Effect of vitamin D supplementation on muscle energy phospho-metabolites: a ³¹P magnetic resonance spectroscopy-based pilot study.

There are several published reports on the prevalence of low vitamin D levels in otherwise healthy Indian population. Vitamin D deficiency has shown variable effect on muscle performance and strength but there is paucity of data on the effect of vitamin D deficiency on muscle energy metabolism. The present study was proposed to investigate the influence of severe vitamin D deficiency on high-energy metabolite levels in resting skeletal muscle and thereafter, monitor the response after vitamin D supplementation using ³¹P magnetic resonance spectroscopy (MRS). Study was conducted on 19 otherwise healthy subjects but with low serum 25(OH)D levels (<5 ng/ml). Subjects were supplemented with cholecalciferol at a dose of 60,000 IU/week for 12 weeks. MRS measurements of inorganic phosphate (Pi), phosphocreatine (PCr), phosphodiester (PDE) and ATP of the calf muscle were taken pre- and post-vitamin D supplementation. The study revealed significantly increased PCr/Pi ratio and decreased [Pi] and PDE/ATP ratio with raised serum 25(OH)D levels after 12 weeks of supplementation. The study indicates that serum 25(OH)D level plays an important role in improving the skeletal muscle energy metabolism and vitamin D deficiency might be one of the primary reasons for prevalence of low PCr/Pi ratio and high PDE values in normal Indian population as reported earlier. The findings of this preliminary study are highly encouraging and warrant further in-depth research, involving larger number of subjects of different age groups, regions and socio-economic sections of the society to further strengthen a correlation between vitamin D levels and muscle energy metabolism.

Enhanced heterodimerization of Bax by Bcl-2 mutants improves irradiated cell survival.

B Cell Lymphoma-2 (Bcl-2) protein suppresses ionizing radiation-induced apoptosis in hemato-lymphoid system. To enhance the survival of irradiated cells, we have compared the effects and mechanism of Bcl-2 and its functional variants, D34A (caspase-3 resistant) and S70E (mimics phosphorylation on S70). Bcl-2 and its mutants were transfected into hematopoietic cell line and assessed for cell survival, clonogenicity and cell cycle perturbations upon exposure to ionizing radiation. The electrostatic potential of BH3 cleft of Bcl-2/mutants and their heterodimerization with Bcl-2 associated X protein (Bax) were computationally evaluated. Correspondingly, these results were verified by co-immunoprecipitation and western blotting. The mutants afford higher radioprotective effect than Bcl-2 in apoptotic and clonogenic assays at D(0) (radiation dose at which 37 % cell survival was observed). The computational and functional analysis indicates that mutants have higher propensity to neutralize Bax protein by heterodimerization and have increased caspase-9 suppression capability, which is responsible for enhanced survival. This study implies potential of Bcl-2 mutants or their chemical/peptide mimics to elicit radioprotective effect in cells exposed to radiation.

Altered brain metabolism after whole body irradiation in mice: a preliminary in vivo 1H MRS study.

UNLABELLED: Abstract Purpose: In the classical description of acute radiation syndrome, the role of central nervous system (CNS) is underestimated. It is now well recognised that ionising radiation-induced oxidative stress may bring about functional changes in the brain. In this study, we prospectively evaluated metabolic changes in the brain after whole body irradiation in mice using in vivo proton ((1)H) nuclear magnetic resonance spectroscopy (MRS). MATERIAL AND METHODS: Young adult mice were exposed to whole body irradiation of 8 Gy and controls were sham irradiated. In vivo (1)H MRS from cortex-hippocampus and hypothalamic-thalamic region of brain at different time points, i.e., as early as 6 hours, day 1, 2, 3, 5 and 10 post irradiation was carried out at 7 Tesla animal magnetic resonance imaging system. Brain metabolites were measured and quantitative analysis of detectable metabolites was performed by linear combination of model (LCModel). RESULTS: Significant reduction in myoinositol (p = 0.03) and taurine (p = 0.02) ratios were observed in cortex-hippocampus region as early as day 2 post irradiation compared to controls. These metabolic alterations remained sustained over day 10 post irradiation. CONCLUSIONS: The results of this preliminary study suggest that the alteration/reduction in the mI and Tau concentration may be associated with physiological perturbations in astrocytes or radiation induced neuro-inflammatory response triggered in microglial cell.

Effect of visual experience on structural organization of the human brain: a voxel based morphometric study using DARTEL.

OBJECTIVE: To investigate structural reorganization in the brain with differential visual experience using Voxel-Based Morphometry with Diffeomorphic Anatomic Registration Through Exponentiated Lie algebra algorithm (DARTEL) approach. MATERIALS AND METHODS: High resolution structural MR images were taken in fifteen normal sighted healthy controls, thirteen totally blind subjects and six partial blind subjects. The analysis was carried out using SPM8 software on MATLAB 7.6.0 platform. RESULTS: VBM study revealed gray matter volume atrophy in the cerebellum and left inferior parietal cortex in total blind subjects and in left inferior parietal cortex, right caudate nucleus, and left primary visual cortex in partial blind subjects as compared to controls. White matter volume loss was found in calcarine gyrus in total blind subjects and Thlamus-somatosensory region in partially blind subjects as compared to controls. Besides, an increase in Gray Matter volume was also found in left middle occipital and middle frontal gyrus and right entorhinal cortex, and an increase in White Matter volume was found in superior frontal gyrus, left middle temporal gyrus and right Heschl's gyrus in totally blind subjects as compared to controls. Comparison between total and partial blind subjects revealed a greater Gray Matter volume in left cerebellum of partial blinds and left Brodmann area 18 of total blind subjects. CONCLUSION: Results suggest that, loss of vision at an early age can induce significant structural reorganization on account of the loss of visual input. These plastic changes are different in early onset of total blindness as compared to partial blindness.

Role of Apoptotic Proteins in REC-2006 Mediated Radiation Protection in Hepatoma Cell Lines.

The present study was carried out to evaluate the role of apoptotic proteins in REC-2006-mediated radiation protection in hepatoma cell lines. REC-2006 treatment 2 h before irradiation strongly inhibited the cleavage of ATM and PARP-1 in HepG2 cells. The expression of nuclear apoptosis inducing factor (AIF) was found to be more inhibited (~17%) in HepG2 cells in REC-2006 + radiation-treated group. More inhibition (~33%) of cytochrome c was observed in HepG2 cells upon REC-2006 treatment 2 h prior irradiation. Similarly, significantly more (P<.05) inhibition of Apaf-1, caspase-9 and caspase-3 was observed in REC-2006 + radition-treated group in HepG2 cells. REC-2006 treatment restored the expression of ICAD in HepG2 cells; however, no restoration was observed in Hep3B cells. Lower nuclear to cytoplasmic CAD ratio was observed in HepG2 cells (~0.6) as compared with Hep3B cells (~1.2) in REC-2006 + radiation-treated group. In conclusion, REC-2006 rendered higher protection in HepG2 cells by inhibiting the expression and translocation of AIF, inhibiting the cleavage of ATM and PARP-1, restoring the expression of ICAD, inhibiting the release of cytochrome c and thus modulating the expression of Apaf-1 caspase-9 and activity of caspase-3.

Brain metabolite changes in alcoholism: localized proton magnetic resonance spectroscopy study of the occipital lobe.

Chronic alcoholism is associated with altered brain metabolism, morphology and cognitive abilities. Besides deficits in higher order cognitive functions, alcoholics also show a deficit in the processing of basic sensory information viz. visual stimulation. To assess the metabolic changes associated with this deficit, (1)H MRS was carried out in the occipital lobe of alcohol dependents. A significant increase in Cho/Cr ratio (p<0.015) was observed in occipital lobe in the alcoholic group indicating altered cell membrane metabolism, which may probably be associated with the alterations in the cognitive abilities associated with vision.

Radiolabeling and dose fixation study of oral alpha-ketoglutarate as a cyanide antidote in healthy human volunteers.

CONTEXT: Radiolabeling and dose fixation study of alpha-ketoglutarate (A-KG). OBJECTIVE: A-KG is a potential oral antidote for cyanide poisoning. Its protective efficacy in animals was best exhibited at a dose of 2.0 g/kg body weight, which when extrapolated to human is very high. The objective of this study was to reduce the dose of A-KG in humans with concomitant increase in its bioavailability, employing pharmacoscintigraphic techniques to assess kinetics in man. MATERIALS AND METHODS: A-KG was radiolabeled with technetium-99m pertechnetate (Tc-99m) and its purity, labeling efficiency, and stability in vitro were determined by instant thin layer chromatography. Time-dependent bio-absorption of the drug in rats and rabbits was assessed by gamma scintigraphy after oral administration of a tracer dose of (99m)Tc-A-KG mixed with nonradioactive A-KG at a concentration of 0.1-2.0 g/kg in the presence or absence of aqueous dilution. Furthermore, scintigraphy and radiometry studies were performed in healthy human volunteers using 5-20 g of A-KG, given in single or split doses followed by different quantity of water. Drug bioavailability was estimated periodically. RESULTS: High radiolabeling (>97%) of A-KG with a stability of 24 h in vitro was obtained. Less than 1% absorption of the drug occurred within 20 min after A-KG was administered in animals at a concentration of 2.0 g/kg body weight. One-tenth reduction in dose increased the bioavailability to 15%. Significant improvement in gastric emptying of the drug was achieved when the drug was administered along with 1-5 mL of water. In humans, two doses of 10 g A-KG given at an interval of 10 min, followed by 300 mL of water, increased the drug bioavailability to 40% as compared to a single dose of 20 g. DISCUSSION: Significant reduction in A-KG dose was achieved in humans as compared to the recommended dose in animals. CONCLUSION: Aqueous dilution improves the bioavailability of A-KG in humans.

Bio-energetic impairment in human calf muscle in thyroid disorders: a 31P MRS study.

Mitochondrial metabolism particularly oxidative phosphorylation is greatly influenced by thyroid hormones. Earlier studies have described neuromuscular symptoms as well as impaired muscle metabolism in hypothyroid and hyperthyroid patients. In this study, we intend to look in to the muscle bioenergetics including phosphocreatine recovery kinetics based oxidative metabolism in thyroid dysfunction using in vivo (31)P nuclear magnetic resonance spectroscopy (MRS). (31)P MRS was carried out at resting state on 32 hypothyroid, 10 hyperthyroid patients and 25 control subjects. Nine out of 32 hypothyroid patients and 17 out of 25 control subjects under went exercise protocol for oxidative metabolism study and performed plantar flexion exercise while lying supine in 1.5 T magnetic resonance scanner using custom built exercise device. MRS measurements of inorganic phosphate (Pi), phosphocreatine (PCr), phosphodiesters (PDE) and adenosine triphosphate (ATP) of the calf muscle were acquired during rest, exercise and recovery phase. PCr recovery rate constant (k(PCr)) and oxidative capacity were calculated by monoexponential fit of PCr versus time (t) at the beginning of recovery. During resting condition in hypothyroid patients, PCr/Pi ratio was reduced whereas PDE/ATP and Pi/ATP were increased. However, in case of hyperthyroidism, an increased PCr/Pi ratio and reduced PDE/ATP and Pi/ATP were observed. The results confirmed differential energy status of the muscle due to increased or decreased levels of thyroid hormone. Our results also demonstrate reduced oxidative metabolism in hypothyroid patients based on PCr recovery kinetics. PCr recovery kinetics study after exercise revealed decreased PCr recovery rate constant (k(PCr)) in hypothyroid patients compared to controls that resulted in decrease in oxidative capacity of muscle by 50% in hypothyroids. These findings are consistent with a defect of high energy phosphate mitochondrial metabolism in thyroid dysfunction.

Prospective evaluation of CECT and 18F-FDG-PET/CT in detection of hepatic metastases.

OBJECTIVES: The purpose of this study was to evaluate the performance of F-fluorodeoxy-D-glucose (FDG)-PET/computed tomography (CT) and contrast-enhanced CT (CECT) in the detection and characterization of hepatic metastases. METHODS: Forty-five patients harboring an extrahepatic primary malignancy, with suspected hepatic metastases on clinical or ultrasonographic examination were enroled prospectively. Each patient underwent contrast-enhanced abdominal CT and F-FDG-PET/CT within 72 h of each other, reported by an experienced radiologist and nuclear medicine specialist, respectively in a blinded manner. CECT and PET-CT findings were compared and analyzed. Final diagnosis was based on histology and/or follow-up (ranging from 6 to 12 months). RESULTS: The sensitivity and specificity of CECT in the detection of hepatic metastases was 87.9 and 16.7%, respectively, whereas that of PET/CT was 97 and 75%, respectively. This study showed the superiority of PET/CT over CECT in the detection of hepatic metastases, irrespective of the primary site. This was especially owing to the latter's inability to reliably distinguish small (less than 15 mm) lesions as benign or malignant. CONCLUSION: Many studies have been conducted on the impact of FDG-PET/CT in the evaluation of hepatic metastases, especially from colorectal primary. Very few prospective studies, however, have been conducted on its role in evaluation of hepatic metastases from nongastrointestinal primaries. Despite its superior performance, it cannot replace CECT for this purpose, owing to the low but definite risk of false positivity based on PET-CT findings alone. Inclusion of CECT in PET/CT protocols may enable us to achieve a higher diagnostic accuracy. This suggests the need for a large prospective study with serial evaluations and pathological correlation.

RAS: target for cancer therapy.

The RAS protein controls signaling pathway are major player in cell growth, its regulation and malignant transformation. Any activation in RAS brings alteration in upstream or downstream signaling component. Activating mutation in RAS is found in approximately 30% of human cancer. RAS plays essential role in tumor maintenance and is therefore an appropriate target for anticancer therapy. Among the anti-RAS strategies that are under evaluation in the clinic are pharmacologic inhibitors designed to prevent: (1) association with the plasma membrane (prenylation and post prenylation inhibitors). (2) Downstream signaling (kinase inhibitor), (3) upstream pathway (kinase inhibitor and monoclonal antibody), (4) Expression of RAS or other component of pathway (siRNA and antisense oligonucleotide). Several of these new therapeutic agents are showing promising result in the clinic and many more are on the way. Here, we review the current status and new hopes for targeting RAS as an anticancer drug.

Petrous apex arachnoid cyst extending into Meckel's cave.

A rare case of arachnoid cyst involving the petrous apex with an unusual clinical presentation has been described with special emphasis in the imaging features and importance of accurate presurgical diagnosis. Differentiation from the other benign lesions involving the petrous apex and the role of newer MR techniques in the diagnosis of these lesions has been highlighted.

Magnetic resonance cholangiopancreatography: evaluation in 150 patients.

BACKGROUND AND AIMS: Magnetic resonance cholangiopancreatography (MRCP) is a non-invasive imaging technique for evaluating the biliary and pancreatic ducts. MRCP has reached a level of resolution and reliability where it may replace diagnostic endoscopic retrograde cholangio-pancreatography (ERCP). We analyzed the results of MRCP in adult patients with biliary or pancreatic disease, and compared the findings with those at surgery or on ERCP. METHODS: Data of 150 patients who underwent MRCP with both single slab and multislice rapid acquisition with relaxation enhancement sequences with half-fourier acquisition single-shot turbo spin echo techniques were analyzed. Patients were divided into four groups according to reason for referral for MRCP: obstructive jaundice (n = 65), chronic/acute pancreatitis (n = 25), screening prior to laparoscopic cholecystectomy (n = 20), and failed ERCP (n = 40). RESULTS: MRCP could accurately identify the level of biliary obstruction in 58 of 61 patients. Characterization of benign or malignant nature of a stricture was possible in 30 of 32 patients when findings of both MRCP and magnetic resonance imaging were analyzed together. MRCP revealed the morphology of the entire pancreatic duct in 13 of 15 patients having ductal changes on endoscopic retrograde pancreatography. CONCLUSION: MRCP has high sensitivity and specificity for detection of biliary dilatation, calculi, strictures and anatomical variants.