Rational design of large flat nitrogen-doped graphene oxide quantum dots with green-luminescence suitable for biomedical applications

Rational synthesis and simple methodology for the purification of large (35–45 nm in lateral size) and flat (1.0–1.5 nm of height) nitrogen-doped graphene oxide quantum dots (GOQDs) are presented. The methodology allows robust metal-free and acid-free preparation of N-GOQDs with a yield of about 100% and includes hydrothermal treatment of graphene oxide with hydrogen peroxide and ammonia. It was demonstrated that macroscopic impurities can be separated from N-GOQD suspension by their coagulation with 0.9% NaCl solution. Redispersible in water and saline solutions, particles of N-GOQDs were characterized using tip-enhanced Raman spectroscopy (TERS), photoluminescent, XPS, and UV-VIS spectroscopies. The size and morphology of N-GOQDs were studied by dynamic light scattering, AFM, SEM, and TEM. The procedure proposed allows nitrogen-doped GOQDs to be obtained, having 60–51% of carbon, 34–45% of oxygen, and up to 7.2% of nitrogen. The N-GOQD particles obtained in two hours of synthesis contain only pyrrolic defects of the graphene core. The fraction of pyridine moieties grows with the time of synthesis, while the fraction of quaternary nitrogen declines. Application of TERS allows demonstration that the N-GOQDs consist of a graphene core with an average crystallite size of 9 nm and an average distance between nearest defects smaller than 3 nm. The cytotoxicity tests reveal high viability of the monkey epithelial kidney cells Vero in the presence of N-GOQDs in a concentration below 60 mg L⁻¹. The N-GOQDs demonstrate green luminescence with an emission maximum at 505 nm and sedimentation stability in the cell culture medium.

This paper reveals the methodology for robust preparation of purified nitrogen-doped graphene oxide quantum dots with non-cytotoxic activity against monkey epithelial kidney cells (Vero ATCC® CCL-81™).     

Mutagenicity and Genotoxicity in Gill Erythrocyte Cells of Poecilia reticulata Exposed to a Glyphosate Formulation

Poecilia reticulata were exposed to herbicide Roundup Transorb^® for micronucleus test, nuclear abnormalities and comet assay. The exposure-concentrations were based on CL_50–96 h following 0, 1.41, 2.83, 4.24 and 5.65 μL L^?1 for 24 h. Micronucleus and comets were significantly increased in the gill erythrocyte cells after herbicide exposure compared with the non-exposed group. Results showed a gradual increase in the number of damaged cells, indicating a concentration-dependent effect and that this herbicide was mutagenic and genotoxic to P. reticulata and this effect could be attributed to a combination of compounds contained in the formulation with the active ingredient glyphosate.     

Transitional Care Coordination in New York City Jails: Facilitating Linkages to Care for People with HIV Returning Home from Rikers Island

New York City (NYC) jails are the epicenter of an epidemic that overwhelmingly affects Black and Hispanic men and offer a significant opportunity for public health intervention. The NYC Department of Health and Mental Hygiene instituted population based approaches to identify the HIV-infected, initiate discharge planning at jail admission, and facilitate post-release linkages to primary care. Using a caring and supportive ‘warm transitions’ approach, transitional care services are integral to continuity of care. Since 2010, over three-quarters of known HIV-infected inmates admitted to jails received discharge plans; 74 % of those released were linked to primary care. The EnhanceLink initiative’s new Health Liaison, a lynchpin role, facilitated 250 court-led placements in medical alternatives to incarceration. Transitional care coordination programs are critical to facilitate continuity of care for people with chronic health conditions including the HIV-infected returning home from jail and for the public health of the communities to which they return.     

Extremely High Body Mass Index is not a Contraindication to Laparoscopic Gastric Bypass

Background: Laparoscopic Roux-en-Y gastric bypass (LRYGBP) is an effective operation for morbidly obese patients who have failed conservative weight loss treatments. It is currently indicated for patients with BMI >40 kg/m² or >35 with significant co-morbidities. Controversy exists whether there is an upper limit to BMI beyond which this operation should not be performed. Methods: Between April 1999 and February 2001, 82 patients (19 male, 63 female) underwent LRYGBP. Average age was 43.6, and average BMI was 56 kg/m². These patients were divided into those with BMI <60 and those with BMI ≥60 kg/m². Results:There were 61 patients with BMI <60 and 21 patients with BMI ≥60. The groups were similar in age, gender, distribution or incidence of co-morbid conditions (diabetes, coronary artery disease, hypertension, sleep apnea, asthma) between the groups. The BMI ≥60 group had a significantly longer length of stay (6.6 days vs 5.3 days, P <0.05), and only 1 patient (BMI 85) developed an anastomotic leak and died. 2 patients in this group (BMI 62 and 73) developed small bowel obstruction requiring lysis of adhesions. 1 patient in the BMI <60 group developed a gastrojejunal stricture requiring balloon dilatation. Conclusion: While patients with a BMI ≥60 are at higher risk for postoperative complications, they are also at higher risk from continued extreme obesity. In our series, 85% of these patients had an uneventful postoperative course and began shedding excess weight. BMI ≥60 should not be a contraindication for LRYGBP.     

Spatial learning and neurogenesis: Effects of cessation of wheel running and survival of novel neurons by engagement in cognitive tasks

Physical exercise stimulates cell proliferation in the adult dentate gyrus and facilitates acquisition and/or retention of hippocampal‐dependent tasks. It is established that regular physical exercise improves cognitive performance. However, it is unclear for how long these benefits last after its interruption. Independent groups of rats received both free access to either unlocked (EXE Treatment) or locked (No‐EXE Treatment) running wheels for 7 days, and daily injections of bromodeoxyuridine (BrdU) in the last 3 days. After a time delay period of either 1, 3, or 6 weeks without training, the animals were tested in the Morris water maze (MWM) either in a working memory task dependent on hippocampal function (MWM‐HD) or in a visible platform searching task, independent on hippocampal function (MWM‐NH). Data confirmed that exposure of rats to 7 days of spontaneous wheel running increases cell proliferation and neurogenesis. In contrast, neurogenesis was not accompanied by significant improvements of performance in the working memory version of the MWM. Longer time delays between the end of exercise and the beginning of cognitive training in the MWM resulted in lower cell survival; that is, the number of novel surviving mature neurons was decreased when this delay was 6 weeks as compared with when it was 1 week. In addition, data showed that while exposure to the MWM‐HD working memory task substantially increased survival of novel neurons, exposure to the MWM‐NH task did not, thus indicating that survival of novel dentate gyrus neurons depends on the engagement of this brain region in performance of cognitive tasks. © 2015 Wiley Periodicals, Inc.     

Total hip prosthesis CT with single-energy projection-based metallic artifact reduction: impact on the visualization of specific periprosthetic soft tissue structures

Objectives

To compare the image quality of CT with iterative reconstruction alone and in association with projection-based single-energy metal artifact reduction (SEMAR) for the visualization of specific periarticular soft tissue structures in patients with hip prostheses.

Methods

CT studies from 48 consecutive patients with a hip prosthesis (24 unilateral and 24 bilateral) were retrospectively reconstructed using two different methods: iterative reconstruction (IR) alone and IR associated with SEMAR. The influence of metallic artifacts on the identification of various periarticular structures was evaluated subjectively by two readers. The image quality was compared in patients with unilateral and bilateral prostheses.

Results

Visualization of periprosthetic soft tissue was significantly improved by the SEMAR algorithm (p?<?0.0001). When SEMAR was associated with IR, the gluteus minimus and medius tendons, obturator internus muscle, prostate/uterus and bladder could be seen with medium or high confidence. There were no significant differences in image quality between patients with unilateral or bilateral prosthesis when SEMAR was used (p?>?0.2). This algorithm increased the detection of periarticular masses by 30 %.

Conclusion

SEMAR significantly improves the image quality of periarticular soft-tissue structures in patients with hip prostheses.     

Influence of Calcium on Choline Measurements by 1H MR Spectroscopy of Thigh Muscles

Objective

To study the effects of calcium on the choline peak measurements with 1H MR spectroscopy.

Material and methods

The thigh muscles of two cadaveric specimens were prospectively evaluated on a 3 T MR unit before and after the injection of calcium carbonate (up to 0.4322 g). The choline peaks of 147 spectra from 10 different anatomic locations were quantitatively evaluated. The influence of the calcium concentration and its disposition with respect to the main magnetic field were considered. B₀ phase maps were used to evaluate field inhomogeneities.

Results

The presence of calcium led to a 43 % underestimation of the choline peak and the choline concentration (p?=?0.0002 and 0.0036). The mean choline concentrations before and after CaCO3 injection were 3.53?±?1.72 mmol/l and 1.58?±?0.63 mmol/l. The influence of calcium carbonate on the choline peak estimations was proportional to the calcium concentration. There was a significant position-dependent difference in the estimation of the choline peak amplitude (p?<?0.0154). Calcium injection led to a measurable increase in field inhomogeneities.

Conclusion

There was a significant underestimation of the choline peak amplitude and concentration in the presence of calcium, which might cause misinterpretations of MR spectra.

Key Points

? The presence of calcium led to significant underestimation of choline measurements. ? The influence of calcium is dependent on its concentration and distribution. ? Quantitative MR spectroscopy of calcified tumours should be interpreted with caution.