High on/off ratios in bilayer graphene field effect transistors realized by surface dopants

The unique property of bilayer graphene to show a band gap tunable by external electrical fields enables a variety of different device concepts with novel functionalities for electronic, optoelectronic, and sensor applications. So far the operation of bilayer graphene-based field effect transistors requires two individual gates to vary the channel's conductance and to create a band gap. In this paper, we report on a method to increase the on/off ratio in single gated bilayer graphene field effect transistors by adsorbate doping. The adsorbate dopants on the upper side of the graphene establish a displacement field perpendicular to the graphene surface breaking the inversion symmetry of the two graphene layers. Low-temperature measurements indicate that the increased on/off ratio is caused by the opening of a mobility gap.

N-3 Fatty Acid Supplementation Influences Membrane Fatty Acids and Phospholipase A2 Activity in Patients at Risk to Develop Psychosis

Introduction

Decreased levels of polyunsaturated membrane fatty acids (PUFA) and increased activity of cytosolic phospholipase A2 (PLA2) enzymes (key regulating enzymes of membrane remodelling and PUFA availability) are supporting pillars of the “membrane phospholipids concept of schizophrenia”. Assuming that membrane PUFA profile and PLA2 activity are altered during the at risk phase of disorder and influenced by fatty acid supplementation, we investigated PUFA profiles and PLA2 activity simultaneously in ultra high-risk (UHR) subjects before and after (n-3) fatty acids supplementation.

Method

In 81 UHR patients (aged between 13 and 25 years) PUFA levels were assessed in erythrocyte membranes using gas chromatography, and cytosolic PLA2 activity was measured in blood serum using a fluorometric HPTLC-based assay. Measurements were performed before and after a 6 month interval of placebo-controlled supplementation with n-3 fatty acids.

Results

At baseline significant associations were found between (n-9) and (n-6)-PUFA levels and psychopathology (especially in negative symptoms) assessed by the PANSS according to PACE criteria. (n-3)-PUFA supplementation caused significant changes in (n-3)- and (n-6)-PUFA levels and a significant decrease of PLA2 activity.

Conclusion

Our results support associations between membrane biochemistry and psychopathology (especially negative symptoms) in people at risk to develop psychosis. Supplementation of n-3 PUFA increases PUFA availability at membrane level and modulates membrane repair and remodelling processes. Assuming that PLA2 activity reflects neuronal damage, PUFA supplementation might unfold neuroprotective effects.

[Meniscal degeneration score and NITEGE expression : immunohistochemical detection of NITEGE in advanced meniscal degeneration]

BACKGROUND

Meniscal degeneration (MD) is a structural change of fibrous cartilage that is common in orthopaedic diagnostics and relevant for health insurance matters. So far, there has been neither a standardised scoring system nor an immunohistochemical marker for MD.

MATERIAL AND METHOD

In this retrospective trial, the meniscal tissue of 60 patients was assessed immunohistochemically for NITEGE (G1 fragment of the proteoglycan aggrecan) expression. NITEGE expression was correlated with defined grades of MD: little (grade 0/1), medium (grade 2), or severe (grade 3).

RESULTS

Detection of extracellular NITEGE deposits in grade 2 or 3 MD had a positive predictive value and specificity of 100%, whereas no deposits were found in grade 0/1 MD. Sensitivity in advanced MD was 55%. Detection of extracellular NITEGE correlated positively with the grade of degeneration, as did patient age and the grade of degeneration. The patient age of those with grade 0/1 MD was significantly lower than for grade 3 (p<0.0001).

CONCLUSION

The thoroughly defined degeneration score (grade 1 - grade 3 MD) is suitable to assess the severity of degeneration. Extracellular NITEGE deposits can be regarded as an immunohistochemical marker for advanced (grades 2 and 3) MD.

S100B in the cerebrospinal fluid--a marker for glial damage in the rabbit model of pneumococcal meningitis

The rabbit model provides an important experimental setting for the evaluation of antibiotic agents against pneumococcal meningitis. One of the primary targets of this model is the study of neuronal and glial cell damage in bacterial meningitis. The aim of this investigation was to evaluate whether a significant increase of S100B in the cerebrospinal fluid (CSF) as an indicator of white matter damage could be observed in this meningitis model. Seven rabbits were infected intracisternally with S. pneumoniae, and CSF S100B concentrations were examined serially before infection, at 12h, 14h, 17h, 20h, and at 24h after infection. The course of CSF S100B increase and its relation to other parameters of brain tissue destruction and CSF inflammation were measured. Axonal damage was visualized by amyloid precursor protein (APP) immunostaining and demyelination by Luxol Fast Blue/Periodic Acid Schiff (LFB-PAS) stain. In each animal, we observed a distinct rise in S100B concentration in the CSF due to pneumococcal meningitis. We conclude that the CSF concentration of the glial S100B protein can be used as an additional parameter for future interventional studies focusing on glial cell damage in the rabbit model of bacterial meningitis.

Tauopathies with parkinsonism: clinical spectrum, neuropathologic basis, biological markers, and treatment options

Tauopathies with parkinsonism represent a spectrum of disease entities unified by the pathologic accumulation of hyperphosphorylated tau protein fragments within the central nervous system. These pathologic characteristics suggest shared pathogenetic pathways and possible molecular targets for disease-modifying therapeutic interventions. Natural history studies, for instance, in progressive supranuclear palsy, frontotemporal dementia with parkinsonism linked to chromosome 17, corticobasal degeneration, and Niemann-Pick disease type C as well as in amyotrophic lateral sclerosis/Parkinson-dementia complex permit clinical characterization of the disease phenotypes and are crucial to the development and validation of biological markers for differential diagnostics and disease monitoring, for example, by use of neuroimaging or proteomic approaches. The wide pathologic and clinical spectrum of the tauopathies with parkinsonism is reviewed in this article, and perspectives on future advances in the understanding of the pathogenesis are given, together with potential therapeutic strategies.

Tauopathies with parkinsonism: clinical spectrum, neuropathologic basis, biological markers, and treatment options

Tauopathies with parkinsonism represent a spectrum of disease entities unified by the pathologic accumulation of hyperphosphorylated tau protein fragments within the central nervous system. These pathologic characteristics suggest shared pathogenetic pathways and possible molecular targets for disease-modifying therapeutic interventions. Natural history studies, for instance, in progressive supranuclear palsy, frontotemporal dementia with parkinsonism linked to chromosome 17, corticobasal degeneration, and Niemann-Pick disease type C as well as in amyotrophic lateral sclerosis/Parkinson-dementia complex permit clinical characterization of the disease phenotypes and are crucial to the development and validation of biological markers for differential diagnostics and disease monitoring, for example, by use of neuroimaging or proteomic approaches. The wide pathologic and clinical spectrum of the tauopathies with parkinsonism is reviewed in this article, and perspectives on future advances in the understanding of the pathogenesis are given, together with potential therapeutic strategies.

Incidentally discovered adrenal tumors: a lesson from observation of 1,444 patients

This study was aimed at summarizing our experience in the management of 1,444 patients with incidentally found adrenal tumors observed at a single endocrinological centre. Hormonal determinations were performed in all patients at the beginning of the observation period to detect subclinical adrenal hyperfunction. The imaging phenotype on CT and MRI was analyzed for defining the malignant potential of the tumors. Based on the results of these examinations we diagnosed among our cohort probably benign masses in 87%, malignant tumors in 10% (adrenal carcinoma - 9%), and metastases in 3%. Subclinical hyperfunction was diagnosed in 8%; the most frequent was the pre-Cushing's syndrome. A subgroup of 480 patients (33%) was submitted to surgery because of oncological or endocrinological indications. The patients not qualified for surgery were carefully controlled by imaging and hormonal examinations. Malignancy is the most serious risk in the group of patients with incidentally discovered adrenal tumors.

Colocalization of C4d deposits/CD68+ macrophages in rheumatoid nodule and granuloma annulare: immunohistochemical evidence of a complement-mediated mechanism in fibrinoid necrosis

Rheumatoid nodule (RN) represents a palisading granuloma with central fibrinoid necrosis, which is not only a classical manifestation of rheumatoid arthritis (RA) and part of the American College of Rheumatology (ACR)-criteria, but also is its diagnostic hallmark. The pathogenesis of RN is still not fully understood. At present, only data on serum analyses indicating a complement-mediated pathogenesis in the development of RA are available. Equivalent examinations for RN have not yet been performed. Granuloma annulare (GA) represents another type of palisading granuloma. A special subtype of GA, subcutaneous GA (SGA), is an important differential diagnosis to RN. Therefore, our aim was to examine RN and SGA regarding the complement deposition (C4d) by immunohistochemical means. All RN and GA were stained by hematoxylin/eosin and different special stains. In addition, all specimens were stained immunohistochemically with antibodies against CD68. Five GA and five RN were analyzed immunohistochemically with antibodies against C4d and CD68, and evaluated using single- and doublestaining immunohistochemistry. All RN and GA displayed depositions of C4d within their central necroses and between the surrounding palisading macrophages. Most importantly, C4d/CD68 double staining was visible in the palisading macrophages next to the necroses, while macrophages in the periphery were negative for C4d but positive for CD68. The main difference between RN and GA was a quantitative phenomenon with less positively reacting macrophages in a more incomplete palisade in GA. The positive reactions of all central necroses to C4d and colocalization of CD68 and C4d suggest that a complement-mediated mechanism may be operative in the formation of fibrinoid necrosis. This mechanism may be involved in any form of "fibrinoid necrosis", since no different patterns of C4d/CD68 expression could be observed in GA. This may explain why RG/GA are not distinguishable morphologically.

Staphylococcal biofilms

Staphylococcus epidermidis and Staphylococcus aureus are the most frequent causes of nosocomial infections and infections on indwelling medical devices, which characteristically involve biofilms. Recent advances in staphylococcal molecular biology have provided more detailed insight into the basis of biofilm formation in these opportunistic pathogens. A series of surface proteins mediate initial attachment to host matrix proteins, which is followed by the expression of a cationic glucosamine-based exopolysaccharide that aggregates the bacterial cells. In some cases, proteins may function as alternative aggregating substances. Furthermore, surfactant peptides have now been recognized as key factors involved in generating the three-dimensional structure of a staphylococcal biofilm by cell-cell disruptive forces, which eventually may lead to the detachment of entire cell clusters. Transcriptional profiling experiments have defined the specific physiology of staphylococcal biofilms and demonstrated that biofilm resistance to antimicrobials is due to gene-regulated processes. Finally, novel animal models of staphylococcal biofilm-associated infection have given us important information on which factors define biofilm formation in vivo. These recent advances constitute an important basis for the development of anti-staphylococcal drugs and vaccines.

1,161 patients with adrenal incidentalomas: indications for surgery

BACKGROUND AND AIMS

The aim of this study is to analyze the clinical data and criteria for surgery in a group of over 1,100 patients with adrenal incidentalomas (AI) observed at the Department of Endocrinology.

PATIENTS AND METHODS

The material consisted of 1,161 patients (842 women and 319 men, 10-87 years old) with AI ranging in size from 1.0 to 23.0 cm. The methods included clinical examination, imaging studies, hormonal determinations in the blood and in the urine as well as histological and immunocytochemical investigations in 390 patients treated by surgery.

RESULTS

Basing on these studies, we diagnosed 112 patients with primary malignant adrenal tumors (100 with carcinoma), 45 with metastatic infiltrations, and 1,004 with probable benign AI. Imaging phenotypes (especially high density on computed tomography, CT) were characteristic of malignant and chromaffin tumors. Subclinical adrenal hyperactivity was found in 8% of the patients with pre-Cushing's syndrome as the most frequent form (6.5%). Chromaffin tumors were detected in 3%.

CONCLUSIONS

(1) Indications for surgery include malignant tumors (both primary and metastatic), tumors with subclinical hyperfunction, and chromaffin tumors. High density on CT, >20 HU, appeared to be an important indication for surgery. (2) A slight prevalence of oncological indications over endocrinological indications (14 vs. 11%) was found.

Analysis of early death based on the prediction model in Wegener's granulomatosis with pulmonary and renal involvement

The prognosis for patients with Wegener's granulomatosis has improved considerably over the last decades. The aim of the study was to assess the early death risk based on the prediction model in a population-based cohort of 60 patients with Wegener's granulomatosis. Clinical analysis has been conducted using the disease extent index (DEI) and Birmingham Vasculitis Activity Score for Wegener's Granulomatosis (BVAS/WG) questionnaires for disease activity. Logistic regression analysis and a Wilcoxon test were included into the statistics. Survival time and death risk were assessed using the Kaplan-Meier estimator and the Cox proportional hazard model. An Receiver Operating Characteristic curve or ROC curve was employed to estimate the value of logistic regression. The early death risk was 16 times higher (P<0.02) in the dialyzed patients and 15 times higher (P<0.05) in the patients with cough as compared with the patients without those predicaments. Predictors of early death are: disease duration, hemoglobin concentration, necessity of dialysis and occurrence of cough. Simultaneous renal and respiratory tract involvement is associated with the highest early death risk.

The role ANCA and anti-GBM antibodies in pulmonary-renal syndrome due to Wegener's granulomatosis

Pulmonary-renal syndrome (PRS) is defined as a diffuse alveolar hemorrhage and rapidly progressive glomerulonephritis. We present a retrospective study of 22 consecutive patients with Wegener's granulomatosis (WG). Logistic regression analysis and a Wilcoxon test were included in the statistics. Survival time death risk were assessed using the Kaplan-Meier estimator and the Cox proportional hazard model. At recognition, the median Birmingham Vasculitis Activity Score for Wegener's Granulomatosis (BVAS/WG) was 30.0 (23.0-32.5), PO2 on air was 5.8+/-0.5 kPa, creatinine level was 7.2+/-1.4 mg/dl. Fifteen patients were PR3 positive, among them 4 patients were also positive for anti-glomerular basement membrane antibodies (anti-GBM). Renal biopsy was performed in 16 patients. Histological examination reviled segmental necrotizing crescentic GN in 15 patients. Thirteen patients were initially dialysis-dependent, and 7 required ventilatory support. All patients were treated with methylprednisolone and cyclophosphamide (pulses). The patients were followed up for 24+/-8 months. Of the survivors, 55% and 31% were alive after 1 and 2 years. Early recognition and proper treatment may improve outcome in PRS.

Pediatric environmental medicine in Eastern Central Europe

Pediatric environmental medicine in Central Eastern Europe needs support and development on national, institutional and individual basis. This situation is quantitatively, but not fundamentally different from what is to be found in Central Europe.

[Differential diagnosis of rheumatoid granuloma]

Rheumatoid granuloma (RG) is histomorphologically defined as a subcutaneous palisading granuloma with central fibrinoid necrosis. Clinically, it presents as a nodule typically localized at pressure points near the joints. From the rheumatic pathological point of view, the main diagnostic challenge is the differentiation of RG from granuloma anulare, especially if clinical information on the site of removal, known diseases, duration of illness, medication and existing American College of Rheumatology (ACR) criteria are missing. Other granulomatous lesions, such as mycobacterial infections, foreign body granulomas, necrobiosis lipoidica or sarcoidosis, can be differentiated from RG by histopathological criteria or by additional examinations such as pathogen specification or PCR. An immunohistochemical marker for the differential diagnosis of granulomas is not yet available. Diagnosis is based on conventional H-E staining, alcian blue-PAS staining, polarizing analysis or PCR. In the following article, the most important granulomatous entities in the differential diagnosis of RG are introduced and the main diagnostic characteristics are discussed.

Persistent strains of coagulase-negative staphylococci in a neonatal intensive care unit: virulence factors and invasiveness

Coagulase-negative staphylococci (CoNS) are the major cause of nosocomial bacteraemia in neonates. The aim of this study was to investigate whether persistent strains of CoNS possess specific bacterial characteristics as compared with sporadic non-cluster isolates. In total, 180 blood culture isolates (95 contaminants and 85 invasive isolates) obtained from a single neonatal unit over a 12-year period were studied. Pulsed-field gel electrophoresis (PFGE) identified 87 persistent CoNS strains (endemic clones). The two largest PFGE clusters belonged to a single clonal complex according to multilocus sequence typing. Patients colonised or infected with endemic clones were of lower gestational age than those infected with non-cluster strains. One Staphylococcus haemolyticus cluster appeared to selectively colonise and infect the most extreme pre-term infants. Endemic clones were characterised by high levels of antibiotic resistance and biofilm formation. All 51 isolates belonging to the two largest PFGE clusters were ica operon-positive. Genes encoding Staphylococcus epidermidis surface protein B and the production of phenol-soluble modulins (PSMs) were also more prevalent among endemic clones than among non-cluster strains. However, endemic clones were not more prevalent among invasive isolates than among contaminants. These findings indicate that multiple selective factors, including antibiotic resistance, biofilm formation, surface proteins with adhesive properties, and PSMs regulated by agr, increase the ability of CoNS to persist in a hospital environment. It may be more prudent, when searching for new therapeutic targets, to focus on ubiquitous components of CoNS instead of putative virulence factors that do not clearly contribute to increased invasive capacity.

Two consecutive fatal cases of acute myocardial infarction caused by free floating thrombus in the ascending aorta and review of literature

Free floating thrombus in the ascending aorta is an uncommon source of acute myocardial infarction. We report on two cases of young women who died of acute myocardial infarction caused by a free floating thrombus in the sinus of Valsalva obstructing the coronary arteries' ostia. The first case reports on a 30-year-old pregnant woman who anamnestically had episodes with short loss of consciousness and weakness. The second case presents a 37-year-old woman suffering from multiple sclerosis with no previous history of thrombotic events. The review of literature revealed a predominance of women (eight females and three males). Interestingly, the coronary arteries bear no preference concerning the right (RCA) or left coronary artery (LCA) being more often occluded by a free floating thrombus. Especially, younger women (mean age 45.5 years, range 30-59 years) with no history of cardiac symptoms and without atherosclerotic changes seem to be predispositioned. The hypothesis that thrombus formation in cases without plaque disruption may depend on an endothelial erosion which seems to be more common in younger women and promoted by a hyperthrombogenic state is supported by our two cases. A comprehensive literature search revealed, that these are the first two reports on a free floating thrombus being the cause of fatal acute myocardial infarction in a pregnant woman, respectively, a woman suffering from multiple sclerosis.

Validation of amyloid-beta peptides in CSF diagnosis of neurodegenerative dementias

Biomarkers for differential diagnosis of the three most frequent degenerative forms of dementia, Alzheimer's disease (AD), dementia with Lewy bodies (DLB) and frontotemporal dementias (FTD), are currently under intensive investigation, but disease-specific biomarkers for FTD and DLB are still lacking. We analyzed 303 cerebrospinal fluid (CSF) samples of 71 AD, 32 DLB and 36 FTD patients in comparison to 93 various other dementias (OD), 20 peripheral neurologic disease (PND) controls, 25 neurodegenerative disorders without dementia (ND) and 26 depressive cognitive complainers (DCC) for distinct CSF amyloid-beta (Abeta) peptide patterns, using the quantitative Abeta-SDS-PAGE/immunoblot. Additionally, the novel electrochemiluminescence technique (MSD) was used to validate the measures on Abeta1-38. The main outcome measures were a striking decrease of Abeta1-42 in AD (P=7.4 x 10(-19)), and most interestingly a pronounced decrease of Abeta1-38 in FTD (P=9.6 x 10(-7)). Moreover, a novel peptide that most probably represents an oxidized alpha-helical form of Abeta1-40 (Abeta1-40(ox)) displayed a highly significant increase in DLB (P=3.7 x 10(-3)) as compared to non-demented disease controls. The overall diagnostic accuracy of percentage Abeta peptide abundances (Abeta1-X%) was clearly superior to absolute CSF Abeta levels. Abeta1-42% and Abeta1-38% enabled contrasts of 85% or beyond to distinguish AD and FTD, respectively, from all other investigated subjects. Abeta1-40(ox)% yielded a diagnostic sensitivity and specificity of 88 and 73% for the detection of DLB among all other investigated patients. We found a strong correlation between Abeta1-38 levels as measured by the Abeta-SDS-PAGE/immunoblot and MSD, respectively. CSF Abeta peptides may reflect disease-specific impact of distinct neurodegenerative processes on Abeta peptide metabolism and represent a potential diagnostic biomarker for AD, FTD and DLB.

Development of an in vitro assay for the investigation of metabolism-induced drug hepatotoxicity

In a number of adverse drug reactions leading to hepatotoxicity drug metabolism is thought to be involved by generation of reactive metabolites from nontoxic drugs. In this study, an in vitro assay was developed for measurement of the impact of metabolic activation of compound on the cytotoxicity toward a human hepatic cell line. HepG2 cells were treated for 6 h with compound in the presence or absence of rat liver S9-mix, and the viability was measured using the MTT test. The cytotoxicity of cyclophosphamide was substantially increased by S9-mix in the presence of NADPH. Three NADPH sources were tested: NADPH (1 mmol/L) or NADPH regenerating system with either NADP(+)/glucose 6-phosphate (G6P) or NADP(+)/isocitrate. All three NADPH sources increased the cytotoxicity of cyclophosphamide to a similar extent. Eight test compounds known to cause hepatotoxicity were tested. For these, only the cytotoxicity of diclofenac was increased by S9 enzymes when an NADPH regenerating system was used. The increased toxicity was NADPH dependent. Reactive drug metabolites of diclofenac, formed by NADPH-dependent metabolism, were identified by LC-MS. Furthermore, an increase in toxicity, not related to enzymatic activity but to G6P, was observed for diclofenac and minocycline. Tacrine and amodiaquine displayed decreased toxicity with S9-mix, and carbamazepine, phenytoin, bromfenac and troglitazone were nontoxic at all tested concentrations, with or without S9-mix. The results show that this method, with measurement of the cytotoxicity of a compound in the presence of an extracellular metabolizing system, may be useful in the study of cytotoxicity of drug metabolites.