Providencia alcalifaciens causes barrier dysfunction and apoptosis in tissue cell culture: potent role of lipopolysaccharides on diarrheagenicity

Providencia alcalifaciens is a member of the Enterobacteriaceae family that occasionally causes diarrheagenic illness in humans via the intake of contaminated foods. Despite the epidemiological importance of P. alcalifaciens, little is known about its pathobiology. Here we report that P. alcalifaciens causes barrier dysfunction in Caco-2 cell monolayers and induces apoptosis in calf pulmonary artery endothelial cells. P. alcalifaciens infection caused a 30% reduction in transepithelial resistance in Caco-2 cell monolayers, which was greater than that for cells infected with Shigella flexneri or non-pathogenic Escherichia coli. As with viable bacteria, bacterial lysates treated with heat, benzonase or proteinase, but not with polymixin B, were also involved in the cellular response. TLR4 antibody neutralisation significantly restored the P. alcalifaciens-induced transepithelial resistance reduction in Caco-2 cells, suggesting that lipopolysaccharides (LPSs) might play a central role in this cellular response. Western blotting further indicated that P. alcalifaciens LPSs reduced occludin levels, whereas LPSs from Shigella or E. coli did not. Although the viability of Caco-2 cells was not altered significantly, the calf pulmonary artery endothelial cell line was highly sensitive to P. alcalifaciens infection. This sensitivity was indeed dependent on LPS, which induced rapid apoptosis. Together, these data show that P. alcalifaciens LPSs participate in epithelial barrier dysfunction and endothelial apoptosis. The findings give insight into the LPS-dependent cell signal events affecting diarrheagenicity during infection with P. alcalifaciens.     

Effects of Icariside II on Corpus Cavernosum and Major Pelvic Ganglion Neuropathy in Streptozotocin-Induced Diabetic Rats

Diabetic erectile dysfunction is associated with penile dorsal nerve bundle neuropathy in the corpus cavernosum and the mechanism is not well understood. We investigated the neuropathy changes in the corpus cavernosum of rats with streptozotocin-induced diabetes and the effects of Icariside II (ICA II) on improving neuropathy. Thirty-six 8-week-old Sprague-Dawley rats were randomly distributed into normal control group, diabetic group and ICA-II treated group. Diabetes was induced by a one-time intraperitoneal injection of streptozotocin (60 mg/kg). Three days later, the diabetic rats were randomly divided into 2 groups including a saline treated placebo group and an ICA II-treated group (5 mg/kg/day, by intragastric administration daily). Twelve weeks later, erectile function was measured by cavernous nerve electrostimulation with real time intracorporal pressure assessment. The penis was harvested for the histological examination (immunofluorescence and immunohistochemical staining) and transmission electron microscopy detecting. Diabetic animals exhibited a decreased density of dorsal nerve bundle in penis. The neurofilament of the dorsal nerve bundle was fragmented in the diabetic rats. There was a decreased expression of nNOS and NGF in the diabetic group. The ICA II group had higher density of dorsal nerve bundle, higher expression of NGF and nNOS in the penis. The pathological change of major pelvic nerve ganglion (including the microstructure by transmission electron microscope and the neurite outgrowth length of major pelvic nerve ganglion tissue cultured in vitro) was greatly attenuated in the ICA II-treated group (p < 0.01). ICA II treatment attenuates the diabetes-related impairment of corpus cavernosum and major pelvic ganglion neuropathy in rats with Streptozotocin-Induced Diabetes.     

Structure‐Dependent Mitochondrial Dysfunction and Hypoxia Induced with Single‐Walled Carbon Nanotubes

Cytotoxicity of nanomaterials on living systems is known to be affected by their size, shape, surface chemistry, and other physicochemical properties. Exposure to a well‐characterized subpopulation of specific nanomaterials is therefore desired to reveal more detailed mechanisms. This study develops scalable density gradient ultracentrifugation sorting of highly dispersed single‐walled carbon nanotubes (SWNTs) into four distinct bands based on diameter, aggregation, and structural integrity, with greatly improved efficiency, yield, and reproducibility. With guarantee of high yield and stability of four SWNT fractions, it is possible for the first time, to investigate the structure‐dependent bioeffects of four SWNT fractions. it is possible Among these, singly‐dispersed integral SWNTs show no significant effects on the mitochondrial functions and hypoxia. The aggregated integral SWNTs show more significant effects on the mitochondrial dysfunction and hypoxia compared to the aggregated SWNTs with poor structure integrity. Then, it is found that the aggregated integral SWNTs induced the irregular mitochondria respiratory and pro‐apoptotic proteins activation, while aggregated SWNTs with poor structure integrity greatly enhanced reactive oxygen species (ROS) levels. This work supports the view that control of the distinct structure characteristics of SWNTs helps establish clearer structure‐bioeffect correlation and health risk assessment. It is also hoped that these results can help in the design of nanomaterials with higher efficiency and accuracy in subcellular translocation.     

Neuropsychology and imaging.

Introduces this special of issue of Neuropsychology, the theme of which is Neuropsychology and Imaging. The question for neuropsychology is no longer how to locate the lesions, but, rather, how to consistently relate neuropsychological dysfunctionings with the image of the lesion. Both questions are easier to answer when lesions are better circumscribed. Answers are more difficult in the presence of multiple, diffuse, or subcortical lesions. In order to address the more difficult questions, this issue includes papers by Levin and High, Wilson et al., Wiednann et al., and Jernigan and Butters which are devoted to challenging clinical diseases (head injury, Alzheimer's, and Huntington's) where lesions and dysfunctionings are not consistently defined. Interestingly, some disease-related correlations emerge from these papers, and SPECT data are viewed as well. Correlating neuropsychological and imaging measurements is both unbounded and restrained. Papers in this special issue on Neuropsychology and Imaging highlight this, and the issues and concerns for future investigations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Impaired reversal but intact acquisition: Probabilistic response reversal deficits in adult individuals with psychopathy.

The performance of adult psychopathic individuals on a novel response reversal task involving 2 reward-punishment contingencies (100-0 and 80-20) was investigated. In line with predictions, adults with psychopathy presented with impairment on the response reversal component but not on the acquisition component of this task. This selective impairment for response reversal was seen for both reward-punishment contingencies and was related to the tendency of individuals with psychopathy to be less likely to stay with a rewarded correct response to a stimulus on the subsequent presentation of that stimulus. Results are discussed with reference to current models of the development of psychopathy. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Inflammation as a cause of malnutrition, atherosclerotic cardiovascular disease, and poor outcome in hemodialysis patients

Cardiovascular disease (CVD) remains the major cause of morbidity and mortality in end‐stage renal disease (ESRD) patients treated by hemodialysis (HD). Although traditional risk factors are common in dialysis patients, they may not alone be sufficient to account for the unacceptable high prevalence of CVD in this patient group. Recent evidence demonstrates that chronic inflammation, a nontraditional risk factor that is commonly observed in HD patients, may cause malnutrition and progressive atherosclerotic CVD by several pathogenetic mechanisms. The cause(s) of inflammation in HD patients is multifactorial and includes both dialysis‐related (such as graft and fistula infections, bioincompatibility, impure dialysate, and back‐filtration) and dialysis‐unrelated factors. Although inflammation may reflect underlying CVD, an acute‐phase reaction may also be a direct cause of vascular injury. Available data suggest that proinflammatory cytokines play a central role in the genesis of both malnutrition and CVD in ESRD. Thus, it could be speculated that suppression of the vicious cycle of malnutrition, inflammation, and atherosclerosis (MIA syndrome) would improve survival in dialysis patients. As there is not yet any recognized, or even proposed, targeted treatment for ESRD patients with chronic inflammation; it would be of considerable interest to study the long‐term effect of various anti‐inflammatory treatment strategies on nutritional and cardiovascular status as well as outcome in these patients.     

Clinical adolescent psychology: What it is, and what it needs to be.

This commentary on the special section on clinical adolescent psychology (G. Holmbeck & P. Kendall, 2002) reviews and critiques the conceptual and empirical articles that this compilation comprises. As articulated in the conceptual contributions to this collection, two fundamental principles should guide research on the etiology, prevention, and treatment of psychological disorder and dysfunction during adolescence: First, drawing on the field of developmental psychopathology, the study of clinical adolescent psychology should focus on the trajectories of disorder that precede, characterize, and follow adolescence. Second, drawing on the literature on normative adolescent development, the study of clinical adolescent psychology must proceed with an explicit recognition of the unique biological, cognitive, psychosocial, and contextual features that define adolescence as a developmental period. Although the study of clinical adolescent psychology, as evidenced by this collection of articles, is appropriately grounded in the broader enterprise of developmental psychopathology, less progress has been made with respect to die integration of the study of clinical phenomena in adolescence with the study of normative adolescent development. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Reading difficulty--a psycho-educational analysis of a cognitive dysfunction.

Although much progress has been achieved in the field of education in the last half-century, it is still a fact that a great number of our children are not achieving their full learning potential, and we are facing an ever growing number of children with reading difficulties. According to a recent survey in a big urban centre in U.S.A., 28 per cent of all sixth-graders were found to read two or more grades below the expected grade level, which is the conventional definition of severe reading retardation. And yet this state of affairs seems paradoxical because reading is considered, and known to be, a very easy learning task. It is a psychologically and educationally known fact that from age 4-5 reading can be acquired at any age as proven by educational movements against illiteracy throughout the world. Although, in essence, reading is a purely educational problem-reading difficulty, its nature, its varieties of expression and its causality, extend far beyond the reaches and comprehension of an educational system. This is why education found itself suddenly embracing confusingly a multitude of professions, each one pulling in its own direction. In our opinion, the problem can be solved only if a sound functional interaction is established between education, psychology and medicine. This interaction was achieved in the Children's Service of Douglas Hospital, where teachers, psychologists and psychiatrists work together. The result of this cooperation is a different approach towards the understanding of reading difficulty and the remedial-corrective measures to be developed. We conceive of reading difficulty primarily as a symptom of a cognitive-dysfunction. Following this basic assumption we are developing a new "Thematic-sequential" reading-primer which will not only give the teacher an educationally conceived method, but also takes into consideration the nature of the reading difficulties on a background of impaired cognitive development. (PsycINFO Database Record (c) 2010 APA, all rights reserved)