7Li NMR of Normal Human Erythrocytes

Lithium has been known to be an effective medication for people with bipolar disorder. The mechanisms of action of lithium in the brain is not very well understood. NMR spectroscopy and imaging are effective both in determining lithium levels in tissue and brain. We have monitored lithium levels in red blood cells. We have been able to separate intra- and extracellular compartments of lithium using shift reagents, thereby obtaining T^1 \u27s of both the compartments. Lithium uptake as a function of hematocrit was monitored weekly over a 3 week period. The time constant of 50 mM lithium uptake at 25°C and 85% hematocrit was found to be 16.5 hrs. The time constant of 1.8 mM lithium uptake at 37 °C and 45% hematocrit was found to be 11.6 hrs. Experiments on the visibility of the quadrupolar nuclei indicate that it is only 74-90% visible and the visibility decreased with decreasing concentrations

Eye banking: an introduction

This article introduces the work of eye banks, institutions responsible for collecting (harvesting) and processing donor corneas, and for distributing them to trained corneal graft surgeons

Blindness and poverty in India: the way forward

A few recent studies have shown that poverty is an exacerbating and often determining factor in the incidence of disabling conditions, including visual impairment. Recent estimates from the World Health Organization indicate that 90 per cent of all those affected by visual impairment live in the poorest countries of the world. India is home to one-fifth of the world's visually impaired people and therefore, any strategies to combat avoidable blindness must take into account the socio-economic conditions within which people live. This paper looks at the relationship between poverty and blindness in India and suggests strategies to address blindness prevention in a comprehensive manner

Double Tuned Cosine Coil for NMR Imaging/Microscopy

The fabrication of a cosine coil having unevenly distributed struts is detailed. Placing the struts in such a manner enables a standing wave at the desired frequency and, hence, only one resonance frequency is obtained. This study details the fabrication of a cosine coil tuned to the LJ-7 frequency (77.76 MHz) and then double-tuned to the H-1 frequency (200.1 MHz) when operated at 4.7 Tesla. Double-tuning is attained by placing an LC trap in series with a capacitor used to single-tune the coil. Also, a method is suggested by which a cosine coil can be broadbanded in the lower frequency range simply by replacing a fixed capacitor

Local charge transfer doping in suspended graphene nanojunctions

We report electronic transport measurements in nanoscale graphene transistors with gold and platinum electrodes whose channel lengths are shorter than 100 nm, and compare them with transistors with channel lengths from 1 \textmu{}m to 50 \textmu{}m. We find a large positive gate voltage shift in charge neutrality point (NP) for transistors made with platinum electrodes but negligible shift for devices made with gold electrodes. This is consistent with the transfer of electrons from graphene into the platinum electrodes. As the channel length increases, the disparity between the measured NP using gold and platinum electrodes disappears.Comment: 11 pages, 3 figures, to appear in Appl. Phys. Let

Principles and Clinical Applications of Magnetic Resonance

A review is presented which covers the basic theory of nuclear magnetic resonance (NMR) with regard to angular momentum, magnetic moments, and the classical mechanical description of the NMR experiment. Longitudinal (T,) and Transverse (T2) relaxation times are defined as well as the basic pulse sequences used for their measurement. In particular, the 180°-t-90° and the Hahn Spin Echo pulse sequences are described in detail. Basic Magnetic Resonance Imaging (MRI) theory is discussed with regard to slice selection, frequency encoding, and phase encoding to define the imaged volume element. The equations defining the amount of Tt , T2 , and proton density which contribute to the images are discussed. Common MRI pulsing sequences are described in detail as well as the imaging time equation. Recent in-vivo magnetic resonance studies involving the use of contrast agents, and the use of localized spectroscopy, specifically 13C, 19F, MNa and 39K, are discussed

The promise of stem cell therapy for eye disorders

This article does not have an abstract

Population-based cross-sectional study of barriers to utilisation of refraction services in South India: Rapid Assessment of Refractive Errors (RARE) Study

AIM: To assess the barriers to the uptake of refraction services in the age group of 15-49 years in rural Andhra Pradesh, India. METHODS: A population-based cross-sectional study was conducted using cluster random sampling to enumerate 3300 individuals from 55 clusters. A validated questionnaire was used to elicit information on barriers to utilisation of services among individuals with uncorrected refractive error (presenting visual acuity 35 years with binocular distance visual acuity of ≥6/12). RESULTS: 3095 (94%) were available for examination. Those with uncorrected refractive errors cited affordability as the main barrier to the uptake of eye-care services. Among people with uncorrected presbyopia, lack of 'felt need' was the leading barrier. CONCLUSION: The barriers that were 'relatively easy to change' were reported by those with uncorrected refractive errors in contrast to 'difficult to change' barriers reported by those with uncorrected presbyopia. Together, the data on prevalence and an understanding of the barriers for the uptake of services are critical to the planning of refractive error services

Corneal nerve alterations in diabetes mellitus

The morphologic status of corneal innervation was studied in rats with streptozocin-induced diabetes. Animals were killed at 1, 4, 16, and 36 weeks. Corneal innervation was studied by light and electron microscopy using nonspecific cholinesterase reaction, gold chloride impregnation, and plastic-embedded sections. Increased irregularity in the periodicity of nerve fiber beading was observed in diabetic corneas with gold impregnation. Ultrastructural evidence of irregularities in the basal lamina of Schwann cells was demonstrated in 16- and 36-week-old diabetic animals, along with occasional axonal degeneration. These alterations constitute a constellation of early pathologic manifestations in the innervation of diabetic cornea. To our knowledge, this study represents the first demonstration of neural changes in diabetic corneas as well as nerve fiber changes in an avascular tissue in diabetes