Establishment of a concept of visceral fat syndrome and discovery of adiponectin

Although obesity is a major background of life style-related diseases such as diabetes mellitus, lipid disorder, hypertension and cardiovascular disease, the extent of whole body fat accumulation does not necessarily the determinant for the occurrence of these diseases. We developed the method for body fat analysis using CT scan and established the concept of visceral fat obesity, in other word metabolic syndrome in which intra-abdominal visceral fat accumulation has an important role in the development of diabetes, lipid disorder, hypertension and atherosclerosis. In order to clarify the mechanism that visceral fat accumulation causes metabolic and cardiovascular diseases, we have analyzed gene expression profile in subcutaneous adipose tissue and visceral adipose tissue. From the analysis, we found that adipose tissue, especially visceral adipose tissue expressed abundantly the genes encoding bioactive substances such as cytokines, growth factors and complements. In addition to known bioactive substances, we found a novel collagen-like protein which we named adiponectin. Adiponectin is present in plasma at a very high concentration and is inversely associated with visceral fat accumulation. Adiponectin has anti-diabetic, anti-hypertensive and anti-atherogenic properties and recent studies revealed that this protein has an anti-inflammatory and anti-oncogenic function. Therefore hypoadiponectinemia induced by visceral fat accumulation should become a strong risk factor for metabolic and cardiovascular diseases and also some kinds of cancers.In this review article, I would like to discuss the mechanism of life style-related diseases by focusing on the dysregulation of adiponectin related to obesity, especially visceral obesity.     

Reduction in the electronic band gap of titanium oxide nanotubes

The structural and electronic properties of individual titanium oxide nanotubes have been studied using both empirical and ab initio calculations. Two different types of titanium oxide nanotubes (A-nanotube and B-nanotube) have been constructed and energy-minimized by molecular mechanics calculations. We found that the A-nanotubes are energetically more favorable than the B-nanotubes. The electronic band structure of the titanium oxide nanotubes was also calculated with respect to the tubule diameter and the tubule type using the ab initio method. The band gap of the A-nanotube was reduced by up to 60% as the tubule diameter decreases from 1.2 nm to 0.5 nm.     

Frequency-Selective Fat Suppression Radiofrequency Pulse Train to Remove Olefinic Fats

CHESS pulse can suppress the signal originating from aliphatic fat protons but cannot suppress the signal from olefinic fat protons, which is near the resonance frequency of water protons. Adipose tissue contains various fat species; aliphatic fat comprises about 90 % and olefinic fat about 10 % of adipose tissue. Thus, CHESS pulse cannot be used to suppress the signal from adipose tissue completely. The purpose of this study was to find a method to suppress the signal from adipose tissue completely. The Fatsat train pulse, created with an arbitrary flip angle and insensitive to B1 inhomogeneity, was used. Because B1 inhomogeneity is larger on higher field magnetic resonance imaging, the fat suppression radiofrequency pulse needs to be B1-insensitive. To investigate a percentage of olefinic fat in adipose tissues, the excitation frequency of the Fatsat train pulse was varied from ?240 to +400 Hz and the images and fat-suppressed images were obtained. The presence of olefinic fat comprising about 10 % of abdominal adipose tissue was identified. The result agreed with some previous papers. Complete fat suppression could be achieved by partial (10 %) inversion of longitudinal aliphatic fat magnetization and by canceling out the two fat magnetizations. The flip angle was identified to about 95°. In conclusion, the cause that the signal from adipose tissues cannot be suppressed completely has been found. Improved images that signals from adipose tissues were suppressed completely have been demonstrated. This technique can also be applied to several pulse sequences.     

Significance of single and multi-voxel 1H magnetic resonance spectroscopy in the quantification of myocellular lipid in young non-obese Asian Indian males

To prospectively assess intramyocellular lipids (IMCL) and extramyocellular lipids (EMCL) using single voxel spectroscopy (SVS) and multi voxel magnetic resonance spectroscopy (MVS) in soleus muscle and correlate results with metabolic variables in non-obese (BMI < 23 kg/m²) Asian Indian males. Thirty one patients with diabetes (cases) and twelve normoglycaemic subjects (controls) underwent point resolved spectroscopy sequence (PRESS) of soleus muscle using SVS and MVS in a 3 T MRI scanner. Visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) were measured from MRI images and body composition was measured from dual-energy x-ray absorptiometry (DXA). The mean IMCL from SVS and MVS were 1.6% and 2.6% in cases and 2.3% and 3.4% in controls respectively. The mean EMCL from SVS and MVS were 1.8% and 3% in cases and 1.5% and 3% respectively in controls. A significant correlation between IMCL and total fat mass (rho = 0.42, p < 0.01) and total body fat (rho = 0.46; p < 0.01) were observed in cases while using the SVS technique and no correlations were found in the MVS technique. The SVS showed significant correlations between total myocellular lipids with VAT and SAT in cases alone. Total myocellular lipids acquired using both techniques showed a significant correlation with BMI, waist circumference, total fat mass, total body fat and truncal fat in cases alone. Quantification of IMCL of soleus muscle using the SVS technique is useful in studying the relationship with metabolic markers in non-obese Asian Indians with diabetes.     

Alterations in the fat body and midgut of Culex quinquefasciatus larvae following exposure to different insecticides

This study describes morphological alterations in the fat body and midgut of Culex quinquefasciatus larvae following exposure to different insecticides. To this end, both third and fourth instars of C. quinquefasciatus larvae were exposed for 30 and 60 min to organophosphate (50 ppb), pyrethroids (20 and 30 ppb), and avermectin derivates (1.5 and 54 ppb). Following incubation, pH measurements of the larvae gut were recorded. The fat body and midgut were also analyzed by light and transmission electron microscopy. These studies demonstrate a decrease in the pH of the larvae anterior midgut following exposure to all of the tested insecticides. Histochemical tests revealed a strong reaction for neutral lipids in the control group and a marked decrease in the group exposed to cypermethrin. Furthermore, a weak reaction with acidic lipids in larvae exposed to deltamethrin, temephos, ivermectin and abamectin was also observed. Insecticide-exposed larvae also exhibited cytoplasm granule differences, relative to control larvae. Finally, we noted a small reduction in microvilli size in the apex of digestive cells, although vesicles were found to be present. The destructive changes in the larvae were very similar regardless of the type of insecticide analyzed. These data suggest that alterations in the fat body and midgut are a common response to cellular intoxication.     

Noninvasive assessment of abdominal adipose tissues and quantification of hepatic and pancreatic fat fractions in type 2 diabetes mellitus

The purpose of this study was to evaluate adipose tissue distributions and hepatic and pancreatic fat contents using a 6-point Dixon MRI technique in type 2 diabetes mellitus (T2DM), and to assess associations between fat distributions and biochemical markers of insulin resistance. Intra-abdominal MRI was investigated in 14 T2DM patients, 13 age- and sex-matched healthy controls (HC) and 11 young HC using a 3 T Prisma MRI scanner. All T2DM subjects completed a fasting comprehensive metabolic panel, and demographic measurements were taken according to standardized methodologies. We observed excellent correlation (R² = 0.94) between hepatic fat fraction quantified using 6-point Dixon MRI and gold standard MRS, establishing the accuracy and reliability of the Dixon technique. Significantly increased visceral adipose tissue (VAT) volumes were found in T2DM patients compared to age-matched HC (1569.81 ± 670.62 cm³ vs. 1106.60 ± 566.85 cm³, p = .04). We also observed a trend of increasing subcutaneous adipose tissues (SAT), and total abdominal fat (TAT) volumes in T2DM compared to age-matched HC. Hepatic fat fraction percentage (HFF%) was 44.6% higher in T2DM compared to age-matched HC and 64.4% higher compared to young HC. Pancreatic fat fractions in the head and body/tail were higher in T2DM patients compared to both healthy cohorts. We also observed correlations between fat contents of the liver and pancreas in T2DM patients, and association between biochemical markers of T2DM with HFF, indicating a risk for non-alcoholic fatty liver disease among T2DM. In summary, this study provides evidence of T2DM patients having increased liver and pancreatic fat, as well as increased adipose tissues.     

Monodispersed Bioactive Glass Nanoparticles Enhance the Osteogenic Differentiation of Adipose‐Derived Stem Cells through Activating TGF‐Beta/Smad3 Signaling Pathway

It is important to understand the interaction mechanisms between nanomaterials and adipose‐derived stem cells for biomedical application. Nanoscale bioactive glass has positive effects on guiding osteoblasts differentiation and bone regeneration. However, the effects and molecular mechanism of monodispersed bioactive glass nanoparticles on the osteogenic differentiation of adipose‐derived stem cells are still not clear up to now. In this study, the effects and underlying molecular mechanism of monodispersed bioactive glass nanoparticles on the osteogenic differentiation of adipose‐derived stem cells are investigated in minute detail. The results show that nanoparticles (100–200 nm) can be absorbed by stem cells and is distributed in cytoplasm and nucleus. In both culture conditions (normal and osteoinductive), nanoparticles (80 µg mL⁻¹) can significantly enhance the osteogenic differentiation of stem cells through upregulating the alkaline phosphatase activity, osteogenic genes and protein expressions, as well as calcium deposition. Further study suggests that the activation of transforming growth factor‐beta/Smad3 signaling pathway plays an important role in the osteogenic differentiation of adipose‐derived stem cells enhanced by monodispersed nanoparticles. This study may have important implications for better understanding of stem cells fate induced by monodispersed nanoparticles and provide a promising approach toward stem cells‐based bone regeneration.     

Dehiscent organs used for defensive behavior of kamikaze termites of the genus Ruptitermes (Termitidae,Apicotermitinae) are not glands

During Isoptera evolution, the caste of soldiers disappeared in some Apicotermitinae termites as in the Neotropical Ruptitermes. Paired dorsolateral structures located between the metathorax and abdomen of foraging workers of Ruptitermes were previously denominated dehiscent glands, and are responsible for releasing an adhesive secretion that immobilizes enemies, causing their death. In this study, we investigated the morphology of dehiscent organs of workers of Ruptitermes reconditus, Ruptitermes xanthochiton, and Ruptitermes pitan and also second instar larvae of R. reconditus using light, laser scanning confocal, and transmission electron microscopy. Additionally, we performed a preliminary protein analysis using SDS-PAGE to further characterize the secretion of Ruptitermes dehiscent organs. Our results showed that the dehiscent organs do not exhibit the typical characteristics of the exocrine glandular cells class I, II or III of insects, suggesting that they constitute a new type of defensive organ. Thus, the denomination dehiscent gland was not used but dehiscent organ. Dehiscent organs in larvae are formed by fat body cells. In workers, dehiscent organs are composed by compact masses of cells that accumulate a defensive secretion and are poor in organelles related to the production of secretion. Since the dehiscent organs are not glands, we hypothesize that the dehiscent organs originate from larval fat body. The defensive secretion may have been produced at younger developmental stages of worker or the defensive compounds were absorbed from food and accumulated in the worker fat body. Histochemical techniques and SDS-PAGE revealed that the secretion of Ruptitermes dehiscent organs is constituted mainly by a protein of high molecular weight (200 kDa). In conclusion, the dehiscent organs are extremely different from the exocrine glands of termites and other insects described until now. In fact, they seem to be a specialized fat body that is peculiar and exclusive of Ruptitermes termites.     

Histological and histochemical features of the oogenesis in the simultaneous protandric hermaphrodite shrimp Exhippolysmata oplophoroides (Decapoda: Caridea)

This study analyzes the dynamics of the vitellogenesis process in the simultaneous protandric hermaphrodite shrimp Exhippolysmata oplophoroides, based on light microscopic observations. The ovotestes of the shrimps at the different gonadal development stages were removed, fixed and submitted an usual histological procedure (HE) and histochemical techniques (Bromophenol Blue, PAS/Alcian Blue, and Von Kossa tests). The germinative cells were classified into oogonias, and oocytes in stages I–IV based on the following features: cell size, cytoplasm appearance, presence of yolk granules, lipid droplets, chorion, and chromatin patterns. In the male initial phase of the gonadal development, the ovotestes present mainly oogonia and oocytes I and II while in the functional hermaphrodite phase, oocytes III and IV predominate in the peripheral zone of the gonads. Oocytes with an atypical appearance of the cellular components indicative of reabsorption were also observed. This study showed an increasing accumulation of proteins, carbohydrates and lipids occurring as the germ cells develop, being the yolk elements deposited in a sequence, in which proteins and carbohydrates are the first to appear both by an endogenous as well as also by an exogenous origin. The presence of calcium was detected mainly in oocytes I, II and inside those in reabsorption, being posteriorly mobilized to chorion constitution and/or to hemolymph due to its role during molting. Although the similarity of the germ cells shape among the crustaceans, this first histochemical characterization of E. oplophoproides ovary increases the comprehension of oogenesis in a caridean simultaneous protandric hermaphrodite species.     

A Fluorescent and Phosphorescent Nanoporous Solid: Crystalline Calix[4]arene

Calix[4]arene forms elongated nanoporous microcrystals. The pores are linear nano-channels (1.7 nm diameter) arranged in a honeycomb network. The crystals luminesce at room temperature according to a variety of processes that include monomer fluorescence (lifetime of ca. 1.1 ns), dimer fluorescence (lifetime of ca. 5.4 ns), and monomer phosphorescence (lifetime of ca. 2 s). The dimers result from pi-orbital overlap of adjacent phenol groups from neighboring nano-channels, with C-C distances of ca. 4 A.     

Optical properties of the subcutaneous adipose tissue in the spectral range 400–2500 nm

The optical characteristics of subcutaneous adipose tissue are studied in the wavelength range 400–2500 nm. The experiments are conducted in vitro using a Cary 2415 spectrophotometer. Based on the measured diffuse reflectance and total transmittance spectra, the spectra of the absorption and transport scattering coefficients are calculated in terms of the inverse adding-doubling method.     

Absorption spectra of photosensitized human fat tissue

We study experimentally the optical characteristics of adipose tissue in vitro in its dye sensitization—by indocyanin green and brilliant green. We conducted experiments on a PerkinElmer Lambda 950 spectrophotometer in the spectral range of 250–900 nm. From an analysis of the measured absorption spectra, we determine the shifts in the maximum of the absorption band for the studied photosensitizers in adipose tissue in comparison to their spectra in solutions. These shifts are explained by the bonding of photosensitizer molecules with the protein matrix of adipose tissue. We find the relative monomer and dimer concentrations of dye molecules in solutions and stained samples.     

Effect of gold nanoparticles on adipogenic differentiation of human mesenchymal stem cells

Gold nanoparticles are very attractive for biomedical products. However, there is a serious lack of information concerning the biological activity of nanosized gold in human tissue cells. An influence of nanoparticles on stem cells might lead to unforeseen consequences to organ and tissue functions as long as all cells arising from the initial stem cell might be subsequently damaged. Therefore the effect of negatively charged gold nanoparticles (9 and 95 nm), which are certified as reference material for preclinical biomedical research, on the adipogenic differentiation of human mesenchymal stem cells (hMSCs) is investigated here. Bone marrow hMSCs are chosen as differentiation model since bone marrow hMSCs are well characterized and their differentiation into the adipogenic lineage shows clear and easily detectable differentiation. In this study effects of gold nanoparticles on adipogenic differentiation are analyzed regarding fat storage and mitochondrial activity after different exposure times (4–21 days). Using time lapse microscopy the differentiation progress under chronically gold nanoparticle treatment is continuously investigated. In this preliminary study, chronically treatment of adipogenic differentiating hMSCs with gold nanoparticles resulted in a reduced number and size of lipid vacuoles and reduced mitochondrial activity depending on the applied concentration and the surface charge of the particles.     

‘Epixenosomes’: Peculiar epibionts of the protozoon ciliate Euplotidium itoi: Do their cytoplasmic tubules consist of tubulin?

Epixenosomes, epibiontic organisms living on the protozoon ciliate Euplotidium itoi, like prokaryotes, lack a true nucleus surrounded by a nuclear envelope. However, their cytoplasm, at least in the mature state, is somehow compartmentalized by the presence of a complex extrusive apparatus surrounded by a form of basket consisting of bundles of tubules (BT), 20–24 nm in diameter, delineated by a wall made of globular subunits. The nature of these tubules was investigated by means of in vivo experiments, ultrastructural analysis and immunocytochemistry by both fluorescence and electron microscopy. It has been found that BT, besides being well preserved when fixed in the presence of tannic acid, are sensitive to factors known to depolymerize cytoplasmic microtubules in a variety of cells such as nocodazole and cold and show a positive immunoreaction against different antitubulin antibodies. On the basis of all the results obtained, the hypothesis that the epixenosomal BT consist of tubulin acquires a strong credibility. This is particularly interesting if we consider that tubulin in prokaryotes has never been conclusively demonstrated.     

Noninvasive detection of intimal xanthoma using combined ultrasound, strain rate and photoacoustic imaging

Background and motivation

The structure, composition and mechanics of carotid artery are good indicators of early progressive atherosclerotic lesions. The combination of three imaging modalities (ultrasound, strain rate and photoacoustic imaging) which could provide corroborative information about the named arterial properties could enhance the characterization of intimal xanthoma.

Methods

The experiments were performed using a New Zealand white rabbit model of atherosclerosis. The aorta excised from an atherosclerotic rabbit was scanned ex vivo using the three imaging techniques: (1) ultrasound imaging of the longitudinal section: standard ultrasound B-mode (74 Hz frame rate); (2) strain rate imaging: the artery was flushed with blood and a 1.5 Hz physiologic pulsation was induced, while the ultrasound data were recorded at higher frame rate (296 Hz); (3) photoacoustic imaging: the artery was irradiated with nanosecond pulsed laser light of low fluence in the 1210-1230 nm wavelength range and the photoacoustic data was recorded at 10 Hz frame rate. Post processing algorithms based on cross-correlation and optical absorption variation were implemented to derive strain rate and spectroscopic photoacoustic images, respectively.

Results

Based on the spatio-temporal variation in displacement of different regions within the arterial wall, strain rate imaging reveals differences in tissue mechanical properties. Additionally, spectroscopic photoacoustic imaging can spatially resolve the optical absorption properties of arterial tissue and identify the location of lipid pools.

Conclusions

The study demonstrates that ultrasound, strain rate and photoacoustic imaging can be used to simultaneously evaluate the structure, the mechanics and the composition of atherosclerotic lesions to improve the assessment of plaque vulnerability.     

Depth profiling of porcine adipose tissue by Raman spectroscopy

Raman spectroscopy was applied on a depth profile of porcine adipose tissue (from skin to meat) with the purpose of (1) discriminating between fat layers and (2) estimating the variation in fatty acid composition as a function of fat depth and fat layer: total degree of unsaturation (iodine value), fractions of saturated, and monounsaturated and polyunsaturated fatty acids. The thickness and composition of the outer layer of porcine adipose tissue influences the final quality of backfat. A too‐thick outer layer is associated with problems such as oily appearance, rancidity development, and difficulties in separating muscle and adipose tissue when cutting. From principal component analysis on standard normal variate preprocessed Raman spectra (1800–800 cm^–1), it was possible to discriminate between the outer and the inner backfat layer. Principal component analysis loadings showed that the separation of layer was mainly explained by variation in the bands originating from vibration of double bond C = C stretching plus = C–H twisting and rocking. In the prediction of iodine value a three‐component partial least squares regression model based on full range Raman spectra showed a root mean square error of cross validation of 2.00 and R² = 0.69. Applying Cauchy–Lorentz band fitting proved that information regarding fat unsaturation was found not only in band intensity, but also in band parameters such as location and width. The results suggest Raman spectroscopy as a potential measurement technique for rapid grading of pork carcasses. Copyright © 2011 John Wiley & Sons, Ltd.     

Experimental evidence of the local character of vibrations constituting the Boson peak in amorphous solids

We report the first measurement of the density of states of low-energy vibrational excitations in a disordered solid via single-molecule (SM) spectroscopy. Optical spectra of many single tetra-tert-butylterrylene (TBT) molecules embedded to amorphous polyisobutylene (PIB) as spectral probes were recorded at low temperatures. The T dependences of SM spectral linewidths showed the broad distribution of local frequencies of vibrations under study. The obtained distribution was compared with the "Boson peak" in pure PIB measured in [R. Inoue, J. Chem. Phys. 95, 5332 (1991)] by neutron scattering. We found that embedding of a small amount of TBT into PIB does not influence markedly on the observed vibrational dynamics. These results prove the local character of low-energy vibrational excitations in glasses and the existence of relationship between these excitations and the Boson peak.     

The frequency-domain method reveals the dimeric structure of Na,K-ATPase

Lucifer yellow and lissamine rhodamine sulfonyl hydrazine were used as the donor and the receptor, respectively, for Förster energy transfer measurements to determine the location of the subunit in the native Na,K-ATPase from pig kidney. It was found that (1) the subunits are located in one functional complex, i.e., the dimer ()₂ appears to be the functional complex of Na,K-ATPase, and (2) the subunits in the functional enzyme complex in the membrane are not located next to each other but are rather well separated. The distance between fluorophores covalently attached to the subunits was found to be 5.3 nm.     

Morpho-physiological analysis of the insect fat body: A review

The insect fat body is the main organ of the intermediate metabolism of insects. The majority of proteins of the haemolymph is synthesized in this tissue, which also presents the functions of lipids, carbohydrates and proteins storage. This tissue is also responsible for the synthesis of vitellogenins, proteins with an important role in the reproduction of the insects, being incorporated into the oocytes during vitellogenesis. The fat body consists of thin layers or strings, generally one or two cells thick, or small nodules suspended in the hemocele through connective tissues and trachea. Within a species, the structure of this tissue is more or less constant, but can have considerable differences between insects of different orders. In this way, this article makes a review about the main morpho-physiological features of the fat body cells of the insects, as well as a phylogenetic study of the fat body between basal and derived species of the Attini tribe ants.     

Rapana thomasiana hemocyanin (RtH): dissociation and reassociation behavior of two isoforms, RtH1 and RtH2

Rapana thomasiana hemocyanin (RtH) is a mixture of two hemocyanin isoforms, termed RtH1 and RtH2. The two subunit types, purified by ion exchange chromatography, were used for macromolecular reassociation studies. In vitro reassociation was achieved with Tris-saline stabilizing buffer at pH 7.4, containing 100mM calcium and magnesium chloride at 4 degrees C. The relatively slow progress of reassociation was monitored, and the different oligomeric forms of RtH1 and RtH2 were studied by transmission electron microscopy, using samples negatively stained with 1% (w/v) uranyl acetate or 5% (w/v) ammonium molybdate containing 1% (w/v) trehalose at pH 7.0. The two subunits reassociate to produce characteristic didecamers, oligomeric and polymeric forms depending on the dissociated material and the reassociation conditions (i.e. divalent ion concentration, duration). In contrast to the didecamers of the freshly isolated RtH preparations, RtH1 and RtH2 show after 2 weeks' reassociation a clear tendency to generate multidecameric structures. The behavior of the native RtH1 and RtH2 during reassociation in the presence of 100mM calcium and magnesium chloride corresponds to the reported common oligomerization characteristics of KLH1/HtH1 and KLH2/HtH2, respectively. It is important to note that during the reassociation of the RtH isoforms: (I) no smaller diameter tubular polymers (ca. 25-27nm) were formed from the subunits as well as from the decamers; (II) multidecamers with one or more 'nucleating' didecamers were detected in addition to the multidecamers, composed of didecamers with associated decamers at one or both ends.