Characterization of the multiple-chamber perifused fat cell system.

A multiple-chamber perifused fat cell system is described. Six chambers containing fat cells were perifused in parallel with buffer. Perifusate was collected for assay of glycerol as an index of lipolytic rates and cells in each chamber can be taken for analysis of biochemical intermediates. The system is so designed that drugs can be infused into the buffer and equally distributed in each chamber or can be individually infused into the buffer to one chamber, allowing for six different conditions to be tested in the same population of fat cells. The time and distribution characteristics of infused material are described. Time relationships are described for isoproterenol and glycerol release and for cyclic AMP levels in the fat cells, and the dose-response relationship between isoproterenol and glycerol release is shown.     

Carbohydrate—Fat Interactions and Obesity Examined by a Two‐Compartment Computer Model

Objective: A systems dynamics computer model was developed to examine how the interactions between carbohydrate and fat metabolism influence body weight regulation. It reflects the operation of a two reservoir‐system: one representing the body's limited glycogen, and the other, its large fat reserves. The outflows from the reservoirs correspond to the oxidation of glucose and fat, whose relative contributions are affected by the size of the prevailing glycogen and fat reserves. Together, they meet the body's energy expenditure. Replenishments occur three times per day, in portions restoring total glycogen content to specific levels. A parameter mimicking the action of insulin is necessary to create realistic responses. Research Methods and Procedures: The model was run for 125‐day periods to establish the degree of adiposity for which rates of fat oxidation become commensurate with fat intake and the influence thereon of various dietary, environmental, lifestyle, and inherited variables. Results: Equivalent degrees of adiposity can be sustained under a variety of conditions. For instance, the impact on steady‐state body fat contents of a 10% increase or decrease in the energy provided by dietary fat is offset by a 26‐gram decrease or increase in mean glycogen levels. Discussion: Environmental factors such as food diversity, palatability, and availability can be expected to raise the range within which glycogen levels are habitually maintained. This restrains fat oxidation, until expansion of the fat mass is sufficient to promote fat oxidation to a rate commensurate with dietary fat intake. This metabolic leverage can explain why increased food offerings tend to raise the prevalence of obesity.     

Epicardial fat: from the biomolecular aspects to the clinical practice

Epicardial fat is the visceral fat depot of heart. It is a metabolically active organ with anatomical and functional contiguity to the myocardium. A dichotomous role has been attributed to the epicardial fat. Under physiological conditions, epicardial fat displays biochemical and thermogenic cardio-protective properties. Under pathological circumstances epicardial fat can locally affect the heart and coronary arteries through vasocrine or paracrine secretion of pro-inflammatory cytokines. Epicardial fat can be measured with imaging techniques. Epicardial fat thickness reflects intra-abdominal and myocardial fat and correlates with metabolic syndrome and coronary artery disease. Epicardial fat measurement may play a role in the stratification of the cardio-metabolic risk and serve as therapeutic target. Weight loss and anti-inflammatory drugs targeting the fat may modulate epicardial fat. Because epicardial and myocardial tissues share the same coronary arterial supply it is reasonable to hypothesize that improved local vascularisation may resume epicardial fat to its physiological role.     

Specific versus non-specific effects of dietary fat on carcinogenesis

It will be apparent from this review that dietary fat can exert both specific and non-specific effects on carcinogenesis, at least in experimental animals. The non-specific effects appear to be related primarily to effects of dietary fat on energy balance. Although a positive energy balance can be achieved on a high-carbohydrate low-fat diet, it is much more likely to occur on a high-fat diet because of the high energy density of fat [101] and the fact that dietary fat is less capable of imparting a sense of satiety [102]. A continuing state of positive energy balance leads to obesity which has been associated with increased risk of cancer at a number of sites, including endometrium [103-106], postmenopausal breast cancer [107-113], renal cancer [114,115] and possibly cancers of the colorectum [116-122], pancreas [103,123] and prostate [124]. Whereas the non-specific effects of dietary fat appear to be deleterious for cancer, the specific effects in some cases can be beneficial. Examples are long-chain n-3 polyunsaturated fatty acids. CLA and tocotrienols. It is still too early to predict whether these may be of value in the prevention and/or treatment of human cancer but they seem worthy of further investigation. Knowledge of their mechanism of action may suggest novel approaches to the cancer problem and, as in the case of vitamins A and D, it may be possible to find analogues with more potent anti-cancer activity.     

A noninvasive method to determine fat content in small fish based on swim bladder size estimation

The presence of fat stores in fish is widely used as a correlate of fish health and fitness. Techniques to measure fat content with some accuracy are available for medium-sized and large fish, but apart from morphometric indices, a noninvasive method to determine fat content in small fish has hitherto been lacking. In this study, we introduce a novel method to measure the fat content in live fish that can be applied also to small fish of less than 0.5?g of body mass. This approach relies on a precise measurement of the swim bladder volume, from which fat content can subsequently be deduced. As fat is positively buoyant, fish with larger fat stores require a smaller swim bladder to attain neutral buoyancy. To determine swim bladder volume, we developed a measuring device, which makes use of the differential compressibility of air and water. A fish is placed in a pressure-tight chamber to which a standardized amount of water is added. The resulting change in pressure Δp is inversely proportional to the volume of the swim bladder. Using juveniles and adults of Simochromis pleurospilus (Nelissen, '78; Pisces: Tropheini) a small cichlid fish, we show that Δp is tightly related to structural size, mass, and body condition. Most importantly, this approach allows to predict the visceral fat content of small fish more precisely than the six most commonly used morphometric body indices.     

Computerized suction lipectomy aspirator monitor for improved results in suction lipectomy

A new computerized suction aspirator monitor is described. This device offers the benefits of instantaneous and concurrent scientifically accurate readout of aspirate contents in five separate bodily areas. Thus knowledge of amounts of blood versus fat can be immediately known without resorting to guess, estimate, or cumbersome lipocrit determination by centrifuging. Advantages of such a device include better accuracy in determination of fat removal from each area, with improvement of symmetrical fat removal. More exact determination of blood loss with improved hemodynamic replacement is also more easily and safely accomplished. In an area of mystique, experience, artistry, and aesthetic appreciation which has cloaked the initial enthusiasm for suction lipectomy, a new generation of scientific accuracy is now possible. Thus accurate determination of aspirate content vis-a-vis fat and blood can now transform this procedure into a more sophisticated and scientifically accurate operation which traditionally is desired by most practitioners of suction lipectomy.     

lncRNA在动物脂肪沉积中的研究进展*

长链非编码RNA(long non-coding RNA,lncRNA),是一种长度大于200个核苷酸的调控性非编码RNA,能在转录水平、转录后水平及表观遗传水平等多个层面影响基因的表达。脂肪生成是一个复杂而有序的过程。大量研究表明,lncRNA在脂肪生成过程中扮演着重要角色,它可以影响脂质代谢及成脂分化等多种生物过程,从而间接影响肉品质。这对于提高畜禽肉品质、避免养殖业饲料过多转化成脂肪所导致的浪费以及对预防和治疗与脂肪代谢相关的疾病都具有重要意义。对lncRNA的基本特征、在动物脂肪沉积中的作用进展进行了综述,以期为培育优质畜禽,预防和治疗与脂肪代谢相关的疾病提供理论依据。     

Abnormalities of Fuel Utilization as Predisposing to the Development of Obesity in Humans

A number of recent investigations in man have demonstrated that a low ratio of fat to carbohydrate oxidation (i.e., a high respiratory quotient or RQ) was associated with actual and/or subsequent body weight gain in obese non-diabetic Pima Indians, in American men of various ages and in post-obese European women investigated shortly after the cessation of a hypocaloric diet. It is well known that numerous exogenous and endogenous factors influence the RQ at rest such as: the level of feeding (positive vs. negative energy balance), the composition of food eaten (high vs. low carbohydrate), the size of the glycogen stores, the amount of adipose tissue as well as genetic factors. It should be stressed that some nutritional situations can coexist during which a low ratio of fat to carbohydrate is observed (i.e., a high RQ) despite weight loss. Furthermore, in most studies mentioned above, the low fat to carbohydrate oxidation ratio explains less then 10% of the variance in weight gain, suggesting that numerous additional factors also play a substantial role in the onset of weight gain. It is concluded that: 1) A low fat to carbohydrate oxidation ratio or an abnormal fat oxidation is difficult to define quantitatively since it is largely influenced by the energy level and the composition of the diet. 2) Following a dynamic adaptation phase to positive energy balance, a low fat oxidation is progressively compensated: increased body fat is the price to pay for normalizing fat oxidation since, at least in resting conditions, there is an increase in fat oxidation of approximately 20 g/day for each 10 kg additional fat gain. The subject with a low fat to carbohydrate oxidation ratio will equilibrate at a body fat level allowing to reach a new fat balance.     

Transconjunctival orbital fat repositioning: transposition of orbital fat pedicles into a subperiosteal pocket

Rejuvenation of the lower eyelid complex is based on the principle that the contour changes characterizing aging involve not only prolapse of orbital fat but also descent of the cheek tissues, resulting in accentuation of the orbital rim and tear trough groove. When a deep groove is present along the orbital rim in the area of the tear trough deformity, it is advantageous, rather than removing orbital fat, to reposition the fat over the orbital rim through the opened arcus marginalis onto the superior face of the maxilla. Orbital fat repositioning can be accomplished through a transconjunctival approach. The arcus marginalis is exposed and incised, and a subperiosteal pocket is created over the superior face of the maxilla. The subperiosteal pocket shape and location are customized based on the desired location of the orbital fat pedicle; often the origins of the levator superioris labialis and the levator alae nasi muscles are partially dissected. Medial and central fat pedicles are created and rotated over the orbital rim into the subperiosteal pocket. A 6-0 polypropylene externalized sutured is used to fixate the fat pedicle in position. The suture can be removed after 3 to 5 days. Twenty-four patients were followed clinically after orbital fat repositioning, with follow-up ranging from 6 to 30 months. Although the fat pedicle undergoes some variable resorption, the viability of the graft, the texture and contour of the repositioned fat after a healing period of 1 to 2 months, and the excellent patient acceptance are indicative of the viability of orbital fat repositioning.     

Proximate composition,lipid utilization and validation of a non‐lethal method to determine lipid content in migrating American shad Alosa sapidissima

Lipid content forms the most important energy reserve in anadromous fish and can limit survival, migration and reproductive success. A fat meter was evaluated and compared with a traditional extractive method of measuring available lipid for migrating American shad Alosa sapidissima in the Connecticut River, U.S.A. The fat meter gives rapid (<10 s) and non‐lethal lipid measurements, whereas traditional methods require lethal sampling that is both time consuming and expensive. The fat‐meter readings had a strong relationship to traditional lipid extractions for 60 fish, 30 whole body (R² = 0·72) and 30 fillet only (R² = 0·81). Additional validation showed that fat‐meter readings captured the gradual decrease of lipid in individual fish over time, were not affected by removal of gonads or scales and were stable for fish exposed to water or air for 24 h after death. These experiments indicate that the fat meter can be used as a reliable tool for future A. sapidissima energetic studies, allowing for larger sample sizes and non‐lethal sampling.     

Lipid Programmes and Life Strategies in Hibernators

Several mammalian hibernators have annual cycles of fat depositionand usage. However, at any time a particular level of fat isdefended. The cycles can therefore be described as ones of set-pointsfor body fat. A programmed change in set-points accounts forprehibernation fattening not proceeding at maximal possiblerates. During the winter phase there is anorexia even when foodis available; reasons are proposed why there must be a loweringof set-points if there is to be prolonged hibernation. Controlmechanisms underlying some instances of weight loss and gainin birds are analysed in similar terms. In hibernators cyclicprogrammes are such that the animals do not usually operateclose to physiological limits. In a quasi-predictable environmentthey derive advantages from a combined use of both homeostaticand rhythmic control of their fat levels.     

External ultrasonic lipoplasty: an effective method of fat removal and skin shrinkage

External ultrasonic lipoplasty is an effective method for the removal of localized fat and the fat due to moderate obesity. The ultrasound is externally applied and transmitted through the skin surface. The acoustic waves are selectively absorbed by previously injected tumescent fluid and fat. It is the combination of this acoustic wave and ultrasound-induced fluid streaming that facilitates fat removal. Multiple, 2.5- to 3.7-mm incisions are made, through which standard thin (2.3 to 3.5 mm) suction lipectomy cannulae are used to aspirate the emulsified fat and oil. A major advantage of this procedure is that superficial subdermal liposuction can be used safely, which enhances the thoroughness of fat removal and the contraction of the overlying skin. A total of 160 consecutive patients successfully underwent this procedure. Recovery was rapid, and patients returned to full activities within 24 to 48 hours. The skin remained soft, with minimal to no bruising throughout the entire postoperative period. The problems seen with internal ultrasonic liposuction, such as end hits and skin burns, were avoided. The large incisions required for internal ultrasound liposuction were not necessary. Previous models of externally applied ultrasound support current observations of the safety of external ultrasound lipoplasty. Only one small seroma was seen. External ultrasound lipoplasty is a safe, effective, and low-cost method of ultrasound-assisted removal of localized fat and the fat due to moderate obesity. Physician and patient satisfaction is high.     

Variation in carotenoid pigmentation of Simocephalus vetulus(Crustacea: Cladocera)

Simocephalus vetulus (O. F. Müller) is coloured by carotenoids, which may befree in globules in the gut wall and fat body, or associated with proteins in the cytoplasm of the fat cells, carapace epidermis, ovary and eggs. A green carotenoprotein is foundin the blood. The transfer of carotenoids from one tissue to another is described; these pigments can be excreted via the gut in fully developed embryos. An intermoult cycle, related to egg laying is shown to cause variation in the pigmentation of the fat cells, carapace and blood.     

Recruitment of brown fat and conversion of white into brown adipocytes: Strategies to fight the metabolic complications of obesity?

The role of white and brown adipose tissues in energy metabolism is well established. However, the existence of brown fat in adult humans was until very recently a matter of debate, and the molecular mechanisms underlying brown adipocyte development remained largely unknown. In 2009, several studies brought direct evidence for functional brown adipose tissue in adults. New factors involved in brown fat cell differentiation have been identified. Moreover, work on the origin of fat cells took an unexpected path with the recognition of different populations of brown fat cell precursors according to the anatomical location of the fat depots: a precursor common to skeletal muscle cells and brown adipocytes from brown fat depots, and a progenitor cell common to white adipocytes and brown adipocytes that appear in certain conditions in white fat depots. There is also mounting evidence that mature white adipocytes, including human fat cells, can be converted into brown fat-like adipocytes, and that the typical fatty acid storage phenotype of white adipocyte can be altered towards a fat utilization phenotype. These data open up new opportunities for the development of drugs for obesity and its metabolic and cardiovascular complications.     

Assessment of body condition in live birds; measurements of protein and fat reserves in the mute swan, Cygnus olor

Condition in animals is often measured in relation to various demands, such as reproduction, migration and cold weather. Usually, indices of protein and fat reserves have to be measured on dead animals. Measurements on live animals enable variations in the condition of individuals to be monitored over time, and can be related to their life histories.
In birds, the size of the breast muscle is the most commonly used measure of protein reserves. A technique for measuring breast muscle thickness was developed, using ultrasound, and was tested on mute swans. The measurements were accurate and highly repeatable. Breast muscle thickness was positively related to the lean dry weight of the breast muscle, and is likely to be a good indicator of total protein reserves.
A system of fat scoring by colour was developed to assess the size of the subcutaneous fat layer. Although the method relies on subjective judgements, the results were highly correlated with the percentage of fat in the subcutaneous layer, and with other measures of fat reserves.
Measurements were made on live, non-breeding swans to monitor seasonal variations in reserves. The seasonal pattern of fat reserves was similar to the normal cycle of weight changes; high in winter and low in summer. There was no change in relation to the moult. No distinct seasonal variation in muscle thickness was found.
There is an unusual pattern of change in the relative size of reserves during emaciation in swans. Muscle reserves appear to be depleted to a greater extent than fat reserves. This is possibly due to the effects of lead poisoning, causing protein necrosis and preventing muscle regeneration.     

Metabolism of substrates: energy substrate metabolism during exercise and as modified by training

The question of what is the source of fuel for oxidation by muscle during exercise has been addressed. A review of experiments spanning more than 60 years supports the concept that the major energy source for the metabolism of exercise is the oxidation of fats and carbohydrates. The relative contribution of these major substrates to the total body metabolism depends on factors such as the intensity and duration of the exercise, the diet consumed on the days before the exercise, and the state of physical training. With light prolonged exercise there is a progressively greater use of fat until it can contribute up to 80% of the total caloric expenditure. However, the relative contribution of fat to the metabolism is less and that of carbohydrate greater as exercise intensity increases. Consumption of a diet rich in fat and protein produces a shift toward a greater use of fat with a concomitant reduction of both the intensity and duration of effort that can be sustained. Conversely, ingestion of a carbohydrate-rich diet increases the percentage of carbohydrate used and increases endurance. The concentration of glycogen in muscle is reduced by fat-protein diets and elevated by carbohydrate-rich diets. Endurance training results in a shift of the metabolism toward a greater use of fat during the same absolute and relative exercise loads. This produces a glycogen sparing that is associated with improving endurance capacity.     

BODY FAT, PUBERTY AND FERTILITY

1. The high percentage of fat, about 26–28% in the mature human female, may influence reproductive ability directly through two mechanisms: ( a ) fat converts androgens to oestrogens; ( b ) relative fatness influences the direction of metabolism of oestrogen to the most potent or least potent forms. The relative degree of fatness thus is directly related to both the quantity of circulating oestrogen and the biological effectiveness of the oestrogen. This is a neat mechanism for relating rates of growth, nutrition and energy outputs to the energy requirements for reproduction. Fat is the most labile body tissue; it therefore reflects environmental changes more rapidly than other tissues of the body.
2. The slow maturation of the hypothalamus and pituitary up to menarche, or first oestrus, is accompanied by a slow maturation of the body, which changes not only in size but in the relative proportion of bone, muscle, and fat. Evidence is presented that a particular threshold ratio of fat to lean mass is normally necessary for puberty and the maintenance of female reproductive ability in the human and in the rat. The synchronizing mechanisms may be metabolic, relating food intake to core temperature and/or fat storage.
3. Undernutrition and weight loss in the range of 10–15 % of normal weight for height delays menarche and causes amenorrhoea. Ballet dancers and athletes also have delayed menarche and amenorrhoea. The cessation of reproduction in both groups can be considered adaptive. Refeeding and/or cessation of intense activity results in the initiation or resumption of menstrual cycles after varying periods of time. A necessary threshold weight for height can be predicted from a fatness index.
4. Differences in the natural fertility of historical and contemporary populations may be explained by a direct effect of food intake and energy outputs on fecundity.
5. The late maturing fat - 'sex fat' - may have a special role in reproduction.     

Preference for dietary fat: From detection to disease

Recent advances in the field of taste physiology have clarified the role of different basic taste modalities and their implications in health and disease and proposed emphatically that there might be a distinct cue for oro-sensory detection of dietary long-chain fatty acids (LCFAs). Hence, fat taste can be categorized as a taste modality. During mastication, LCFAs activate tongue lipid sensors like CD36 and GPR120 triggering identical signaling pathways as the basic taste qualities do; however, the physico-chemical perception of fat is not as distinct as sweet or bitter or other taste sensations. The question arises whether “fat taste” is a basic or “alimentary” taste. There is compelling evidence that fat-rich dietary intervention modulates fat taste perception where an increase or a decrease in lipid contents in the diet results, respectively, in downregulation or upregulation of fat taste sensitivity. Evidently, a decrease in oro-sensory detection of LCFAs leads to high fat intake and, consequently, to obesity. In this article, we discuss recent relevant advances made in the field of fat taste physiology with regard to dietary fat preference and lipid sensors that can be the target of anti-obesity strategies.     

Interaction of bodymass,fat, foraging and stopover period in trans-Sahara migrating passerine birds

Summary The effect of body mass and fat reserves on the choice of the stopover place and on the stopover period was investigated in 3 species of passerine birds migrating through the Sahara in Egypt. Birds grounded in an oasis with food and water were more than 10% lighter than those from a desert stopover place which offered shade only. Stopover period was in general one day except for the light portion of oasis birds which stopped for up to three weeks during which they regained fat. A calculation of the maximum range which can be covered with the available fat depots revealed that nearly all birds from the desert stopover place should be able to cross the desert whereas about 60% of the oasis birds should not. An intermittant migratory strategy for the desert crossing is proposed with flight during the night and stopover during the day, even without drinking and feeding.