Differing roles of protein kinase C-zeta in disruption of tight junction barrier by enteropathogenic and enterohemorrhagic Escherichia coli

BACKGROUND & AIMS: Enteropathogenic Escherichia coli and enterohemorrhagic E. coli harbor highly homologous pathogenicity islands yet show key differences in their mechanisms of action. Both disrupt host intestinal epithelial tight junctions, but the effects of enteropathogenic E. coli are more profound than those of enterohemorrhagic E. coli. The basis for this is not understood. The atypical protein kinase C isoform, protein kinase C-zeta, associates with and regulates the tight junction complex. The aim of this study was to compare the role of protein kinase C-zeta in the disruption of tight junctions after infection with enteropathogenic E. coli and enterohemorrhagic E. coli. METHODS: Model intestinal epithelial monolayers infected by enteropathogenic E. coli or enterohemorrhagic E. coli were used for these studies. RESULTS: Neither bisindolylmaleimide nor G?6976, which block several protein kinase C isoforms but not protein kinase C-zeta, protected against the decrease in transepithelial electrical resistance after enteropathogenic E. coli infection. Rottlerin at concentrations that block novel and atypical isoforms, including protein kinase C-zeta, significantly attenuated the decrease in transepithelial electrical resistance. The specific inhibitory peptide, myristoylated protein kinase C-zeta pseudosubstrate, also significantly decreased the enteropathogenic E. coli -associated decrease in transepithelial electrical resistance and redistribution of tight junction proteins. In contrast to enteropathogenic E. coli, the level of protein kinase C-zeta enzyme activity stimulated by enterohemorrhagic E. coli was transient and minor, and protein kinase C-zeta inhibition had no effect on the decrease in transepithelial electrical resistance or the redistribution of occludin. CONCLUSIONS: The differential regulation of protein kinase C-zeta by enteropathogenic E. coli and enterohemorrhagic E. coli may in part explain the less profound effect of the latter on the barrier function of tight junctions.     

Angiotensin-II receptor subtypes in fetal tissue of the rat: autoradiography, guanine nucleotide sensitivity, and association with phosphoinositide hydrolysis.

Quantitative autoradiography revealed large numbers of angiotensin-II (AT) receptors in the 18-day-old rat embryo. The selective AT-1 antagonist DuP 753 readily competed for AT receptors in liver, lung parenchyma, and choroid plexus, and these receptors are classified as AT-1 receptors. The selective AT-2 displacers CGP 42112 A and/or PD 123177 competed with high affinity with AT bound to most receptors located in skeletal muscle, skin, diaphragm, bronchi, and stomach, and these receptors are classified as AT-2 receptors. The amount of AT-2 receptors in fetal tissue was more than 10-fold higher than that of AT-1 receptors. In skeletal muscle and skin, DuP 753 competed with AT in the presence of 10(-7) M CGP 42112 A, indicating the presence of small numbers of AT-1 receptors. In liver and lung parenchyma, binding to AT-1 receptors was sensitive to guanine nucleotides. AT binding to AT-2 receptors in fetal skin and skeletal muscle was insensitive to guanine nucleotides. AT stimulated phosphoinositide hydrolysis in liver (ED50, 64 nM) and in skin and skeletal muscle (ED50, 62 nM); this was inhibited by DuP 753 (liver IC50, 38 nM; skin and skeletal muscle IC50, 26 nM), but not by PD 123177 in concentrations up to the micromolar range. AT-1 receptors are probably coupled to G-proteins, and their stimulation increases phosphoinositide hydrolysis. AT-2 receptors may not be linked to G-proteins, their stimulation is not associated with phosphoinositide hydrolysis, and the nature of their second messenger system(s) is presently unknown.     

Basal Cell Adenoma of the Parotid Gland—A Rare Entity

Salivary gland tumors are uncommon and constitute about 2.0 to 6.5 % of all head and neck tumors. Incidence of basal cell adenoma is about 1 to 3 % of salivary gland tumors. We present a rare case of basal cell adenoma of the parotid and a review of literature.     

Validation of the Osteoporosis-Specific Morisky Medication Adherence Scale in long-term users of bisphosphonates

Purpose

To examine the psychometric properties and validity of the 8-item Osteoporosis-Specific Morisky Medication Adherence Scale (OS-MMAS-8) in postmenopausal women prescribed bisphosphonates (BPs) for at least 15 months.

Methods

A random sample of women aged ≥55 years with osteoporosis prescribed daily or weekly BPs was identified. Pharmacy fill data were extracted to calculate the medication possession ratio (MPR). Eligible women were stratified by low (<0.50), medium (0.50–0.79), or high (≥0.80) MPR, with the a priori goal of recruiting 133 participants in each group. OS-MMAS-8 scores can range from 0 to 8 and were categorized as low (<6), medium (6 to <8), and high (8) adherence. Internal consistency reliability (Cronbach’s alpha), test–retest reliability [intraclass correlation coefficients (ICCs)] and convergent validity (correlating OS-MMAS-8 with MPR and other self-reported measures) were assessed.

Results

A total of 400 women out of 449 respondents reported that they were still taking their BPs at the time of the survey and completed OS-MMAS-8. Overall, 38.5, 34.3, and 27.3 % of participants had low, medium, and high OS-MMAS-8 scores, respectively. The mean (SD) MPRs according to OS-MMAS-8 scores (<6, 6 to <8 and 8) were 56.9 (22.6), 69.0 (24.9), and 76.7 (26.4), respectively. The correlation between OS-MMAS-8 and MPR was 0.36; p < 0.0001. Cronbach’s alpha was 0.74, and the ICC was 0.83 (95 % CI 0.76–0.88).

Conclusions

OS-MMAS-8 has acceptable psychometric properties for assessing medication adherence in postmenopausal women prescribed therapy for osteoporosis. Additional studies are needed to investigate the psychometric properties of OS-MMAS-8 in other settings and populations.     

Diagnostic challenge of large congenital liver cyst in the newborn

Liver cysts in the newborn often pose significant diagnostic challenges. Described herein is a case of large congenital liver cyst that was difficult to diagnose both antenatally and postnatally and which was later diagnosed as Caroli disease.