High resolution electron paramagnetic resonance imaging of biological samples with a single line paramagnetic label

The application of electron paramagnetic resonance imaging (EPRI) to obtain information from biological samples has been limited by the lack of ideal single line radical labels. The commonly used nitroxides exhibit multiple lines causing either hyperfine-based limitations in the maximum obtainable image resolution or hyperfine-based artifacts in the reconstructed image. The use of a novel single-line triarylmethyl paramagnetic label that enables marked enhancement in image quality and resolution is reported. This label exhibits a single line EPR spectrum that is sharp (linewidth ～60 mG in the absence of oxygen) and relatively stable in tissues. The potential of this label in enabling high resolution EPR imaging of biological samples was demonstrated in a series of phantoms and isolated biological organs such as the rat kidney. The images demonstrate that resolutions better than 100 μm could be obtained at L-band on samples of up to 20 mm in size.     

Ghrelin expression in hyperplastic and neoplastic proliferations of the enterochromaffin-like (ECL) cells

Ghrelin, a recently discovered peptide isolated from the gastric corpus mucosa, is believed to be important in the regulation of growth hormone secretion and has been shown to increase appetite and food intake as well. It may also have other gastrointestinal and cardiac functions. Because a cell of origin for ghrelin has not been convincingly identified in the gastric mucosa thus far, we studied the immunohistochemical expression of ghrelin in proliferative lesions of the enterochromaffin-like (ECL) cells—a cell that is not only exclusively confined to the gastric corpus mucosa but is its dominant endocrine cell type as well. Formalin-fixed, paraffin embedded tissues from three cases of gastric ECL cell hyperplasia and five ECL carcinoids (three with coexisting foci of diffuse, linear, and micronodular hyperplasia) were immunohistochemically stained for ghrelin, using a commercially available antibody. The Sevier-Munger stain for ECL cells and immunohistochemical stains for chromogranin, gastrin, serotonin, somatostatin, and vesicular monoamine transporter-2 (VMAT-2) were performed on parallel sections for correlation with the ghrelin staining results. All ECL cell carcinoids and hyperplastic lesions were positive for both the Sevier-Munger and the immunohistochemical stains for chromogranin and VMAT-2. Immunoreactivity for ghrelin was seen in 4/5 ECL carcinoids, all cases of ECL cell hyperplasia, as well as in all areas with linear and micronodular hyperplasia adjacent to the ECL cell carcinoids. In each instance, such staining was confined to the Sevier-Munger, and VMAT-2 positive cells only. Our findings indicate that the ECL cells are either the ghrelin-producing cells of the gastric mucosa or acquire the capability to synthesize ghrelin during proliferative states encompassing the entire hyperplasia to neoplasia spectrum. In view of the orexigenic and other known actions of ghrelin, the functional and/or biologic significance of ghrelin production in such ECL cell proliferations needs to be investigated further.     

Vitamin C-induced loss of redox-dependent viability in lung microvascular endothelial cells

Recent clinical trials have shown that vitamin C, at pharmacological concentrations (milligram to approximately gram), upon infusion into circulation, modulates vasodilation and vascular tone in humans. This also results in the elevated concentrations of vitamin C in circulation in the millimolar range. Here, it was hypothesized that vitamin C at pharmacological concentrations (millimolar) would induce oxidative stress and cause loss of redox-dependent cell viability in vascular endothelial cells (ECs). To test the hypothesis, bovine lung microvascular ECs (BLMVECs) in monolayer cultures were exposed to vitamin C (0-10 mM) for different time periods (0-2 h). Electron paramagnetic resonance spectroscopy revealed the intracellular formation of ascorbate free radical in a dose- and time-dependent fashion. Vitamin C also induced formation of intracellular reactive oxygen species in a dose-dependent fashion. It was observed that vitamin C induced morphological alterations and loss of cell viability in a dose- and time-dependent fashion, as measured by light microscopy and Alamar Blue redox cell viability assay, respectively. Vitamin C analogues failed to induce such changes. Vitamin C depleted cellular GSH levels in a dose-dependent fashion, suggesting that vitamin C altered thiol-redox status in BLMVECs. Antioxidants, intracellular iron chelator, and catalase protected cells against vitamin C-induced loss of redox-dependent cell viability, confirming the role of hydrogen peroxide and iron during redox cycling of vitamin C. These results, for the first time in detail, established that vitamin C at pharmacological doses induced oxidative stress and loss of redox-dependent cell viability in microvascular ECs.     

Cardiac applications of EPR imaging

This review summarizes the development and application of a variety of EPR imaging modalities including spatial, spectral-spatial (spectroscopic), gated-imaging and oxygen mapping to cardiovascular studies. It has been hypothesized that free radical metabolism, oxygenation and nitric oxide generation in biological organs such as the heart may vary over the spatially defined tissue structure. We have developed instrumentation optimized for 3D spatial and 3D or 4D spectral-spatial imaging of free radicals at 1.2 GHz. Using this instrumentation high quality 3D spectral-spatial imaging of nitroxyl (nitroxide) metabolism was performed, as well as spatially localized measurements of oxygen concentrations, based on the oxygen-dependent line-broadening of the EPR spectrum. Both exogenously infused probes and endogenous radicals were used to obtain the images. It is demonstrated that the EPR imaging is a powerful tool which can provide unique information regarding the spatial localization of free radicals, oxygen and nitric oxide in biological organs and tissues.     

Glycosylated hemoglobin-defined prediabetes and cardiovascular risk markers in rural India: the Nallampatti noncommunicable disease study

The aim of this study is to assess the associations between glycosylated hemoglobin in the prediabetes range and cardiovascular risk markers in a rural South Indian population. Local Ethics Committee approval and informed consent was obtained from all participants. Inclusion criteria were participants, aged ≥20 and ≤85 years, from Nallampatti, a classical farming village from Tamil Nadu State, India. Those with known history of diabetes were excluded from this analysis. All participants were administered a detailed questionnaire, had anthropometric measurements including height, weight, and waist circumference. Bloods were drawn for random blood glucose, glycosylated hemoglobin, nonfasting lipid profile, cystatin C, uric acid, and hemoglobin. All participants had carotid intima thickness done by high-resolution B-mode carotid ultrasound. Progressive hyperglycemia across the glucose tolerance continuum based on glycosylated hemoglobin levels in a rural South Indian population seems to be associated with worsening cardiovascular risk markers. A cut-off value of ≥6% (42 mmol/mol) seems to herald a much more significant increase in such markers. Long-term follow-up of this cohort for incident cardiovascular disease will help to substantiate the associations between glycosylated hemoglobin levels within the prediabetes range and cardiovascular disease in an Indian population. Evidence-based race-specific criteria for diagnosis of prediabetes and diabetes are the need of the hour for risk stratification and appropriate management.     

Management practices of tuberculosis in children among pediatric practitioners in Mangalore,South India

Introduction

In spite of having BCG vaccination and tuberculosis control program for the last 50 years, prevalence of tuberculosis continues to be high in India. Inadequate diagnostic methods, suboptimal treatment and monitoring, and the lack of vigilant reporting system are some of the contributing factors for the failure of TB control.

Prevalence of peripheral neuropathy among type 2 diabetes mellitus patients in a rural health centre in South India

International Journal of Diabetes in Developing Countries - There is a huge burden of diabetes-related complications, both microvascular and macrovascular, in India. With the rising prevalence of...