Characterization of gene expression in naturally occurring feline degenerative joint disease-associated pain

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Nervous system tissue from cats with painful degenerative joint disease (DJD) was analyzed.

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Gene expression was determined to investigate the neurobiological signature of DJD pain.

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There was decreased NGF and increased CX3CL1 expression in the spinal cord in DJD-affected cats compared to healthy controls.

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There was increased expression of ATF3 and CX3CL1 in dorsal root ganglia, in DJD-affected cats compared to healthy controls.

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Such studies have the potential to inform about relevant targets for the control of chronic feline pain.

Degenerative joint disease (DJD) associated-pain is a clinically relevant and common condition affecting domesticated cats and other species including humans. Identification of the neurobiological signature of pain is well developed in rodent pain models, however such information is lacking from animals or humans with naturally occurring painful conditions. In this study, identification of housekeeping genes (HKG) for neuronal tissue and expression levels of genes considered associated with chronic pain in rodent models were explored in cats with naturally occurring osteoarthritic pain. Fourteen adult cats were evaluated — seven without clinical signs of osteoarthritic pain, and seven with hind limb radiographic DJD and pain. Expression of an investigator-selected set of pain signaling genes (including ASIC3, ATF3, COX2, CX3CL1, NAV1.7, NAV1.8, NAV1.9, NGF, NK1R, TNFα, TRKA) in lumbar spinal cord dorsal horn and lumbar dorsal root ganglia tissues from clinically healthy cats and cats with DJD were studied using quantitative RT-PCR (qPCR).

HKG identified as the most stable across all tissue samples were many of the ribosomal protein genes, such as RPL30 and RPS19. qPCR results showed ATF3 and CX3CL1 up-regulated in DJD-affected dorsal root ganglia compared to clinically healthy controls. In spinal cord, CX3CL1 was up-regulated and NGF was down-regulated when DJD-affected samples were compared to healthy samples. Further work is needed to understand the neurobiology of pain in naturally occurring disease and what rodent models are predictive of these changes in more heterogeneous populations such as domestic cats.

Early postnatal kinetics of colostral immunoglobulin G absorption in fed and fasted piglets and developmental expression of the intestinal immunoglobulin G receptor

The transport of IgG across the epithelial barrier and into the circulation is achieved in part by the neonatal Fc receptor (FcRn), and this provides passive immunity to the neonate. The objective of this study was to determine the effect of time and feeding state on IgG absorption, intestinal morphology, and expression of IgG receptors in the first 24 h postbirth. Twenty newborn pigs were obtained immediately after birth and fitted with umbilical arterial catheters. Colostrum was manually collected from 12 lactating sows and centrifuged to produce defatted colostrum. Piglets were orally gavaged with 32 mL defatted colostrum per kilogram of BW (given in 2 doses 1 h apart) either at birth (0 h) or at 12 h postbirth under either fed (milk replacer) or fasted (saline solution) condition (n=5 per treatment). A fifth reference group (n=5) was euthanized at birth. Blood was collected every hour for the first 2 h immediately after the catheter was inserted and then every 4 h until 12 h (i.e., 0, 1, 2, 4, 8, and 12 h) for the treatment in which the defatted colostrum was given right after birth. For the treatment gavaged at 12 h postbirth, the sampling schedule was at 12, 13, 14, 16, 20, and 24 h. At 12 h postgavage, pigs were euthanized and jejunum tissues were collected for measurement of villi height, width, crypt depth, and gene expression of FcRn and β2-microglobulin (β2M) via reverse transcription PCR. Pig serum IgG concentration was determined by radial immunodiffusion. Data were analyzed according to a 2×2 factorial arrangement of treatments (0 h-fed, 0 h-fasted, 12 h-fed, and 12 h-fasted). There was no interaction between the time (age) of offering defatted colostrum (0 vs. 12 h) and nutritional state (fed vs. fasted) for any of the measurements, and there were no differences between fed and fasted pigs. Serum IgG concentrations increased progressively with time. Piglets offered defatted colostrum at 0 h had greater (P<0.05) overall IgG absorption and greater (P<0.05) villi height than those offered defatted colostrum at 12 h postbirth. Abundance of mRNA of FcRn and β2M were normalized to glyceraldehyde-3-phosphate dehydrogenase. Abundance of FcRn transcript was lower (P=0.006) in pigs euthanized at birth compared with those euthanized at 12 h of age. In conclusion, the effects of delayed offering of defatted colostrum and age-dependent changes in IgG receptor were modest over the first 24 h of life.

A preliminary study of the effect of norfenfluramine on lipogenesis by human adipose tissue in vitro

1 Norfenfluramine is thought to be the major active metabolite of fenfluramine in man. Therefore its in vitro effect on lipogenesis in human adipose tissue from twelve patients was investigated. 2 Although inhibition of lipogenesis was demonstrated, the concentrations of norfenfluramine necessary (>1 mM) were much higher than normal blood levels of the drug. 3 There was no correlation between the degree of inhibition by norfenfluramine in vitro and fat cell size, age or relative weight of the subject. Greater degrees of inhibition were however associated with samples of tissue from patients with higher blood glycerol concentrations and lower blood triglyceride concentrations.

Waist-to-height ratio is a better screening tool than waist circumference and BMI for adult cardiometabolic risk factors: systematic review and meta-analysis

Our aim was to differentiate the screening potential of waist-to-height ratio (WHtR) and waist circumference (WC) for adult cardiometabolic risk in people of different nationalities and to compare both with body mass index (BMI). We undertook a systematic review and meta-analysis of studies that used receiver operating characteristics (ROC) curves for assessing the discriminatory power of anthropometric indices in distinguishing adults with hypertension, type-2 diabetes, dyslipidaemia, metabolic syndrome and general cardiovascular outcomes (CVD). Thirty one papers met the inclusion criteria. Using data on all outcomes, averaged within study group, WHtR had significantly greater discriminatory power compared with BMI. Compared with BMI, WC improved discrimination of adverse outcomes by 3% (P < 0.05) and WHtR improved discrimination by 4-5% over BMI (P < 0.01). Most importantly, statistical analysis of the within-study difference in AUC showed WHtR to be significantly better than WC for diabetes, hypertension, CVD and all outcomes (P < 0.005) in men and women. For the first time, robust statistical evidence from studies involving more than 300 000 adults in several ethnic groups, shows the superiority of WHtR over WC and BMI for detecting cardiometabolic risk factors in both sexes. Waist-to-height ratio should therefore be considered as a screening tool.

Proceedings of the Rank Forum on Vitamin D

The Rank Forum on Vitamin D was held on 2nd and 3rd July 2009 at the University of Surrey, Guildford, UK. The workshop consisted of a series of scene-setting presentations to address the current issues and challenges concerning vitamin D and health, and included an open discussion focusing on the identification of the concentrations of serum 25-hydroxyvitamin D (25(OH)D) (a marker of vitamin D status) that may be regarded as optimal, and the implications this process may have in the setting of future dietary reference values for vitamin D in the UK. The Forum was in agreement with the fact that it is desirable for all of the population to have a serum 25(OH)D concentration above 25 nmol/l, but it discussed some uncertainty about the strength of evidence for the need to aim for substantially higher concentrations (25(OH)D concentrations>75 nmol/l). Any discussion of 'optimal' concentration of serum 25(OH)D needs to define 'optimal' with care since it is important to consider the normal distribution of requirements and the vitamin D needs for a wide range of outcomes. Current UK reference values concentrate on the requirements of particular subgroups of the population; this differs from the approaches used in other European countries where a wider range of age groups tend to be covered. With the re-emergence of rickets and the public health burden of low vitamin D status being already apparent, there is a need for urgent action from policy makers and risk managers. The Forum highlighted concerns regarding the failure of implementation of existing strategies in the UK for achieving current vitamin D recommendations.

Measurement of 25-hydroxyvitamin D in the clinical laboratory: current procedures, performance characteristics and limitations

In this review we describe procedures, performance characteristics and limitations of methods available for the measurement of 25-hydroxyvitamin (25OHD) since the year 2000. The two main types of methods are competitive immunoassay and those based on chromatographic separation followed by non-immunological direct detection (HPLC, LC-MS/MS). Lack of a reference standard for 25OHD has, until recently, been a major issue resulting in poor between-method comparability. Fortunately this should soon improve due to the recent introduction of a standard reference material in human serum (SRM 972) from the National Institute of Standards and Technology (NIST). For immunoassay, specificity can be an issue especially in relation to the proportion of 25OHD2 that is quantified whereas HPLC and LC-MS/MS methods are able to measure the two major vitamin D metabolites 25OHD2 and 25OHD3 independently. HPLC and LC-MS/MS require more expensive equipment and expert staff but this can be offset against lower reagent costs. Increasingly procedures are being developed to semi-automate or automate HPLC and LC-MS/MS but run times remain considerably longer than for immunoassays especially if performed on automated platforms. For most HPLC and LC-MS/MS methods extraction and procedural losses are corrected for by the inclusion of an internal standard which, in part, may account for higher results compared to immunoassay. In general precision of immunoassay, HPLC and LC-MS/MS are comparable and all have the required sensitivity to identify severe vitamin D deficiency. Looking to the future it is hoped that the imminent introduction of a standard reference method (or methods) for 25OHD will further accelerate improvements in between method comparability.

A study of central fatness using waist-to-height ratios in UK children and adolescents over two decades supports the simple message--'keep your waist circumference to less than half your height'

OBJECTIVE

To examine the influence of age and gender on the waist:height ratio (WHTR) in children and to compare changes over time in WHTR, a measure of central fatness in British children.

DESIGN

Representative cross-sectional surveys in 1977, 1987 and 1997.

SETTING

Great Britain and Northern Ireland.

PARTICIPANTS

Survey 1: children aged 5-16 years measured in 1977 (boys) and 1987 (girls) (BSI, n=8135) and Survey 2: children aged 11-16 measured in 1997 (NDNS, n=773).

OUTCOME MEASURES

From Survey 1, waist: height ratio related to age and sex and the proportion of children with a WHTR greater than 0.500 (a boundary value suggested for adults). From Survey 2, comparison of WHTR in children with that from Survey 1 and the actual proportion of children with a WHTR greater than 0.500 compared with the expected proportion using the survey 1 as reference.

RESULTS

WHTR decreased with age (P<0.01 for trend), with the mean WHTR being significantly lower in girls (P<0.01). WHTR was significantly greater in children in Survey 2 compared with those measured 10 and 20 years earlier in Survey 1 (P<0.0001). The proportion of children where WHTR exceeded the 0.500 boundary value in Survey 2 was 17% of boys and 11.7% of girls (against 5.0 and 1.5%, respectively, in Survey 1, P<0.0001). The increase in WHTR in boys exceeded that in girls.

CONCLUSIONS

Values of WHTR during the past 10-20 years have increased greatly showing that central fatness in children has risen dramatically. WHTR is more closely linked to childhood morbidity than body mass index (BMI) and we suggest it should be used as an additional or alternative measure to BMI in children as well as adults. A simple public health message that is the same for adults and children of both sexes and all ages could be stated as 'keep your waist circumference to less than half your height'.

Association of anthropometric indices with elevated blood pressure in British adults

OBJECTIVE

To investigate which of six anthropometric indices was most strongly associated with elevated blood pressure and frank hypertension in a representative population sample of young and middle-aged British adults.

SUBJECTS

A representative random sample of British adults (2712 men and 3279 women) aged between 18 and 64y, who were resident in England, Scotland and Wales, were studied in the 1984-85 Health and Lifestyle Survey.

MEASUREMENTS

Following an interview where demographic, health and lifestyle details were recorded, measurements of height, weight and waist and hip circumference were made by a nurse at a home visit, where blood pressure and medication to control blood pressure were also recorded. BMI and the ratios of waist circumference to height (WHTR) and waist circumference to hip (WHR) were calculated. Respondents with a blood pressure above 140 mm Hg (systolic) and/or 90 mm Hg (diastolic) or who were being treated for hypertension were classified as having elevated blood pressure.

RESULTS

For men and women aged 18-39 and 40-64 y the prevalence of elevated blood pressure increased across the quintiles of BMI, weight, waist, WHTR and WHR was P < 0.001 for each, with waist and WHTR having the highest odds ratios. Waist and height adjusted for each other were independently related to the prevalence of elevated blood pressure in 40-64 y old men and women. Height, on its own, was inversely related (P < 0.05) only in the 40-64 y old men. The age adjusted partial correlations between systolic and diastolic blood pressure measurements and the measurements of BMI, weight, waist, WHTR and WHR were close and significant, P < 0.001 for each. The ranking and significance of the correlations were hardly affected by excluding the treated hypertensives.

CONCLUSIONS

The prevalence of elevated blood pressure was associated with quintiles of BMI, waist, WHTR, WHR and weight, with WHTR and WHR having the highest odds ratios. Waist and height were independently related to the prevalence of elevated blood pressure.

Obesity in men and women

The prevalence of obesity in the UK, defined as a Body Mass Index (BMI) exceeding 30, is increasing. Obese people with BMI greater than 30 have a much greater risk of dying earlier than people with desirable levels of fatness (as do extremely lean people with BMI less than 20). The relationship between obesity and the likelihood of suffering certain metabolic diseases such as coronary heart disease, stroke and diabetes is now thought to be associated as much with the distribution of the excess fat as with the amount of excess fat. Fat distribution is usually measured in the population by the waist to hip circumference ratio (WHR). A high WHR seems to be a proxy measurement for an excess of intra-abdominal fat. Subcutaneous fat mass can be estimated using skinfold measurements. Exact determinations can only be performed directly using expensive equipment, such as computed tomography (CT). People with high WHR measurements can be said to have a 'central' fat distribution: people with low WHR measurements can be said to have a 'peripheral' fat distribution. 'Central' fat distribution carries most metabolic risks and is associated with a predisposition towards coronary heart disease, stroke, diabetes, breast cancer and gallstones. In some cases, the distribution of fat is a stronger risk factor than total obesity. 'Peripheral' fat distribution carries least metabolic risk. However, risks related to the mechanical problems of carrying excess fat, such as varicose veins, are increased. The risks of obesity therefore depend on the distribution of fat as well as total fatness.(ABSTRACT TRUNCATED AT 250 WORDS)

beta-deuterium kinetic isotope effects in the purine nucleoside phosphorylase reaction

1. [2'-2H]Inosine was made from inosine by tetraisopropyldisiloxanyl protection of the 3'- and 5'-positions, oxidation with dimethyl sulphoxide and acetic anhydride, immediate NaB2H4 reduction of the oxo sugar product and inversion at C-2' of the resultant protected [2'-2H]arabino-inosine by trifluoromethanesulphonylation and reaction with caesium propionate, followed by deprotection. 2. The equilibrium-perturbation technique was used to measure beta 2H(V/K) for phosphorolysis of this compound by the purine nucleoside phosphorylase of Escherichia coli as a function of pH. 3. The pH variation indicates an intrinsic effect of 1.068 masked by isotopically silent steps near the pH optimum. 4. The similar pH variation of these beta-deuterium effects and the alpha-deuterium effects measured previously [Stein & Cordes (1981) J. Biol. Chem. 256, 767-772; Lehikoinen, Sinnott & Krenitsky (1989) Biochem. J. 257, 355-359] for this reaction provides the first experimental reassurance for the common assumption that pH changes merely mask and unmask the chemical steps in an enzyme-catalysed reaction, and do not detectably alter transition-state structure. 5. The dihedral angle between the C-H-2' bond and the electron-deficient p-orbital at the transition state is in the range 32-48 degrees, in accord with an essentially planar furanose ring.

The synthesis of some branched-chain-sugar nucleoside analogues

1-(2,3-Epoxy-5-O-trityl-beta-D-lyxofuranosyl)uracil was treated with a number of carbon nucleophiles. Ethynyl lithium gave 3'-deoxy-3'-ethynyl-5'-O-trityl-ara-uridine, which was reduced to the corresponding 3'-ethenyl compound. Sodium cyanide gave 3'-cyano-3'-deoxy-5'-O-trityl-ara-uridine which upon alkaline hydrolysis gave the corresponding 3'-carboxamido compound. 1,3-Dithian-2-yl lithium gave 3'-deoxy-3'-(1,3-dithian-2-yl)-5'-O-trityl-ara-uridine. The trityl group was removed from each of these compounds by mild acidic hydrolysis. Treatment of 2 with 0.1M H2sO4 and mercury (II) acetate afforded 3'-acetyl-3'-deoxy-ara-uridine which upon reduction with NaBH4 gave 3'-deoxy-3'-(1-hydroxyethan-1-yl)-ara-uridine. Acetylation of 6 yielded 5'-O-acetyl-3'-acetyl-2',3'-didehydro-2',3'-dideoxyuridine which upon reduction with NaBH4 produced a mixture of 5'-O-acetyl-2',3'-didehydro-2',3'-dideoxy-3'-(1-hydroxyethan -1-yl)uridine and 1-(R)[5-(S)-acetoxymethyl-4-(1-hydroxyethan-1-yl)-tetrahydrofuran- 2-yl]- uracil. Reduction of 14 with Raney nickel followed by removal of the trityl group gave 3'-deoxy-3'-methyl-ara-uridine.

Effect of warm or cold exposure on GDP binding and uncoupling protein in rat brown fat

The effects of acute and chronic exposure to different environmental temperatures on the total tissue cytochrome oxidase activity, level of mitochondrial GDP binding, and specific mitochondrial concentration of uncoupling protein have been investigated in rat brown adipose tissue, a radioimmunoassay being used to measure uncoupling protein. Acclimation at different temperatures for 3 wk produced parallel changes in GDP binding, the concentration of uncoupling protein, and the activity of cytochrome oxidase, each parameter rising with decreasing temperature between thermoneutrality (29 degrees C) and 4 degrees C. Acute exposure of warm-acclimated (29 degrees C) rats to the cold (4 degrees C) led to a rapid increase in GDP binding without any alteration in the amount of uncoupling protein. The increase in binding was accompanied by an increase in the rate of acetate-induced swelling of the mitochondria. The concentration of uncoupling protein in warm-acclimated rats was significantly raised only after 48 h exposure to cold. When cold-acclimated rats were exposed acutely to the warm, there was a rapid decrease in GDP binding without any alteration in the amount of uncoupling protein. It is concluded that after alterations in environmental temperature the concentration of uncoupling protein in brown adipose tissue mitochondria changes much more slowly than GDP binding and that binding can therefore be dissociated from the amount of the protein.

Decreased brown adipose tissue thermogenic activity following a reduction in brain serotonin by intraventricular p-chlorophenylalanine

The effects of reducing brain serotonin (5-HT) levels by means of intracerebral-ventricular injections of the tryptophan antagonist p-chlorophenylalanine (PCPA) were investigated in male rats. Six days after the operation, PCPA-treated rats, either fed ad libitum or pair-fed to the food intake of control rats, showed decreased thermogenic activity and capacity in their interscapular brown adipose tissue (BAT) and also increased fat storage in their white adipose tissue (WAT). These results indicate that serotonergic synapses might play a regulatory role in the sympathetic control of BAT thermogenesis and in the rate of WAT deposition (by an as yet unidentified mechanism), in addition to their well established role in controlling food intake.

Immunological, histological and biochemical assessment of brown adipose tissue activity in neonatal, control and beta-stimulant-treated adult dogs

Significant levels of mitochondrial uncoupling protein were demonstrated on neonatal dog mitochondria prepared from perirenal, bladder and subcutaneous adipose tissue sites. The protein was not detected in homogenates of adipose tissue samples from the same sites in adult, control dogs. However, chronic treatment of adult dogs with a beta-stimulant (LY 79730) led to the appearance of detectable amounts of uncoupling protein in perirenal and bladder but not subcutaneous adipose tissue depots. Decreases in mean cell diameter, increases in the frequency of multilocular cells and of cytochrome oxidase and creatine kinase were also associated with the effects of treatment on dog adipose tissue. The results demonstrate the age-related decline in dog brown adipose tissue and its reversal by chronic treatment with beta-stimulant.

Pre- and postnatal development of adipose tissue at four sites in the guinea pig: effect of maternal diet restriction during the second half of pregnancy

The effect of maternal diet restriction on the subsequent development of four adipose tissue depots has been studied in the guinea pig. Fetuses taken from, and pups born to, pregnant sows fed ad libitum (AL) displayed an increase in fat pad mass and in fat cell mass with increasing body mass at the four selected depots (interscapular (IS), retroperitoneal (RP), groin side subcutaneous (GS) and behind arm subcutaneous (BA)). The effect of maternal diet restriction (50% AL rations during the second half of pregnancy) was to significantly reduce the body masses at birth of the pups. The masses of the BA and GS fat pads and the mass of fat cells in the depots were reduced accordingly. However, the fat depot masses and fat cell masses of the IS and RP fat pads were larger than those of pups of comparable body mass born to AL fed sows. Diet restriction during the second half of pregnancy exerted preferential 'sparing' effects on the 'thermogenic' adipose tissue depots (IS and RP) suggesting the possibility that 'thermogenic' adipose tissue is more likely to be 'programmed' earlier in pregnancy than 'storage adipose tissue' (BA and GS).

Brown adipose tissue triacylglycerol fatty acids of obese and lean mice: in situ and in transplants

The triacylglycerols of white adipose tissue (WAT) from animals with high rates of lipogenesis, such as obese hyperglycemic mice or hypothalamically lesioned rats, contain high proportions of palmitoleic acid (16:1) and low proportions of linoleic acid (18:2). These differences appear to result from dilution of dietary 18:2 by synthesized fatty acids, particularly 16:1. To test this we have investigated the triacylglycerol fatty acid composition of brown and white adipose tissue of lean and obese mice, as brown adipose tissue (BAT) has a higher lipogenic rate than WAT and lipogenesis is faster in obese than in lean mice. Between three and eight weeks of age the proportions of fatty acids in the tissues changed, with a marked fall in milk-derived lauric and myristic acids. From 8 to 16 weeks they were more stable and the proportions of 16:1 and 18:2 in the different tissues were as expected, with the highest and lowest proportions, respectively, in BAT from obese mice. When BAT from obese mice was transplanted under the kidney capsule of lean mice, or vice versa, for one month, the fatty acid composition of the grafts changed toward that of the host BAT. The proportions of 18:2 and, to a lesser extent, 16:1 were slightly higher in the grafts than in the hosts but since this also occurred in lean-to-lean and obese-to-obese grafts it was probably a transplantation artifact. Overall, the results confirm that the physiological environment, rather than the source of the adipose tissue, is the major determinant of its fatty acid composition.

Brown adipose tissue: contributions of nature and nurture to the obesity of an obese mutant mouse (ob/ob)

The aim of this investigation was to compare the contributions of the genotype of the brown adipose tissue (BAT) and of its environment to the obesity of the mutant mouse C57 BL/6J ob/ob. Pieces of interscapular BAT from lean or obese mice were transplanted to a site underneath the kidney capsule of recipient lean or obese mice. The grafts were left in place for 6 to 12 weeks and then examined by histological methods by electron microscopy to examine the ultrastructure of the mitochondria and by fluorescence histochemistry to examine the catecholaminergic innervation of the grafts. When lean BAT was grafted into obese mice, or when obese BAT was grafted into lean mice, kept at ambient temperatures, the characteristics of the donor BAT (i.e. lipid droplet size, mitochondrial ultrastructure and catecholaminergic innervation) transformed partially, but not completely, towards those of BAT in the host mouse. However, if lean mice containing obese BAT grafts were cold-acclimated at 4 degrees C or obese mice containing lean BAT grafts were warm-acclimated at 33 degrees C, the characteristics of the donor BAT transformed completely towards those of the BAT in the host mouse. This complete transformation occurred even if the host mice were returned to 23 degrees C after the period of temperature acclimation. Fluorescent histochemical observations indicated that the sympathetic innervation of BAT grafts was only indistinguishable from that of the lean or obese host BAT when the mice received a period of temperature acclimation (cold for lean mice; warm for obese mice). We conclude that BAT grafts from lean mice can assume the typical characteristics of BAT in obese hosts and that BAT grafts from obese mice can assume the typical characteristics of BAT in lean hosts provided that both the sympathetic innervation and the vascularization of the grafts is the same as in the host. Intrinsic properties of BAT in genetically obese mice are therefore unlikely to be of paramount importance in determining the obesity of the ob/ob mouse. Our results support the conclusions of other workers in implicating the low activity of the sympathetic innervation of BAT as being crucially important in causing the reduction of thermogenic activity.

Fluorescent histochemical demonstration of catecholamines in brown adipose tissue from obese (ob/ob) and lean mice acclimated at different temperatures

Fluorescent histochemistry was used to visualize catecholamines in brown adipose tissue (BAT) of lean and genetically obese mice after they had been acclimated at different temperatures. At all temperatures, strong catecholamine-dependent fluorescence, attributable to the sympathetic innervation, was seen around the blood vessels of BAT from both lean and obese animals. Additionally, catecholamine-dependent fluorescent varicosities, in direct contact with the adipocytes were seen in abundance in lean mice acclimated at 23 degrees, 13 degrees or 4 degrees C and in obese mice acclimated at 13 degrees C. This latter compartment was greatly reduced in lean mice acclimated at 33 degrees C and in obese mice acclimated at 23 degrees and 33 degrees C. Three acute treatments (pretreatment with a monoamine oxidase inhibitor; 24 h food deprivation; and short-term cold exposure followed by short-term warm exposure) all increased the varicose fluorescence associated with adipocytes in obese mice housed at 23 degrees C, which suggests that the low resting level in these animals is attributable, at least in part, to subthreshold concentrations of catecholamines in existing varicosities rather than the absence of sympathetic varicosities per se. These results are in accordance with the results from noradrenaline turnover studies which suggest that the difference in sympathetic nervous system (SNS) activity in BAT from lean and obese (ob/ob) mice is best demonstrated at normal environmental temperatures. The reduced SNS activity in BAT of obese mice (which our studies show to be at the 'cellular' level) is likely to be a major factor in their reduced non-shivering thermogenesis and resultant high efficiency of energy storage as previously suggested by other workers.

Obesity: new insight into the anthropometric classification of fat distribution shown by computed tomography

Twenty eight women presenting for routine computed tomography had their waist, hip, and thigh circumferences measured. The ratio of the area of intra-abdominal fat to the area of subcutaneous fat shown in the computed tomogram taken at the umbilical level was calculated and found to correlate highly significantly with the ratio of waist to hip circumference. The correlation between these two ratios remained significant after allowing for the degree of obesity (weight (kg)/height (m)2) and age. In contrast, there was no significant correlation between the ratio of intra-abdominal to subcutaneous fat and degree of obesity. A high ratio of waist to hip circumference has been shown to be associated with a high proportion of intra-abdominal fat. Thus women with a centralised distribution of fat (high waist to hip ratio: "apples") tend to have a greater proportion of their fat in the intra-abdominal depot than do women with a peripheral fat distribution (low waist to hip ratio: "pears"). The metabolic complications of obesity, which are associated with a high ratio of waist to hip circumference, may therefore relate specifically to the amount of intra-abdominal fat.

Measurement by radioimmunoassay of the mitochondrial uncoupling protein from brown adipose tissue of obese (ob/ob) mice and Zucker (fa/fa) rats at different ages

The concentration of the 'uncoupling protein' in brown adipose tissue mitochondria has been measured in lean and obese (ob/ob) mice and Zucker (fa/fa) rats at different ages using a specific radioimmunoassay. During the suckling period the concentration of the protein was similar in normal and mutant animals of both types, despite the decrease in mitochondrial GDP binding observed in the obese. The concentration of uncoupling protein was, however, decreased in adult ob/ob mice and adult Zucker rats compared with their respective lean siblings, in parallel with the decrease in GDP binding. It is concluded that there is a 'masked', or inactive, form of uncoupling protein in young ob/ob mice and fa/fa rats.

The use of the adipose tissue transplantation technique to demonstrate that abnormalities in the adipose tissue metabolism of genetically obese mice are due to extrinsic rather than intrinsic factors

Adipose tissue transplantation between genetically obese mice and their lean counterparts using the kidney capsule as the transplantation site has shown that the abnormally large fat cells of obese mice normalize in size when they are placed into a 'lean' environment. Furthermore, the abnormal fatty acid composition of the white adipose tissue of obese mice (higher proportion of palmitoleic acid and lower proportion of linoleic acid compared with lean) normalizes on transplantation into a 'lean' environment. Such experiments lead us to conclude that the differences in the lipolytic and lipogenic enzymes in the adipose tissue of genetically obese mice must be due to extrinsic factors rather than factors intrinsic to the adipocyte.

Brown adipose tissue in the parametrial fat pad of the mouse

Cold acclimation has been shown to produce a substantial increase in the number of brown adipocytes in the parametrial fat pad of female BALB/c mice-a site normally thought to consist of typical white adipocytes. The brown adipocytes have been identified not only on the basis of their morphology using light and electron microscopy, but also on the basis of the content of the mitochondrial 'uncoupling protein' (Mr = 32000) which is characteristic of the proton conductance pathway of brown adipose tissue.

Adaptive changes in the concentration of the mitochondrial 'uncoupling' protein in brown adipose tissue of hamsters acclimated at different temperatures

The effect of acclimation at different temperatures on the activity of interscapular brown adipose tissue has been investigated in the hamster, a hibernator. Between 31 degrees and 4 degrees C the cytochrome oxidase activity of the tissue increased 4- to 5-fold, mitochondrial GDP binding per mg of mitochondrial protein doubled, and the amount of uncoupling protein rose from 1.7% to 5.4% of total mitochondrial protein. It is concluded that there are clear adaptive changes induced by temperature in brown adipose tissue of the hamster, but the changes are limited in comparison with those in the mouse.

Fatty acid composition of triglycerides from adipose tissue transplanted between obese and lean mice

The subcutaneous adipose tissue of genetically obese mice (ob/ob) differs from that of lean littermates not only by virtue of its larger cells but also in its fatty acid composition; it contains a higher proportion of palmitoleic acid and a lower proportion of linoleic acid. To determine whether these differences in fatty acid composition were inherent in fat cells, subcutaneous adipose tissue from obese and lean mice was transplanted under the kidney capsules of lean and obese host mice and the fatty acid composition of the neutral lipids of the graft and of the host perirenal and subcutaneous fat was determined 1 or 2 months later. The fatty acid composition of grafts from lean donors in obese mice resembled that of the perirenal adipose tissue of the obese hosts after 1 month, with a lower proportion of linoleic acid and a higher proportion of palmitoleic acid than in lean mice. Grafts from obese mice in lean mice had fatty acid compositions which were either unchanged, partially changed or which completely resembled that of the host. The use of grafts prelabeled by feeding the donor margaric acid indicated that total lack of fatty acid turnover, rather than selective metabolic processes, was responsible for the failure of some grafts from obese mice in lean mice to acquire the fatty acid composition of the perirenal adipose tissue of the host.

Effect of acclimation temperature on the concentration of the mitochondrial 'uncoupling' protein measured by radioimmunoassay in mouse brown adipose tissue

The effect of acclimation temperature on the concentration of the mitochondrial 'uncoupling' protein (Mr 32000) from brown adipose tissue of mice has been investigated. The uncoupling protein was measured by a specific radioimmunoassay. Between 33 degrees C (thermoneutrality) and -2 degrees C there was a progressive increase with decreasing environmental temperature in the amount of uncoupling protein. For mice at -2 degrees C the mitochondrial concentration of the protein was 9-times higher than at 33 degrees C, while the total amount of the protein in interscapular brown adipose tissue was estimated to be nearly 80-times greater at -2 degrees C compared to 33 degrees C.

Measurement of rat brown-adipose-tissue mitochondrial uncoupling protein by radioimmunoassay: increased concentration after cold acclimation

A specific antiserum has been raised against the 32 000-mol.wt. uncoupling protein from the mitochondria of rat brown adipose tissue and a sensitive radioimmunoassay for the protein has been developed. The uncoupling protein is present in large amounts in brown adipose tissue; its concentration is increased substantially by cold acclimation. The protein has not been detected in the liver, heart, or parametrial white adipose tissue of rats.