computerised analysis of auscultatory sounds associated with vascular patency of haemodialysis access

Vascular access for renal dialysis is a lifeline for about 120 000 individuals in the United States. Stethoscope auscultation of vascular sounds has some utility in the assessment of access patency, yet can be highly skill-dependent. The objective of the study was to identify acoustic parameters that are related to changes in vascular access patency. The underlying hypothesis is that stenoses of haemodialysis access vessels or grafts cause vascular sound changes that are detectable using computerised data acquisition and analysis. Eleven patients participated in the study. Their vascular sounds were recorded before and after angiography, which was accompanied by angioplasty in most patients. The sounds were acquired using two electronic stethoscopes and then digitised and analysed on a personal computer. Vessel stenosis changes were found to be associated with changes in acoustic amplitude and/or spectral energy distribution. Certain acoustic parameters correlated well (correlation coefficient=0.98, p<0.0001) with the change in the degree of stenosis, suggesting that stenosis severity may be predictable from these parameters. Parameters also appeared to be sensitive to modest diameter changes (>20%), (p<0.005, Wilcoxon rank sum test). These results suggest that computerised analysis of vascular sounds may be useful in vessel patency surveillance. Further testing using longitudinal studies may be warranted.     

Beta-catenin abnormalities and associated insulin-like growth factor overexpression are important in phyllodes tumours and fibroadenomas of the breast

The aim of this study was to assess the expression of IGF-I and IGF-II in phyllodes tumours and fibroadenomas and to see if there is any correlation between nuclear beta-catenin expression and IGF-I and IGF-II expression in these tumours. In a previous study, it has been shown that Wnt signalling is important in the pathogenesis of phyllodes tumours of the breast. Epithelial Wnt5a overexpression and stromal Wnt2 overexpression were associated with abnormal, nuclear localization of beta-catenin in the stromal cells of these tumours. However, not all tumours with beta-catenin accumulation showed Wnt overexpression. One other possible cause of beta-catenin accumulation is overexpression of insulin-like growth factors (IGFs), as both IGF-I and IGF-II have been shown to stabilize beta-catenin. In this study, 30 fibroadenomas of the breast were assessed for beta-catenin expression using immunohistochemistry and the results were compared with previous data from 119 phyllodes tumours. In situ hybridization was used to assess IGF-I and IGF-II expression in 23 phyllodes tumours and 16 fibroadenomas. Nineteen phyllodes tumours (83%) showed widespread overexpression of IGF-II and 5/23 (22%) showed widespread overexpression of IGF-I. IGF-I expression correlated with nuclear beta-catenin staining in phyllodes tumours. Malignant phyllodes tumours showed no or little IGF-I expression. There was a degree of nuclear beta-catenin expression in the stroma (weak in 33%, moderate in 27%, and strong in 40%) in all fibroadenomas and nuclear beta-catenin staining correlated with IGF-I overexpression. Extensive IGF-II overexpression was also found in the majority of fibroadenomas (12/16). These results support the hypothesis that IGF-I and IGF-II overexpression may be important in the pathogenesis of fibroepithelial neoplasms of the breast and that IGF-I overexpression is likely to be contributing to the nuclear beta-catenin localization observed in the tumours.     

Median frequency of the myoelectric signal

Summary A study was performed to investigate the changes that occur in the median frequency of the myoelectric signal during local ischemia or reduction of intramuscular temperature produced by surface cooling. Data was obtained from experiments which involved the first dorsal interosseous muscle of 10 female and 16 male subjects. These subjects were asked to perform isometric constant-force abduction contractions of the index finger at 20% and 80% of maximal voluntary contraction level. The initial median frequency (IMF) of the myoelectric signal during the first 0.5 s of contraction was calculated. Results showed a significant reduction of the IMF in contractions performed under ischemic conditions; upon release, the IMF recovered quickly. At 80% maximal voluntary level of contraction, a greater decrease of the IMF was recorded. Similar results were demonstrated during reduction of intramuscular temperature with gradual recovery of the IMF after cooling. These results demonstrate that the median frequency of the myoelectric signal displays behavior similar to that reported for conduction velocity and this is consistent with the notion that accumulation of metabolic byproducts in muscle tissue causes a decrease in the conduction velocity of the muscle fibers.Dr. R. Merletti was on a leave of absence from the Institute of Electrical Engineering, Politecnico di Torino, Italy     

Human immunodeficiency virus-associated changes in signal transduction

It is well established that the activation of T lymphocytes by mitogen/antigen is accompanied by a rise in intracellular free calcium ([Ca²⁺]_i), changes in membrane potential, metabolism of inositol phospholipid, and activation of protein kinase C. Theseearly events of signal transduction culminate inlate events of lymphocyte activation, namely, DNA synthesis, lymphokine production, and cellular proliferation. In this study we examined the effect of human immunodeficiency virus (HIV) on changes in membrane potential and [Ca²⁺]_i levels. The membrane potentials were markedly decreased (depolarized) in T cell lines infected with HIV (H9/HTLV IIIb) and did not respond normally to phytohemagglutinin (PHA) or anti-T3 (anti-CD3) monoclonal antibody compared to uninfected H9 cell line. The basal [Ca²⁺]_i levels in H9/HTLV IIIb cells were increased in comparison to those in H9 cells; however, there was very little further increase in [Ca²⁺]_i in H9/HTLV IIIb cells following activation with PHA or anti-T3 monoclonal antibody. This is in contrast to a significant rise in [Ca²⁺]_i in H9 cells following similar stimulation. These data demonstrate abnormalities in the plasma membrane potential and [Ca²⁺]_i levels in chronically infected T cells with HIV. These abnormalities in signal transduction of the T-cell activation pathway could be responsible for T-cell dysfunction in patients with HIV infection.     

Improvement in Doppler ultrasound human foetal heart rate records by signal correlation

An improved method for the determination of foetal heart rate from Doppler ultrasound signals is described and evaluated. It determines the most probable pulse interval from the recurrence times of multiple echoes generated by each cardiac pulse. The method, when optimised, is shown to offer an improvement over current systems, especially in reduced signal loss.