Fast and direct measurements of the electrical properties of graphene using micro four-point probes

We present measurements of the electronic properties of graphene using a repositionable micro four-point probe system, which we show here to have unique advantages over measurements made on lithographically defined devices; namely speed, simplicity and lack of a need to pattern graphene. Measurements are performed in ambient, vacuum and controlled environmental conditions using an environmental scanning electron microscope (SEM). The results are comparable to previous results for microcleaved graphene on silicon dioxide (SiO(2)). We observe a pronounced hysteresis of the charge neutrality point, dependent on the sweep rate of the gate voltage; and environmental measurements provide insight into the sensor application prospects of graphene. The method offers a fast, local and non-destructive technique for electronic measurements on graphene, which can be positioned freely on a graphene flake.

A randomized trial of punctuated antiretroviral therapy in Ugandan HIV-seropositive adults with pulmonary tuberculosis and CD4⁺ T-cell counts of ≥ 350 cells/μL

BACKGROUND

Optimal treatment of human immunodeficiency virus (HIV)-associated tuberculosis in patients with high CD4⁺ T-cell counts is unknown. Suppression of viral replication during therapy for tuberculosis may block effects of immune activation on T cells and slow HIV disease progression.

METHODS

We conducted a randomized trial in 214 HIV-infected patients with active tuberculosis and CD4⁺ T-cell counts of ≥ 350 cells/μL to determine whether 6 months of antiretroviral therapy given during tuberculosis treatment would improve clinical outcomes. Subjects were randomized to receive 6 months of abacavir-lamivudine-zidovudine concurrent with tuberculosis therapy or delayed antiretroviral therapy. Endpoints were CD4⁺ T-cell counts of < 250 cells/μL, AIDS, or death.

RESULTS

Intervention and comparison arms had similar median CD4⁺ counts (517 and 534 cells/μL, respectively) and HIV RNA levels (4.6 and 4.7 log₁₀ copies/μL, respectively). Viral suppression was achieved in 86% of patients allocated to intervention. Seventeen subjects (15.6%) in the intervention arm developed study outcome compared to 25 subjects (22.8%) in the comparison arm (P = .17). Grade 3 or 4 adverse events were less frequent in the intervention arm. By 2 months, 90% of subjects in both arms were culture-negative for tuberculosis.

CONCLUSIONS

Short-term antiretroviral therapy during tuberculosis treatment in patients with CD4⁺T-cell counts of >350 cells/μL was safe and associated with clinical benefits.

Endovascular treatment of carotid embolic occlusions has a higher recanalization rate compared with cardioembolic occlusions

BACKGROUND AND PURPOSE

Treatment of large artery cerebral occlusions is rapidly evolving. We hypothesized that patients with intracranial embolic occlusions secondary to an extracranial carotid artery stenosis or occlusion have a higher probability of successful endovascular recanalization compared with those with cardioembolic occlusions.

METHODS

We retrospectively reviewed the databases of three institutions (University of Pittsburgh Medical Center (UPMC), Michigan State University (MSU) and Cleveland Clinic Foundation (CCF)) for acute anterior circulation ischemic strokes treated with endovascular therapies from January 2006 to July 2008. After collection of demographic, radiographic and angiographic variables, two groups were identified: artery to artery embolic occlusions and cardioembolic/cryptogenic intracranial occlusions. We defined recanalization as TIMI 2 or 3 flow. A binary logistic regression model was constructed to determine which characteristics were unique to patients with carotid embolic occlusions.

RESULTS

A total of 207 patients were identified (UPMC=100, CCF=71, MSU=36) with a mean age of 69±11 years and mean NIHSS of 17±5. Of these, 157 (75%) were due to a cardiac or cryptogenic source and 50 (25%) were from a carotid embolic source. The use of multimodal therapy (OR 2.6 (1.2-5.6), p<0.009) and the presence of a carotid embolic intracranial occlusion (OR 3.6 (1.2-7.1), p<0.012) were associated with successful recanalization, while carotid terminus occlusions were associated with unsuccessful recanalization (OR 0.35 (0.18-0.68), p<0.002).

CONCLUSIONS

Patients with intracranial occlusions secondary to an extracranial carotid stenosis or total occlusion appear to have more successful recanalization rates when treated with endovascular therapy compared with those with cardioembolic occlusions.

Subcellular distribution of L-type calcium channel subtypes in rat hippocampal neurons

L-type calcium channels play an essential role in synaptic activity-dependent gene expression and are implicated in long-term alterations in synaptic efficacy underlying learning and memory in the hippocampus. The two principal pore-forming subunits of L-type Ca2+ channels expressed in neurons are the Ca(v)1.2 (alpha(1C)) or Ca(v)1.3 (alpha(1D)) subtypes. Experimental evidence suggests that calcium entry through Ca(v)1.2 and Ca(v)1.3 Ca2+ channels occurs in close proximity to key signalling molecules responsible for triggering signalling pathways leading to transcriptional responses. Determining the subcellular distribution of Ca(v)1.2 and Ca(v)1.3 L-type channels in neurons is clearly important for unravelling the molecular mechanisms underlying long-term alterations in neuronal function. In this study, we used immunogold-labelling techniques and electron-microscopy (EM) to analyse the subcellular distribution and density of both Ca(v)1.2 and Ca(v)1.3 Ca2+ channels in rat hippocampal CA1 pyramidal cells in vivo. We confirm that both Ca(v)1.2 and Ca(v)1.3 channel subtypes are predominantly but not exclusively located in postsynaptic dendritic processes and somata. Both Ca(v)1.2 and Ca(v)1.3 are distributed throughout the dendritic tree. However, the smallest (distal) dendritic processes and spines have proportionally more calcium channels inserted into their plasma membrane than located within cytoplasmic compartments indicating the potential targeting of calcium channels to microdomains within neurons. Ca(v)1.2 and Ca(v)1.3 Ca2+ channels are located at the postsynaptic density and also at extra-synaptic sites. The location of L-type Ca(v)1.2 and Ca(v)1.3 channels in distal dendrites and spines would thus place them at appropriate sites where they could initiate synapse to nucleus signalling.

Effect of AbGn-7, a glycotope-specific monoclonal antibody, on apoptosis in colon cancer cells and tumor growth in xenograft models

e15118

Background: While clinical benefit against colorectal cancer has been observed with therapeutic monoclonal antibodies such as bevacizumab, cetuximab and panituzumab, the death rate of advanced colorectal cancer remains high that warrants further development of more potent therapeutics. Methods: A cell-based immunization approach was used to generate monoclonal antibodies against targets expressed on human colorectal cancer cells. A chimeric monoclonal antibody, AbGn-7, was selected and evaluated for the potential clinical use to treat colorectal cancer. Results: Expression of AbGn-7 antigen: Carbohydrate competition assay demonstrated that AbGn-7 recognizes a Lewis-A-like carbohydrate antigen (AbGn-7 antigen). Immunohistochemical studies showed that AbGn-7 antigen is expressed in colorectal cancer tissue. No significant binding could be detected in non-tumor tissues except in the epithelia of GI track. Effector function of AbGn-7: AbGn-7 triggered dose-dependent apoptosis in COLO 205 colon cancer cell. In addition, AbGn-7 elicited potent complement-dependent cytotoxicity (CDC) and antibody-dependent cell-mediated cytotoxicity (ADCC) in a dose-dependent manner. Molecular mechanism of apoptosis induced by AbGn-7: Tunel assay, PARP cleavage assay as well as caspase inhibitor studies demonstrated that AbGn-7 induced apoptosis in COLO 205 colon cancer cells via a caspase-independent pathway. Xenograft study: AbGn-7 alone, or in combination with 5FU-Leucovorin, effectively inhibited the growth of COLO 205 xenograft in SCID mice and prolonged their survival. Conclusions: The results of the present study suggest that AbGn-7 is a potential candidate for effective treatment of colorectal cancer.

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Phase IIb trial of fluorouracil, leucovorin, oxaliplatin, and paclitaxel (POF) compared with fluorouracil, feucovorin, and irinotecan (IF) as first-line treatment for advanced gastric cancer (AGC)

e15642

Background: Primary results of POF as 1st and 2nd line treatment for AGC have been presented at ASCO 2007 and 2008. We report here data on the feasibility and the toxicity of POF versus IF(Dank, et al, ASCO 2005) in 1st line treatment of AGC. Methods: Patients with previously untreated, advanced, unresectable, and histologically confirmed adenocarcinoma of the gastric or gastroesophageal junction were randomly assigned to POF or IF regiment. Treatment was continued until disease progressed, unacceptable toxicity, or patient choice. Results: 25 patients were entered in this study between March 2007 and July 2007: 13 in the POF group and 12 in the IF group. The median patient age was 55 years (range, 36 to 67 years), 18 were males and 7 were females. No complete response was observed. The response rate was 62.5% (POF) and 33.3% (IF) respectively. At a median follow-up of 285 days, 7(POF) versus 6(IF) patients were still alive. Hematological toxicity was the most frequent toxicity in both groups. Grade 3 to 4 neutropenia were 38.5% (POF) versus 8.3% (IF). Diarrhea was found 0% and 8.3% in POF and IF group respectively. No grade 3 peripheral neurotoxicity was observed. Conclusions: Compared with IF regiment, POF could also be used as first-line treatment for AGC with acceptable safety profile, good efficacy, and more encouraging results.

No significant financial relationships to disclose.

Nutrition and children's respiratory health in Guangzhou, China

OBJECTIVE

To investigate the role of nutrition in children's respiratory health in subjects participating in a study on air pollution and respiratory health.

STUDY DESIGN

Cross-sectional survey.

METHODS

The relationships between consumption of fresh fruit, vegetables and milk and pulmonary function (forced expiratory volume in 1 s, FEV(1)) and respiratory symptoms (phlegm with cold, phlegm without cold, cough with cold, and cough without cold) were examined in 2228 children (age 10.07+/-0.86 years) in Guangzhou, China.

RESULTS

A positive association was found between consumption of leafy vegetables and lung function in children. Subjects with the highest consumption of leafy vegetables had significant higher FEV(1) values than subjects who ate leafy vegetables less than once per week (1.68 l vs 1.56 l; P=0.047). Children with high consumption of fresh fruit and milk had higher lung function values than children with low consumption, although the differences were not statistically significant. Milk consumption was a protective factor for phlegm with cold, cough with cold, and cough without cold [odds ratio (OR) 0.62, 95% confidence interval (CI) 0.39-0.97; OR 0.53, 95% CI 0.36-0.79; OR 0.43, 95% CI 0.21-0.92, respectively, in the highest intake group]. Consumption of vegetables was a protective factor for cough with cold (P for trend=0.003) and cough without cold (P for trend=0.028). Consumption of fresh fruit was marginally associated with reduced prevalence of respiratory symptoms.

CONCLUSIONS

This study suggests that dietary nutrients are important protective factors for children's respiratory health. Following-up these children may provide more evidence to confirm these associations.