Analysis of bone marrow fatty acid composition using high-resolution proton NMR spectroscopy

Favorable fatty acid composition in adipose tissue in healthy Iraqi- compared to Swedish-born men - a pilot study using MRI assessment

Middle Eastern immigrants are at high-risk for insulin resistance. Fatty acid composition (FAC) plays an important role in the development of insulin resistance but has not been investigated in people of Middle Eastern ancestry. Here, the aim was to assess the FAC in visceral and subcutaneous adipose tissue (VAT and SAT) in healthy Iraqi- and Swedish-born men using a magnetic resonance imaging (MRI) method.This case-control study included 23 Iraqi- and 15 Swedish-born middle-aged men, without cardiometabolic disease. Using multi-echo MRI of the abdomen, the fractions of saturated, monounsaturated, and polyunsaturated fatty acids (fSFA, fMUFA, and fPUFA) were estimated in VAT and SAT. SAT was further analyzed in deep and superficial compartments (dSAT and sSAT).

In all depots, fPUFA was significantly higher and fSFA significantly lower in Iraqi men, independently of age and BMI. In both Iraqi- and Swedish-born men, higher fPUFA and lower fMUFA were found in sSAT vs. dSAT. Among Iraqi men only, higher fPUFA and lower fMUFA were found in SAT vs. VAT.Iraqi-born men presented a more favorable abdominal FAC compared to Swedish-born men. This MRI method also revealed different FACs in different abdominal depots. Our results may reflect a beneficial FAC in Middle Eastern immigrants.

  

Synthesis of Fatty Acid Methyl Ester from Croton macrostachyus (Bisana) Kernel Oil: Parameter Optimization, Engine Performance, and Emission Characteristics for Croton macrostachyus Kernel Oil Fatty Acid Methyl Ester Blend with Mineral Diesel Fuel

Utilization of agricultural waste such as nonedible seed oil for the synthesis of biodiesel via catalytic transesterification is one of the effective ways for the partial replacement of petroleum-based fuels in the area of renewable energy development and is beneficial to CO, CO₂, and unburned hydrocarbon (HC) emission reduction to the environment. In this regard, the current study investigates the synthesis of fatty acid methyl esters (FAMEs) from Croton macrostachyus kernel oil by considering parameter interaction and optimization to maximize the yield of fatty acid methyl esters (FAMEs). The response surface methodology-central composite design (RSM-CCD) was applied to optimize the C. macrostachyus fatty acid methyl ester (CMKO-FAME) synthesis process by varying the process parameters such as reaction time (1-2 h), molar ratio (6:1-12:1), and catalyst loading (1-2 wt %). The optimum conditions for the transesterification of C. macrostachyus kernel oil (CMKO) were found to be a methanol to oil ratio of 11.98:1, catalyst loading of 1.03 wt %, and reaction time of 2 h, resulting in the conversion of 95.03 wt % C. macrostachyus kernel oil into its mono FAMEs. The fuel properties of CMKO and its FAMEs were determined based on ASTM D6751 and EN 14214 standards. Further, the CMKO and its FAMEs were characterized using Fourier transform infrared (FT-IR), gas chromatography-mass spectrometry (GC-MS), and nuclear magnetic resonance spectroscopy (NMR). The fatty acid composition of CMKO was myristic acid (1.36%), palmitic acid (11.35%), stearic acid (5.11%), oleic acid (18.64%), gadoleic acid (0.34%), linoleic acid (49.084%), and linolenic acid (14.1%). The purity of the produced methyl esters was determined by ¹H NMR and found to be 95.52%, which was quite in good agreement with the experimentally observed yield of 95.39 wt %. The produced CMKO-FAME was blended with diesel fuel at various ratios (B5, B10, B15, and B20) to evaluate the engine performance and emission characteristics in a diesel engine. The engine brake thermal efficiency is lower, the brake-specific fuel consumption (BSFC) using CMKO-FAME blends is higher, and the temperature of exhaust gas emitted after combustion also increased as compared to diesel fuel. Similarly, using produced FAME blends, the emission emitted such as HC, NOx, and CO is reduced. However, the engine fueled with the produced FAME blends increased the level of CO₂ into the atmosphere when compared to diesel fuel. The performance and emission characteristics of diesel engine result show that the blend of CMKO-FAME and diesel can be used as a fuel in a diesel engine without any modification of the engine.

Saponification Value of Fats and Oils as Determined from 1H-NMR Data: The Case of Dairy Fats

The saponification value of fats and oils is one of the most common quality indices, reflecting the mean molecular weight of the constituting triacylglycerols. Proton nuclear magnetic resonance (1H-NMR) spectra of fats and oils display specific resonances for the protons from the structural patterns of the triacylglycerols (i.e., the glycerol backbone), methylene (-CH2-) groups, double bonds (-CH=CH-) and the terminal methyl (-CH3) group from the three fatty acyl chains. Consequently, chemometric equations based on the integral values of the 1H-NMR resonances allow for the calculation of the mean molecular weight of triacylglycerol species, leading to the determination of the number of moles of triacylglycerol species per 1 g of fat and eventually to the calculation of the saponification value (SV), expressed as mg KOH/g of fat. The algorithm was verified on a series of binary mixtures of tributyrin (TB) and vegetable oils (i.e., soybean and rapeseed oils) in various ratios, ensuring a wide range of SV. Compared to the conventional technique for SV determination (ISO 3657:2013) based on titration, the obtained 1H-NMR-based saponification values differed by a mean percent deviation of 3%, suggesting the new method is a convenient and rapid alternate approach. Moreover, compared to other reported methods of determining the SV from spectroscopic data, this method is not based on regression equations and, consequently, does not require calibration from a database, as the SV is computed directly and independently from the 1H-NMR spectrum of a given oil/fat sample.

Long-Chain Fatty Acids in Bones and Their Link to Submicroscopic Vascularization Network: NMR Assignment and Relaxation Studies under Magic Angle Spinning Conditions in Intramuscular Bones of Atlantic Herring Fish

The long-lasting proton signals in bones are identified as long-chain fatty acids, including saturated, mono-, and di-unsaturated fatty acids, with direct nuclear magnetic resonance evidence. We used intramuscular bones from Atlantic Herring fish to avoid interference from lipid-rich marrows. The key is to recognize that these signals are from mobile phase materials and study them with J-coupled correlation spectroscopies under magic angle spinning conditions. We kept extensive ¹H-spin-echo records that allowed us to examine the effect of magic angle spinning on the transverse relaxation time of water and lipids over time. While it is impossible to distinguish based on chemical shifts, the relaxation data suggest that the signals are more consistent with the interpretation of phospholipid membranes than triglycerides in lipid droplets. In particular, the simultaneous T₂ changes in water and lipids suggest that the centrifugal impact of magic angle spinning alters the lipid's structure in very tight spaces. Additional evidence of phospholipid membranes came from the choline-γ resonance at 3.2 ppm in fresh samples, which disappears with magic angle spinning. Thus, the fatty acid signals are at least partially from membrane bilayer structures, and we propose that they are linked to the submicroscopic vascularization channels similar to the dense canaliculi network in mammalian bones. Our detection of phospholipids from bones depended critically on two factors: (1) the elimination of the overwhelming triglyceride signals from marrows and (2) the preservation of water that biomembranes require. The relaxation data reveal aspects of lipid fluidity that have not been elucidated by previous order parameter studies on model membranes. Relaxation times have long been considered difficult to interpret. A robust and renewed understanding may be beneficial.

The Paradoxical Role of Uric Acid in Osteoporosis

Because of its high prevalence worldwide, osteoporosis is considered a serious public health concern. Many known risk factors for developing osteoporosis have been identified and are crucial if planning health care needs. Recently, an association between uric acid (UA) and bone fractures had been explored. Extracellular UA exhibits antioxidant properties by effectively scavenging free radicals in human plasma, but this benefit might be disturbed by the hydrophobic lipid layer of the cell membrane. In contrast, intracellular free oxygen radicals are produced during UA degradation, and superoxide is further enhanced by interacting with NADPH oxidase. This intracellular oxidative stress, together with inflammatory cytokines induced by UA, stimulates osteoclast bone resorption and inhibits osteoblast bone formation. UA also inhibits vitamin D production and thereby results in hyper-parathyroidism, which causes less UA excretion in the intestines and renal proximal tubules by inhibiting the urate transporter ATP-binding cassette subfamily G member 2 (ABCG2). At normal or high levels, UA is associated with a reduction in bone mineral density and protects against bone fracture. However, in hyperuricemia or gout arthritis, UA increases bone fracture risk because oxidative stress and inflammatory cytokines can increase bone resorption and decrease bone formation. Vitamin D deficiency, and consequent secondary hyperparathyroidism, can further increase bone resorption and aggravated bone loss in UA-induced osteoporosis.

Increased Bone Marrow-Specific Adipogenesis by Clofazimine Causes Impaired Fracture Healing, Osteopenia, and Osteonecrosis Without Extraskeletal Effects in Rats

Mycobacterium leprae infection causes bone lesions and osteoporosis, however, the effect of antileprosy drugs on the bone is unknown. We, therefore, set out to address it by investigating osteogenic differentiation from bone marrow (BM)-derived mesenchymal stem cells (MSCs). Out of 7 antileprosy drugs, only clofazimine (CFZ) reduced MSCs viability (IC50 ∼ 1 μM) and their osteogenic differentiation but increased adipogenic differentiation on a par with rosiglitazone, and this effect was blocked by a peroxisome proliferator-activated receptor gamma antagonist, GW9662. CFZ also decreased osteoblast viability and resulted in impaired bone regeneration in a rat femur osteotomy model at one-third human drug dose owing to increased callus adipogenesis as GW9662 prevented this effect. CFZ treatment decreased BM MSC population and homing of MSC to osteotomy site despite drug levels in BM being much less than its in vitro IC50 value. In adult rats, CFZ caused osteopenia in long bones marked by suppressed osteoblast function due to enhanced adipogenesis and increased osteoclast functions. A robust increase in marrow adipose tissue (MAT) by CFZ did not alter the hematologic parameters but likely reduced BM vascular bed leading to osteonecrosis (ON) characterized by empty osteocyte lacunae. However, CFZ had no effect on visceral fat content and was not associated with any metabolic and hematologic changes. Levels of unsaturated fatty acids in MAT were higher than saturated fatty acids and CFZ further increased the former. From these data, we conclude that CFZ has adverse skeletal effects and could be used for creating a rodent ON model devoid of extraskeletal effects.

The solid-state proton NMR study of bone using a dipolar filter: apatite hydroxyl contentversusanimal age

The hydroxyl content of bone apatite mineral has been measured using proton solid-state NMR performed with a multiple-pulse dipolar filter under slow magic angle spinning (MAS). This new method succeeded in resolving and relatively enhancing the main hydroxyl peak at ca. 0 ppm from whole bone, making it amenable to rigorous quantitative analysis. The proposed methodology, involving line fitting, the measurement of the apatite concentration in the studied material and adequate calibration, was proved to be convenient and suitable for monitoring bone mineral hydroxylation in different species and over the lifetime of the animal. It was found that the hydroxyl content in the cranial bone mineral of pig and rats remained in the 5–10% range, with reference to stoichiometric hydroxyapatite. In rats, the hydroxyl content showed a non-monotonic increase with age, which was governed by biological processes rather than by chemical, thermodynamically driven apatite maturation.

Mineral hydroxylation in whole bone can be accurately studied using proton MAS NMR with a multiple-pulse dipolar filter.

Imaging of Lipids in Native Human Bone Sections Using TOF-Secondary Ion Mass Spectrometry, Atmospheric Pressure Scanning Microprobe Matrix-Assisted Laser Desorption/Ionization Orbitrap Mass Spectrometry, and Orbitrap-Secondary Ion Mass Spectrometry

A method is described for high-resolution label-free molecular imaging of human bone tissue. To preserve the lipid content and the heterogeneous structure of osseous tissue, 4 μm thick human bone sections were prepared via cryoembedding and tape-assisted cryosectioning, circumventing the application of organic solvents and a decalcification step. A protocol for comparative mass spectrometry imaging (MSI) on the same section was established for initial analysis with time-of-flight secondary ion mass spectrometry (TOF-SIMS) at a lateral resolution of 10 μm to <500 nm, followed by atmospheric pressure scanning microprobe matrix-assisted laser desorption/ionization (AP-SMALDI) Orbitrap MSI at a lateral resolution of 10 μm. This procedure ultimately enabled MSI of lipids, providing the lateral localization of major lipid classes such as glycero-, glycerophospho-, and sphingolipids. Additionally, the applicability of the recently emerged Orbitrap-TOF-SIMS hybrid system was exemplarily examined and compared to the before-mentioned MSI methods.

Characterization and compositional analysis of highly acidic karanja oil and its potential feedstock for enzymatic synthesis of biodiesel

In the present study, we focused on the synthesis of biodiesel fromPseudomonas cepacia, crude karanja oil by the process of enzymatic transesterification using bio-support materials, such as lipase immobilized on polyvinyl alcohol/AlgNa.

MRI Study on the Changes of Bone Marrow Microvascular Permeability and Fat Content after Total-Body X-Ray Irradiation

In this study, we investigated microvascular perfusion status, changes to fat content and fatty acid composition in the bone marrow of rat femurs after total-body irradiation by quantitative permeability parameters of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and ex vivo high-resolution magic angle spinning (HRMAS) ¹H nuclear magnetic resonance spectroscopy (NMRS). Thirty-six Sprague-Dawley rats were randomly assigned to either an irradiated or nonirradiated control group. Permeability imaging using DCE-MRI and HRMAS ¹H NMRS was performed before irradiation, as well as at days 4 and 7 postirradiation. The volume transfer constant (K^trans) values increased to 2.219 ± 0.418/min ( P < 0.01) at day 4 and to 2.760 ± 0.217/min at day 7 ( P < 0.01) postirradiation. The plasma fraction (v_p) values gradually decreased. The proportion of (n-6) polyunsaturated fatty acids (PUFA) gradually reached a peak at day 7, the proportion of (n-3) PUFA gradually decreased and the proportion of saturated fatty acids gradually increased. After irradiation, K^trans at different times showed significant negative correlation with (n-3) PUFA ( r = -0.6393, P < 0.01) and significant positive correlation with (n-6) PUFA ( r = 0.6841, P < 0.05). These findings indicate that bone marrow microcirculation perfusion and vascular permeability correlated with fat content at an early time point after irradiation. A pathophysiological mechanism may exist based on fat-vascular permeability in the case of injury to bone marrow microcirculation.

Unsaturation level decreased in bone marrow fat of postmenopausal women with low bone density using high resolution magic angle spinning (HRMAS) 1H NMR spectroscopy

There are increasing evidences suggesting bone marrow adiposity tissue (MAT) plays a critical role in affecting both bone quantity and quality. However, very limited studies that have investigated the association between the composition of MAT and bone mineral density (BMD). The goal of this study was to quantify MAT unsaturation profile of marrow samples from post-menopausal women using ex vivo high-resolution magic angle spinning (HRMAS) proton nuclear magnetic resonance (¹H NMR) spectroscopy, and to investigate the relationship between MAT composition and BMD. Bone marrow samples were obtained by iliac crest aspiration during surgical procedures from 24 postmenopausal women (65-89years) who had hip surgery due to bone fracture or arthroplasty. Marrow fat composition parameters, in particular, unsaturation level (UL), mono-unsaturation level (MUL) and saturation level (SL), were quantified using HRMAS ¹H NMR spectroscopy. The patients were classified into three groups based on the DXA BMD T-scores: controls, osteopenia and osteoporosis. Marrow fat composition was compared between these three groups as well as between subjects with and without factures using ANOCOVA, adjusted for age. Subjects with lower BMD (n=17) had significantly lower MUL (P=0.003) and UL (P=0.039), and significantly higher SL (P=0.039) compared to controls (n=7). When separating lower BMD into osteopenia (n=9) and osteoporosis (n=8) groups, subjects with osteopenia had significantly lower MUL (P=0.002) and UL (P=0.010), and significantly higher SL (P=0.010) compared to healthy controls. No significant difference was observed between subjects with osteopenia and osteoporosis. Using HRMAS ¹H NMR, significantly lower unsaturation and significantly higher saturation levels were observed in the marrow fat of subjects with lower BMD. HRMAS ¹H NMR was shown to be a powerful tool for identifying novel MR markers of marrow fat composition that are associated with bone quality and potentially fracture, and other bone pathologies and changes after treatment. A better understanding of the relationship between bone marrow composition and bone quality in humans may identify novel treatment targets, and provide guidance on novel interventions and therapeutic strategies for bone preservation.

Salinity induced lipid production in microalgae and cluster analysis (ICCB 16-BR_047)

This work aimed to gain mechanistic insights into the salt stress mediated enhanced lipid accumulation in microalgae. Two freshwater microalgae were isolated from North Guwahati Assam, and were identified as Chlorella sorokiniana CG12(KR905186) and Desmodesmus GS12(KR905187). The effects of various salts such as NaCl, KCl, MgCl₂ and CaCl₂ were investigated where CaCl₂ exhibited the maximum effect on lipid enhancement up to 40.02% and 44.97% in CG12 and GS12, respectively. Furthermore, the substantial increase was observed in oleic acid content up to 64.18% and 53.46% in CG12 and GS12 in the presence of 25mM and 5mM CaCl₂, respectively. Cluster analysis revealed the correlation between lipid profile alterations by varying concentration of salts. Based on the outcomes of the present study, it is hypothesized that Ca²⁺ plays a decisive role in the cell signaling under salt stress conditions and subsequently enhances the synthesis of lipid molecules.

Characterization of Fatty Acid Composition in Bone Marrow Fluid From Postmenopausal Women: Modification After Hip Fracture

Bone marrow adipose tissue (BMAT) is associated with low bone mass, although the functional consequences for skeletal maintenance of increased BMAT are currently unclear. BMAT might have a role in systemic energy metabolism, and could be an energy source as well as an endocrine organ for neighboring bone cells, releasing cytokines, adipokines and free fatty acids into the bone marrow microenvironment. The aim of the present report was to compare the fatty acid composition in the bone marrow supernatant fluid (BMSF) and blood plasma of postmenopausal women women (65-80 years old). BMSF was obtained after spinning the aspirated bone marrow samples; donors were classified as control, osteopenic or osteoporotic after dual-energy X-ray absorptiometry. Total lipids from human bone marrow fluid and plasma were extracted, converted to the corresponding methyl esters, and finally analyzed by a gas chromatographer coupled with a mass spectrometer. Results showed that fatty acid composition in BMSF was dynamic and distinct from blood plasma, implying significance in the locally produced lipids. The fatty acid composition in the BMSF was enriched in saturated fatty acid and decreased in unsaturated fatty acids as compared to blood plasma, but this relationship switched in women who suffered a hip fracture. On the other hand, there was no relationship between BMSF and bone mineral density. In conclusion, lipid composition of BMSF is distinct from the circulatory compartment, most likely reflecting the energy needs of the marrow compartment. J. Cell. Biochem. 117: 2370-2376, 2016. © 2016 Wiley Periodicals, Inc.

Bone Marrow Lipid Profiles from Peripheral Skeleton as Potential Biomarkers for Osteoporosis: A 1H-MR Spectroscopy Study

RATIONALE AND OBJECTIVES

To characterize the lipidic profile of bone marrow in the calcaneus and femoral neck of healthy, osteopenic, and osteoporotic women, by using magnetic resonance spectroscopy (MRS) at 3T. The final goal was to identify specific metabolites with the potential ability to discriminate between healthy, osteopenic, and osteoporotic subjects.

MATERIALS AND METHODS

Sixty-two and thirty three postmenopausal women recruited to investigate calcaneus and femoral neck, respectively, underwent a bone mineral density (BMD) measurement to be classified as healthy subjects (n = 22), osteopenic (n = 45), or osteoporotic (n = 28) patients. MRS spectra were used to quantify and compare bone marrow fat resonances between the three BMD groups. Between-group differences were tested using a Welch analysis of variance. Multiple comparisons were made with the Games-Howell correction. Relationships between pairs of variables were assessed with linear correlation analysis. Reproducibility analysis was performed for all the lipid resonances in both sites.

RESULTS

The reproducibility was satisfactory. In femoral neck, methylene (L13), glycerol (L41, L43), and total lipid resonances were significantly lower in healthy as compared to osteoporotic subjects. On the other hand, in calcaneus, L13/glycerol significantly discriminated between osteopenic and osteoporotic subjects whereas L13/(unsaturated lipid) discriminated between healthy and osteopenic group. However, the reproducibility of both unsaturated lipid and glycerol resonances were less optimal.

CONCLUSIONS

MRS of bone marrow lipid profiles from peripheral skeletal sites may be a promising tool for screening of large population to identify individuals with or at risk for developing osteoporosis. Moreover, it provides information about the metabolic changes occurring in bone marrow with the development of osteoporosis, which are skeletal site dependent.

Qualitative Aspects of Bone Marrow Adiposity in Osteoporosis

The function of marrow adipocytes and their origin has not been defined although considerable research has centered on their presence in certain conditions, such as osteoporosis. Less work has focused on the qualitative aspects of marrow fat. Bone marrow serum is composed of multiple nutrients that almost certainly relate to functional aspects of the niche. Previous studies using non-invasive techniques have shown that osteoporotic individuals have more marrow fat and that the ratio of saturated: unsaturated fatty acid is high. We recently reported that bone marrow sera from osteoporotic patients with fracture showed a switch toward decreased content of total saturated versus unsaturated fatty acids, compared to patients without fracture highlighting a dynamic relationship between the composition of fatty acids in the bone microenvironment and the metabolic requirements of cells. The relative distribution of fatty acids differed considerably from that in the serum providing further evidence that energy utilization is high and that marrow adipocytes may contribute to this pool. Whether these lipids can affect osteoblast function in a positive or negative manner is still not certain but will require further investigation.

Understanding the local actions of lipids in bone physiology

The adult skeleton is a metabolically active organ system that undergoes continuous remodeling to remove old and/or stressed bone (resorption) and replace it with new bone (formation) in order to maintain a constant bone mass and preserve bone strength from micro-damage accumulation. In that remodeling process, cellular balances--adipocytogenesis/osteoblastogenesis and osteoblastogenesis/osteoclastogenesis--are critical and tightly controlled by many factors, including lipids as discussed in the present review. Interest in the bone lipid area has increased as a result of in vivo evidences indicating a reciprocal relationship between bone mass and marrow adiposity. Lipids in bones are usually assumed to be present only in the bone marrow. However, the mineralized bone tissue itself also contains small amounts of lipids which might play an important role in bone physiology. Fatty acids, cholesterol, phospholipids and several endogenous metabolites (i.e., prostaglandins, oxysterols) have been purported to act on bone cell survival and functions, the bone mineralization process, and critical signaling pathways. Thus, they can be regarded as regulatory molecules important in bone health. Recently, several specific lipids derived from membrane phospholipids (i.e., sphingosine-1-phosphate, lysophosphatidic acid and different fatty acid amides) have emerged as important mediators in bone physiology and the number of such molecules will probably increase in the near future. The present paper reviews the current knowledge about: (1°) bone lipid composition in both bone marrow and mineralized tissue compartments, and (2°) local actions of lipids on bone physiology in relation to their metabolism. Understanding the roles of lipids in bone is essential to knowing how an imbalance in their signaling pathways might contribute to bone pathologies, such as osteoporosis.

3 Tesla (1) H MR spectroscopy of hip bone marrow in a healthy population, assessment of normal fat content values and influence of age and sex

PURPOSE

To evaluate in a healthy population normal spectroscopic fat content (FC) values of the hip bone marrow and to assess the influence of age and sex on bone marrow conversion.

MATERIALS AND METHODS

Eighty volunteers (40 men; 40 women; ages: 20-60 years; divided into four consecutive groups) underwent acetabulum, femoral head, femoral neck, greater trochanter, and diaphysis localized (1) H MR spectroscopy. FC values of each anatomical site were obtained according to the following formula: Fat content = CH2 /(CH2  + Water)*100. To assess bone marrow conversion, a spectroscopic conversion index (SCI) was calculated as FC neck/FC greater trochanter.

RESULTS

FC values showed a gradient as follows: greater trochanter > femoral head > femoral neck > diaphysis > acetabulum in every age group both in men and in women. SCI increased with age both in men and women, showing lower values in women for every age group.

CONCLUSION

We obtained normal spectroscopic FC values from different areas of the hip, according to age and sex. These values may be used as reference values to evaluate, by the means of (1) H MR spectroscopy, pathological conditions affecting hip bone marrow.

In situ fatty acid profile of femoral cancellous subchondral bone in osteoarthritic and fragility fracture females: implications for bone remodelling

We report here differences in the fatty acid profile of cancellous bone matrix, including n-3, n-6, mono- and poly-unsaturated, as well as saturated fats, between femoral heads from female OA (n=8, aged 68-88years), fractured neck of femur (#NOF) (n=19, 67-88years) and autopsy controls (CTRL) (n=4, 85-97years). Femoral heads were collected from individuals undergoing orthopaedic surgery for OA or #NOF; the fatty acid profile of sub-samples from the superior principal compressive and superior principal tensile regions were determined by gas chromatography. A total of 42 individual fatty acids were detected at varying concentrations with significant differences between subchondral bone from OA subjects, subchondral bone from #NOF subjects and subchondral bone from CTRL subjects, as well as between the superior principal compressive and superior principal tensile regions (for saturated fats only). Subchondral bone from OA subjects had higher total n-6 (OA=10.89±3.17, #NOF=11.11±1.83, CTRL=8.32±2.05, p=0.008) and total n-3 (OA=1.34±0.38, #NOF=1.19±0.18, CTRL=1.15±0.48, p=0.011) percentages than subchondral bone from #NOF subjects and subchondral bone from CTRL subjects, and there was no difference in the n-6:n-3 ratio, nor within the percentage of n-9 fatty acids. Arachidonic acid (OA=0.42±0.16, #NOF=0.26±0.06, CTRL=0.28±0.06, p=0.01), and γ-linolenic acid (OA=0.11±0.03, #NOF=0.05±0.02, CTRL=0.04±0.02, p<0.001) were higher in subchondral bone from OA subjects than subchondral bone from #NOF subjects and subchondral bone from CTRL subjects. In conclusion, there is a wide diversity of fatty acids in cancellous bone matrix from the femoral heads of OA and #NOF, suggesting they may have regulatory effects on inflammatory processes, and their metabolites. This article is part of a Special Issue entitled "Osteoarthritis".

Enhanced refocusing of fat signals using optimized multipulse echo sequences

Endogenous magnetic resonance contrast based on the localized composition of fat in vivo can provide functional information. We found that the unequal pulse timings of the Uhrig's dynamical decoupling multipulse echo sequences significantly alter the signal intensity compared to conventional, equal-spaced Carr-Purcell-Meiboom-Gill sequences. The signal increases and decreases depending on the tissue and sequence parameters, as well as on the interpulse spacings; particularly strong differences were observed in fatty tissues, which have a highly structured morphology and a wide range of chemical shifts and J-couplings. We found that the predominant mechanism for fat refocusing under multipulse echo sequences is the chemical structure, with stimulated echoes playing a pivotal role. As a result, specialized pulse sequences can be designed to optimize refocusing of the fat chemical shifts and J-couplings, where the degree of refocusing can be tailored to specific types of fats. To determine the optimal time delays, we simulated various Uhrig dynamical decoupling and Carr-Purcell-Meiboom-Gill pulse sequence timings, and these results are compared to experimental results obtained on excised and in vivo fatty tissue. Applications to intermolecular multiple quantum coherence imaging, where the improved echo refocusing translates directly into signal enhancements, are presented as well.

Hepatic lipid composition differs between ob/ob and ob/+ control mice as determined by using in vivo localized proton magnetic resonance spectroscopy

OBJECT

Hepatic lipid accumulation is associated with nonalcoholic fatty liver disease, and the metabolic syndrome constitutes an increasing medical problem. In vivo proton magnetic resonance spectroscopy ((1)H MRS) allows the assessment of hepatic lipid levels noninvasively and also yields information on the fat composition due to its high spectral resolution.

MATERIALS AND METHODS

We applied (1)H MRS at 9.4T to study lipid content and composition in eight leptin-deficient ob/ob mice as a model of obesity and in four lean ob/+ control mice at 24 weeks of age. PRESS sequence was used. For accurate estimation of signal intensity, differences in relaxation behavior of individual signals were accounted for each mouse individually. Also, in order to minimize spectral degrading due to motion artifacts, respiration gating was applied.

RESULTS

Significant differences between ob/ob and ob/+ control mice were found in both lipid content and composition. The mean chain length was found to be significantly longer in ob/ob mice with a higher fraction of monounsaturated lipids.

CONCLUSION

(1)H MRS enables accurate assessment in hepatic lipids in mice, which is attractive for mechanistic studies of altered metabolism given the large number of genetically engineered mouse models available.

Remediation of biodiesel wastewater by chemical- and electro-coagulation: a comparative study

The remediation of biodiesel wastewater was carried out using chemical and electrochemical techniques. Initially the fatty acid methyl esters (FAME or biodiesel) and free fatty acids (FFA) were chemically removed from the wastewater using three types of mineral acids, H(2)SO(4), HNO(3) and HCl, at different pH values within the range of 1.0-8.0. Optimally, approximately 24.3 ml/l of FAME/FFA were removed from the wastewater when using H(2)SO(4) to set a final pH of 2.5 for 7 min. All pollutant levels were markedly reduced during this step. That is, approximately 38.94%, 76.32% and 99.36% of COD, BOD5 and oil & grease were respectively removed. The acidic aqueous phase left after the removal of the FAME/FFA phase was then treated by chemical- and electro-coagulation processes. The results demonstrated that both investigated treatment processes were effective for treating wastewater from a biodiesel production plant. The chemical coagulation provided a lower operating cost (1.11 USD/m(3)) compared with the electro-coagulation process (1.78 USD/m(3)). However, the latter process provided a better quality of wastewater compared with the former process, with the exception of the BOD levels.

Post-mortem volatiles of vertebrate tissue

Volatile emission during vertebrate decay is a complex process that is understood incompletely. It depends on many factors. The main factor is the metabolism of the microbial species present inside and on the vertebrate. In this review, we combine the results from studies on volatile organic compounds (VOCs) detected during this decay process and those on the biochemical formation of VOCs in order to improve our understanding of the decay process. Micro-organisms are the main producers of VOCs, which are by- or end-products of microbial metabolism. Many microbes are already present inside and on a vertebrate, and these can initiate microbial decay. In addition, micro-organisms from the environment colonize the cadaver. The composition of microbial communities is complex, and communities of different species interact with each other in succession. In comparison to the complexity of the decay process, the resulting volatile pattern does show some consistency. Therefore, the possibility of an existence of a time-dependent core volatile pattern, which could be used for applications in areas such as forensics or food science, is discussed. Possible microbial interactions that might alter the process of decay are highlighted.

In vivo NMR detection of diet-induced changes in adipose tissue composition

We introduce an in vivo spectroscopic method to assess the effects of diet on fatty acid composition of the predominant chemical constituent of adipocytes in mice. To do this, we make use of a nonlinear NMR signal that, unlike a standard NMR signal, is intrinsically insensitive to local magnetic field inhomogeneities and which naturally suppresses the large water signal from nonfatty tissues. Our method yields fat composition information from fat depots distributed over large sample volumes in a single experiment, without requiring the use of tedious shimming procedures, voxel selection, or water suppression. Our results suggest that this method can reveal clear differences in adipose tissue composition of mice fed a standard chow diet compared with mice fed a diet rich in polyunsaturated fatty acids. With further developments this method could be used to obtain information on human lipid composition noninvasively and to track changes in lipid composition induced by diet intervention, pharmaceutical drugs, and exercise.

T(2) determination of the J-coupled methyl protons of lipids: In vivo ilustration with tibial bone marrow at 3 T

PURPOSE

To demonstrate how J-coupling modulations of the CH(3) lipid resonance can be minimized enabling a representative T(2) to be measured.

MATERIALS AND METHODS

Experiments were conducted on canola oil and in vivo on tibial bone marrow of four volunteers at 3 T. The T(2) of the CH(2) protons was measured with a standard point resolved spectroscopy (PRESS) sequence, whereas the T(2) of the CH(3) protons was determined with a PRESS sequence composed of narrow bandwidth refocusing pulses designed to exploit the chemical shift displacement effect and rewind the J-coupling evolution of the CH(3) protons in the desired voxel. Spectra were acquired at five echo times.

RESULTS

The narrow bandwidth PRESS sequence rewound the J-evolution of the CH(3) protons resulting in a T(2) curve that was well described by a monoexponential function. The mean T(2) of the bone marrow CH(3) protons was calculated to be 132.6 msec. The mean T(2) of the bone marrow CH(2) protons was estimated with a regular PRESS sequence to be 88.0 msec. The mean CH(2):CH(3) tibial bone marrow composition was estimated to be 12.0:1.

CONCLUSION

The presented technique permits the T(2) of the methyl protons of lipids to be determined with more accuracy by minimizing contributions from J-coupling.

Application of high-resolution 1H MAS NMR spectroscopy to the analysis of intact bones from mice exposed to gamma radiation

Herein we demonstrate that high-resolution magic angle spinning (MAS) 1H NMR can be used to profile the pathology of bone marrow rapidly and with minimal sample preparation. The spectral resolution obtained allows several metabolites to be analyzed quantitatively. The level of NMR-detectable metabolites in the epiphysis + metaphysis sections of mouse femur were significantly higher than that observed in the diaphysis of the same femur. The major metabolite damage to bone marrow resulting from either 3.0 Gy or 7.8 Gy of whole-body gamma radiation 4 days after exposure were (1) decreased total choline content, (2) increased fatty acids in bone marrow, and (3) decreased creatine content. These results suggest that the membrane choline phospholipid metabolism (MCPM) pathway and the fatty acid biosynthesis pathway were altered as a result of radiation exposure. We also found that the metabolic damage induced by radiation in the epiphysis + metaphysis sections of mouse femur was higher than that of the diaphysis of the same femur. Traditional histopathology analysis was also carried out to correlate radiation damage with changes in metabolites. Importantly, the molecular information gleaned from high-resolution MAS 1H NMR complements the pathology data.

A study of bone marrow and subcutaneous fatty acid composition in subjects of varying bone mineral density

Osteoporosis is associated with an increase in marrow fat. Fats, particularly polyunsaturated fats, either in co-cultures or diet, have been shown to significantly influence bone remodeling. Whether the increase in marrow fat seen in osteoporosis is also associated with a change in fatty acid composition is not known. This study was undertaken to investigate the fatty acid composition in subjects of varying bone mineral density (BMD). Samples of marrow fat and subcutaneous fat from 126 subjects (98 females, 34 males, mean age 69.7+/-10.5 years) undergoing orthopedic surgery were analyzed for fatty acid composition by gas chromatography. These results were correlated with BMD assessed by DXA. A total of 22 fatty acids were identified in marrow and subcutaneous fat. Significant differences in fatty acid composition existed between marrow and subcutaneous fat as well as between marrow fat samples obtained from the proximal femur and proximal tibia. Other than cis-7-hexadecenoic acid [C16:1 (n=9)] and docosanoic acid [C22:0], no difference in marrow fatty acid composition was evident between subject groups of varying BMD (normal, low bone mass, and osteoporosis). In conclusion, there exists a wide range of individual fatty acids in marrow fat. Marrow fatty acid composition differs from that of subcutaneous fat and varies between predominantly erythropoetic and fatty marrow sites. Other than cis-7-hexadecenoic acid [C16:1 (n=9)] and docosanoic acid [C22:0], no difference in marrow fatty acid composition was evident between subjects of varying BMD.

Composition of adipose tissue and marrow fat in humans by 1H NMR at 7 Tesla

Proton NMR spectroscopy at 7 Tesla (7T) was evaluated as a new method to quantify human fat composition noninvasively. In validation experiments, the composition of a known mixture of triolein, tristearin, and trilinolein agreed well with measurements by ¹H NMR spectroscopy. Triglycerides in calf subcutaneous tissue and tibial bone marrow were examined in 20 healthy subjects by ¹H spectroscopy. Ten well-resolved proton resonances from triglycerides were detected using stimulated echo acquisition mode sequence and small voxel (∼0.1 ml), and T₁ and T₂ were measured. Triglyceride composition was not different between calf subcutaneous adipose tissue and tibial marrow for a given subject, and its variation among subjects, as a result of diet and genetic differences, fell in a narrow range. After correction for differential relaxation effects, the marrow fat composition was 29.1 ± 3.5% saturated, 46.4 ± 4.8% monounsaturated, and 24.5 ± 3.1% diunsaturated, compared with adipose fat composition, 27.1 ± 4.2% saturated, 49.6 ± 5.7% monounsaturated, and 23.4 ± 3.9% diunsaturated. Proton spectroscopy at 7T offers a simple, fast, noninvasive, and painless method for obtaining detailed information about lipid composition in humans, and the sensitivity and resolution of the method may facilitate longitudinal monitoring of changes in lipid composition in response to diet, exercise, and disease.